Term
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Definition
| complex mammary exudate- composition varies by animal, season, through milking session; Components: Water (22%), CHO 5%, mostly lactose but also glucose and galactose), Protein (3.5% mostly casein, why, and enzymes, fat ( 3.3-3.7% commercially, varies and may be up to 5%), vitamins, minerals, flavor components |
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Term
| Components- liquids in Milk |
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Definition
- Fat content varies by breed
- Lipids w/in milk fat highly varied- 64 different fatty acids
(Butyric 3.3%- short chain, Palmitic 26%- saturated, Oleic 25%- polyunsaturated, Linoleic 2.4%- polyunsaturated
3. Fat Globules -fatty acids as triaglycerides - dispersed as fat globules
- Membrane of phospholipids, proteins, lipoproteins,
and enzymes
- Lipoproteins – act as emulsifiers with the
lipophyllic portion facing in and the hydrophyllic
portion interfacing with water --keeps fat molecules dispersed in milk |
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Term
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Definition
-1 cup milk = 11-12 g CHO
-Mostly lactose –-Difficult to dissolve and keep in solution --Readily crystallizes at refrigeration temperatures or below (contribute gritty texture to ice creams) --Contributes to browning in milk products
CHO crystallization
- α-lactose crystals primary problem
• β-lactose crystals also form and gradually isomerize into α-lactose crystals
• Continue to form in cold and frozen products until very gritty
• Crystals also form in dried milk from the amorphous form of lactose (very
hygroscopic) – milk will be lumpy if not controlled |
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Term
Components – Proteins in
Milk (CASEIN fraction) |
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Definition
– make up 80% of cow’s milk
--Alpha, beta, kappa, and gamma caseins
Caseins are primarily hydrophobic except
for kappa which has a polar end
--Precipitate out at IP of 4.6 collectively
(although each has a different IP) or if kappa
is cleaved by enzyme (rennet)
--Found in micelles surrounded by kappa
caseins on the surface and the other caseins
in the interior |
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Term
Components – Proteins in
Milk - Precipitation (ACID Precipitation) |
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Definition
-done at PI for protein of 4.6, usually with heat.
--Precipitation results due to there being
no net charge on the protein –
resulting in minimum solubility. No
longer have net (-) charges repelling
each other – get clumping |
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Term
| Components – Vitamins,Minerals and Flavor Components in Milk |
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Definition
-Vitamins/Minerals – good source of most
nutrients except for iron and Vitamin C
--Vitamin D added to most milk products
-- Calcium – contributes to the texture of many
milk products due to the ability to cross-link
proteins in curds or gels
--- Example - custards
-Flavor components – varied but contain
aldehydes, ketones, acids, fermentation
products |
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Term
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Definition
Raw milk – no heat treatment
• Certified raw – produced in environment clean enough |
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Term
| Milk Processing -Homogenization |
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Definition
-Creaming (occurs in milk that is not homogenized)
--separation of fat from the aqueous portion of the milk where
fat globules aggregate and rise to the top
-Homogenization – milk forced under pressure (2000-2500
psi) through tiny apertures.
--Splits the fat molecule into smaller and smaller units
--Caseins become absorbed on the fat globule surfaces
--Difference between homogenized and non-homogenized
milk?
