Food Colloids 2016 ______________________________________________________________________________________________ 1 Oral presentation abstracts Engineered Interfaces KEY-EI Engineering stability through interfacial rheology: where do we stand? Jan VERMANT Department of Materials, ETH Zürich, Switzerland Stability of thin films (as in foams and emulsions) can be engineered by the surface active components which accumulate in the interfacial region. There are different aspects which can be changed, which include the compressibility of the interface, the absolute value of surface tension, or imparting rheological properties at the interface, either in shear or dilation. Under some conditions, the different possible contributions can be separated. Special emphasis will be given to interfaces where the extra rheological stresses can be influenced by engineering the colloidal interactions at the interface.
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Experimental exploration of triglyceride ordering at surfactant-covered oil-water interfaces
Nicole L. GREEN1, Dérick ROUSSEAU1, Stephen R. EUSTON2 1 Department of Chemistry & Biology, Ryerson University, Toronto, Canada 2 School of life Sciences, Heriot-Watt University, Edinburgh, Scotland
Triglyceride crystallization behavior at an oil-water interface in the presence of emulsifier and fat has been
directly observed using a temperature-controlled tensiometer. Recent experimental observations by Ghosh
et al. [1] have suggested that the similar molecular structures of glycerol monooleate (GMO) and
hydrogenated canola oil (HCO) promoted the formation of interfacial crystals, leading to water-in-oil
emulsions simultaneously stabilized by Pickering and network-type crystals. [1] Without surfactant (HCO
only) or with surfactant lacking molecular complementarity (HCO + polyglycerol polyricinoleate (PGPR)),
interfacial crystallization was not promoted. We carry out experiments in similar systems, testing the
effects of surfactant-fat complementarity by using PGPR, GMO, and glycerol monostearate (GMS). We use
a tensiometer to create a water droplet within the oil medium, akin to a water-in-oil emulsion. We find
that, in the absence of surfactant, fat lacks the surface activity to preferentially crystallize at the interface
and will nucleate spontaneously in the bulk oil. Conversely, the addition of surfactant can yield full, partial,
or no crystallization interfacial crystallization depending on the chosen surfactant and surface coverage.
The results are compared to accompanying molecular dynamics simulations conducted by Euston in a
separate presentation.
[1] Ghosh, S. and Rousseau, D. Cryst. Growth Des. 2012, 12, 4944–4954
Miro KIRIMLIDOU1, Christos AMPATZIDIS2, Thodoris D. KARAPANTSIOS2, Vassileios KIOSSEOGLOU1,
Constantinos V. NIKIFORIDIS3 1 Food Chemistry and Technology, School of Chemistry, Aristotle University, Thessaloniki, Greece 2 Chemical Technology, School of Chemistry, Aristotle University, Thessaloniki, Greece 3 Biobased Chemistry and Technology, P.O. Box 17, 6700 AA Wageningen, the Netherlands
Microbubble engineering is one of the emerging scientific topics, due to the numerous potential
applications in medical science and foods.1 Most of the cases, complex materials have to be used as
stabilizers, therefore the formation of microbubble foams with natural ingredients is a challenging field.
Moreover, plant protein-stabilized foams have attracted considerable research interest due to their
sustainable production and potential technology applications.2
In this work, highly efficient, green fractionation practices have been developed for producing sesame seed
isolate, containing 96 wt% proteins. Physico-chemical characterization of the isolate showed that it is
mainly comprised of relatively low molecular weight hydrophobic proteins, soluble at alkaline pH values
and ionic strengths above 0.25 M.
The adsorption behaviour of sesame proteins at air-water interfaces was investigated by employing static
and dynamic surface tension measurement techniques. Sesame proteins exhibit an outstanding ability to
drastically decrease the surface tension, even at very low concentrations. Furthermore, their presence in
aqueous solutions at very low concentrations such as 0.06 wt% was enough to produce stable microbubble
foams, by ultrasonication. The foam stability was evaluated by monitoring the evolution of bubble size. The
results pointed to a remarkable stability of the sesame seed foams, which retained 25% of their initial
volume even 28h after their production.
Finally, all the above research has given insights in the mechanisms behind foam stabilization by sesame
seed proteins, such as interfacial asorption and lamella viscosifying, This work could have direct
impilications in the production of sophisticated, health promoting and stable aired products.
1. Swanson, E. J., Mohan, V., Kheir, J., & Borden, M. A. (2010). Phospholipid-Stabilized Microbubble Foam for
Microbubbles Stabilised by Mixtures of Hydrophobin + Casein : Experimental Results and
Theoretical Considerations
Rammile ETTELAIE1, Pappole VALADBAIGI1, Brent MURRAY1 1 Food Colloids Group, School of Food Science and Nutrition, University of Leeds, Leeds LS2 9JT, UK
Long term stabilisation of small bubbles of micron size dimensions remains a particularly challenging
problem in colloid science generally, and in food colloids more specifically. While in recent years the
Pickering stabilisation mechanism has been explored as one of the promising routes to overcoming this
problem, the lack of very fine edible nanoparticles, with appropriate surface chemistries, so far has limited
this approach in foods. The fungal protein hydrophobin, possessing a highly globular structure that does
not unfold upon adsorption at air-water interfaces, may provide one possible solution forward. The idea is
that the interfacial behaviour of hydrophobin is in many respects closer to that of a genuine nanoparticle
rather than a typical biomacromolecule. However, at present the price of hydrophobin is quite expensive.
Therefore it is of some practical importance that this protein is utilised in the most efficient way. To this
end, we report here on stabilisation of microbubbles achieved by a combination of hydrophobin + casein.
It is found that at an optimum mix ratio of the above two proteins, small microbubbles with excellent long
term stability can be realised. Furthermore, these are produced upon application of relatively moderate
levels of shear. That such small micron sized bubbles can be generated under such shearing conditions
points to the possibility that the bubbles incorporated are originally much larger, but that they
subsequently shrink and become stable at a much smaller size. We present theoretical calculations,
analysing the problem of shrinkage of bubbles in the presence of such nanoparticles, where the
concentration of particles happens to be small. We show that the effect of shrinkage, followed by stability,
arises from the interplay between the kinetics of bubble dissolution, the rate of arrival and adsorption of
the nanoparticles onto the surface of the bubbles, and the competition of different sized bubbles to gather
a sufficient number of particles required to stabilise them [1,2].
[1] Ettelaie R; Murray BS, Journal of Chemical Physics 140 204713-1-204713-13,2014
[2] Ettelaie R; Murray BS, Colloids and Surfaces A: Physicochemical and Engineering Aspects 475 27-36, 2015.
Creation of textured dairy emulsions by connecting oil droplets through whey protein
aggregates
Thibault LOISELEUX1, Catherine GARNIER1, Thomas CROGUENNEC2, Valérie BEAUMAL1 Camille
JONCHERE1, Marc ANTON1, Alain RIAUBLANC1 1 UR1268 INRA, Biopolymères Interactions Assemblages, Nantes, France 2 UMR 1253 INRA, Science and technologie of milk and egg, Rennes, France
Heat treatment applied on whey proteins solutions causes protein denaturation and induces the formation of aggregates of different sizes and shapes depending on the experimental conditions. Even if cold gelation of whey protein aggregates is well known [1], their role in emulsions and their interfacial properties are less studied. Recent works showed that emulsions containing 30% of milk fat can be textured by modulating the ratio Aggregates (Ag)/Native Whey Protein (NWP) and by taking into account the size and the distance between droplets [2]. Based on these results, our challenge in this study was to texture emulsions with low oil volume fractions using aggregates We investigated the texture of dairy emulsions composed of 5-30% (w/w) of milk fat stabilized by a mixture of fractal aggregates having an average size of 240 nm and NWP. After homogenization (500 bars), emulsions were analyzed at 20°C by visual observation, granulometry, confocal laser microscopy and dynamic oscillatory measurements. When oil content was 30%, emulsions were already textured after homogenization at 60°C which is in contrast with 5% oil-in-water emulsions that remain liquid. Surprisingly, these low oil content emulsions texturize over time with increasing firmness. It is suggested that Ag allows the formation of a network by connecting oil droplets leading to emulsion texture. Tuning the Ag/NWP ratio induces very different textures for these low oil content emulsions ranging from heterogeneous systems exhibiting syneresis for 2 and 0.1% (w/w) of Ag and NWP respectively to smooth and stable emulsions for 3% of Ag and the same proportion of NWP. Confocal laser microscopy evidenced a rough microstructure with serum pores for emulsions with 2% of Ag and 0.1% (w/w) of NWP (Figure 1A) whereas more homogeneous systems were observed for 3% of Ag (Figure 1B). Moreover, rheological properties of these emulsions are recovered after shearing that could be very interesting for food application perspectives (Figure 1C). In conclusion, tuning Ag/NWP ratio can be a tool to control and guide emulsion texture even at low oil volume fraction by creating a network. In this way, fractal aggregates may be an alternative to additives use in dairy emulsions.
[1] V. Leung Sok Line, G. E. Remondetto, and M. Subirade, “Cold gelation of β-lactoglobulin oil-in-water emulsions,”
Food Hydrocoll., vol. 19, no. 2, pp. 269–278, 2005.
[2] C. Surel, J. Foucquier, N. Perrot, A. Mackie, C. Garnier, A. Riaublanc, and M. Anton, “Composition and structure of
interface impacts texture of O/W emulsions,” Food Hydrocoll., vol. 34, pp. 3–9, 2014.
