Milk and Milk Products

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Milk and Milk Products
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1. Introduction

• Raw materials
• Manufactured items
• a. processed outter, cheese, ice cream, dairy
  products
• b. modified by condensing, drying, flavoring,
  fortifying, demineralizing
• c. combined with other substances milk
  chocolate, bread, cakes, sausage, confectionery,
  soups

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2. Composition of milks
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3. Legal standards

• Milk is the most legally controlled of all food
  commodities
• (i) Content nutritional standpoint
• (ii) Sanitary milk handling health
• milk processing disease
• ?Fat? ranging from 3.0 to 3.8
• ?Total solid? 11.2 to 12.25

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4. Milk production practices (farm)

• Milking (vacuum, squeeze, suck) (milking machine
  cups)
• Cooling 4.4? (control bacterial growth)
• Central receiving station (processing plant)

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5. Quality control tests (at a processing plant)

• Inspections (incoming product)
• Determination of "fat" and "total solids"
• Estimation of sediment (through filter)
• Determination of bacterial counts
• "total count", "coliform count", "yeast"
  and "mold count"
• Determination of freezing point as an index to
  possible water pick-up
• Evaluation of milk flavor a. feeds
• b. bacterial (lipase) (oxidation)
• c. copper, iron (pipes, equipment)
• (vi) Detection of antibiotic residues and
  pesticide residues (feed)
• Public Health Service/ Food and Drug
  Administration

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6. Milk processing sequence

• (1) Clarification
• Centrifugal clarifier
• Remove a. sediment, b. body cells, c. some
  bacteria

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• (2) Pasteurization
• Purpose
• (i) To rid the milk of any disease-producing
  organisms (inactivates about 95 of the
  comtaminating microorganisms)
• (ii) To destroy lipase and other natural milk
  enzymes
• Condition
• Temp. Time
• Destruction of Mycobacterium tuberculosis
  (Heat-resistant nonspore-forming bacterium)

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• Method
• (i) Batch 63?, 30min
• (ii) HTST 72?, 15 sec (Fig. 13.2)
• (iii) Ultrapasteurization 138?, 5 sec
• (iv) Sterilization 116?, 20min
• (v) UHT 150?, 4sec
• Means
• (i) It was not "sterile"
• (ii) alkaline phosphatase (indicator) inadequate
  processing (improper pasteurization)

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• (3) Homogenization
• (i) Countless fat globules (0.1-20 um, 80-90
  globules are 2-6 um, mean 3.5 um) ?clumps and
  rise
• Objective
• a. to subdivide the fat globules (to 1 um)
• b. prevents the cream from rising to the top
  (creaming)
• (ii) After homogenization
• a. A richer taste (flavor) due to an
  increase in surface area
• b. A whiter appearing color
• Ex. Greater whitening powder (coffee) (Fig. 13.3)

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7. Related milk products

• (1) Vitamin D milk
• (i) Children is deficient in Vit. D
• (ii) Added before pasteurization
• (2) Multivitamin mineral milk
• Indiscriminate fortifying
• Vitamins Vit. A, Vit. D, Thiamin, Riboflavin,
  Niacin, Iron, and Iodine
• (3) Low-sodium milk
• (4) Soft-curd milk
• Casein (coagulate with enzyme)
• Calcium
• For infants and young children

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• (5) Low-lactose milk
• (i) Lactose intolerance (Lactase ? glucose
  galactose)
• adsorbed in the small intestine
• Disaccharides lactose
• Microbial fermentation ? causing intestinal
  distress
• (ii) Resolve Adding enzyme (lactase) in
  processing or home
• (6) Sterile milk
• (i) UHT 150?, 2-3 s, quickly and aseptically
  packaged
• (ii) cooked flavor and color change (Fig. 13.4)

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(7) Evaporated milk

• (i) one of concentrated milk
• (ii) Conc. 2.25 times
• (iii) Characteristics caramelized and cooked
  color and flavor
• (iv) Procedures
• raw whole milk ? clarification ? concentration ?
  fortifying (Vit. D) ? homogenization ? filling
  (can) ? sterilization (118?, 15 min) ? cooling

