FDNS 1301 Introduction to Foods Milk and Dairy Products - PowerPoint PPT Presentation

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FDNS 1301 Introduction to Foods Milk and Dairy Products

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clusters grow in size during standing; results in cream layer at top. Carbohydrates ... creme fraiche (sour cream, yogurt and buttermilk fermented together) ... – PowerPoint PPT presentation

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Title: FDNS 1301 Introduction to Foods Milk and Dairy Products


1
FDNS 1301Introduction to FoodsMilk and Dairy
Products 
2
Composition of milkProteins
  •     82 casein, rest in whey (lactalbumin,
    lactoglobumin)    casein dispersed in milk
    serum susceptible to coagulation by low pH
    (4.6)    whey proteins not affected by acid but
    are coagulated by heat

3
    Whey Protein concentrate (WPC) and Whey
Protein Isolates (WPI) produced by
ultrafiltration (gelling agent) 
4
Fats
  •     milk is an emulsion (oil in water)   
    mainly composed of triglycerides     fats
    normally form loose clusters in unhomogenized
    milk     clusters grow in size during
    standing results in cream layer at top

5
Carbohydrates
  •     main sugar is lactose (glucose /
    galactose) Lactose Intolerance    inability
    to breakdown lactose in small intestine due to
    low quantities of the enzyme lactase    gas,
    cramping and diarrhea results    simple test
    (mucus reaction on tongue)

6
Color
  •     light reflection from casein and calcium
    phosphate salts    contains two pigments
  • 1. Carotene in milkfat    levels depend upon
    feed and metabolism (change to Vitamin A) 2.
    Riboflavin     water soluble suspended in whey

7
Flavor
  •     sweet from lactose    mouth feel from fat
    content     off-flavors from the following1.
    heat processing2. feed consumed3. bacteria
    action4. chemical changes5. foreign flavors6.
    oxidation

8
Acid levels
  •     pH of 6.6    lowers over time from release
    of CO2     sour milk produced from lactose in
    unpasteurized    pasteurized milk spoiled from
    putrefactive bacteria

9
Milk Classifications
  • 1. Fluid Milk Whole    Fresh milk from the
    cow with nothing removed or added (except Vitamin
    D) Skim or nonfat     Most of the fat removed
    (less than 0.5 )    Can be fortified

10
Fluid Milk cont.
  • Low fat    Fat content between 0.5 and 3    
    Can be fortified Ultrahigh-temp. processed   
    sterilized milk in tetra packaging

11
2. Concentrated Fluid Milk
  • Evaporated    Milk, whole or skim with 60 of
    its water removed, sterilized and canned (cooked
    flavor) Condensed    Whole milk with 60 of
    its water removed and sweetened with sugar

12
3. Dry Milk (moisture 3)  
13
4. Cultured or Fermented Products
  • Yogurt    Milk cultured by bacteria to a
    custardlike consistency    Most has additional
    milk solids added    Some is flavored and
    sweetened

14
4. Cultured or Fermented Products
  • Cultured Buttermilk    fresh milk cultured or
    soured by bacteria Real Buttermilk    Liquid
    remaining after the whey is drained off after
    butter making Acidophilus    Milk cultured by
    bacteria that consume lactose    Used by
    lactose intolerant people

15
Milk Classifications
  • 5. Filled Milks (other fat with nonfat milk
    solids) 6. Imitation milks (no milk products)

16
Cream
  •     high fat liquid separated from whole milk
        min. 18 milkfat

17
Types of cream
  •     half and half (18)    light (30-36)   
    heavy (36 minimum)    sour cream
    (commercially cultured light cream)    creme
    fraiche (sour cream, yogurt and buttermilk
    fermented together) Non-dairy Products   
    Cool Whip

18
Sanitation concerns
  • Pasteurization    heating of a product to
    specific temperatures to destroy most bacteria,
    decrease spoilage and increase storage
    times.    two typesA.145F for 30
    minutesB.162F for 15 seconds

19
Sterilization
  •     ultrahigh temperatures to kill all
    microbes    280F - 302F for 2 to 6 seconds

20
Storage Concerns
  •     remember that pasteurization does not kill
    all microbes    refrigerate at 45F or
    lower    prevent light exposure (oxidation of
    fat, degradation of vitamin D)    tight seal to
    prevent odors

21
Food Preparation ConcernsEffects of heat
  •     whey proteins precipitate due to
    insolubility    coagulation at 150F   
    collection on bottom and sides of pots when
    exposed to direct heat    casein does not
    coagulate at normal levels and temperatures   
    accelerated coagulation in presence of acid   
    some browning due to Maillard reaction

22
Acid coagulation
  •     very sensitive to acid     lowered pH
    coagulates casein (curd)

23
Enzymes
  •     rennet at optimum temp and pH coagulates
    casein

24
Freezing
  •     ruptured emulsifying agent    fat globules
    coalesce    setting of proteins

25
Milk foams
  •     foaming agent (protein) thats dispersed in
    a liquid (water) with a stabilizing agent (fat)
    to hold gas bubbles (air)     whipping cream
    sometimes not homogenized     most proteins
    tied up around increased fat globules     not
    enough to cover air bubbles

26
Factors affecting Milk Foams
  • 1. Temperature    cold temp cream whips
    better    want to increase clumping of fat for
    stabilization    agitation results in
    clumping    lower temp. increases viscosity

27
2. Viscosity
  •     thicker creams have more fat globules
    therefore stabilize foam    aging increases
    viscosity

28
Factors affecting Milk Foams
  • Fat Content
  • 4. Amount of Cream
  • 5. Other Substances    sugar decreases volume
    and stiffness    sugar increases time of
    whipping if added at beginning of process

29
Cheese and Cheese Products
  •     draining the whey after the coagulation of
    casein due to acid and/or enzymatic activity
    resulting in curds    curds may have further
    action by heat, bacteria or pressure    high
    quality milk used

30
Steps to form cheese
  • 1)        Curd formation2)        Cutting curd
    into small pieces to release whey3)        Heat
    curds to remove additional whey4)       
    Draining, salting and ripening5)        Curing
    or ripening

31
Ripening
  •     otherwise known as aging    outer rind
    formed (either naturally or by spraying with a
    culture)    lactose converted to lactic
    acid    proteins broken down and curd
    softens    flavors developed from above process
    and initial milk components

32
Types of ripening
  • Interior ripened    occurs throughout entire
    bodybacteria cheddar, Swiss, parmesanmold
    blue cheeses 
  • Surface ripening     ripening from surface to
    insidebacteria limburgermold brie,
    camembert 
  • Unripened (Cottage, cream)

33
Classification of cheeses
  • 1)    Soft, unripened (cottage)2)  Firm,
    unripened (mozzarella)3)  Soft, ripened
    (brie)4)  Semisoft, ripened (Monterey
    Jack)5)  Firm, ripened (cheddar, Colby,
    gouda)6)  Very hard, ripened (parmesan,
    romano)7)  Blue-vein mold ripened
    (blue)8)  Goat Cheeses

34
Cheese Products
  • 1. Cold-Pack Cheese-    mixture of cheeses
    (cheaper Parmesan imitations) 2. Process
    Cheese (Kraft slices) 3. Process Cheese Food /
    Spread (Velveeta, Cheez Whiz)
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