18 p 12_23_e

L1N18P085 www.professionalpasta.it [email protected]

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Evolution in dough ingredientsThe migration of water, theinfluence of water content andthe increase in temperatureduring dough formation havebeen the subject of a number ofstudies in recent years.Some testing has examineddoughs with a range of mois-ture content which were thenheated by conventional meansto various temperatures. Watercontent was monitored with aprobe throughout the conven-tional heating in three points:at the centre of the samples,midway between the centreand surface layer and on thesurface layer.The rheology of the samplessubjected to heat treatment wasmeasured using stress tests, themicrostructure of the sampleswas evaluated using CLSM(Confocal laser scanning micros-copy), while microstructuralparameters were evaluatedusing image analysis.

The most significant resultsshowed that there was abso-lutely no water migrationwithin the dough up to an inter-nal sample temperature of 80°C;clear confirmation also exists toindicate that water content andheating range have a bearing onthe rheologic and structuralproperties of the dough.In dough samples with highmoisture levels, the formationof the gluten lattice structure ismore pronounced and reducesthe hydration capacity of thestarch particles; similarly, lowmoisture levels produce a looserprotein lattice structure thatfacilitates starch hydration.At higher temperature, starchparticles have less time toabsorb water, thus causing anincrease in the swelling temper-ature.Rapid heating subjects the pastato increased structural deforma-tion and leads to the formationof smaller pores; it could be that

the size of the pores has a bear-ing on the sample’s capacity toresist stress before breaking.Low moisture samples havesmaller-sized pores. The energyrequired to obtain breaks in therapidly-heated dough is higherthan that in samples heatedslowly (Thorvaldsson, K. et al.,1999).Evaluation of the variation ingluten strength, rheologic prop-erties and cooking quality ofspaghetti has shown increasedinvolvement of the protein frac-tion of hard wheat not soluble inwater. The viscosity of thedissolved gluten in a suitablebuffer is strictly correlated to theamino acid balance of theproteins, with the strength ofthe protein lattice structure thatis formed and the cooking qual-ity of the spaghetti (Dexter, J.E.et al., 1980).Pasta quality is influenced notonly by the protein content, butalso the properties of the

IS PASTA AS GOOD AS IT USED TO BE? SOME SUGGESTIONS

FOR A “NEW” PRODUCT WITH 2000 YEARS OF HISTORY

Alessio Marchesani - Ilaria Soncini

Food industry research continues tobear new fruit. To bring ourselvesup-to-date, we undertook a surveyof leading international publica-tions and what follows is oursummary of the technical and tech-nology-related informationcontained in the articles, edited tomake it more accessible. We areconfident that a close study willprovide the basis for a wealth of newideas as well as new applications fortechnologies already in use.

starch. As a matter of fact,although gluten remains theprimary agent involved on anultra-structural level, starch isalso involved, since glutenforms a protein network thatretains it and lends body andstructure to the product. Thesecharacteristics, together withthe hydration capacity of thestarch and its gelatinizationproperties, are the principlequality attributes in pasta(Delcour, J.A. et al., 2000).The removal of surface proteinsand lipids from starch particlesclearly influences both rheologicand structural properties, butnot interaction with othercomponents. Lipids andproteins present on the surfaceof starch particles do not influ-ence the latter’s interactionwith gluten which is primarilyconnected with phenomena ofphysical inclusion of theamylaceous particles by thegluten lattice structure. Highdrying temperatures promoteformation of the protein latticestructure that renders starchparticles less educible andlimits their gelatinization and

swelling during cooking. As aconsequence, the quality andquantity of this lattice structureare correlated to the physicalproperties of the cooked pasta(Vansteelandt, J. et al., 1998).

Starch and GlutenDuring kneading, the hydro-gen and hydrophobic sulfidebonds that affect the proteinsare partially split and the mainresult is a change in solubility,which generally increases. Thisis caused by the decrease in thesize of the protein compoundsfollowing the disaggregationand depolymerization of thegluteninic sub-units of heavymolecular weight.During the extrusion phase, theproteins are denatured and thechemical bonds are weakened asa result of the rise in temperatureand the mechanical action of thescrew conveyor and die on thedough. The primary result is areduction in protein solubility.The changes encounteredduring the kneading phase canbe more evident than thedifferences normally encoun-tered between various types of

wheat. Lamination reducesgluten content and increasesprotein gel. This could becaused by the increase intemperature during lamination(as a result of the mechanicalenergy provided) that dena-tures the proteins (Hayta, M. etal., 2001).In soft and hard wheat, starchgelatinization is not completedwithin a temperature range of60°C and 100°C; the final degreeof gelatinization (FDG) of softwheat starch is higher, both inthe lab and on-site, and theprocess kinetics are higher.These differences are due to thevariation in structure andtexture of the two types ofwheat.The aspects mentioned formthe basis of the different waysthe two types of wheat behaveduring pasta making. As amatter of fact, during produc-tion of dry pasta, gelatinizationis quite undesirable because itnoticeably reduces pasta qual-ity during cooking by makingits texture less resilient to cook-ing and promoting the loss ofstarch part ic les from the