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(8) Sweetened condensed milk

• (i) is not sterilized
• (ii) sugar preservative, 63 of the final
  product (sucrose)
• Prevent multiplication of bacteria
• (iii) Raw material made from pasteurized milk
• (iv) Used for baking, ice cream, confectionery
  industries (Fig. 13.5)

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(9) Dried whole milk (milk powder)

• (i) dehydrated by spray, vacuum drying to about
  97 solid
• (ii) Procedures
• Raw milk ? standarize ? vacuum condense (1/4)
  (Vit. A, D) ? spary drying (150-170?) ? cooling
  (Vit. B1, C) ? sieving ? filling, canning,
  packing (N2) ? products
• skim milk, instant milk

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8. Separation of milk

• Centrifugal cream separator
• Cream Butter oil
• Skim milk Beverage, Manufactured foods, Animal
  feeds
• ?Low fat milk (0.5, addition of Vit. A. D)

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9. Milk substitutes

• (i) Butter's Oils of vegetable, marine
• Various subsitutes Margarine
• (ii) Vegetable fat frozen desserts (ice cream
  substitutes)
• Vegetable fat coffee whiteners
• Vegetable fat whipped toppings
• (iii) Imitation milks and beverage
• Casein derivatives (caseinates)
• Soybean protein
• Vegetable oil (nutrition, lower cost)
• Imitation milk resemble milk but contain
  neither milk fat nor other important dairy
  ingredients
• (iv) Fermented milk products (sour milk, yoghurt,
  kefit and kumiss)

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• Yoghurt
• Raw materials (skim milk, sugar), stabilizer
  (alginate, gelatin, gums) ? filtration ?
  homogenization ? sterilization (85?, 30 min or
  90.6?, 25 sec) ? cooling ? starter (Lactobacillus
  bulgaricus, Streptococcus thermophilus 2-3) ?
  filling ? fermentation (40?, 4-6 h, acidity
  0.7-0.8) ? cold storage (1.7?) ? product ? cold
  storage

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10. Ice cream and related products

• (1) Composition
• milk fat (butter fat) 12
• milk soild-nonfat (MSNF) l1
• sugar 15
• stabilizer 0.2
• emulsier 0.2
• flavoring materials
• water 61
• air

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(2) Functions

• (i) milk fat (butter fat)
• a. give the product a rich flavor
• b. improve it body and texture
• c. concentrated source of calories
• (ii) milk solid-nonfat (MSNF)
• a. flavor
• b. body
• c. texture
• d. high overrun
• ovrerun (volume of ice cream volume of mix)/
  volume of mix 100

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(2) Functions

• (iii) stabilizer
• improve body and texture?form gel
• prevent large ice crystals forming?binding water
  (coarse texture)
• Ex. gelatin, guar gum, karaya gum, seaweed gum,
  pectin carboxymethyl cellulose
• (iv) emulsifier (glycerin monofatty acid ester,
  sucrose fatty acid ester)
• a. disperse the fat globules
• b. prevent clumping together and churning out as
  butter granules
• c. improve whipping properties to reach desired
  overrun
• d. make ice cream dry and stiff
• egg yolk (lecithin), monoglycerides, diglycerides

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(2) Functions

• (v) sugar (sucrose, dextrose)
• a. sweetness
• b. lowers the freezing point
• (vi) flavoring materials
• Give ice cream varyiety and consumer appeal
• Ex. Vanilla, chocolate, strawberry, fruit, nut
• (vii) water
• (viii) air
• Ice cream is made to contain deal of air and
  is truly a whipped product
• air air cells, is necessary to prevent too
  dense, hard, cold in mouth

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(3) Manufacturing procedure

• Mixing
• Ice cream mix (liquid ingredients)
• ?Mixing vat (43?)
• ?Adding (sugar dry ingredients)
• (i) Pasteurization
• a. batch heating 71?, 30min
• b. continuous HTST, 82?, 25sec