• Does not cream
• Increases viscosity and whiteness
• Less heat stable, more sensitive to light, foams more readily
• Distinctive cooked flavor but less distinctive milk flavor
• Forms softer curds than non-homogenized milk
Mi |
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Term
| Milk Processing - Evaporation |
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Definition
-Evaporation– reduces the amount of water, increasing fat and protein percentage
--Done at 70˚C under partial vacuum
--Homogenization essential
--Must undergo thermal treatment -
241˚F for 15 minutes
---Results in Maillard reaction and browning
of the milk |
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Term
| Milk Processing – Sweetened Condensed |
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Definition
-Sweetened Condensed Milk
--Evaporated milk with additional sugars
added (sucrose and lactose)
• Sugars promote browning during storage
and heating
• Sugars also serve as antimicrobial agent |
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Term
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Definition
Drying – drum drying or by spray
drying
--Advantages -reduces refrigeration
needed during storage and reduces
transportation costs/energy
--Problem – hygroscopicity – lumpiness
--- Solution – instantized dried milk – dried,
moistened and redried to achieve small
crystals and prevent clumping of milk
powders |
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Term
Milk Processing –
Fermentation |
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Definition
-Lactic acid starter cultures are used which contain:
A) Lactobacilli bacteria, streptococci
bacteria and which produce lactic acid
-Milk thickens due to association of
casein micelles along with beta
lactoglobulin
-Fermented products: Buttermilk,
yogurt, kefir, cheeses |
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Term
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Definition
- Milks
Whole (3.25+% fat)
Reduced-fat (2.0 % fat)
Low-fat (1.0 % fat)
Skim (0.1% fat)
-Creams
Half-and-half (10.5-18% fat)
Light cream (18-30% fat)
Light whipping (30-35% fat)
Heavy whipping (36% fat)
Manufacturing cream (36-40% fat)
Common |
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Term
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Definition
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Term
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Definition
-Blend ingredients (milk, cream, flavors, stabilizers, etc.), rapidly cool and freeze with agitation. This promotes formation of small ice crystals and incorporates some air (overrun) which softens texture of frozen product.
-A ice/salt solution can be used to freeze ice cream; ice melts & salt solution is formed; lower pressure of salt makes ice continue to melt to equalize pressures, takes energy to melt ice; so temp of mixture goes down, max effect is 3:1 ice to salt ratio (-22 C). |
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Term
| Components-Proteins in milk (WHEY fraction) |
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Definition
Whey – make up 20% of milk proteins
--Made up of lactoglobulin, alpha lactalbumin,
immunoglobulins, serum albumin
--Fairly soluble
--Do not precipitate out at pH 4.6
--Are heat sensitive and form coat on bottom
of pan when milk is heated
--Contribute to the cooked flavor of milk due to
the formation of hydrogen sulfide
Comp |
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Term
Components – Proteins in
Milk - Precipitation (RENNET Precipitation) |
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Definition
– achieved with the addition of rennet
enzyme
--Rennet serves to cleave the polar end of the kappa casein
molecule yielding para-kappa casein which is uncharged –
get clumping
--Best pH is 5.8 for the rennet enzyme
--Best if milk isn’t heat treated prior to curd formation –
complexing of proteins can make enzyme unavailable
--Temperature must be between 15-60˚C
-Difference between acid and rennet precipitated curds?
--Rennet curds are firmer
---This is due to the fact that calcium in the micelles becomes
soluble under acid conditions and leaves the micelles under
acid precipitation (ie Ca+ no longer there to firm up the curds)
---In the rennet curd, Ca+
remains to crosslink between micelles
to make the curd firmer
Comp |
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Term
Components – Proteins in
Milk (ENZYMES) |
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Definition
--Alkaline phosphatase – not heat stable –
breaks down at the pasteurization temps –
good test for sufficient pastuerization
--Lipases – catalyzes lipolysis
--Proteases – heat resistant – catalyzes
protein breakdown
--Xanthine oxidase – catalyzes breakdownof
flavin-adenine dinucleotide (FAD) to
riboflavin |
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Term
| Milk - Processing (PAUSTERIZED) |
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Definition
- heat treatment to reduce pathogens
