CARBOHYDRATES P o l y s a c c h a r i d
e s
INTRODUCTION
Carbohydrates are organic molecules in which carbon, hydrogen, and oxygen bond together in the ratio: Cx(H2O)y, where x and y are whole numbers that differ depending on the specific carbohydrate to which we are referring.
Synonym of saccharide (sugar)
CHEMICAL GROUPINGS
Monosaccharides Disaccharides Oligosaccharides Polysaccharides
POLYSACCHARIDES
Serve for the storage of energy (e.g., starch and glycogen) and as structural components (e.g., cellulose in plants and chitin in arthropods).
important ingredients in many food products particularly in wide range of food emulsions such as mayonnaise and ice cream
They can be used in natural form but in many cases the functionality is adapted by chemical
Modification for example to improve the solubility and water-binding capacity
It has a wide range of capacities among the whole group.
Gel formation is often thermo- reversible and it might melt on heating or set on heating.
TYPES OF POLYSACCHARIDES
STRUCTURAL POLYSACCHARIDES Unbranched polymers e.g. Chitin and
Cellulose
STORAGE POLYSACCHARIDES Branched polymers e.g. Glycogen and
Starch
GOALS
To study the physical and chemical properties of polysaccharides
To determine the changes in polysaccharides during processing
METHODS
EXPERIMENT 3.1MICROSCOPE EXAMINATION OF STARCH
GRANULES
To determine the appearance of starch granules from different materials
Place water
dispersion of
samples on slides
Observe under
the microscope
Draw the
starch granul
es
RESULTS
Figure 3.1.a Sago Starch Figure 3.1.b Sago Starch Figure 3.1.c Potato Starch
Figure 3.1.d Rice Starch Figure 3.1.e Corn Starch
RESULTS
Starch Appearance Size, Shape
Rice Transparent, closely packed Irregular
Corn Transparent, closely packed Irregular oblong
Potato Transparent, loosely packed Oval
Sago Transparent, scattered Oval
Cassava Violet, thread-like Thread-like
Table 3.2 Consistency and appearance of starch mixture at different temperatures
DISCUSSION
Q1 How would you be able to identify the type of starch using a microscope?Starch molecules arrange themselves partially crystalline granules in plants. Each plant species has a unique starch granular size and so it is possible to identify the type of starch using a microscope: rice starch is relatively small (about 2μm) while potato starch have larger granules (up to 100μm).
Q2:If you are given a starchy food item and you are asked to develop a similar food product, what basic information do you have to know? The information that we need to know: The molecular weight the type of saccharide units and linkages
between saccharide units The degree of branching
METHODS
Experiment 3.2 Rheological Properties of Polysaccharides (Starch)
To determine the rheological properties of starches To determine the effect of heat on starch
Mix 100ml water and 2g of corn
starch. Examine
under microscope
Heat to 50 degree Celsius
remove and reexamine. Note any changes
Continue heating to 60 and 70 degrees and
observe under the microscope .
Note any changes and difference on
appearance and consistency
RESULTS
Figure 3.2.a Wet Corn Starch (400x) Figure 3.2.b Wet Corn Starch at 500C (400x)
Figure 3.2.b Wet Corn Starch at 600C (400x) Figure 3.2.b Wet Corn Starch at 700C (400x)
RESULTS
Temperature Appearance Consistency
500C White, very
small
Thick
600C White, small Thicker
700C Dirty white,
medium
thickest
Table 3.2 Consistency and appearance of starch mixture at different temperatures
DISCUSSION
Q1: What is gelatinization? Gelatinization is a process that
breaks down the intermolecular bonds of starch molecules in the presence of water and heat, allowing the hydrogen bonding sites (the hydroxyl hydrogen and oxygen) to engage more water.
Q2: What is a gel?Gel is defined as a substantially dilute cross linked system, which exhibits no flow when in the steady-state.
METHODSEXPERIMENT 3.3: TYPES OF STARCH GELS To compare the characteristics of different starch gels To determine the effect of sugar on starch gels
A. Starch Gels from Various SourcesPlace 15, 5 and 2 g in
individual
beakers add 5ml of cold
water.
Add boiling water
in such an
amount as
to adjust total
weight to
100g
Heat and stir
after comple
tely dispers
ing remove from heat and
place in a
molder
Allow to
cool under
ice bath, once
cooled remove from molde
r
Properly
label then obser
ve consistenc
y, color and
firmness
RESULTS
StarchTransparency Texture
2 g 5 g 15 g 2 g 5 g 15 g
Corn 2 2 3 1 1 3
Rice
C41 2 3 1 2 3
Rice
malagk
it
1 2 3 1 2 3
Sago 2 2 2 1 2 3
Table 3.3.A. Comparison of gels obtained from different starches.
Transparency: transparent – 1; neither – 2; opaque – 3Texture: soft – 1; neither – 2; hard - 3
METHODS
Prepare gels each
with rice C-4 and
malagkit. Add 5g
starch and 40ml water
Add 3 levels of
sugar 3, 6 and 9 g for
each mixture. Cook and
cool
Observe gel for
transparency,
viscosity, and
texture
B. Effect of Sugar on the Characteristic Sugar
RESULTS
StachTransparency viscosity
3 g 6 g 9 g 3 g 6 g 9 g
Rice C4 3 3 3 1 2 3
Rice
malagkit3 3 3 1 2 3
Table 3.3.B. comparison of gel obtained from rice starch cooked with different amount of sugar
Transparency: transparent -1; neither – 2; opaque – 3Texture: soft – 1 ; neither – 2; hard – 3
DISCUSSION
Q1:For each starch, what amount of starch gave a firm moldable gel? As the amount of sugar increases the fluidity of the sample becomes apparent. Thus, the sample with increased amount of sugar is more viscous. As for the ones with low amount of sugar, moldability and firmness is high.
DISCUSSION
Q2: How does sugar affects the physical properties of starch gels?
Therefore the moldable nature of
polysaccharides becomes less when added with sugar as it increase the temperature at which gelatinization occurs, by doing so viscosity is increased while decreasing the firmness of the solution.
DISCUSSION
Q3: How will you use the results in figuring out formulations for sauces, granules and pudding?
If a liquid sauce is needed, addition of high amount of sugar to polysaccharide solution is done. If on the other hand granulated substance is needed, less sugar should be added. For pudding, since it needs a lot of sugar for stability, the sugar content as well as the temperature is increased.
CONCLUSION
The role of polysaccharides in the stabilization of emulsions is very important. In fact it can be said that their main functionality lies in their ability to thicken the emulsion, which is intended to reduce the creaming rate and to improve the texture to the emulsion.
REPORTED BY
FLORES, NOEME MALINAO, MARIELLE PASCUAL, MITCHEL OLIVE