The influence of size and concentration of silica particles and salt on foaming property of
casein/silica system
M. CHEN1,2, G. SALA1,2,3, M.B.J. MEINDERS1,3, E. VAN DER LINDEN1,2 1 Top Institute Food and Nutrition, P.O. Box 557, 6700 AN Wageningen, The Netherlands 2 Wageningen UR, Physics and Physical Chemistry of Foods, P.O. Box 17, 6700 AA Wageningen, The
Netherlands 3 Wageningen UR, Food and Biobased Research, P.O. Box 17, 6700 AA Wageningen, The Netherlands
Previous research indicated that casein micelle aggregates have a large influence on foam stability of casein
micelle dispersions. However, to what extend the amount of aggregates and their size influence the
foaming properties is not clear yet. In this study, we used silica particles with different sizes (10 nm, 200
nm, 1 µm and 5 µm) to mimic casein micelle aggregates and mixed them with casein in different ratios at
pH=6.7. Samples were characterized for particle size, shear viscosity and microstructure by SEM.
Furthermore, the effect of different concentrations of NaCl (50 mM, 100 mM and 200 mM) was
investigated. Foamability and foam stability of samples were tested by foamscan. Thin film structure and
stability were also investigated by CLSM and micro interferometry. By analysing correlations between the
data obtained with these experiments, we assessed the role of particle size and concentration on foaming
properties of casein/silica mixture and uncovered the interaction between casein and silica particles under
YANG1 1 Food Colloids and Processing Group, School of Food Science and Nutrition, University of Leeds, LS2 9JT,
United Kingdom.
Emulsions stabilized by soft whey protein microgel particles have gained research interest due to their
combined advantages of biocompatibility and high degree of resistance to coalescence. We designed
Pickering oil-in-water emulsions using whey protein microgels using a facile route of heat-set gel
formation followed by mechanical shear and studied the influence of heat treatment on emulsions
stabilized by these particles. The aim of this study was to compare the barrier properties of the microgel
particles and heat-treated fused microgel particles at the oil-water interface in delaying the digestion of the
emulsified lipids using an in vitro digestion model. A combination of transmission electron microscopy and
surface coverage measurements revealed increased surface of heat-treated microgel particles at the
interface. The heat-induced microgel particle aggregation and therefore, a fused network at the oil-water
interface was more beneficial to delay the rate of digestion as compared to that of intact whey protein
microgel particles in presence of pure lipase and bile salts, as shown by measurements of zeta potential
and free fatty acid release, plus theoretical calculations (Figure 1). However, simulated gastric digestion
with pepsin impacted significantly on such barrier effects, due to the proteolysis of the particle network at
the interface irrespective of the heat treatment, as visualized using sodium dodecyl sulfate polyacryl amide
gel electrophoresis measurements.
Figure 1. Kinetics and schematic diagram of proposed mechanism of fatty acid release (lipolysis) from 20 wt% O/W emulsions stabilized whey protein microgels (solid circles) with or without heat treatment (open circles) when they are exposed to pure lipase and bile salts. Kinetics (theoretical fit) of lipolysis of whey protein stabilized emulsion (gray solid line) with or without heat treatment (black dashed line). Insets represent transmission electron microsgraphs. Error bars denote standard deviation of three measurements.
Interfacial aspects underlying the inhibitory effects of Green Tea extract on lipolysis in-vitro
Teresa DEL CASTILLO-SANTUELLA1, Julia MALDONADO-VALDERRAMA1, Deyanira RONDON-
ROGRIGUEZ2, MaJose GALVEZ-RUIZ1, Miguel Angel CABRERIZO-VILCHEZ1
1 University of Granada, Department of Applied Physics, Campus de Fuentenueva, sn., 18071 (University of
Granada, Granada, Spain) 2 Biosearch Life S.A. Department of Biotechnology. Camino de Purchil, 66., 18004 (Biosearch Life S.A.,
Granada, Spain)
Inhibition of lipase activity is one of the approaches to reduced fat intake with nutritional prevention promoting healthier diet. Literature works have shown that tea and phenolic components such as catechins from tea have antiobesity and antidiabetic effect in humans, reduce adipose mass in rodent models, and influence lipid digestion in vitro [1]. In this work we evaluate the inhibition of lipolysis provided by a Green Tea Extract (GTE) provided by Biosearch Life S.L. To this end, we have used a novel methodology to investigate the interfacial mechanism underlying the inhibition of lipolysis of GTE [2]. The inhibitory potential is first correlated with the reduction of the interfacial activity of lipase and also compared with commercial inhibitor (Xenical®). Then, the dilatational response of the mixture lipase/GTE allows identification and discussion of the specific mode of action of GTE on lipase. Our results suggest that GTE operates by inducing conformational changes in the molecule which can be quantified by the dilatational response. The interfacial tension study provides new insights into the mechanism underlying the inhibition of lipase by GTE and allows optimising the concentration to be used in food formulations [2].
Acknowledgements: This work has been funded by CDTI (Center for the Development of Industrial Technology) and cofinanced with FEDAER funds (FEDER INNTERCONECTA: ITC-20131081), RYC-2012-10556, MAT2014-60615-R, MAT2012-36270-C04-02, COST-MPN-1106-Green Interfaces, CEI BIOTIC BS14.2015, and CEI BIOTIC BS28.2015. References: [1] Inhibitory effect of oolong tea polyphenols on pancreatic lipase in vitro. M. Nakai, Y. Fukui, S. Asami, Y. Toyoda-Ono, T. Iwashita, H. Shibata, T. Mitsunaga, F. Hashimoto, Y. Kiso. J. Agric. Food Chem. 2005, 53 (11), 4593-4598 [2] Natural Inhibitors of Lipase: Examining Lipolysis in a Single droplet. T. del Castillo-Santaella, J. Maldonado-Valderrama, M.A. Cabrerizo-Vilchez, C. Rivadeneira-Ruiz, D. Rondon-Rodriguez, M.J. Galvez-Ruiz. J. Agric. Food Chem. In press (DOI: 10.1021/acs.jafc.5b04550)
Food structure, oral processing behaviour and dynamic texture perception
Markus STIEGER1,2 1 Wageningen University, Division of Human Nutrition, P.O. Box 8129, 6700 EV Wageningen, The Netherlands 2 TI Food and Nutrition, P.O. Box 557, 6700 AN Wageningen, The Netherlands
Oral processing is key to dynamic sensory perception as food properties are constantly transformed during
consumption from first bite to swallow. Food structure is broken down by oral processing and contributes
to dynamic perception of texture, taste and flavour. The transformations depend on the physical-chemical
properties of the foods, the human physiology and the oral processing behaviour of the individual
consumer.
Food oral processing as the bridge between the transformation of food structure during consumption and
its association with dynamic sensory perception has gained enormous interest in the last decade. An
overview of the interplay between the structure of liquid and semi-solid foods, oral processing behaviour
and dynamic sensory perception is provided. Semi-solid model gels are described as suitable foods to
systematically investigate these relationships. Physical-chemical and rheological characterizations of bolus
properties of a variety of foods are discussed in relation to oral processing behaviour and sensory
perception. Special emphasizes is given on the influence of food structure on oral processing behaviour.
Oral processing behaviour can be characterized by methodologies such as Electromyography (EMG) to
monitor muscle activity, jaw tracking techniques to monitor spatial displacement of the jaw and
Electromagnetic articulography (EMA) to monitor tongue movements during oral processing. Oral
processing behaviour during drinking of liquids and mastication of semi-solid foods can be influenced by
modifications of the food structure. Oral processing behaviour is adaptive and consequently changes with
the changing properties of the bolus in the mouth. Recently, it was suggested that food preferences and
mastication behaviour might be linked and consumers were grouped based on their preferred chewing
behaviour. Preferred chewing time of a specific food varies between consumers and can determine the
properties of the bolus and can explain difference in dynamic texture perception between consumers. This
allows to design specific breakdown pathways of foods which are associated with desired dynamic sensory
properties and to develop foods for specific consumer groups by designing foods which match the
structural breakdown to the preferred oral processing behaviour.
Oral processing of food – structure breakdown and reorganisation
Sofia KIHLMAN ØISETH1, Graham EYERS2,3, Li DAY1,4, Leif LUNDIN1,5, Ingrid APPELQVIST2
1 CSIRO, 671 Sneydes road, Werribee, VIC 3030, Australia 2 CSIRO, 11 Julius Avenue, North Ryde, NSW 2113, Australia 3 Present affiliation: Department of Food Science, University of Otago, Dunedin, New Zeeland 4 Present affiliation: AgResearch, Palmerston North, New Zealand 5 Present affiliation: SP Food and Bioscience, Gothenburg, Sweden
We have been studying the oral breakdown of various food products (cheese, breakfast cereal, snack foods
and gels) to obtain information of how the food is naturally processed in mouth in preparation for
swallowing. Food samples were chewed by volunteers until the urge to swallow point or for shorter
intervals to follow the breakdown from solid pieces of food, through incorporation of saliva, to the
formation of a mass that could be swallowed. The chewed food was spat out and collected under strict
biohazard protocols. In conjunction with collection of naturally masticated samples, food samples were
placed in thin plastic bags and chewed upon to investigate the oral breakdown without the influence of
saliva. Masticated samples were analysed to determine particle size distribution by sieving or image
analysis and microstructural changes was investigated by microscopy.