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protein lattice struc-ture, making the prod-uct sticky (Turhan, M.et al., 2002).During the first doughdrying phase, thestarch particles (espe-cial ly the smallerones), become lesseducible, probablydue to the interactionwith the gluten andphysical/structuralincorporation. Thesechanges are not tied toeither the amylosecontent or the struc-tural variations intheir alignment withinthe dough, given thefact that the environ-mental temperatureand humidity do notpromote these varia-tions.The majority of thechanges observedregarding starchbehaviour are seenduring the first dryingphase even if, in real-ity, they should also beevident during otherphases of pastadrying. As a result ofthe changes under-gone by the starch,there should be areduction in viscosityand gelatinizationtemperature and anincrease in swellingand solubility.In particular, hightemperature dryingtreatments provokemost changes in thechemica l -phys ica lcharacterist ics ofstarch, with a conse-quent hardening of

the structure and decrease in the solubility andswelling capacity of the particle. This leads moregenerally to a loss in permeability and a reductionin amylose loss during the product cooking phase(Vansteelandt, J. et al., 1998).In terms of gluten, drying at high temperaturescauses a reduction in its content with consequentformation of protein gel and increase in its latticestructure.At low temperatures, starch undergoes verydifferent types of change. At moisture levels ofover 30%, it takes on a definite regular lamellarstructure. During freezing, the expansion of thefree water outside the lamellae causes thesemi-crystal lamellar structure in the particles tocompress; contrariwise, the more rigid crystallinefraction remains predominantly unaltered. Thisis because the unformed lamellae themselves actas cushions to absorb the compression pressure,thus protecting the crystal structure. Once maxi-mum compression has been reached (with areduction in volume of up to one-third the initialvalue), if further stress is applied, the lamellae arebent out of shape losing their perpendicularalignment, and a wavy structure is created withinthe semi-crystal growth rings.This occurs above all in starches with a low percent-age of amylose (i.e., corn), that are therefore moresensitive to freezing. From this it can be deducedthat amylose is critical in response to applied stress.An initial hypothesis would suggest that the pres-ence of amylose within the unformed lamellaecould limit the amount of compression possible to acertain degree; the entanglements between thelinear amylose chains and amylopectin helixescould react as a type of temporary physicalcross-link, rendering the unformed lamellae fairly

rigid and incapable ofbeing compressed.A second hypothesisconcerns the presenceof amylose withinunformed particle areaswhich could act as“diluent”, reducing thecoupling between theamylopectin branchesin the neighbouringlamellae, as well as thetransmission of stressthrough the particle.More generally, itcould be stated thatlow temperatures donot cause significantdamage to the starchpart ic le structure.Those changes that dooccur are completelyreversible followingheating. Even follow-ing a freezing/thaw-ing cycle, no signifi-cant damage is noted(Perry, P.A. et al. ,2000).Following thawing,complex foodstuffspreserved at lowtemperatures couldundergo structuraldamage, underminingproduct integrality.Temperature fluctua-tions during storagelead to re-crystal-lization that has drasticeffects on producttexture.The ice crystals formedgradually increase insize and create internalrupturing. Starch gel,like other gels withhigh water content, areparticularly susceptibleto this type of damage.

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The evolution of the phasesthat make up the freezingprocess (nucleation, crystalpropagation, maturation) isinfluenced by the ingredientsin food products.Hydrocolloids are frequentlyused as additives to control thetexture and stability of frozenfoods. Polysaccharides, espe-cially, could cause a significantreduction in the presence ofgrowth of ice crystals, but theexact mechanism involved isnot known. Polysaccharidesolutions increase the viscosityof the system, although thisdoes not seem to be the deter-mining factor in the growth ofice crystals. In fact, it has beennoted that there is a reducedcorrelation between viscosityand crystal development,while their steric hindrance issignificant. As they expand,they are trapped within thepolymeric chains, the result ofwhich is the formation of poly-mer gel that reduces crystalliza-tion in relation to the level ofbranching and gel strength.Polysaccharides of variousorigins and shapes, such asxanthane (complex, hel i-cal-shaped polymer) andgalactomannan (with linearstructure and galactose sidechains), do not gelatinizeexcept when used simulta-neously, influencing ice crys-tallization using differentmechanisms. Therefore, thepresence of polysaccharideadditives can influence freez-ing stability of starch gel to agreater or lesser degree,depending on its origin andinteractions produced (Lo, C.T.et al., 2000).

