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PHFS Exam 3 > Milk Grading and Processing > Flashcards

Milk Grading and Processing Flashcards

1
Q

top 3 milk producers

A
  1. India
  2. EU
  3. US
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2
Q

functional unit for milk production

A

alveolus of mammary gland (udder)

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3
Q

two layers of cells that make up mammary gland

A
  • lactocytes (mammary epithelial cells)
  • basal myoepithelial cells
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4
Q

what do lactocytes do, where are they located

A
  • milk producing cells
  • located on surface inside mammary gland
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5
Q

what do basal myoepithelium cells do, where are they located

A
  • like smooth muscle
  • located surrounding lactocytes
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6
Q

what is each alveolus surrounded by

A
  • capillaries
    • to get nutrients
    • synthesize and express milk
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7
Q

how much blood is needed to form 1 L of milk

A

~800-900 L of blood

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8
Q

how is milk secretion from mammary gland performed

A

myoepithelial cells squeeze each alveolus to discharge milk into lumen of ductules under influence of oxytocin

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9
Q

which hormone is required to release milk from udder

A

oxytocin (released from pituitary gland)

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10
Q

where is milk stored

A

60-80% in alveoli
20-40% in cistern

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11
Q

true or false: each quarter of a cow udder is independently working

A

true

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12
Q
A
  1. gland cistern
  2. teat cistern
  3. teat canal
  4. alveolus
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13
Q

how long and when is colostrum production, how long is milk production

A
  • colostrum production starts nearly pre partum and continues post partum
  • colostrum produced for 3-5 days
  • milk production for ~305 days
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14
Q

comparison of colostrum and mil appearance

A
  • colostrum
    • viscous, thick, waxy, yellowish
  • milk
    • thin, liquified, white
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15
Q

comparison of colostrum to milk - dry matter, minerals, proteins, fat soluble vitamins

A
  • colostrum has 2x more dry matter
  • colostrum has 3x more minerals
  • colostrum has 5x more proteins
  • colostrum has more fat soluble vitamins
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16
Q

is colostrum suitable for processing, should it be shipped to milk processing facilities

A

colostrum is not suitable for processing and should not be shipped to milk processing facilities

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17
Q

true or false: milk is nearly a complete diet and does not have pH and moisture danger zones

A

false - milk is nearly a complete diet but does have pH and moisture danger zone naturally

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18
Q

milk composition

A
  • 87% water
  • 4.9% carbs
  • 3.4% fat
  • 3.3% protein
  • 1.4% vitamins and minerals
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19
Q

what does the deviation of milk compositions from normal proportions indicate

A

adulteration or contamination of milk

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20
Q

milk fat composition

A

65% saturated fat
29% monounsaturated fat
6% polyunsaturated fat

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21
Q

what is a saturated fat

A

type of fat in which the fatty acid chains have all single bonds

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22
Q

two broad categories of milk proteins based on solubility in water

A
  • whey proteins (20%) - albumin, antibodies
  • caseins (80%)
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23
Q

which milk proteins are soluble, which are insoluble

A
  • whey proteins are soluble
  • caseins are insoluble
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24
Q

whey protein fractions

A
  • B-lactoglobulin - 49%
  • a-lactalbumin - 18%
  • protease peptone fraction - 15%
  • immunoglobulins - 12%
  • blood serum albumin - 6%
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25
Q

casein proteins fractions

A
  • caseins as1-casein - 40%
  • caseins B-casein - 34%
  • caseins k-casein - 12%
  • caseins as2-casein - 10%
  • caseins y-casein - 4%
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26
Q

which milk protein is the major raw material for cheese making

A

caseins

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27
Q

vitamins and minerals found in large amounts in milk

A
  • vitamin B12 (cobalamin)
  • vitamin B2 (riboflavin)
  • calcium
  • phosphorous
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28
Q

testing milk aroma

A

if off-odor retest
ensure sample not too hot
if off odor still persists get second opinion from plant manager

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29
Q

testing milk pH

A

normal - 6.5-6.8 (at 25C)
ensure milk sample at correct temperature and pH meter is calibrated
if pH is out of range contact plant manager and retest
if retest <6.5 or >6.8, reject

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30
Q

testing milk titratable acidity

A

normal - 0.13-0.17
if retest between 0.13 and 0.18 milk may be ok if all other tests ok
discuss history of load
if retest <0.13 or >0.17, reject

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31
Q

seven major parameters routinely checked by regulatory agencies for quality raw milk production

A
  • somatic cell count - 750,000 cells/mL
  • bacteria count - 100,000 cfu/mL
  • organoleptic quality - color, odor, taste, consistency
  • milk chemical composition (nutrition) - water, fat, protein, minerals
  • adulteration or residues
  • pH - 6.5-6.8
  • temperature - <4C
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32
Q

what nutritional composition must regulated milk have

A
  • 87% water
  • > 3.325% fat
  • > 8.25% non fat solids
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33
Q

what are somatic cell counts related to

A

mastits

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34
Q

what SCC must regulated raw milk have

A

less than 750,000 SCC/mL

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35
Q

how are bacterial counts in milk measured

A

standard plate count (aerobic colony count)