The oral breakdown of food is clearly related to the formation of a material that is physiologically safe to
swallow. We found that a material that forms a bolus required much less chewing to get to the point of
swallowing compared to a food that breaks down into individual non-cohesive particles. Furthermore, for
non-bolus forming materials, the urge to swallow was related to the hardness of the food. Here, more
chewing and thus fracturing into smaller fragments was required for firm compared to softer materials.
As fat is a main carrier of taste compounds, it is important to find out how its properties changes through
mastication. We found that the microstructure of the fat phase for a soft material as cheese remained
generally constant throughout the chewing cycle, i.e. the fat inclusions stayed separated within the protein
matrix and did not merge or break up into smaller entities. On the other hand, for a solid snack food
product (potato chips) the fat phase ended up being partly emulsified by the chewing action. The increased
surface area caused by the emulsification would possibly lead to a faster and/or increased sensory
detection of fat soluble taste and aroma compounds as well as having an impact on digestion rates.
Underlying mechanisms for sensory perception of double emulsions with gelled and non-gelled
w1 phase
Anika OPPERMANN1,2, Elke SCHOLTEN1, Markus STIEGER2 1 Physics and Physical Chemistry of Foods (Wageningen University, Wageningen, The Netherlands) 2 Division of Human Nutrition (Wageningen University, Wageningen, The Netherlands)
The use of double emulsions (w1/o/w2) has been acknowledged as a promising strategy to reduce oil
content in several food applications. In double emulsions, water droplets (w1) are included in oil droplets
(o) which are dispersed in another aqueous phase (w2). It is generally assumed that using double
emulsions, oil content can be reduced while maintaining sensory properties, especially perception of fat-
related attributes. However, while sensory perception of single emulsions (o/w2) has been studied
extensively, a study on fat-related sensory properties of double emulsions has not been reported yet.
In this study, we investigated the sensory perception of double emulsions by descriptive sensory
profiling using a trained panel. Double emulsions varying in composition (gelled and non-gelled inner w1
phase) and fat reduction level were evaluated on attributes describing the taste (T), mouthfeel (MF) and
after-feel (AF) perception, including thickness (MF), creaminess (MF, AF), fattiness (MF, AF), and
cohesiveness (MF). Single emulsions (o/w2) with the same dispersed phase fraction (oil) were used as
references. Oil droplet sizes and viscosities of the emulsions were similar to minimize the effect of those
properties on sensory perception.
We found that the replacement of oil with small water droplets w1 did not decrease perception of
fat-related attributes, and even increased when inner droplets were gelled. This indicates that the sensory
perception of single and double emulsions is mainly determined by the total droplet surface area. The
sensory properties are correlated to the lubrication properties of the emulsions as a function of the
composition and amount of inner water phase. This study shows that fat reduction of up to 45% can be
achieved using double emulsions while maintaining or enhancing perception of fat-related attributes. This
insight confirms the potential of double emulsions as oil replacers.
The structure of dairy products effects gastrointestinal digestion at multiple length-scales
Alan MACKIE1, Anabel MULET-CABERO1, Neil RIGBY1, Simon LOVEDAY2, Janiene GILLILAND2, Maria FERRUA2 1 Institute of Food Research, Norwich, UK 2 The Riddet Institute, Palmerston North, New Zealand)
Using a semi-dynamic in vitro simulation and gastric emptying rates determined in vivo1, we describe a
comparison of the digestion of a liquid in which the lipid is in the form of an emulsion and semi-solid dairy
based food, where much of the lipid is embedded in a protein matrix. Both foods contained the same
amount of protein and lipid. The changes in gastric pH as a function of time indicated that the different
structures led to differences in buffering capacity. However, this was complicated by the emptying profiles
of both the protein and lipid from the two meals. Analysis of the lipid droplet size showed very little change
in the gastric phase but the differences in large-scale structure led to differences in the timing of lipid
digestion.
In addition to comparing the two food systems we also studied the effect of physical processing by
digesting the same foods in a simple minimally stirred simulation and the “human gastric simulator” (HGS)
published previously2 that more closely mimics the peristaltic action of the stomach. For these two foods,
the results were remarkable similar, suggesting that accurate simulation of physical processing may only be
important for solid meals.
The analysis of lipid and protein hydrolysis is interpreted in the light of in vivo data previously published
and confirms that the food structure tailored to alter physiological response.
1. Mackie, A. R., Rafiee, H., Malcolm, P., Salt, L. & van Aken, G. (2013). Specific food structures supress appetite
through reduced gastric emptying rate. American Journal of Physiology - Gut and Liver Physiology, 304(11), G1038-
G1043
2. Kong, F. B. & Singh, R. P. (2010). A Human Gastric Simulator (HGS) to Study Food Digestion in Human Stomach.
Tribological and sensory properties of food particles in liquid and semi-solid foods
Kun LIU 1, 2, Markus STIEGER 1, 2, Erik VAN DER LINDEN 1, 2, Fred VAN DE VELDE 1,3 1 TI Food & Nutrition, Wageningen, The Netherlands 2 Wageningen University, Wageningen, The Netherlands 3 NIZO Food Research, Ede, The Netherlands
The application of tribology in food research has revealed important relationships between lubrication properties and perception of fat-related sensory attributes of foods. We investigated the tribological and sensory properties of two micro-particle fat replacers (microparticulated whey protein (MWP) and rice starch), and fat droplets differing in solid fat content (SFC) and interaction of fat droplets with the gel matrix (bound/unbound) in liquid and semi-solid model foods. Fat droplets embedded in semi-solid gels reduced friction due to formation of fat films following a plate-out mechanism. The formation of fat films was enhanced by 1) increasing the amount of fat; 2) releasing unbound fat droplets from the gel matrix and 3) coalescence of fat droplets due to high SFC. Emulsifiers influenced the friction through formation of emulsifier films. Sensory results (QDA) showed that both 1) and 2) were able to increase the perception of fat-related sensory attributes, whereas 3), high SFC had no significant effect, probably due to in-mouth melting of the fat and structure breakdown. Spherical MWP particles effectively reduced friction in both liquid and semi-solid matrices due to a ball-bearing lubrication mechanism. Ball-bearing lubrication was restricted by gel matrices. Sensory results (QDA) revealed that MWP did not contribute to the perception of fat-related sensory attributes as fat droplets did, which could be related to their different lubrication mechanisms. In liquids, small MWP particles contributed to creaminess perception maybe due to ball-bearing lubrication while larger MWP particles contributed to roughness perception, which was negative on creaminess perception. Irregular-shaped native and gelatinized rice starch particles increased friction due to 3-body abrasion. Therefore, the fat-mimicking functionality of rice starch might be mainly due to increasing bulk viscosity or saliva-relevant effect. We conclude that the morphology of food particles in liquid and semi-solid foods influences the mechanisms underlying the lubrication properties that can influence sensory perception.
Ethylcellulose interactions with colloidal particles and its effect on structuring jammed systems
Alejandro G. MARANGONI, Terri A. STORTZ
University of Guelph, Guelph, Canada
Recent work by our group has shown that sucrose crystals have the ability to interact with ethylcellulose (EC) and form a network within food materials that provides mechanical strength and thermal stability. We recently reported on the ability of EC to impart heat resistance in chocolate using a solvent-substitution (SS) method. In the SS method, EC dissolved in ethanol is incorporated into a food matrix. Upon removal of the ethanol by evaporation, the EC will interact with different structures within the matrix. Evidence suggests that the sucrose present in the chocolate plays a major role in the heat resistance. Here we show that EC is able to hydrogen bond with sucrose which allows for the creation of an oil-trapping network. Atomic scale molecular dynamics simulations and FTIR spectroscopy both showed the ability of EC to hydrogen bond with sucrose. Large deformation mechanical testing and scanning electron microscopy showed the ability of EC and sucrose to form a network within an oil medium which resisted deformation. Here we also show that the presence of lecithin at the surface of sucrose reduced heat resistance by impeding interactions between EC and sucrose. These techniques along with fluorescence microscopy also showed that the ethanol used in the SS method was able to remove the ethanol- soluble lecithin phospholipids from the surface of the sucrose. Removal of the lecithin and the slight solubility of sucrose in ethanol both have positive impacts on heat resistance. It was also found that ethanol can reduce heat resistance by destabilizing the casein micelle in samples made with skim milk powder. Finally, results have indicated that EC is likely able to interact with the lactose in skim milk powder and the starch in cocoa powder leading to greater heat resistance. These results have led to an understanding of the mechanism of heat resistance in EC solvent substitution chocolate and will be useful in developing new food products containing EC as a functional ingredient that enhances sugar networks. Furthermore, there is evidence that a strong, heat resistant network can be created for various particles other than sucrose including glucose, starch, and even diamond dust.
Stortz, T. and Marangoni, A.G. 2011. Heat Resistant Chocolate. Trends in Food Science and Technology 22: 201-214. Stortz, T.A. and Marangoni, A.G. 2013. Ethylcellulose Solvent Substitution Method of Preparing Heat Resistant Chocolate. Food Research International 51: 797-803. Stortz, T.A., Laredo, T. and Marangoni, A.G. 2014. Molecular interactions of sucrose and ethylcellulose. RSC Adavances 4: 55048-55061. Stortz, T.A., Laredo, T. and Marangoni, A.G. 2015. The role of lecithin and solvent addition in ethylcellulose-stabilized heat resistant chocolate. Food Biophysics 10: 253-263.