Microscopic analysis andstructural evaluationThe microscope is the mostuseful instrument for studyingthe structure and changes instarch particles. Non-invasivestudy of particles using polar-ized light is the simplest andmost useful for monitoring theinternal changes that take placeduring the growth, storage andprocessing of the kernel.Following prolonged contactbetween starch and a liquidmedium, surface exudationfrom the inside towards theoutside of the medium can benoted. This could be importantfor its behaviour in varioustransformation stages: swell-ing, agglomeration and main-tenance of granular appear-ance of the processed product.Illumination of the starch parti-cles using polarized light andlaser rays perpendicular to thepolarized light ray guaranteesthat exudation can be observedthrough an optical microscope(Starzyk, F. et al., 2001).Recently, a fairly new tech-nique, CLSM microscopy, hasbeen introduced for the struc-tural analysis of biological andalimentary material. Unlike theoptical microscope, the lightsource is replaced by a laserwith a scanning unit and suit-ably-sized hole in the rear focalplane that improves the limitedfocusing depth. This systemhas proved useful for obtainingthree-dimensional informationon the structure of tuber paren-chyma and the properties ofprotein and amylose lattices inwheat-based products. It mayalso be used to study the surfaceproperties of pasta through“reflectometric” examination(Durrenberger, M.B. et al., 2001).

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The high resolution electron microscope mayalso be utilized to study the microstructure ofdry or cooked pasta if a sample is preparedthrough freezing and fracturing.Pasta represents an interesting water-starch-protein system in which, during processing andcooking phases, competition over water iscreated between the starch and protein thatgives rise to structural changes and two-wayinteraction. Understanding of these phenom-ena can be enhanced by studying the “fine”structure of pasta. In this case, it has been shownthat the “freeze-fracturing” method mentionedabove is one of the most effective methods forobserving the heat-induced modifications onthe starch ultrastructure in systems with lowwater content. These are not easily observableusing other electron microscopy methods (Lo,C.T. et al., 2000).

Microwave heatingAnalysis of various microwave-treated samplesreveals an inverse correlation between thefrequency utilized and the sample temperature.This occurs because radiation penetration andenergy absorption are more efficient at lowfrequencies (e.g., 900 mHz). However, on an

industrial level, higher frequency levels arepreferred because it is easier to control thetemperature within the food matrix.When using microwaves, the shape (size andsymmetry) of the sample and the direction of therays are of fundamental importance and boththese variables have a direct bearing on uniformenergy distribution. The presence of a highcontent of ionic solutes influences heating effi-ciency: given the same sample and parity ofconditions, high concentrations produce highertemperatures.Of special interest is the diffusion of heat withinthe sample. If the sample is fairly large, heat isdiffused slowly from the surface towards theinterior, while if it is small, heating occurs moreevenly.Axial rotation of the samples and productionsystem with on/off cycles represents a techno-logical improvement (Oliveira, M.E.C. et al.,2002).Given the high kinetics, heated amylose prod-ucts have lower starch gelatinization. Micro-wave heating of moist solid products creates apositive flow of water towards the outside andcauses an increase in internal steam pressurewhich also enhances surface evaporation(Sumnu, G., 2001).Recently, microwave technology has also beenintroduced into the pasteurizat ion ofpre-packaged, ready-to-serve products. This hasproven to be an excellent solution because thevolumetric transfer of heat assures rapid heatingof the package contents, thus avoidingprolonged autoclave treatment that is moreharmful for heat-sensitive substances (nutrientsor organoleptic components).

