NDFDS 250

corn, wheat, rice, potato, tapioca, arrow root

Root startches are similar and grain starches are similar

Just remember that starches are different 

Microscopic packages, within plant cells, of starch molecules arranged in an orderly fashion. Unique for each type of starch.

due to crystalline and noncrystallineregions

–Linear

–Actually it’s a coil, but it’s still linear (no branching)

Branched

• Most starch granules contain about
• 1/4 amylose and 3/4 amylopectin

Amylose

Glucose polymer with alpha 1, 4 linkages.

  Linear fraction of starch.

Glucose polymer with alpha  1, 4 and alpha  1, 6 linkages.

Branched fraction of starch; branches contain 20-25 glucoses

occurs (Starch granule absorbs water and swells)

•Irreversible swelling

• •Loss of birefringence (Maltese cross
• disappears)

•Rapid increase in viscosity

•occurs (Additional swelling and amylose leaches into the cook water)

•Thickness due to enlarged granules and amylose exudate

• Uncooked starch granules under polarized light, exhibiting birefringence (Maltese cross)
• 

•Granule swelling limited because sugar competes for H2O

•Decreases thickness of gelatinized starch

•Increases gelatinization temperature

•Makes swollen granules more resistant to rupture

•Hydrolyze starch, reducing viscosity

•(Slight hydrolysis may open granule producing a thicker paste)

•Generally not much effect; may increase gelatinization temp.

• •Fats “water proof” the granules so that water cannot penetrate
• easily.

•Surfactants markedly increase the gelatinization temperature

Liqiud draining from a gel.

(re-crystallization of starch molecules) affects texture

–Thin-boiling starch prepared by heating starch below its gelatinization temperature in dilute acid.

–When heated, it’s low in viscosity; this allows for pumping while hot

–When cooled, a clear gel forms; used in gum drops.

–Starches containing molecules that have been cross-linked with one another with ether or ester linkages.

–Cross-linking minimizes breakdown of the starch in acid.

–Good for frozen foods

–Starch that is precooked and dried, i.e.,instantized; dispersible in cold water

–Used in instant pudding.

•Ice in ice cream, sucrose in fudge

•Fried foods

•Limits gluten development by coating flour particles in biscuits, muffins, pastry, cakes.

•Cheese, ground beef

•Smoothness of cream, mayonnaise

•Moist sensation when crystals melt in mouth

•Fats are solid at room temperature

•Oils are liquid are room temperature

•Two terms are often used interchangeably

•The building blocks of fat made of hydrocarbons

•Saturated and unsaturated

•Fatty acids esterified to Glycerol

•Synonym: acylglycerols

•1 fatty acid + glycerol = monoglyceride

•2 fatty acids + glycerol = diglyceride

•3 fatty acids + glycerol = triglyceride

HOOC CH2 CH2 CH3 or H3C CH2 CH2 COOH    

HOOC (CH2)10 CH3

HOOC (CH2)14 CH3

HOOC (CH2)7 HC = CH (CH2)5 CH3

HOOC (CH2)16 CH3

HOOC (CH2)7 HC = CH (CH2)7 CH3

HOOC (CH2)7 HC = CH CH2 HC = CH (CH2)4 CH3

HOOC (CH2)7 HC = CH CH2 HC = CH CH2 HC = CH CH2 CH3

Glycerol

More than one crystal form

Temperature range over which a fat exhibits plasticity

Fats with a wide plastic range have some crystalline fat at elevated temperatures and some liquid fat at low temperatures

• Important
• for shortening

• Temperature
• range where there is some crystalline fat present 

Interesterification

Hydrogenation

Mixing different fats

Adding emulsifiers (superglycerination)

•Addition of H2 to the double bonds of unsaturated fats, converting them to saturated fats.

• •The oil is heated with a finely divided nickel catalyst.  The
• system is evacuated and H2 gas is admitted.

•Converts unsaturated fats to saturated fats, changing textural properties and improving stability.

•Process of heating fat in the presence of a suitable catalyst to hydrolyze the fatty acids and re-esterify them with glycerol in a more random order.

•The molecules become more heterogeneous, resulting in smaller crystals and a wider plastic range.