Hybrid oleogel made of polymer and crystalline gelators
Maya DAVIDOVICH-PINHAS1, Andrew GRAVELLE2, Shai BARBUT2, Alejandro MARANGONI2 1 Technion – Israel Institute for Technology, Haifa, Israel 2 University of Guelph, Guelph, Canada
Oleogel formulations have been studied extensively over the last few years for various applications.
Oleogels can be classified into two major groups depending on the gelator component used, low and high
molecular weight oleogelators (LMOGs and HMOG). The physical properties of LMOG based gel systems are
strongly affected by geometric properties of the primary structurant, such as surface area and volume,
which, in turn, are directly affected by cooling rates and shearing. HMOG based gels, on the other hand,
offer different properties for possible applications, the consequence of extended polymeric chains. The
current research aims to combine both strategies to form a hybrid oleogel system which benefits from both
worlds. Oleogel system with 6 %Wt ethyl-cellulose (EC) and 3% or 5% Wt steryl alcohol /stearic acid 7:3
ratio (SOSA) was formulated and investigated using mechanical, thermal, and structural analysis. Sol-gel
transition was investigated using rheological approach. Reduction in the sol-gel cross-over temperature was
observed with the increase in SOSA concentration suggesting a plasticizing effect of the SOSA molecules.
The melting/crystallization transitions of the SOSA was evaluated using differential scanning calorimetry
(DSC). Shift in the SOSA crystallization peak to higher temperatures was observed in the presence of EC.
This observation was related to possible interactions between the polymer and the SOSA leading to the
formation of nucleation points which promote crystal growth. Unique crystal feather-like organization was
observed by optical microscopy imaging for EC/SOAS/oil mixture compare to SOSA/oil needle-like crystals.
X-ray diffraction analysis verified the existence of β and β' polymorphs in the SOSA crystal. These
polymorph structures were maintained after EC addition implying on the formation of two individual
networks, the polymer EC network and the SOSA crystal network. According to the DSC and imaging results,
it seems that these two networks are connected. Mechanical analysis also revealed a synergistic
enhancement in the final gel strength, possibly due to interactions between the SOSA and EC during
gelation. This research provide a first investigation of hybrid system using two different oleogelation
techniques. Such systems can benefit from synergistic effects, which can potentially offer enhanced
Protein aggregates as building blocks for oil structuring
Auke DE VRIES1,2, Erik VAN DER LINDEN1, Elke SCHOLTEN1,2 1 Top Institute Food and Nutrition, Nieuwe Kanaal 9A, 6709 PA Wageningen, The Netherlands. 2 Wageningen University, Physics and Physical Chemistry of Foods, Bornse Weilanden 9, 6708 WG
Wageningen, The Netherlands.
Over the recent years, structuring of oil into organogels or oleogels has gained much attention from colloid,
material and food scientists. An oleogel can be defined as an organic liquid with low polarity, entrapped
into a three-dimensional network. Such oleogels could potentially be used as an alternative for saturated-
and trans fats within the food industry. Besides chemically synthesized molecules, many biocompatible
organo- and oleogelators have been identified and characterized over the last years and can be classified as
either low molecular weight or polymeric organogelators. For food applications, it is of importance to
identify oleogelators that are sustainable, cost effective, and biocompatible. Therefore, there is still a great
need to identify food-grade biopolymers that are able to gelate a common oil.
Proteins are one of nature’s greatest resources of biopolymers and their gelation of water is well known.
Due to their hydrophilic character, however, their use as oleogelator is limited. In this presentation, we will
show that whey proteins can be used as a structuring agent for oil gelation. To this end, first, heat-set
protein gels or protein aggregates are created in an aqueous environment. Then, the continuous aqueous
phase is exchanged for a continuous liquid oil phase via an intermediate solvent. We show that by using
this procedure, the resulting protein matrix is capable of binding a large amount of liquid oil without any
necessary protein modification.
The use of protein aggregates as building blocks for organogelation shows interesting versatility. Different
protein networks can be formed since the properties of the building blocks and their interactions can be
controlled. This allows in turn to control rheological properties, such as gel strength, yield stress and plastic
behavior. Our results show that whey proteins can act as a cheap and versatile oil structuring biopolymer.
Casein micro-particle as carriers for hydrophobic substances - a new approach for its isolation
and characterization
Yu ZHUANG1, Julia STERR2, Alica SCHULTE1, Ulrich KULOZIK3, Ronald GEBHARDT1* 1 Chair of Food Process Engineering and Dairy Technology, Technische Universität München, 85354,
Freising-Weihenstephan, Germany 2 Chair of Food Packaging Technology, Technische Universität München, 85354, Freising, Germany 3 Institute for Food and Health (ZIEL) – Technology Unit, Technische Universität München, 85354, Freising-
Weihenstephan, Germany
Micro-particles received abundant attentions from food research because of their potential use as carriers
for bioactive substances. In this talk, we report on a new method to form casein micro-particles using
casein/pectin blend films. The underlying mechanisms for the micro-particle formation are depletion forces
due to volume exclusion. Confocal Raman microscopy, liquid chromatography and IR spectroscopy were
applied to characterize their composition and microstructure in both blend film and liquid phase. Raman
images showed incompatibility between both polymers because particles consisted of casein and the
surrounding matrix of pectin only. Deformation of micro-particles into an oblate shape took place during
film formation indicating a compaction of the structures. After isolation by enzymatic hydrolysis, micro-
particle remained stable in solution. Their size ranged from 10 to 50 µm similar to those in films. IR and
Raman spectra indicated that micro-particle mainly consisted of caseins. Furthermore, compared to the
composition of native caseins, an increased amount of α-S2 casein was found in the micro-particles. To give
them functionality, casein micro-particles were loaded with α-tocopherol. The porous structure of the
micro-particles supported the inclusion of α-tocopherol. Their linkage to the casein matrix within the
particles will be discussed in detail. Our approach demonstrates a new route to form micro-particles with
bio-functionality which might play a future role in the design of functional foods.
Fig. Color-coded Raman microscopic image in blend film in (A) vertical and (B) horizontal direction, casein-rich region, and pectin-rich (green). References: Maroziene, A.; de Kruif, C. G (2000): Interaction of pectin and casein micelles. In Food Hydrocolloids.Zhuang, Y; Sterr, J; Kulozik, U; Gebhardt, R (2015): Application of confocal Raman microscopy to investigate casein micro-particles in blend casein/pectin films. In International Journal of Biological Macromolecules.
Delivery of functional ingredients by self-assembled modified food biomacromolecules
Yuan LI1, Wei LI1, Luhai ZHAO1, Mengxuan SHI1, Willem NORDE2 1 College of Life Science and Technology (Beijing University of Chemical Technology,Beijing, China) 2 Laboratory of Physical Chemistry and Soft Matter (Wageningen University, Wageningen, The Netherlands)
The natural bioactive ingredients are usually sensitive to the environmental stimuli such as acid, heat, light and oxygen. It is important to develop an effective strategy to protect them from early degradation. Moreover, delivering them to the specific sites such as small intestine can increase their bioavailability. Biopolymers based on food grade materials are desirable in food application due to its biocompatibility and biodegradability. Here β-carotene is used as the model for hydrophobic bioactives, and the anthocyanin is used as the model for hydrophilic bioactives. We have developed a microsphere multi-nutrients delivery system based on cross-linked oxidized polysaccharides – oxidized Konjac Glucomannan1-5. Those microspheres are capable of encapsulating the hydrophilic and hydrophobic compounds simultaneously, and delivering them into intestine for targeted absorption (Fig.1). Secondly, we also developed a structurally well-controlled amphiphilic peptides obtained by enzymatically hydrolysed whey protein. This amphiphilic peptide has a well-defined structure, which can self-assemble into nanotubes and micelles at different conditions. β-carotene can be incorporated into the whey protein micelles via hydrophobic interaction, and the staining dye (representing anthocyanin) can be absorbed into whey protein nanotubes cavity through electrostatic interaction. Those modified polysaccharides and protein delivery system opened new option for encapsulating bioactives, which may facilitate their application in all kinds of foods, and improve their nutritional and health value in functional foods.
References : 1Langmuir,28,1545-1551,2012 ;
2Biomacromolecules,15,2166-2171,2014 ;
3 Food Hydrocolloids, 51, 476-485, 2015 ;
4Colloids and Surfaces B :Biointerfaces,127,96-104,2015 ;
5JAFC,63,8669-8675,2015.
Fig.1.CLSM images of anthocyanins absorbed
polymer phase(left) and β-carotene contained
oil phase(Middle)and the overlay of the two
phases. The multi-nutrients delivery microspheres made by double emulsion method.