High pressureA number of different products may be treated,but they must possess some common character-istics: minimum water content, not be overly-porous (given temporary deformation duringtreatment) and must be packed in flexible pack-aging materials. This technique makes it possi-ble to treat semi-processed products inlarge-size packages as well as consumer foods. Italso has very low environmental impact becauseno polluting emissions are produced.There is significant published research onlow-acid foods sanitized using high pressure

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and low temperatures. However, the problem ofmicrobial spores cannot be solved through theuse of high pressure alone - high temperaturesmust also be employed.Data is available regarding the destruction ofBacillus stearothermophilus (one of the mostheat-resistant bacteria) in the range of 6 decimalpoints with a treatment at 600 MPa (approx. 6000atm) and temperature of 70°C for 5 minutes,repeated 5 times (Hayakawa, I. et al., 1994).Other methods (Pulsed High Pressure, PHP)make use of initially low pressure cycles (60MPa) that subsequently increase (500 MPa), at atemperature of 70°C. If the cycle is repeatedapprox. 10 times, any spores present are alsoeliminated because they germinate betweencycles and are deactivated by the succeedingcycle (Sojka, B. et al., 1997).In recent studies, thanks to significant testing,the exact ideal conditions for obtaining sanitiza-tion of certain products such as macaroni andcheese have been identified.Strains of Clostridium sporogenes and Bacilluscereus were used as indicators of successful treat-ment, with significant attention given to theinitial spore level, treatment times and tempera-tures as well as number of cycles.With the use of fairly low temperatures, it isobvious that final product quality is enhanced.However, this also depends on the quality of thepackaging (suitably designed and adapted tothe chemical/physical features of the product)and the fluid used to exert pressure (Meyer, R.S.et al., 2000).In terms of starch, treatment at a few hundredMPa causes the gelatinization with characteris-tics quite different from that obtained throughheating. In particular, the particle structure -completely destroyed by heat - remains intact.In the pasta industry, this type of treatmentcould be used for “mild” pasteurizing of pack-aged fresh pasta or ready-to-serve pasta disheswhose organoleptic qualities are stronglyaffected by higher temperatures.

Modified atmosphereThe chemical/physical principles on whichmodified atmosphere packaging (MAP) is basedcall for the replacement of the atmospheresurrounding the product with a special mix ofgas, in conjunction with refrigeration. The

results that can be obtained through this packag-ing technology are a reduction in the rate of manybiochemical processes that cause product deteri-oration and, more generally, the inhibition of thegrowth of contaminating micro-organisms. Thepreserving action of the gas is enhanced byrefrigeration that reduces the speed of microbeproliferation and enzymatic reactions ingeneral, the primary causes of organolepticdecrease of the product. Through study of“balanced” dishes, it has been verified that, froma nutritional standpoint, initial product charac-teristics remain substantially unchanged withMAP.A number of tests performed on ready-to-servepasta dishes show that the fatty acids (and peroxyacids) in the event the pasta was prepared withanimal fats, remains unchanged, whereas vege-table pasta reveals a higher level of peroxides,probably due to a residual oxidative-type enzy-matic reactivity. Failure to blanch fresh vegeta-bles and the mild way they are cooked couldexplain the continued presence of an oxidativeprocess and, therefore, the high number ofperoxides found in this type of product.To evaluate suitability and trends in preserva-

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tion technology, oxidation

reactions for β-carotene andvitamin E were monitored. Thedata collected confirms that themaintenance of samples inoptimal condition throughouttheir shelf-life does not alterthese quality indices.Comparing freezing technol-ogy with MAP, the percentageof resistant starch formed dueto retrogradation was also eval-uated. The results obtained donot show any differencesbetween the two preservationmethods.Overall, the results of the anal-yses performed on samplesshowed that, for the nutritionalprinciples evaluated, a combi-nation of modified atmosphereand refrigeration technologiesis capable of conserving the

nutritional value of a productfor over three weeks. The use ofpositive temperature MAP toavoid the formation of ice crys-tals, results in a product withbetter texture and flavour thanthe same product when frozen.On the other hand, it must beconsidered that the efficacy ofMAP in guaranteeing the qual-ity of both a single productcategory and a prepared dishdepends on the quality of theraw materials and preservationmethod (Simpson, M.V. et al.,1994).

Hygienic quality and shelf-lifeof fresh pastaFilled fresh pasta is often modi-fied atmosphere packaged. Inthis type of product, primarilybacillus-type bacteria have

been isolated, but no patho-genic bacteria.As a result of the variety incomposition and heat treat-ments which the samples pres-ent on the market have beensubjected to during produc-tion, shelf-life at 4°C variedgreatly, from less than 3 days toapproximately 30. The resultsobtained suggest that theshelf-life for this product cate-gory is not just influenced bythe number of bacteria cellsthat have survived heat treat-ment, but also by themicro-structural and texturechanges caused by the treat-ment itself. Through testing, itwas seen that Staphylococcusaureus cel ls reproduce attemperatures over 7°C, espe-cially if the water activity valueis greater than 0.97 (ChavesLopez, C. et al., 1998).From the findings of a particu-lar study on the parameters (awand pH) that influence micro-bial proliferation in filled pastaand gnocchi, it emerged thatsome products available on themarket have values that wouldallow the germination ofClostridium botulinum spores.This microbial development isclearly favoured only in modi-fied atmosphere packagedproducts since this is strictly ananaerobic pathogen. This givesrise to the need for enhancedmonitoring of the aboveparameters, as well as storagetemperature (not to exceed4°C), in order to guarantee highlevel product safety (Schebor,C. et al., 2000).