-- The higher the temp, the shorter the time
--- LTLT - Hold method – heat to 145˚F, hold 30 min, quick
cool to 45˚F
---HTST method - heat to 161˚F, hold 15 sec, quick cool
to 50˚F
--- UHT method - heat to 280˚F, hold 2 sec, store in sterile
containers
----Shelf-stable (unopened) but cooked flavor results |
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Term
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Definition
- Buttermilk (low-fat and cultured)
- Sweet Acidophilus Milk (contains, L.acidophilus, not
allowed to ferment so tastes sweet, 3.25% fat)
- Kefir – fermented to ~3% alcohol
- Yogurt – clotted milk (0.1-3.25% fat) – fermented only
to 5.5pH
a) May have additional inulins or prebiotics added during
manufacturing
b) Reduced fat yogurt stabilized with gelatin, modified food
starches, whey protein concentrate, agar, and/or pectin
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Term
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Definition
Lactaid (lactase added to break down most lactose,
fat% varies by type) |
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Term
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Definition
-technically a water in oil
emulsion
--15-20% non-fat solids and water
-- 80-85% fat
--Crystals should in β-prime formation
--Salted/fermented (slightly tangy),
sweet unsalted, or salted |
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Term
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Definition
-natural, process cheese foods, process cheese spreads
Whey Protein Concentrate
-Up to 97% protein
Use in:
• Meat products for water retention
• In fat replacers
• In candies and baked products |
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Term
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Definition
- Ice cream – mixture of milk, cream, milk solids, and
flavorings which is aerated during freezing (10% fat,
20% milk solid, 0.5% stabilizers)
• Plain – no flavoring particles show
• Composite – visible flavoring components
• Frozen custard – addition of cooked egg yolk
• Overrun - increase in volume (air) expressed in %,
achieved through agitation during freezing
-Ice milk – (2-7% fat, 11% milk solids)
-Sherbet (2-5% milk solids, no milk fat)
-Mellorine (fat not from milk)
-Parevine – (no milk solid and no milk fat) –
appropriate for Jewish food laws |
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Term
| Why is Ice Cream Agitated During Freezing? |
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Definition
-To maintain uniform temperature, to prevent growth of larger crystals at edges of container which make a grainy product
-Promotes coalescence of fat globules, to give smoother mouth feel, has to be done carefully to prevent over-churning of mixture
-Adds air which makes texture smooth and light (70 to 80% over run in ice cream is good; in sherbets - 30 to 40%; no more than 50% home-made) |
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Term
| What Changes Happen to Ice Cream During Storage? |
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Definition
-Ice crystals will gradually increase in size due to recrystallization (stabilizers slow this process down), any fat in mixture will tend to restrict this process
-Can develop sandy texture due to presence of lactose crystals which have formed, can use stabilizers or small amts of corn syrup to slow down
-Foam loses air/shrinks |
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Term
| What Changes Happen to Ice Cream During Storage? |
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Definition
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Term
| How is cheddar cheese made? |
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Definition
Step 1: Milk heated to 31 C, bacterial starter culture added (lactic acid bacteria; Lactobacilli and Streptococci sp.), rennet added, fermented for 30 min.
Functional - curd of coagulated casein forms, liquid whey surrounds curd
Physico-chemical - rennet cleaves ĸ-casein to para ĸ-casein, this form of casein then complexes with calcium on surface of casein micelles to insoluble material.
Step 2 - The curd is cut into small cubes; size depends on cheese
Functionality - increased surface area permits more removal of whey from curd
Physico- chemistry - Casein continues to form tight curd through association of proteins in casein micelles
Step 3 - Curd is cooked at 38 C for about 1 hour.
Functionality - more whey is lost, curds shrink, more acid is produced
Physico-chemistry - Casein proteins becomes more insoluble as the pH is lowered due to acid production
Step 4 - In cheddar cheese production; the cheese is cheddared. Curds are drained of whey and allowed to mat into slab. The mat is cut, turned & placed into piles of blocks, this process is repeated for 2 hr., until lactic acid is 0.5 to 0.6%.
Function & Physico-chemistry - more of continued process begun in step 3
Step 5 - The curd is milled (cut into small pieces) and salted (salt is added at 2.5% of weight of curd).