Smart delivery vehicles based on the self-assembled complexes of the food biopolymers with
polyunsaturated lipids stabilized by plant antioxidants: structure-functionality relationships
Maria G. SEMENOVA1, Anna S. ANTIPOVA1, Natalia S. VOROBYEVA1, Natalia V. SMOTROVA2, Vera
A. SENINA3, Nadezda P. PALMINA1, Tamara A. MISHARINA1, Ekaterina S. ALINKINA1, Vladimir I.
BINYUKOV1, Natalia G. BOGDANOVA1, Valerii V. KASPAROV1 1 N. M. Emanuel Institute of Biochemical Physics of Russian Academy of Sciences, Kosygin str. 4, 119334
Moscow, Russian Federation 2 D. I. Mendeleyev University of Chemical Technology of Russia, Miusskaya sq. 9, 125047 Moscow, Russian
Federation 3 M. V. Lomonosov Moscow State University, Leninsky hills, 1, 119991 Moscow, Russian Federation
There is a considerable current interest in the elaboration of both the protective and the controlled–release
delivery vehicles for the wide variety of nutraceuticals, which could be used as the health-promoting food
ingredients, in particular under the functional food formulation. The polyunsaturated fatty acids (PUFAs),
especially omega-3 and omega-6 are the most important nutraceuticals. However, there are the real
challenges of using the PUFAs in the functional low- fat food elaboration. The first and most important one
is their high susceptibility to an oxidative degradation during the food product preparation, transport, and
storage, and the second one is their low solubility in water and in biological liquids in a body that can
decrease their bioavailabilty. In order to solve these problems we have tried to use, on the one hand, the
expected high both encapsulation ability and solubility in an aqueous medium of such biopolymer
amphiphilic particles like sodium caseinate and covalent conjugate (sodium caseinate (SC) + maltodextrin
(MD-SA2)), produced by the Mailllard reaction, and, on the other hand, the effective plant antioxidants as
either an ether oil of clove or oleoresins of ginger. As the main lipid objects of our investigation we have
chosen different mutually complementary combinations of the polyunsaturated lipids, which can provide
the equimass omega-6/omega-3 PUFAs ratio : the equimass mixture of -linolenic (ALA) and linoleic (LA),
the mixtures of the the soy phosphatidylcholine (PC) liposomes enriched in LA with both ALA and
docosahexaenoic DHA, the soy lysophosphatidylcholine (LPC) LPC micelles enriched in LA with both ALA
and DHA. In such a manner in our work we have tried to get a more deep insight into the structure –
functionality relationships for the supramolecular complex particles formed.
As the functional properties of the complex particles we have considered both their protective abilities
against oxidation of the lipids, their solubility in an aqueous medium and their abilities to the controlled
release of the lipids in the simulated gastro-intestinal tract in vitro.
With this object in view we have used a combination of such basic physico-chemical methods as the
spectrophotometry, the static and dynamic multiangle laser light scattering, the particle electrophoresis,
the atomic-force microscopy, and the electron spin resonance spectroscopy.
Acknowledgements: Authors are most grateful to the Russian Science Foundation for the financial support
Oleosome Based Gels Prepared by Hydrocolloid Trapping
Behic MERT1, Thomas A. VILGIS2 1 Food Engineering Department Middle East Technical University, Ankara Turkey 2 Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
Lipids are in general preserved in the form of triacylglycerols (TAG) in seeds and plants. These TAGs are
segregated into nano to micrometer spherical bodies. These spherical oil bodies, also called oleosomes,
possess unique surface properties as they must stabilize water-insoluble TAGs in a hydrophilic
environment. When oleosomes are extracted from seeds or plants they are in the form of concentrated
emulsions with their natural emulsifier oleosins. In this study oleosome based oleogels were developed by
trapping oleosomes in a hydrocolloid matrix. Physical trapping of oleosomes were accomplished through
electrodeposition procedure consisting of coating negatively charged oleosomes with a positively charged
hydrocolloid at low pH values. Stabilized oleosome emulsions were further stabilized by removal of water
through drying, then the resulting dry structures were sheared using a high speed mixer and oleogels were
obtained. Final oleogels contained mainly oil and minor amounts hydrocolloids and storage proteins.
Rheological studies conducted on the oleogels samples revealed that oleogels had solid like structures and
low degree of thixotropic behavior. As an application of the oleosome based oleogels hazelnut oleogels
were mixed with cocoa and extra fine sugar to obtain saturated fat and palm free spreads.
Extended Colloidal Networks in Emulsions. 3-D imaging by Ptychographic X-ray computed
tomography
Jens RISBO1, Mikkel Schou NIELSEN2, Merete BOGELUND MUNK1, Ana DIAZ3, Emil Bøje LIND4
PEDERSEN, Mirko HOLLER3, Stefan BRUNS5, Kell MORTENSEN2, Robert FEIDENHANS’l2
1 Department of Food Science, University of Copenhagen, Rolighedsvej 30, 2000 Frederiksberg, Denmark 2 Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark 3 Paul Scherrer Institute, 5232 Villigen – PSI, Switzerland 4 Department of Energy Conversion, Technical University of Denmark, Frederiksborgvej 399, 4000
Roskilde, Denmark 5 Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
Colloidal networks in food and food materials like cheese, yoghurt, whipped cream and fat is decisive for
the texture and mouthfeel. The ability to image by optical means and thereby obtain knowledge structure
is often limited by the high degree of light scattering and so far only few 3D structures has been obtained of
such networks. We have made use of synchrotron x-ray radiation to perform the non-destructive 3D
imaging technique ptychographic X-ray computed tomography (PXCT) [1] and obtained a 3D electron
density map of partially coalesced samples of whippaple O/W emulsions with a resolution 300 nm. The
resolved electron density values are within 4% of reference values of the components of the emulsion. The
study revealed network formation where about 98% of the fat particles was a part of the same network
structure. Analysis using a watershed algorithm highlighted how the structure was constructed from
colloidal elements with a size distribution close to the one of the original emulsion sample. A 3D printed
plastic model of the colloidal network was produced to along with computer based 2D visualization.
Altogether, PXCT is a promising tool for spatial and quantitative investigation of food products on the sub-
micron scale.
[1] M. Dierolf, A. Menzel, P. Thibault, P. Schneider, C. M. Kewish, R. Wepf, O. Bunk, F. Pfeiffer, Ptychographic x-ray
computed tomography at the nanoscale, Nature 467 (7314) (2010) 436–439.
Figure 1. 3D colloidal network in emulsions system
Structure of soybean oleosomes studied by small angle neutron scattering (SANS)
Birgitta I. ZIELBAUER1, Sania MAURER1, Gustav WASCHATKO1, Andrew J. JACKSON2,3, Marta
GHEBREMEDHIN1, Richard K. HEENAN4, Lionel PORCAR5, Thomas A. VILGIS1 1 Max Planck Institute for Polymer Research, Mainz, Germany 2 European Spallation Source, Lund, Sweden 3 Lund University, Lund, Sweden 4 ISIS Facility, STFC Rutherford Appleton Laboratory, Didcot, United Kingdom 5 Institut-Laue-Langevin, Grenoble, France
In oleaginous plants such as oil seeds or nuts, fat is stored in oil bodies, also called oleosomes. Their size is depending on the plant species and ranges from several hundred nanometers (soybeans) up to a few micrometers (cocoa). These colloidal particles are composed of a lipid core, stabilized by a monolayer of phospholipids and proteins. These proteins play a crucial role for the stability of the droplets. The most abundant of them, the so-called oleosins, contain one of the longest hydrophobic domains known in nature, anchoring them deep inside the oil core (Fig. 1). Their terminal ends are orientated towards the aqueous environment and keep the droplets apart from each other through steric hindrance and electrostatic repulsion.
Fig. 1: Schematic view of an oleosome.
Oleosomes can be extracted by aqueous processes yielding highly stable emulsions and thus bear a high potential to be employed in various food and cosmetic systems. However, those applications may involve harsh environmental conditions such as shearing or temperature treatment, so it is important to know the oleosomes’ stability limits. Studying the native structure of oleosins is extremely difficult due to their long hydrophobic domain, causing aggregation upon extraction. Also, the exact conformation of the hydrophilic domains, as well as changes therein that may result from varying environmental conditions, are still a matter of debate [1]. Small angle neutron scattering is a non-destructive method that allows studying the outer shell of the oleosome in its native state. Soybean oleosomes are studied here due to their extraordinary stability. We employ the contrast variation method to obtain information about the size of the oleosomes as well as the thickness of the layer surrounding their lipid core and thus the protein conformation, in different environmental conditions. No change was found for heat treatments up to 80 °C, indicating the enormous heat stability of these oil bodies. [1] S. Maurer, G. Waschatko, D. Schach, B. I. Zielbauer, J. Dahl, T. Weidner, M. Bonn, T. A. Vilgis, The role of intact oleosin for the stabilization and function of oleosomes, The Journal of Physical Chemistry B, 117 (2013), 13872-13883
Dynamic interfacial tension of emulsions studied with microfluidics
Kelly MUIJLWIJK1, Claire BERTON-CARABIN1, Karin SCHROËN1, 1 Food Process Engineering group, Wageningen University, Wageningen, The Netherlands
Many food products are emulsion-based systems, and generally they are made using high shear devices that induce fast droplet break-up (i.e., in the millisecond range) in the presence of emulsifiers. It is expected that emulsifier adsorption occurs at similar time scales as droplet breakup during emulsification; it is therefore crucial to understand the early steps of emulsion droplet formation and emulsifier adsorption. However, conventional tensiometry techniques are not able to measure changes in interfacial tension related to emulsifier adsorption at such small time scales. A device that can enable the measurement of interfacial tension in the millisecond range is the microfluidic Y-junction (Figure 1, left), which is the focus of the present work. Here, the droplet size depends on the shear of the continuous phase, and on the interfacial tension. A reduction in the interfacial tension, as a result of emulsifier adsorption, leads to the formation of smaller droplets. Based on the droplet size and flow rates, the interfacial tension at the moment of droplet break-up, also called dynamic interfacial tension, can be measured in the millisecond range. We constructed a model that relates the droplet size to the shear exerted by the continuous phase, and to the interfacial tension. With this model, the interfacial tension at the moment of droplet formation (typically between 0.5-10 milliseconds) could be calculated. The emulsifier coverage of the oil droplet depends on the process conditions, leading to different values of the dynamic interfacial tension at the moment of droplet break-up, and we were able to link this to droplet formation time and emulsifier concentration (Figure 1, right). The proposed method allows exploration of emulsifier behaviour at the oil-water interface at very short time scales, which is not possible through any other technique. It is expected that this information will help the food industry to optimise their ingredient formulation and processing conditions, using adsorption behaviour as a starting point of their product and process designs.