•Process of incorporating 3-6 % emulsifier (glyceryl monostearate) into shortening to improve its baking qualities.

Off-odors and off-flavors due to fat breakdown

Two types:

Oxidative rancidity, due to lipid oxidation (autoxidation)

Hydrolytic rancidity, due to lipid hydrolysis

Both types may be caused by enzymes technically are not, enzymes destroyed/slowed down

Oxidative – lipoxygenase

Hydrolytic – lipase

Can occur even when only small amounts of fat are present

A major cause of food deterioration and shortened shelf life

occurs at the double bonds

occurs when short fatty acids are hydrolyzedfrom the glycerol

• Antioxidants
• are substances that delay rancidity

• Bind
• metal pro-oxidants (EDTA)

• Stop
• free radical reactions

• Butylated
• Hydroxyanisole  (BHA)

• Butylated
• Hydroxytoluene (BHT)

Tertiary Butylhydroquinone

(TBHQ)

Propyl Gallate (PG)

• Alpha-tocopherol
• (Vitamin E)

Oil bearing portion of seed, etc. is cleaned, ground and tempered

Pressing or solvent extraction

Removes the oil

Refined with alkali to remove free fatty acids and non-fatty material

Bleached

• with
• fuller’s earth to lighten color

Deodorized

• by
• steam distillation in a vacuum to remove volatiles.

• After vegetable oil is bleached with fuller’s earth, the oil
• to be made into shortening is then:
• Hydrogenated

Deodorized

Emulsifier added and antioxidant if desired

Chilled and agitated to produce desired texture (crystal size)

Whipped to aid in desired texture

Usually soybean oil is used, prepared with partial hydrogenation

Addition of:

NaCl

Na benzoate

Vitamin A, Vitamin D,

• Emulsifiers:
• lecithin, or mono- or diglycerides

Diacetyl for flavor, and Annatto for yellow color (all optional but almost universal)

Melted fat is agitated or churned with skim milk that was pasteurized and cultured with bacterial starter.

Lard comes from the fatty tissue or fat back of pork, cut into small pieces.

Rendered – heated with or without water to remove fat

Prime steam lard is heated with water

Kettle rendered lard is without the addition of water in an open, steam-jacketed kettle.  Has a cooked flavor desired by some.

Antioxidant added.

• Bleaching,
• hydrogenation, deodorization, emulsification, and interesterification

• Additional
• modifications to improve baking performance

Cream and milk separated by centrifugation.

Pasteurized to inactivate enzymes and kill microbes of pathogenic nature.

Starter culture added to produce lactate.

Ripened a few hours

Churned so that buttermilk separates from clumps of butterfat.

Oil in water cream emulsion changes to water in oil emulsion of butter during churning; inversion.

Buttermilk is drawn off and butter worked and salted

worked to distribute salt and to remove excess water.

Natural production of diacetyl and free fatty acids contribute to flavor.

(Most food emulsions) 

butter and margarine

Substance that lower the interfacial tension of a liquid 

• An emulsifier, such as a monoglyceride, has both polar regions and non-polar regions on the same molecule.  The
• non-polar tail is attracted to the oil (discontinuous phase) and the polar head is attracted to the water (continuous phase). This allows the two phases to associate into an emulsion.

Phenomenon due to unequal forces exerted on molecules at a surface

Forces acting on molecules in the interior and on the surface of a liquid

Same phenomenon existing at interface between two liquid phases, e.g., oil and water

a – 1 cm2 interfacial area

• b – 300 m2 interfacial area when oil
• droplets are   0.1 μm in diameter

•Separation into two emulsions

•Unhomogenized milk or whipping cream in the refrigerator

•Change of emulsion type: o/w     w/o

•Churning of cream to butter 

•Merging of droplets

• •French dressings that are temporary emulsions or margarine in
• a hot fry pan

– increases surface tension of water

– removes a protective layer around droplets

– evaporates the water phase

 (e.g., solid particles not as stable as monoglyceride)

•³ > or= 65 % by weight of oil

•³ 30% by weight of oil

• •Not less than 4% liquid egg yolk (or
• equivalent yolk ingredients)

