SAUCES 1 Flashcards
what are starch granules
plant cell’s unit for storing starch
what are some common sources of starches
Cereals (wheat, rice, corn)
* Corn starch is major U.S.
starch source (95%)
* Roots (potatoes, cassava)
* Legumes (beans, peas
what are the functions of starches in food products
thickening/gelling agent (main use), sweetener source, edible films
how are starches sweetener sources
through dextrose and syrups
whats dextrose equivalent
Degree of starch conversion into dextrose is expressed
what proportion of starch in US is converted to syrup
over 50%
what are the two forms of starches
amylose (linear) and amylopectin (highly branched)
what do amount and ratio depend on
plant source / also influence texture
what functional characteristics are directly affected by the amylose/amylopectin ratio
viscosity, gelatinization,
solubility, texture, gel stability, retrogradation, shear resistance)
what proportion of amylose/amylopectin do waxy starches have
Waxy starches have 100% amylopectin (e.g., Amioca)
what do starches with high levels of amylose tend to do
gel
what are starches with high levels of amylopectin considered
non-gelling
what are the four transformations that starches undergo
gelatinization, gel formation (gelation), retrogradation, dextrinizatioon
what determines the degree to which starch transformations occur
Concentration of
amylose/amylopectin
what happens to starch molecules and their viscosity, volume, and translucency during gelatinization?
starch molecules expand upon heating in water; viscosity, volume, and translucency of granules ↑
what does heat do to hydrogen bonds
causes hydrogen bonds between starch molecules to
weaken
what happens to starch granules when water penetrates them
causes them to swell and new hydrogen bonds form between water and starch
what do amylose and amylopectin do during gelatinization
amylose migrates out of the granules while amylopectin
hydrogen bonds with water in the granule
what does water-binding do to the mixture
makes it thicker
whats unique to each starch
temperature of gelatinization, ability to thicken, transluncecy, texture
what are the seven factors influencing gelatinization
water, temperature, heating time, stirring, acid, sugar, fat
why does water influence gelatinization
need adequate amount available for absorption
how does gelatinization occur in warm liquids
granules swell and burst, releasing starch particles into liquid
describe difference in gelatinization temps of large and small granules
- Large granules gelatinize at lower temps
- Smaller granules, at higher temps
describe gelatinization temp range
- Gelatinization temp range is usually narrow
- Depends on starch type
how does heating time impact gelatinization
continued heat will cause granules to break (bonds holding them together weaken)
how does stirring impact gelatinization
continued or vigorous stirring will cause granules to rupture prematurely
how does acidity impact gelatinizatoin
pH<4.0 weakens ability to thicken, ↓viscosity
how does sugar impact gelatinization
competes with starch for available water
* Delay’s onset of gelatinization and ↑required temp
how does fat impact gelatinization
delays gelatinization by coating starch molecules
and blocking water absorption