Technology and qualityFor an evaluation of the effectof high pasta drying tempera-tures, an analysis of pasta cook-

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ing quality and starch proper-ties was made. The most signifi-cant results indicate that betterf inal product quali ty isobtained using the VHT (VeryHigh Temperature) methodrather than the HT (HighTemperature) method. It isimportant to stress that it is thechanges in starch particleshape during drying that influ-ence, above all, the pasta’scooking properties, reducingthe levels of starch loss (Güler,S. et al., 2002).Unfortunately, these dryingtreatments promote theunwanted formation of Maillardcompounds.At temperatures lessthan 120°C it is very low, while at150°C it increases seven-fold. Thecoloured molecules with lowmolecular weight are trapped inthe lattice formed by the glutenprotein with high molecularweight, giving the product abrownish tint (Fogliano, V. et al.,1999).Knowledge of redox phenom-ena caused by oxygen reductaseand mechanisms of this reactionduring dough making isextremely important.The study of peroxidase,p o l y p h e n o l o x i d a s e ,l ipoxigenase and catalaseenzyme activity has made itpossible to better understandthe productive phases in whichtheir effects become importantin light of some special qualita-tive characteristics of pasta,such as colour and cookingquality. Polyunsaturated fattyacids are easily oxidizable andproduce a negative evolutionnot only in organoleptic qual-ity, but above all in structure,negatively impacting onvisco-elasticity and stickiness(fundamental characteristics in

the cooking phase). Just asimportant would be an exami-nation of the effect of redoxphenomena on the structuralproperties of the gluten, on theevolution of phenolic compoundsand carotenoid pigmentswhich lead to a loss in colour(yellow) and “gloss” of thefinished product (Icard, C. etal., 1997).In fatty flour extrusion technol-ogy, the use of additives influ-ences the loss of the product’slipidic fraction. If the lipidiccontent is high, there is a highand unwanted reduction in fatsduring the extrusion and toast-ing phases. Using electricalconductivity analysis, it hasbeen shown that lecithin (asopposed to gum arabic andguar) is the best additive forpreventing the loss of fat inoil/water emulsions.A pilot production of extrudedflakes from pre-gelatinizedrice, wheat and almond flourswith added soy lecithin,subjected to rheologic, chemi-cal and physical tests, as well assensory analysis, has shown, inaddition to lecithin as an addi-tive, wheat flour is the best basefor the production of almondsnacks (De Pilli, T. et al., 2001).

A

Acids (polyunsaturated fatty)

Fatty acids that possess more than one double bond

between carbon atoms within a hydrocarbon chain.

They are generally of vegetable origin and have

greater resistance to oxidation than saturated fats

thanks to the double bond between them.

Amylopectin

Main component of cereal and tuber starch, formed

by branching glucose chains.

Amylose

Portion of the starch composed of long linear glucose

chains; comprises approx. 20% of cereal starch.

Amino acid

Organic compounds which, through special chemi-

cal bonds, form the basis of protein structures.

C

Catalase

Enzyme* that promotes the decomposition of hydro-

gen peroxide with the production of oxygen gas.

Catalyst

Substance that increases the speed of a chemical

reaction without undergoing transformation or any

other type of chemical change.

CLSM (Confocal Laser Scanning Microscopy)

New microscopy technology that makes it possible to

produce an optic section of a sample through the use

of a laser beam. The progressive shift of the focal

plane towards the interior of the sample makes it

possible to obtain complete 3-dimensional images

of the product.

Cooking quality

When referring to pasta, all those characteristics that

give cooked pasta the best appearance and texture.

It may be quantified through measuring such param-

eters as elasticity, bite, surface stickiness, water

absorption, cooking resistance, amount of swelling,

etc.

D

Dough

Product obtained by the mixture of raw materials (for

example, water and semolina) in the correct propor-

tions. Correct preparation, fundamental to obtain-

ing a quality product, requires uniform hydration of

the solid particles (semolina, flour) with subsequent

gluten formation.

