84 terms

FS test 1

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Heat of fusion
heat (80 kcal / g) released from liquid (water) at 0c to become solid (ice)
Heat of vaporization
liquid (water) absorbs 540 kcal per g of h2o to become steam
Atmospheric pressure
decreases in pressures = decrease boiling (table 2.3), 1F / 500 ft
Vapor pressure
pressure excreted as molecules of liquid attempt to be in the gaseous rather than liquid state
Water activity
vapor pressure of a food sample over the vapor pressure of pure water

can be referred to as either reabsorption (uptake of water - pasta) or desabsorption ( loss of water - baking)
water activity at about 0.95
decreases pseudomonas, Escherichia, C.perfringens
water activity about 0.91 - 0.95
increased salmonella, C. botulinum, vitro parahaemolyticus
water activity 0.87 - 0.91
increased yeast
water activity 0.80 - 0.87
increased molds
Dispersions
Many foods and beverages are dispersions where a discontinuous phase is dispersed in a continuous phase
Examples include solutions, suspensions, gels, foams, and emulsions
Alter the Aw of a food for storage:
drying, freezing, addition of salt, sugar, and additives
Irradiation
of water produces hydrogen peroxide which is very toxic to microbes
Energy involved is expressed in rads (ionizing energy = 10-5 joule per gram)
Gamma rays
capable of penetrating a food
Beta Rays
can penetrate food, but not aluminum
Alpha particles
cannot penetrate foods but can be effect on its surface
Dispersions solute
substance dissolved in a liquid to form a true solution
Dispersion: Solvent
liquid in which the solute is dissolved to form a true solution
Dispersion: true solution
solution mixed with solvent most stable solution with solutes less than 1 millimicron

- solute mixed with solute
i.e. water and sugar
Collidial dispersion
2 phase system containing at least 1 colloid
phase 1 - continuous
phase 2 - discontinuous
Continuous dispersion
throughout the system, surrounding all parts of the system, most prominent
Discontinuous dispersion
isolated or disconnected part of the system
Emulysifying agents
compound between with both polar and nonpolar groups to interface between 2 phases of the emulsion
coarse suspension
mixture of substance larger than colloidal dimensions (>1 millimicron)
-influenced by gravity and easily separated
Hydrolysis
splitting of a molecule by uptake of water molecule
Caramelization
fragmentation of monosaccharides into a variety of compounds, including organic acids, aldehydes, and ketone as a result of extremely intense heat
Mailard reaction
non enzymatic browning that occurs when the protein and sugar are heated or stored for a certain time

- only occurs with reducing sugars
Invert sugar
sugar formed by hydrolysis of sucrose (equal parts fructose and glucose)
Synersis
irreversible separation of liquid out of the gel
Retrogradation
gradual increase of crystalline aggregates in starch gels during storage that results from breaking of hydrogen bonds between amylose molecules and slow arrangement into more orderly confirmation and establishes new hydrogen ions
How do solutes impact boiling freezing temps?
High soluble substances: decrease freezing point, but increase boiling

ex: sugar
salt with twice greater effect

decreased atm pressure, decreased boiling point, 1 F / 500 ft

- long boiling time at high altitude
-low pressure cooking - decreased color change, increased flavor conversion
-pressure cooker - increased boiling point, decreased cooking time
Radiation effects on cooking
direct transfer of heat from its source
-heat from electromagnetic waves
- broiling and inferred heat lamps
- direct heat onto the food for a shorter amount of time
Conduction effects on cooking
transfer of energy from 1 molecule to the adjustment molecule in a continuing and progressive fashion
-good conductors - heavy cast ion, aluminum
- not good for conduction - thin metals
Convections effect on cooking
transfer heat by the circulation of currents of hot air or liquid resulting from change in density when heated
- oven: lower temp, reduce baking time, promote browning
Crystalline candies
fudge - small crystals
fondant - a saturated sugar solution in which small sugar crystals are dispersed (cream centers)

hold shape when cut, easily bitten, firmness varies, taste sweet, no grittiness
Problems with crystalline candies
too high temp - hard candy
too low temp - sticky
humid - sticky
slow boiling and acid - very soft
too little beating - coarse texture, lightened color
too fast boiling - gritty
Amorphous candies
higher temp, higher concentrates
types: candies and brittles (2% or less moisture, glasslike); caramels and taffy (15-22% moisture, amporpho);