Figure 1. Oil droplet formation in a Y-junction microfluidic device (left), and dynamic interfacial tension of 0.01 (●), 0.1 (♦) and 0.5 (▲)wt. % SDS as a function of the droplet formation time (right).
Milk protein hydrolysis during in-vivo and in-vitro digestion:
Peptide generation and degradation
L. EGGER1, H. STOFFERS1, P. SCHLEGEL2, D.GUGGISBERG1, P. STOLL2, G. VERGERES1, R. PORTMANN1 1 Agroscope Institute for Food Sciences, Schwarzenburgstr. 161, 3003 Bern, Switzerland 2 Agroscope Institute for Livestock Sciences, Tioleyre 4, 1725 Posieux, Switzerland
The digestion processes are the interface between food and bioavailability of nutrients and understanding
the molecular mechanisms is a prerequisite to develop food with improved properties. During the digestion
process, protein hydrolysis and subsequent generation of peptides and free amino acids depend on the
structure and sequence of each protein. During the gastric phase, proteins are denatured in the acidic
conditions of the stomach and protein hydrolysis starts through the action of pepsin. At the intestinal stage
of digestion, proteases, such as trypsin, chymotrypsin, elastase and others, further degrade the proteins
and peptides until they are absorbed through the intestinal epithelium. Generation and destruction of
specific peptides during digestion of skim milk powder were investigated in vitro using the international
consensus COST Infogest digestion protocol and verified in vivo in a pig model. The hydrolysis of the five
most abundant milk proteins – their peptides and free amino acids – was investigated by mass
spectrometry and HPLC after the gastric and the intestinal compartment and compared between both
models. Moreover, with time-resolved in vitro digestion experiments, generation and degradation of
specific peptides and release of free amino acids were followed and compared with the in vivo pig data. The
protein specific hydrolysis was visualized by generation of abundance-dependent peptide patterns. Highly
abundant peptides observed after complete digestion indicate digestion-resistant protein sequences and
represent interesting sources of bioactive peptides or allergenic epitopes.
Molecular interactions, phase behavior and transport phenomena from a low-solid gel to a high-
solid glass
Stefan KASAPIS
School of Applied Sciences, RMIT University, Melbourne, Australia
Intelligent manipulation of the phase behaviour in biopolymer mixtures remains one of the basic tools of achieving the required structural properties and textural profile in novel food product formulations. As ever, the industrialist is faced with the challenge of innovation in an increasingly competitive market in terms of ingredient cost, product added-value, and long shelf-life to mention but a few. It appears, however, that a gap persists between fundamental knowledge and direct application to food related concepts with a growing need for scientific input. Furthermore, within the context of materials science, there is a tendency to examine research findings in either low- or high-solid systems without considering synergistic insights/benefits to contemporary needs, spanning the full range of relevant time-, temperature- and concentration scales. This review highlights the latest attempts made to utilize and further develop fundamental protocols in order to bridge the divide in the analysis from low to high-solid systems. Small and large deformation rheology, micro and modulated thermal analysis, and light/electron microscopy images constitute powerful tools in the characterization and quantification of such systems. Theoretical schools of thought from the
“sophisticated synthetic polymer” literature were adapted to address the specific requirements of research on structure/function relationships of biomaterials with changing solvent quality.1 Thus, the morphology of low-solid co-gels was explored using the isostress/isostrain blending laws, the Davis analytical expression, and the Lewis and Nielsen theoretical equations.2 In the high-solid counterparts, the combined free-volume/WLF framework was utilised to define the mechanical glass transition temperature that takes into account the presence of aqueous solvent in biomaterials.3 The coupling model of molecular dynamics identified the chemical moieties responsible for the local segmental motions at the vicinity of Tg.4 Understanding the molecular dynamics of biopolymers as glassy matrices allows monitoring the kinetics of diffusional mobility of entrapped bioactive compounds via a spectroscopic shift factor.5 Combining the physics of vitrification with Fickian kinetics of transport phenomena leads to the development of a mathematical expression that links the concept of micromolecular diffusion coefficient with the free volume of the polymeric matrix.6
1. Kasapis, S. & Tay, S.L. (2009). Morphology of molecular soy protein fractions in binary composite gels. Langmuir, 25, 8538 2. Shrinivas, P., Kasapis, S. & Tongdang, T. (2009). Morphology and mechanical properties of bicontinuous gels of
agarose and gelatin and the effect of added lipid phase. Langmuir, 25, 8763
3. Kasapis, S. (2006). Building on the WLF / free volume framework: Utilisation of the coupling model in the relaxation
dynamics of the gelatin / co-solute system. Biomacromolecules, 7, 1671
4. Kasapis, S., Al-Marhoobi, I.M., Deszczynski, M., Mitchell, J.R. & Abeysekera, R. (2003). Gelatin vs. polysaccharide in
mixture with sugar. Biomacromolecules, 4, 1142
5. Jiang, B. & Kasapis, S. (2011). Kinetics of a bioactive-compound (caffeine) mobility at the vicinity of the mechanical glass transition temperature induced by gelling polysaccharide. Journal of Agricultural and Food Chemistry, 59, 11825
6. Panyoyai, N., Bannikova, A., Small, D.M. & Kasapis, S. (2015). Diffusion kinetics of ascorbic acid in a glassy matrix of
high-methoxy pectin with polydextrose. Food Hydrocolloids, in press
Effects of disulfide bonding between added whey protein aggregates and other milk
components on the rheological properties of acidified milk model systems
Guanchen LIU1, Marianne LUND1, Colin RAY1, Søren NIELSEN2, Tanja JAEGER2, Richard IPSEN1 1 Department of Food Science, University of Copenhagen, Frederiksberg C, Denmark 2 Arla Foods Ingredients Group P/S, Videbæk, Denmark
Microparticulated whey protein (MWP) are colloidal particles usually formed by combined heating and
shearing of whey protein concentrates, typically having particle sizes ranging from 1.0 to 10 µm.
Nanoparticulated whey protein (NWP) is also produced from whey protein but having a smaller particle
size. In this research MWP and NWP were added to non-fat milk model systems and subjected to
laboratory scale homogenization (20 MPa) and heat treatment (90 °C 5 mins), and processed into
chemically acidified milk gels (glucono--lactone). The model systems contained 5% protein in total and
were made at two levels of casein (2.5% and 3.5% protein, w/w, based on micellar casein isolate powder)
with and without the thiol-blocking agent N-ethylmaleimide (NEM). Samples with added whey protein
ingredients were compared to four references: 5% (w/w) MWP, NWP or casein and a sample with 2.5%
(w/w) casein and 2.5% whey protein isolate (WPI) (w/w). The systems were characterized during processing
(homogenisation, heat treatment and acidification) by quantification of thiol groups, gel electrophoresis,
particle size, and rheology. The results showed that the formation of disulfide-linked structures in milk
model systems was closely related to the particle size and gels’ rheological behavior. The native whey
protein from WPI dominates the thiol/disulfide exchange reactions since not much native whey protein is
present in NWP and MWP. The systems with NWP exhibited obvious increase in particle size and higher
firmness of acidified gel through both covalent and non-covalent interactions. However, in MWP systems
the whey protein isolate (WPI) dominated formation of the protein network while MWP in itself resulted in
a weak protein network with low connectivity of the resulting gels. In addition, results show that
casein/whey protein ratio also plays an important role in aggregation during heating.
Effect of non-ionic emulsifier on structure and properties of a bench-scale model cheese
Seyed H. HOSSEINI-PARVAR1,2, Mita LAD2, Christina COKER2, Palatasa HAVEA2, Matt GOLDING1,2 1 Massey University, Palmerston North, New Zealand 2 Fonterra Research and Development Centre, Palmerston North, New Zealand
The use of W1/O/W2 double emulsion structures is considered a potentially useful technology for
replacement of fat in food applications. By using these emulsions, the amount of fat in a food formulation
can be decreased while maintaining the same amount of interface [1]. W1/O/W2 double emulsions are
often produced in a two-step method: first, the inner W1/O emulsion is produced and then this single
emulsion is emulsified in a second aqueous phase (W2) to obtain the double emulsion.