E

Enzyme

Protein that acts as a catalyst* in biochemical reac-

tions; each enzyme is specific to a given reaction or

group of similar actions.

F

Freezing (crystal nucleation, propagation,

maturation)

Method of conservation at low temperatures (no

higher than -18°C). There are three different phases

in freezing. Nucleation begins with the appearance

of pointed ice crystals, normally around 0°C to -7°C;

propagation increases ice nuclei through the addi-

tion of new small crystals; maturation is attained

when most of the water has been frozen.

G

Galactomannan

Polymer of galactose and mannose present, in

particular, between legume glucides and yeasts.

Galactose

Simple sugar, it has the same chemical formula as

glucose, but with a different atomic arrangement.

Gelatinization

Surface modification of the amylaceous seed

through the combined effect of heat and moisture. A

gelatinized starch takes on new chemical/physical

properties; an impermeable film forms on the prod-

uct surface that reduces the loss of hydro-soluble

nutrients during soaking or cooking in water.

Gluten (gluten lattice)

Gluten is a protein compound comprised of gliadin

and glutenin*, protein fractions present within the

wheat kernel. In flour and semolina, these proteins

are separated, but in the presence of water (knead-

ing phase) they become hydrated, creating a

complex structure. The gliadins take on a fibril shape

(dough extendibility), while the glutenins become

more compact in structure. Together they form a

lattice that captures the starch particles present in

the flour to form the dough.

Glutenin (gluteninic sub-unit)

Proteins with a distinct tendency to combine, primar-

ily through hydrogen bonds, sulfide bridges and

hydrophobic* interaction. Following the severing of

sulfide bridges in the presence of a reducer, a

number of sub-units with different molecular weight

and characteristics are formed. Together with

gliadin, makes up gluten.

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GLOSSARY

H

Humidity

Absolute amount of water contained in the atmo-

sphere.

Hydrocolloids

High molecular weight polysaccharides with hydro-

phobic and hydrophilic areas; this guarantees their

emulsifying and thickening properties on localized

elements in the aqueous phase of a food product.

These products (natural or man-made) are used as

additives to lend viscosity or gelification to a food

product.

Hydrogen bond

Type of electrostatic interaction between molecules

with hydrogen atoms bonded to other atoms such as

fluorine, nitrogen and oxygen.

Hydrophilic

Substance with an affinity for water, rendering it

soluble in water.

Hydroperoxide

Product of the oxidation of a fatty acid.

Hydrophobic

Substance with little (or no) affinity for water because

of its molecular structure, rendering it insoluble in

water.

I

Ionic solutes

Substances dissolved within a matrix in the form of

ions (molecules or atoms with an electrical charge).

L

Lamination (of the dough)

The dough* may be laminated by passing through

rollers set variable distances apart. Through this

operation, the pasta is stretched to reduce sheet

thickness. Passage through a series of rollers that are

increasingly close together creates the desired

dough thickness. A series of passes instead of just

one is used to avoid the dough being subjected to

excessive compression.

Light polarization

Process by which the vibrations of the electrical

vector of the light waves are forced along a single

direction.

Lipoxygenase

Enzyme* of vegetable and microbial origin, respon-

sible for the oxidation of polyunsaturated essential

fatty acids to produce hydroperoxides*.

Lipoxygenase action provokes the destruction of

oxidizable liposoluble vitamins.

M

Maillard Reaction, Compounds

Reaction that takes place between an amino acid*

and a sugar during prolonged heating (or at very

high temperatures) of a food. Among the final prod-

ucts of this reaction are dark compounds responsible

for the non-enzymatic browning of the food surface

and volatile compounds responsible for aroma. In

general, the intensity of the reaction is proportional

to the amount of heat, increases as pH increases and

is at its maximum at a relative humidity of between

40% and 70%. It should be stressed that in some

products it is undesirable (for example, in dry pasta),

while in others it is an essential aspect of the product

itself (e.g., bread).

Mannose

Simple sugar, it has the same chemical formula as

glucose, but with a different atomic arrangement.

Microbial spores

Forms of resistance developed by certain types of

micro-organisms in order to survive in unfavourable

environments. They are very resistant to external

agents, heat in particular, and are capable of

re-germinating once conditions optimal to them

have been restored.

Microwave heating

Electromagnetic energy, absorbed primarily by

water, causes friction on a molecular level that is

translated into heat loss. The microwaves heat the

food from the centre, not from the surface. Biochem-

ical effects seem comparable to those observed

using traditional methods.