Prep: ingredient sugar/ water, often fat and cream
uniform heating by aluminum sauce pan, accurate temp reading (trapped air may mislead reading, increased risk of burning or scorching)
Unsaturated true solution
capable of dissolving additional solute at temp of solution
Saturated true solution
containing as much solute in solution as possible to dissolve at room temp
Supersaturated true solution
containing more solute than theoretically can be dissolved at that temp
-often in candy making
Emulsion (colloid)
liquid w/n liquid (salad dressing)
Sol (colloid)
solid dispersed in a liquid (gravy)
-continuous phase
-flow properties
Gel (colloid)
liquid dispersed in a solid (pudding)
-continuous phase
-less energy
-syneris can happen when liquid escapes gel
Foam (colloid)
gas dispersed in a liquid (egg white foam)
Supensoid (colloid)
gas dispersed in a solid ( chocolate moose)
Sugar
sucrose from sugar cane and beets
Granulated sugar
used in most applications
confectioner's sugar
pulverized with cornstarch (3%) to prevent caking and binds to water
Brown sugar
less refined
contains molasses
types: light, dark, raw, turbinado brownulated
frutose
higher sweetness, slowly absorbed
Lactose
low hygroscopicity, anti-caking, prevents surface stickiness, used a preservative
Sugar (monosaccharide)
galactose, glucose, and fructose
Sucrose
glucose + frutose
lactose
glucose + galactose
maltose
glucose + glucose
Corn syrup
hydrolyzed cornstarch
high fructose corn syrup
high use in commercial products; isomerase using streptomyces converts glucose to fructose

Positives: cheap, shelf life, acts more like sugar than any other sweetener
Dextrose equivalent
used to measure free dextrose in sugars alternatives
Molasses
a byproduct of the manufacture of sugar.
subsequently boiling makes stronger color and flavor
honey
riches source of fructose in natural sugars
Sorgum
from boiling the juice of grain sorghum
Alternatives to sugar
Polyhydric alcohol:
xylitol, sorbitol, manitol
polyhydric alcohols
alcohols with several hydroxyl groups
-absorbed more slowly, produce intestinal gas, endothermic, non cariogenic
Xylitol
common in chewing gum
Sorbitol
used for humectant and bulking agents
-commonly in baked products to beverages
- limits mold growth and increases shelf life
Mannitol
bulking agent
-used for gum
-low hygroscopicity: in powdered products
Saccharin
non-caloric
300 times sweeter
pink packet
-bitter after taste, mix with other sweetness
-sweet and low, sugar twin
-cant cook as one to one for sugar
Aspartame
low calorie sweetener (4 kcal /g)
200 x sweeter
aspartic acid and phenlylalanine (pro / aa)
acidic environment favorable pH 3-5
not heat stable, can't cook with
nutrasweet, Equal (blue packet)
PKU pt can't use
Acesulfame
low kcal sweetener (4 kcal /g), 200 x sweeter, k salt of acetoacetic acid
heat stable, good in baked products, puddings, more common in europe

*caution with cardiac pt or renal dz
Sucralose
600X sweeter, Cl replaces OH
heat stable, used for cooking and baking
splenda, approved 1998
used cup for cup
yellow packet
Stevioside
300x sweeter, plant from South america, list on generally recognized as safe august 2009
Function of sugar
sweetness
color
volume
texture
mouthfeel
stabilizer
Amylose
linear form
-straight chain fraction 1,4 alpha glucoside linkage)
-forms loose, flexible coils dispersed - the reason it reacts
-sweet taste
-slightly soluble: important in starch cooking
-iodine binds to glucose and gets trapped in the helix
-iodine turns blue can be used to test for this
-average content 17-30%
-root and tuber starches < cereal grains
Amylopectin
branched fractioned starch
-1,4 alpha linkages
-some 1,6 linkages
-non linear, dense
- iodine test: reddish / purple d/t no helical configuration
-more common than the counter part (other a word)
-root and tuber starches 80%
-cereal starches 75%
Process of gelatinization
heat is applied to starch / water mixture
-starch granules swell as they take in water, some amylose migrates into cooking fluid
-granules become thick
pasting
loss of amylose and implosion of granule
Process of gelation
-gelatinized starch maintains sole when hot
- gelation occurs when it cools
-amylose molecules align and hydrogen bonds entrap water
-waxy starch do not form gels under normal circumstances
-for max gel strength allow to cool undisturbed
Factors that effect gelatinization
type of starch
-root starch: translucent
- cereal starch: more translucent
- corn starch 2x thickening power of flour - bc pro slows
-endpoint temperature
-dextrinization, acids (hydrolyzes chain of amylose), time (high temps for long period of time lowers viscosity), added sugars (decreases thickening ability), milk proteins, fat
Factors affecting gelation
-type of concentration of starch
-less gelation at low concentration, low amylose starch solution
-extent of heating
-under enough water, amylose is released by heat
-avoid vigorous stirring, agitation disturbs hydrogen bonds between amylose
-sugar, acid (can case hydrolysis), fat, protein
pregelatinized starch application
cold water swelling: suited for microwave cooking
Ex: instant pudding, instant rice, instant mashed potatoes
Thin boiling starch application
acid hydrolysis of amylopectin branches
easy to mold: hot thin boiling starch forms strong gels when cooled
used in gum drops
oxidized starches
sodium hypochlorite produces oxidized starches
-similar to hydrolyzes starches but softer cells
cross linked starches
amylose + ethylene oxide --> hyroxyethyl amylose
formed under alkaline condition
reduced hydroxyl group for thickening
reduce retrogradation
thickener and stabilizer of salad dressings
Starch phosphates
esterfied with sodium tripolyphosphate
increased stability and improved texture
decreases syneresis
Example: gravies in frozen dinners
modified starch
altered either by physical or chemical means