In this study, we investigated the incorporation of W1/O emulsions into a model cheese system, and
determined how the microstructure of this double emulsion system influenced cheese material and
functional properties. Initially, the stability of the water-in-oil (W1/O) emulsion prepared with milk fat was
determined as a function of emulsifier (polyglycerol polyricinoleic (PGPR)) concentration and water volume
fractions. Secondary emulsification took place when the stable W1/O emulsions were dispersed into fat-
free cheese through a mixing-cooking process (using a Rapid Visco Analyser) creating the final water-in-oil-
in-protein model cheese. The material properties and functionality of the cheese samples were evaluated
using small amplitude oscillatory shear test, particle size analysis, confocal laser scanning microscopy
(CLSM), cryo-SEM and modified Schreiber melt test.
The results demonstrate the ability of the secondary emulsification process to incorporate the W1/O
emulsion into the cheese matrix, providing a structure that has discrete fat domains (i.e. dispersed phase)
with internally filled water droplets. Increasing emulsifier concentration and water volume fraction had
minor effects on the fat structure within the cheese matrix.
Reference :
[1] Pawlik, A., Cox, P. W., & Norton, I. T. (2010). Food grade duplex emulsions designed and stabilised with different
osmotic pressures. Journal of Colloid and Interface Science, 352(1), 59-67.
The Effect of Competition for Calcium Ions on Heat-induced Aggregation and Gelation of
Mixtures of Whey Protein Isolate and Sodium Caseinate
Trong Bach NGUYEN1, Christophe CHASSENIEUX2, Christophe SCHMITT3, Lionel BOVETTO3, Taco
NICOLAI2 1 Faculty of Food Technology -Nha Trang university, Nha Trang, Vietnam 2 IMMM UMR CNRS 6283-Université du Maine, Le Mans, France 3 Department of Food Science and Technology-Nestlé Research Center, Lausanne, Switzerland
Whey proteins and caseins are the major protein components of milk. Heat-induced aggregation and
gelation of whey proteins is very sensitive to the presence of calcium ions that is the most often present in
the food products. Here we present an investigation of the effect of adding CaCl2 on the heat-induced
aggregation and gelation of Whey Protein Isolate (WPI) in the presence of sodium caseinate (NaCas) using
dynamic light scattering, confocal laser scanning microscopy (CLSM) and oscillatory shear rheology. We will
show that at neutral pH and below a critical CaCl2 concentration, NaCas does not aggregate by itself nor co-
aggregates with WPI in the mixtures. The presence of a few Ca2+ ions per protein drove a transition of the
morphology of WPI aggregates from relative small strands to larger spherical microgels causing the
turbidity to increase with increasing CaCl2, see figure 1. Addition of CaCl2 above a critical amount induced
gelation of heated WPI solutions.
Addition of NaCas to the WPI solutions shifted the transition to higher CaCl2 concentrations so that at a
fixed CaCl2 concentration the turbidity of solution decreased with increasing NaCas concentration, see
figure 2. This effect can be understood by the strong affinity of caseinate to bind Ca2+ so that less Ca2+ is
available for WPI. Addition of NaCas also reduced the critical CaCl2 concentration needed to induce gelation
of WPI at 3.4wt%, which can be explained by the competition for Ca2+. Remarkably, however, addition of
more than 6wt% NaCas induced gelation of WPI even in the absence of CaCl2. As a consequence of these
two antagonistic effects, in a limited range of CaCl2 concentrations WPI solutions formed gels at low and
high concentrations of added NaCas, but remained liquid when at NaCas intermediate concentrations.
Figure 1. Heated solutions of WPI at 4wt% and different CaCl2 concentrations indicated in the figure.
Figure 2. Heated solutions of WPI at 3.4 wt% and 2.54 mM CaCl2 with different NaCas concentrations
Mixed biopolymer gels prepared from cellulose microfibrils and whey protein isolate - the role
of cellulose in structuring of foods
Jinfeng PENG1 , Paul VENEMA1 , Krassimir VELIKOV2,3 , Erik VAN DER LINDEN1,2 1 Physics and Physical Chemistry of Foods, Department of Agrotechnology and Food Sciences, Wageningen
University, Wageningen, the Netherlands 2 Unilever R&D Vlaardingen, Vlaardingen, The Netherlands 3 Soft Condensed Matter, Debye Institute for NanoMaterials Science, Utrecht University, Utrecht, The
Netherlands
Bacterial cellulose (BC) has gained increasing interest in the past years due to its high purity compared with
plant cellulose and its remarkable properties such as high aspect ratio, high crystallinity and mechanical
strength. Considerable attention has been received in a variety of research fields, from medical to material
science. In food technology, they are of interest because of their multifunctional properties and potential
use as e.g. thickening, gelling, stabilizing agent, texture modifier and fat substitute. Nevertheless, the
behaviour of bacterial cellulose in complex food systems has not yet been fully exploited and well
understood. Protein and polysaccharide are the two main components in foods, which together contributes
to the structure, texture and stability of the foods. Interactions between protein and polysaccharide can be
varied under different conditions. In this study, we investigated the mixed gel prepared from
microfibrillated bacterial cellulose(MFC) produced from nata de coco and whey protein isolate (WPI) at
neutral pH upon heating. In particular, we investigated their rheology, microstructure and mechanical
properties. Results showed that the mixture of MFC and WPI forms a bicontinuous gel. The gelation of
whey protein isolate is not influenced by the presence of BC, and the addition of BC leads to an increase of
the storage modulus and enhancement of the stiffness and brittleness of the gel. Understanding the
interactions between WPI and BC under different conditions will aid the design of novel structures in foods.
Acknowledgement: This research is financially supported by NanoNextNL (consortium of Dutch
Quantitative confocal microscopy and probe diffusion in bicontinuous phase separated
structures
N. Loren1,4 , E. SCHUSTER1,4 , M. RUDEMO2,4 , A-M. HERMANSSON1,3,4 1 Structure- and Materialdesign, SIK – The Swedish Institute for Food and Biotechnology, Box 5401, SE-402
29 Göteborg, Sweden 2 Mathematical Sciences, Chalmers Univeristy of Technology, SE-412 96 Göteborg, Sweden 3 Department of Chemical and Biological Engineering, Chalmers University of Technology,SE-412 96
Göteborg, Sweden 4 SuMo Biomaterials, VINN Excellent Center, Chalmers University of Technology, SE-41296 Gothenburg,
Sweden
Diffusion is vital for many food properties such as water management in pasta and pastry products, oil
migration induced fat bloom in chocolate and oral taste release. These examples show that it is important
to have good control over the diffusion properties to obtain desired functionality. Therefore thorough
understanding of structure - mass transport relationships at different length scales in the structure and
good measurement techniques for global and local for diffusion are essential. In this talk, the coupling
between structure and diffusion1 at different length scales in Foods and soft porous heterogeneous
materials will be discussed.
Quantitative microscopy allows for simultaneous determination of the detailed microstructure at
micrometer level and local quantitative information regarding mass transport, electrostatic interactions,
rheological properties etc. A brief overview of different microscopy based techniques to characterize local
diffusion will be given in this presentation. Confocal laser scanning microscopy (CLSM) in combination with
Flourescence recovery after photobleaching (FRAP)1 or raster image correlation spectroscopy (RICS) are
versatile methods to determine quantitative diffusion properties locally directly in the microscope. They
can be used in many types of soft porous homogeneous and heterogeneous foods and biomaterials. A new
powerful RICS technique that gives precise measurements on the local diffusion coefficient will be
presented2. In addition, examples from the use of FRAP and RICS will be presented.
Food properties change as a function of time and surrounding conditions. CLSM-FRAP combined with
different stages to control surrounding conditions is powerful to monitor effects of kinetics on the diffusion
properties. Here, results on microstructure and probe diffusion in phase separated biopolymer mixtures
determined by FRAP and NMR diffusometry will be presented3. The effect of the characteristic wavelength
and the equilibrium concentration on the diffusion in bicontinuous phase separated biopolymer mixtures
will be demonstrated using quantitative microscopy and Lattice-Boltzmann simultations. In addition,
possibilities to quantitatively monitor diffusion in alginate gels4 and very recent results that reveal the
effects of charg -
lactoglobulin gels will be presented5.
[1] Lorén et al. (2015) Quarterly Reviews of Biophysics 48, 3 (2015), pp. 323–387.
[2] Longfils et al. (2015) Manuscript submitted to J. Microscopy.
[3] Wassén et al. (2014) Soft Matter DOI: 10.1039/c4sm01513d
[4] Schuster et al. (2014) Soft Matter, DOI: 10.1039/c3sm52285g.
Process stability of whey protein-pectin complexes as new structuring elements in fat-reduced
food systems
Kristin PROTTE1, Alina SONNE1, Jochen WEISS2, Jörg HINRICHS1 1 Department of Soft Matter Science and Dairy Technology (University of Hohenheim, Stuttgart, Germany 2 Department of Food Physics and Meat Science (University of Hohenheim, Stuttgart, Germany)
Pectins and whey proteins are often used as stabilizers in diverse dairy products. Mixing these two
biopolymers in an aqueous solution results in the formation of electrostatically attracting complexes. It is
postulated that these complexes can be used as structuring agents in fat-reduced food systems. However,
since electrostatically-stabilized complexes are highly sensitive to dissociation due to changes in their local
environment, e.g. heating, shearing and ionic strength, a major challenge is to generate whey protein-
pectin complexes that maintain their expected functionalities upon variations in substrate composition and
during processing. The aim of this study was to identify processing conditions to generate process stable
whey protein-pectin particles with improved functional properties in comparison to the biopolymers alone.