“Mild” pasteurization

Pasteurization is utilized to obtain a hygieni-

cally-safe product. Its purpose is to destroy the

saprophyte and pathogenic microbial level present

in a food, generally through a heat treatment. The

adjective “mild” indicates the use of technologies

that do not impair the nutritional and organoleptic

characteristics of a food (as do microwaves or high

pressure, for example).

Modified atmosphere packaging (MAP)

Packing technology used for perishable products to

extend shelf-life. Consists of the elimination of air

within a package and its substitution with a mixture

of inert gases (normally carbon dioxide and nitro-

gen). The function of the gases is to block the prolif-

eration of certain micro-organisms (does not affect

Gram positive bacteria) and certain enzymes, but

without altering the food product. The packaging

utilized must be impervious to gas and water in order

to avoid exchange with the outside environment.

MAP products must be refrigerated to guarantee a

level of stability over time. However, much of

shelf-life depends on the initial characteristics of the

food product (pH, quality of ingredients, initial level

of contamination).

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P

Peroxidase

Enzyme that promotes substrate oxidation in the

presence of hydrogen peroxide and peroxides.

Polarized light

Light beam that behaves differently in all directions

around the propagation beam. Polarized light is

differentiated from natural light by the fact that its

vibrations, instead of being directed in all directions

perpendicular to the propagation vibrations, follow

defined trajectories.

Polymer

Substance made up of giant molecules formed by

smaller, repeating structural units.

Polypeptides, polypeptide chains

Organic compounds which, organized in complex

structures, form the basis of complex proteins. They

are comprised of chains of 10 or more amino acids*

joined together.

Polyphenoloxidase

Enzymatic system whose function is to oxidize mono-

and polyphenols. These are the cause behind the

enzymatic darkening seen in a number of vegetable

products.

Polisaccharide

Compound comprised of long chains of simple

sugars (monosaccharides).

Protein depolymerization/denaturation

Partial or complete development of the complex

structure of polypeptide chains* that leads to the loss

of specific protein functions.

R

Redox phenomena

Phenomena connected to oxidation-reduction reac-

tions of biological matrices or compounds. They are

catalyzed by specific enzymes and are effected

through the transfer of electrons from one substrate

to another.

Relative humidity

Amount of water present in the atmosphere calcu-

lated on the basis of the relationship between the

water present in a cubic metre of free air, and that

which should be contained in a cubic metre of air

saturated with vapour at a given temperature.

Rheology (rheologic properties)

Studies the motion and deformation of natural

bodies with special emphasis on fluids without

consistency and include, as extreme cases, purely

viscous (newtonian) fluids and elastic solids. There-

fore, the unique characteristic of rheology is the

study of the behaviour of substances that are both

elastic and viscous.

S

Sanitization

Series of cleaning and disinfecting operations

performed periodically on equipment and the produc-

tion environment; also used in reference to tech-

niques utilized to prevent or combat the presence of

micro-organisms in the product.

Shelf-life

In reference to a food product, it means how long a

product can stay on the shelf. It is the length of time the

organoleptic, nutritional and hygienic characteristics of

a food are maintained unaltered. It refers to commercial

stability and is not the same as product deterioration.

Stabilization

Series of operations that allow a food to reach a

condition of equilibrium from a chemical, physical

and microbiological standpoint (sterilization, drying,

addition of preservatives-stabilizers, etc.).

Starch retrogradation

Physical phenomenon comprised of a return to the

innate, crystalline structure of a starch which had previ-

ously undergone gelatinization* during heating and

whose linear amylose chains tend to return to their

initial structure. Starch retrogradation may be hindered

by the use of chemical agents (texture agents) that

prevent amylose returning to its innate configuration by

inserting itself between the starch chains separated by

gelatinization. In pasta, this is a negative factor that

creates stickiness and problems during cooking.

Steric hindrance

Effect by which a chemical reaction is slowed or

hindered because of the presence in a reagent of

large-size groups that make it impossible for another

reagent molecule to approach.

Sulfide bridge

Bond between two sulphur atoms within a complex

molecule.

T

Texture

All those physical, mechanical and rheologic proper-

ties of a food product perceived by the sense organs.

V

Viscosity

Physical magnitude that describes the attrition within a

fluid, i.e. the tendency of a fluid layer in motion to pull

other, immediately-adjacent, layers along with it.

X

Xanthane

Polysaccharide of microbial origin comprised of glucose

chains; used as a texture agent in the food industry

because of its hydrocolloid* properties.