•³ 35% by weight of oil

• •May include egg or emulsifier, but not
• more than 0.75%

fruit juice clarification 

—flours for bread 

—low-lactose milk

Cheese

meat tenderizer

High fructose corn syrup

candies

glucose removal to prevent   Maillard browning 

-Gelatin (e.g. Jello)

-Casein (e.g. cheese curd, custard)

-Jams and Jellies

-Candies

-Puddings

-Candies (gum drops)

is a protein in animal tissue that exists as a triple helix formed from 3 left handed helices

(flavored/sweetened gelatin) – solubilizes in hot water

 presoak in cold water 4-8 mins, then add hot water

- presoak in cold water 4-8 mins), then add hot water (has lighter color, cleaner flavor than coarse)

žGelatin solubilized/dispersed in hot water

žAs gelatin sol cools, viscosity increases due to molecular interaction between polymers

žWith further cooling viscous liquid changes to viscoelastic solid

•Too much:  gel is stiff, rubbery

•Too little: gel converts to sol

•Just right: gel holds shape, yet tender and quivery

•Add fruit (or vegetable) after gel partially thickens

•Prevents floating

•Do not add raw figs, kiwi or pineapple

•Proteases hydrolyze peptide bonds of gelatin

•Foam/Gel combination

•Make gelatin sol

•Cool to 10 C and allow to thicken but not set

•Beat to incorporate air and make foam

žPrimarily extracted from citrus albedo and apple pomace, both agricultural waste products

Pectin structure

žα-D-galacturonic acid (and its methyl ester)

žJoined by alpha-1,4-glycosidic linkages

ž(a type of hydrolase that cleaves esters)

Pectin methyl esterase activity increases during natural maturation of fruits

•Forms three-dimensional network that entraps water

•Solvent for other components

• •Decreases ionization of carboxyl groups to allow for junction
• zone formation

•pH 2.8 to 3.4 needed for HMP

•Disrupts water around methyl groups, allowing junction zone formation through hydrophobic interaction

•Competes for water, partially dehydrating pectin and allowing junction zone formation through H-bonding between pectin polymers (instead of pectin-water) 

If pH too high, too many negative charges exist and repulsion results – weak or no gel

If pH is very low, then association is too tight and a brittle gel is formed with water eventually being expelled through syneresis

žGel formed by balance of acid and sugar

pH 2.8-3.4

40 to 70 % sugar  (Usually 60-65%)

žJunction zones formed by calcium “bridges”: COO- groups on separate polymers bind Ca++

pH 3.2-4.0 is needed to ensure enough acid groups are negatively charged, to allow interaction with Ca++

Less or no sugar is needed

Requires addition of calcium ions

• ¡Application:
• Low
• calorie jams and jellies

A Jelmeter measures viscosity of a pectin extract, which indicates its sugar-carryingcapacity.

The Jelmeter is calibrated to read in cups of sugar required for each cup of extract.

A soft, elastic food product containing pectin from fruit juice

žA tender jelly with small pieces of fruit distributed evenly throughout, commonly contains citrus

žA viscous food product containing pectin from crushed or ground fruit

Tends to hold shape, but less firm than jelly

žJams made from mixtures of fruit including citrus, raisins, and sometimes nuts

žWhole or large pieces of fruit suspended in a thick syrup

•Livetin

•Phosvitin

•binds certain metal ions

•contains 10% phosphorus

•4% of egg yolk solids

•Ovalbumin

•Glycoprotein

•Conalbumin

•Ovomucin 

•Associated with thick white; fibrous

•Glycoprotein

•Ovomucoid (11%)

•Glycoprotein; Not coagulated by heat

•Trypsin inhibitor

•Lysozyme (3.5%)

•Lyses cell walls of gram (+)

•Contributes to whipping

A quality test where eggs are rotated over bright light in dark room

• Reveals condition of shell, size of ai cell, and size, distinctness, and mobility of the yolk; also detects blood
• spots and meat spots

Egg white; 134°F for 3.5 to 4 minutes

Whole egg: 140-143°F for 3.5 to 4.0 minutes

• lOne of the following additives must be
• added to yolk or whole egg before freezing

lNaCl (1/2 tsp/cup)

lSugar (1-2 Tbs/cup)

lCorn syrup (1 Tbs/cup)

l  Why?

lWithout additives, yolk has a lumpy texture after thawing