For this purpose, we studied the response of those associated complexes to changes in calcium
concentration, shear rates and nature of pectin on different plant scales. Biopolymer mixtures consisting of
native whey protein and pectin with varying distribution of esterification have been generated at a ratio of
5:1. Different concentrations of calcium chloride were added to simulate use of whey. The biopolymer
mixtures were shear-heat-treated for 250 s at 90 °C. Shear rates have been varied at 0-500 s-1 to investigate
process stability under different processing conditions. Generated structures were characterized by means
of particle size, microscopic analysis, and fluorescence spectroscopy. Results revealed that the structural
and mechanical characteristics of whey protein-pectin particles are strongly affected by pectin type and
biopolymer concentration level. In particular, heat treatment is a promising way to generate shear stable
whey protein-pectin complexes which are tolerant towards changes in calcium concentration. Particle size
analysis indicated that pectin-stabilized whey protein aggregates are able to meet size characteristics of
milk fat globules (1 – 10 µm) and thus might have potential to replace parts of fat in fermented dairy
products. This study outlines that functional properties of whey protein - pectin complexes can be designed
towards the desired application in food systems by choice of process parameters.
References:
Krzeminski, A., Prell, K., Weiss, J. and Hinrichs, J. (2014). Environmental response of pectin-stabilized whey protein
aggregates. Food Hydrocolloids, 35, 332 –340.
Salminen, H. and Weiss, J. (2013). Effect of pectin type on association and pH stability of whey protein-pectin
Multilayered interfaces to delay in vitro lipolysis in O/W emulsions
Meinou N. CORSTENS1a, Claire C. BERTON-CARABIN1a, Annemarie KESTER1a, Remco FOKKINK1b,
Johanna M. VAN DEN BROEK1b, Renko DE VRIES1b, Freddy J. TROOST2, Ad A.M. MASCLEE2, Karin
SCHROËN1a 1 Wageningen University, Department of Agrotechnology & Food Sciences, a Food Process Engineering and
b Physical Chemistry and Colloid Science group, Wageningen, the Netherlands 2 Maastricht University Medical Centre, Department of Internal Medicine, division of Gastroenterology-
Hepatology, Maastricht, the Netherlands
Lipid fractions that escape digestion and absorption in the upper gastrointestinal tract are believed to induce feelings of satiety, and to inhibit food intake through the ileal brake mechanism (Maljaars, Peters, Mela, & Masclee, 2008). This could be used to modulate the energy balance and, hence, body weight regulation. However, the gastrointestinal tract is designed to efficiently digest a broad range of foods, and dietary lipids need to be protected to reach the ileum. During digestion, lipolysis takes place at the surface of lipid droplets, where lipase comes into contact with lipid substrate. Hence, encapsulates need to have an oil-water interfacial structure that protects against the action of lipase (Corstens et al., accepted manuscript). In this context, our aim is to develop interfacial structures able to encapsulate dietary lipids and control lipolysis. The present work focused on multilayered emulsions (d32 ~ 5-30 μm), which were produced by sequentially adsorbing oppositely charged biopolymers at pH 3.0 (whey proteins; and pectin or chitosan) as schematically shown in Figure 1. Emulsions with a chitosan layer were not physically stable in simulated intestinal fluid, in contrast to pectin-based emulsions. Adsorbing a second and third interfacial layer considerably delayed lipolysis in these emulsions, while further increase of the number of layers led to similar results. The lipolysis susceptibility of multilayered emulsions could be related to the structural stability of the interfacial layers, which was investigated through confocal fluorescence microscopy (CLSM) and reflectometry. The CSLM results provided details of the multilayer structure, and the reflectometry results showed that when exposed to a neutral pH corresponding to the small intestines (pH 7.0), multilayered interfaces with more than three layers lost their outer layers instantaneously when switching to pH 7.0. In addition, we also found that the conditions used for in vitro digestion greatly affected the rate and extent of lipolysis.
This work shows that lipolysis in emulsions can be substantially delayed by controlling the oil-water interfacial design, which needs to be tuned to the conditions in which the food is ingested. Corstens, M. N., Berton-Carabin, C. C., de Vries, R., Troost, F. J., Masclee, A. A. M., & Schroën, K. (accepted manuscript). Food-grade Micro-encapsulation Systems that May Induce Satiety via Delayed Lipolysis: A Review. Critical Reviews in Food Science and Nutrition, http://doi.org/10.1080/10408398.2015.1057634. Maljaars, P. W. J., Peters, H. P. F., Mela, D. J., & Masclee, A. A. M. (2008). Ileal brake: a sensible food target for appetite control. A review. Physiology & Behavior, 95(3), 271–81.
Regulation of Lipid Digestion via encapsulation in protein gels with differing structures
T. J. WOOSTER1, J-M. JUAN1, S. ACQUISTPACE1, E. KOLODZIEJCZYK1, A. SARKAR1, L. DONATO1 1 Nestle Research Centre, Lausanne, CH-1000, Switzerland
For the past 10-20 years there has been keen interest in understanding how foods in general and lipids in particular are transformed during consumption, digestion, and absorption. This research has yielded great insight into digestive physiology and the description of different strategies to control digestion. We ourselves, like many other excellent groups have been particularly interested in the regulation of fat digestion because of its high caloric density, strong hedonic appeal and relatively mild satiating power. The main mechanisms that these works have used to regulate fat digestion are to control lipases’ ability to bind to the interface of emulsified fat droplets, either by; inhibiting enzyme activity [1, 2], controlling the composition of the interface [3-6], controlling the area of the interface [7, 8] or encapsulation [9]. A number of groups have demonstrated in vitro and/or in vivo that such approaches can have considerable effects on; the rate [7, 8] and/or the extent [1, 10] of fat digestion. Whilst most of these studies have focused on controlling the adsorption of lipase to the interface of fat droplets, there have been relatively few studies that focus on controlling the transport of lipase to interface, using (protein) hydrogels, for example.[11, 12] In this presentation we will describe how entrapment of lipid emulsions within protein gels of various types impacts the kinetics of fat digestion.[13] We aim to develop a mechanistic understanding of how gel architecture (particularly gel digestibility, porosity, and network architecture) impacts the transport of enzymes/digesta through a protein hydrogel and how this relates to the rate of lipolysis. In addition we will highlight how the mesoscale structure of a protein gel can impact not only the kinetics of fat digestion, but also the time of initiation. We hope these new findings help to evolve our detailed understanding of the digestion in simple systems to more complex mixed food structures.
[1] Carriere, F., Renou, C., Ransac, S., Lopez, V., et al., Effect of Orlistat on lipolysis following standard test meals. Gastroenterology 1999, 116, A543-A543. [2] Daher, G. C., Cooper, D. A., Zorich, N. L., King, D., et al., Olestra ingestion and dietary fat absorption in humans. Journal of Nutrition 1997, 127, 1694S-1698S [3] Chu, B. S., Rich, G. T., Ridout, M. J., Faulks, R. M., et al., Modulating Pancreatic Lipase Activity with Galactolipids: Effects of Emulsion Interfacial Composition. Langmuir 2009, 25, 9352-9360 [4] Sandra, S., Decker, E. A., McClements, D. J., Effect of interfacial protein cross-linking on the in vitro digestibility of emulsified corn oil by pancreatic lipase. Journal of Agricultural and Food Chemistry 2008, 56, 7488-7494. [5] Wickham, M., Garrood, M., Leney, J., Wilson, P. D. G., Fillery-Travis, A., Modification of a Phospholipid Stabilized Emulsion Interface by Bile Salt: Effect on Pancreatic Lipase Activity. Journal of Lipid Research 1998, 39, 623-632. [6] Maldonado-Valderrama, J., Wilde, P., Macierzanka, A., Mackie, A., The role of bile salts in digestion. Advances in Colloid & Interface Science 2011, 165, 36-46. [7] Golding, M., Wooster, T. J., Day, L., Xu, M., et al., Impact of gastric structuring on the lipolysis of emulsified lipids. Soft Matter 2011, 7, 3513-3523 [8] Seimon, R. V., Wooster, T., Otto, B., Golding, M., et al., The droplet size of intraduodenal fat emulsions influences antropyloroduodenal motility, hormone release, and appetite in healthy males. American Journal of Clinical Nutrition 2009, 89, 1729-1736. [9] Li, Y., Hu, M., Du, Y.-M., Xiao, H., McClements, D. J., Control of lipase digestibility of emulsified lipids by encapsulation within calcium alginate beads. Food Hydrocolloids 2010, 25, 122-130 [10] Sjostrom, L., Rissanen, A., Andersen, T., Boldrin, M., et al., Randomized placebo-controlled trial of orlistat for weight loss and prevention of weight regain in obese patients. Lancet 1998, 352, 167-173. [11] Guo, Q., Ye, A., Lad, M., Dalgleish, D., Singh, H., Impact of colloidal structure of gastric digesta on in-vitro intestinal digestion of whey protein emulsion gels. Food Hydrocolloids 2016, 54, 255-265 [12] Guo, Q., Ye, A., Lad, M., Ferrua, M., et al., Disintegration kinetics of food gels during gastric digestion and its role on gastric emptying: an in vitro analysis. Food Funct. 2015, 6, 756-764. [13] Sarkar, A., Juan, J.-M., Kolodziejczyk, E., Acquistapace, S., et al., Impact of P rotein Gel Porosity on the Digestion of Lipid Emulsions. J. Agric. Food Chem. 2015, 63, 8829-8837