22


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Chavez Lopez C., Vannini L., Lanciotti R.,Guerzoni E. (1998). Microbiological quality of filledpasta in relations to the nature of heat treatment. J. ofFood Protection, 61 n. 8, pp. 994-999.

De Pilli T., Severini C., Baiano A., GuidolinE., Legrand J., Massini R. (2001). Application duprocédé d’extrusion aux farines grasses: cas de la fari-ne d’amande. Sciences des aliments, 21, pp.519-536.

Delcour J.A., Vansteelandt J., Hythier M.C.,Abécassis J., Sindic M., Deroanne C. (2000). Frac-tionation and reconstitution experiments provideinsight into the role of gluten and starch interactionsin pasta quality. J. Agric. Food Chem., 48, pp.3767-3773.

Dexter J.E., Matsuo R.R. (1980). Relationshipbetween durum wheat protein properties and pastadough rheology and spaghetti cooking quality. J. ofAgriculture and Food Chemistry, 28, pp.899-902.

Durrenberger M.B. , Handschin S. ,Conde-Petit B., Escher F. (2001). Visualization offood structure by confocal laser scanning microscopy(CLSM). Lebnsm. - Wiss. U. Technol., 34, pp.11-17.

Fogliano V., Monti S.M., Musella T.,Randazzo G., Ritieni A. (1999). Formation of colo-ured Maillard reactions products in a gluten-glucosemodel system. Food Chemistry, 66, pp. 293-299.

Güler S., Köksel H., Ng P.K.W. (2002). Effectsof industrial pasta drying temperatures on starchproperties and pasta quality. Food Research Inter-national, 35, pp. 421-427.

Hayakawa I., Kanno T., Yoshiyama K., FujioY. (1994). Oscillatory compared with continuoushigh pressure sterilization on Bacillus stearother-mophilus spores. J. Food Science, 59, pp. 164-167.

Hayta M., Alpaslan M. (2001). Effects ofprocessing on biochemical and rhelogical propertiesof wheat gluten proteins. Nahrung/Food, 45 n. 5,pp. 304-308.

Icard C., Feillet P. (1997). Effets des phénomé-nes d’oxydoreductions au cours de la fabrication despâtes alimentaires. Ind. Alim. Agr., gen.-feb., pp.4-19.

Lo C.T., Ramsden L. (2000). Effects of xanthanand galactomannan on the freeze/thaw properties ofstarch gel. Nahrung, 44 n. 3, pp. 211-214.

Meyer R.S., Cooper K.L., Knorr D., LelieveldH.L.M. (2000). High pressure sterilization of foods.Food Technology, 54 n. 11, pp. 57-72.

Oliveira M.E.C., Franca A.S. (2002). Micro-wave heating of foodstuffs. J. of Food Engineering,53, pp. 347-359.

Perry P.A., Donald A. M. (2000). The effects oflow temperatures on starch granule structure.Polymer, 41, pp. 6361-6373.

Schebor C., Chirife J. (2000). A survey of wateractivity and pH values in fresh pasta packed undermodified atmosphere manufactured in Argentinaand Uruguay. J. of Food Protection, 63 n. 7, pp.965-969.

Simpson M.V., Smith J.P., Simpson B.K.,Ramaswamy H., Dodds K.L. (1994). Storagestudies on a sous vide spaghetti and meat sauceproduct. Food Microbiology, 11, pp. 5-14.

Sojka B., Ludwig H. (1997). Effects of rapidpressure changes on the inactivation of Bacillussubtilis spore. Pharmazeutische Industrie, 59,pp. 436-438.

Starzyk F., Lii C., Tomasik P. (2001). Visiblelight absorption, transmission and scattering bypotato starch granules. Polish J. of Food andNutrition Sciences, 10/51 n. 4, pp. 27-34.

Thorvaldsson K., Stading M., Nilsson K.,Kidman S., Langton M. (1999). Rheology and struc-ture of heat-treated pasta dough: influence of watercontent and heating rate. Lebnsm. - Wiss. U.Technol., 32, pp. 154-161.

Turhan M., Gunasekaran S. (2002). Kineticsof in situ and in vitro gelatinization of hard and softwheat starches during cooking in water. J. of FoodEngineering, 52, pp. 1-7.

Vansteelandt J., Delcour J.A. (1998). Physicalbehavior of durum wheat starch (Triticum durum)during industrial pasta processing. J. of Agricultu-re and Food Chemistry, 46, pp. 2499-2503.

BIBLIOGRAPHY

18 p 12_23_e

Documents

dough samples

dough formation

migration of water

water migration

samples capacity

protein content

heated dough

influence of water content