Functionality - salt added to
1 -draw out more whey by osmosis 2 - inhibit spoilage microbes 3 - add flavor
Physico -chemical - protein firms up even more
Step 6 - The curd is pressed to remove more whey, then stored at 16 C, 60% RH for 4 days.
Functionality - creates shape of final cheese, surface hardens
Physico-chemical - determines final amt of acid based on amount of whey left in curd, influences type of microbes during ripening
Step 7 - The curd is ripened at 2 C, 85% RH for at least 60 days, can be up to 18 months, longer the ripening the sharper the cheddar
Functionality - texture becomes drier, flavor more intense
Physico-chemical - lactose, other organic molecules fermented to acid and aroma cmpds, milk fat & fatty acids broken down; protein undergoes proteolysis to peptides and free amino acids |
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Term
| How is cottage cheese made? |
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Definition
Warm milk to 22 C, add lactic acid starter culture (Streptococci, Leuconostoc sp.)
Ferment for 14 hr, pH drops, Calcium solubilizes; cut curd into small cubes
Cook curd for 90 min, stir, heat to 50 C, curd protein associates more, more calcium solubilizes
Drain whey, wash curd to limit acidity Drain water, add a little salt Blend with cream to get 2 or 4% fat (if done
is called creamed cottage cheese. |
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Term
| Other microbes added to ripening cheese |
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Definition
Molds (Penicillium sp) - act upon fatty acids in cheese during ripening to give distinct flavors and color to final cheese
Propionibacterium gives flavor to Swiss type cheeses due to propionic acid, breakdown of fatty acids, supplies the holes in cheese, sweetness from proteolysis
Penicillium mold surface of Camembert and Brie softens interior of cheese due to proteolysis |
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Term
| What is processed cheese? |
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Definition
-Made by heating natural cheeses with an emulsifier, then cooking in brick form;
-Moisture level of 41% ( protein is made more soluble due to presence of citrate and phosphate salts)
• Some aged cheese is added to keep from being too rubbery |
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Term
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Definition
Process cheese food - more moisture level in cheese (45%) to make softer
Process cheese spread - up to 50% moisture so cheese can be spread
Coldpack (Club) Cheese - has added emulsifiers but no cooking done so protein is not as soluble as in processed cheese products |
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Term
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Definition
Can reduce fat by using lower fat milk, is limited by texture and flavor considerations
Can remove all butterfat and add back some oil, is more flexible since oil moves more to restrict protein interactions; can use gums to achieve desired texture |
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Term
| How Does Heat Affect Cheeses? |
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Definition
Tends to coagulate proteins more
Higher moisture blend better during heating than lower moisture cheeses
Lower moisture; low fat cheeses get more rubbery when they are heated
• but aging of lower moisture, low fat cheeses improves the solubility of the proteins and the consequent ability to blend during cooking
Can make cheeses stringy |
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Term
| How Does Excessive Heating Affect Cheeses? |
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Definition
Stringiness, toughness and fat separation can all occur
--the protein continues to coagulate (ppt) and thus water and fat are forced out, the result being a less soluble protein and a destabilized cheese with loss of oily lipid material
Emulsifiers added to processed cheeses prevents the loss of lipids, so the proteins do not interact as much, the cheese is more heat stable |
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Term
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Definition
Whipping cream with 30% fat can be beaten, 36% is better, is better done when cream is chilled, fat is principal component to stabilize the foam walls, so important to whip when cold, aged cream whips better than fresh cream due to slight drop in pH (more soluble proteins)
Sugar added for flavor, softens texture but makes it harder to over beat (protective effect on proteins)
Homogenization interferes with ability of fat to partially coalesce and to stabilize foam |
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Term
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Definition
Recombinant Bovine Somatotropin
-1994 – approval for use
-Genetically engineered hormone that stimulate milk production in cows
-May increase milk production by as much as 1800 pounds per year
-Milk is essentially the same as milk produced without hormones |
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