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(3) Manufacturing procedure

• (ii) Homogenization
• Two stage homogenizer (with pressure)
• ?to break up fat globules and fat globule clumps
• ?together with the added emulsifiers, prevents
  churning of fat into butter granules during the
  freezing operation
• ?to improve the body and texture
• ?cooled to 4.4?
• (iii) Aging the mix
• During aging
• a. the melted fat solidify
• b. the gelatin of other stabilizer swells and
  combines with water
• c. the milk proteins swell with water
• d. the viscosity of the mix is increased
• Purposes The changes lead to quicker whipping to
  desired overrun in the freezer, smoother ice
  cream body and texture, and slower ice cream melt
  down.

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(3) Manufacturing procedure

• (iv) Freezing (mixing air)
• a. continuous freezer
• b. mix and air enter the freezing cylinders
• c. freezing operation to -5.5?, and to beat in
  and subdivide air cells
• Attention growth of large ice crystal?coarse
  texture
• Air cells muxt be small?give a stable frozen foam
• (v) Ice cream hardening (stiff the product)
• semisolid ice cream placed in a hardening room
• (-34?)

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(4) Physical structure of ice cream

• a ice crystals, b air cells
• three phase system air, oil/water

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11. Cream

• fat globule average size 3 um, O/W emulsion
• Raw mllk ? heating (32-38?) ? cream separation
  (skim milk) ? sterilization ? cooling ? aging ?
  product

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12. Butter

• Raw milk ? Cream separation (fat 30-40) ?
  Neutralization cream (Na2CO3) ? Sterilization ?
  Cooling ? Aging ? Adding pigment (carotene) ?
  Churning (O/W ? W/O) ? Removal butter-milk ?
  Washing ? Adding salt (2) working ? Forming ?
  Packaging ? Product
• Butter oil powder
• Butter casein (alkaline) solution ? mixing ?
  spray drying ? product

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13. Cheese

• (curd of the milk)
• milk rennin lactic acid ? coagulation of
  casein ? heating ? pressure ? salt ? ripening
  (selected microorganisms) (fermentation)

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(1) Cheddar cheese

• Curdmaking and subsequent operations
• Milk (raw milk, pasteurized milk) ?Adding rennin
  or acid ? Coagulation (curd)
• Casein, fat, lactose, water, minerals
• Curd controlled by temp., acidity, rennin conc.
• (i) Setting the milk
• Pasteurized whole milk (vat) ? 1, Streptococcus
  lactis (31?) (lactic acid producing starter) ?
  after 30 min, adding rennin solution (calf,
  microorganism) ? setting (curd form) ? squeeze
  out much of the trapped whey
• (ii) Cutting the curd

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(1) Cheddar cheese

• (iii) Cooking
• Temp. 38?, 25 min
• a. Heat increase the rate of acid production and
  makes the curd cubes shrink
• b. Expel the whey and toughen the curd cubes
• (iv) Draining whey and matting curd
• (v) Milling and salting (salt 2.5)
• Salt a. to further draw whey out of the curd by
• osmosis
• b. to inhibit proteolytic and other types
  of
• spoilage organisms
• c. to add flavor to the final cheese

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(1) Cheddar cheese

• (vi) Pressing (20 psi)
• (vii) Curing or ripening
• Cool room 16?, 60 RH, for 3-4 days
• ?cause mild surface drying and forms a slight
  rind
• ?curing or ripening room 2?, 85 RH, over 60 days
• a. by partial hydrolysis of the milk fat and
  further breakdown of fatty acids
• b. by milk proteolysis of the protein
• (viii) Advanced processes
• Hand operation ? mechanical equipment

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(2) Process cheese

• water, emulsifier, salt, powdered skim milk ?
  heating ? mixing ?extruding
• a. mixing or grinding different lots of natural
  cheese
• b. melting 71?
• c. Adding emulsifier to prevent fat separation

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(3) Cheese substitutes

• a. cheese analogs, imitation cheese
• b. replaced with vegetable fat and protein

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