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36
Q

bacteria counts of regulated milk

A

less than 100,000 CFU/mL

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37
Q

bacterial count by standard plate count

A
  • targets general bacteria
  • counts overall number of aerobic bacteria in milk
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38
Q

bacteria count by preliminary incubation count

A
  • targets sub groups - cold loving bacteria
  • involves holding milk at 12.8C for 18 hours prior to plating
  • detects bacteria that grow well at fridge temperatures (psychrotrophic bacteria)
39
Q

bacterial counts by lab pasteurization count

A
  • targets sub groups - heat resistant bacteria
  • involves holding milk at 63.8C for 30 minutes prior to plating
  • bacteria that survive heat treatment (thermoduric bacteria) are enumerated using standard plate count
40
Q

bacterial counts by coliform bacteria counts

A
  • targets sub groups - fecal or environmental bacteria
  • selects for bacteria most associated with manure or environmental contamination
  • requires selective media for coliforms and inhibiting other bacteria
41
Q

most frequent cause of high SPC bacterial counts

A

poor cleaning of milking systems

42
Q

sources of high bacterial counts

A
  • mastitis - staph aureus, streptococcus, coliforms
  • soiled cows
  • unsanitary milking conditions
  • failure to cool milk rapidly to less than 4C
  • failure of water heater
43
Q

normal color of milk

A

whitish

44
Q

normal odor of milk

A

no off-odor

45
Q

normal taste of milk

A

pleasantly sweet

46
Q

normal consistency of milk

A

liquid but not watery

47
Q

three major sources or causes of bad flavor and odor development in milk

A
  • absorbed or transmitted form environment
  • bacterial or microbial
  • chemical, enzymatic, processing
48
Q

how does absorbed or transmitted from environment affect milk flavor

A

feedy, barny, cowy, weedy, unclean, lacks freshness, stale, refrigerator or cooler odors

49
Q

how does bacteria or microbes affect milk flavor

A

acid, bitter, malty, lacks freshness, unclean, fruity or fermented, putrid, rancid

50
Q

how does chemical, enzymatic, processing affect milk flavor

A

cowy (ketosis), salty, rancid, bitter, oxidized, sunlight, foreign, astringent, medicinal, flat, cooked

51
Q

organoleptic characteristic of typical normal milk flavor

A

very little distinct odor
pleasantly sweet
clean with no aftertaste

52
Q

organoleptic characteristic of acid (sour) milk

A

sour like lemon due to lactic acid production by microbes due to poor refrigeration

53
Q

organoleptic characteristic of barny milk

A

barn (feces) odor due to ventilation and unclean barn conditions or ketosis

54
Q

organoleptic characteristic of bitter (beer taste) milk

A

bitter like hops in beer or coffee due to breakdown of milk proteins by microbial enzymes

55
Q

organoleptic characteristic of carton/paperboard milk

A

resembles freshly dampened cardboard becasue milk absorbed odor of carton pack

56
Q

organoleptic characteristic of cooked milk flavor

A

suggestive of boiled milk
results from improper pasteurization

57
Q

organoleptic characteristic of cowy flavor milk

A

cow breath or fecal odor due to acetone such as during ketosis or acetonemia

58
Q

organoleptic characteristic of feed flavor milk

A

milk has silage, hay, grassy flavor
feeding should be done after milking as milk absorbs odor
poor ventilation could also cause feed flavor

59
Q

organoleptic characteristic of flat (watery) milk flavor

A

loss of normal flavor of milk due to adulteration, particularly water addition

60
Q

organoleptic characteristic of garlic or oniony milk flavor

A

cows may consume garlic weed

61
Q

organoleptic characteristic of rancid (soapy) milk flavor

A

putrified fat due to release of free fatty acid by microbial destruction of milk fat

62
Q

organoleptic characteristic of salty milk flavor

A

like salt, which is linked to late lactation or mastitis

63
Q

advantages to grading milk

A
  • standardizes milk prices
  • determines type of milk sold in liquid form
  • determines type of milk that requires further processing (cheese) before consumption
64
Q

criteria for milk grading

A
  • chemical constituents (water, fat, non fat)
  • load of bacteria count
  • bulk tank SCC
  • organoleptic features of milk
65
Q

milk grades based on bacteria counts

A
  • certified milk - <10,000 cfu/mL - expensive milk (for famous people)
  • grade A - < 100,000 cfu/mL - supermarket milk
  • grade B - <500,000 cfu/mL - low quality
66
Q

what is grade B milk used for

A

cheese
further processed products
illegal to sell as milk

67
Q

characteristics of certified milk

A
  • 3.5-4% fat
  • 8-8.5% total solid non fat
  • <10,000 cfu/mL aerobic bacteria count
  • 0 zero tolerance coliform plate count
  • <0.17% total acidity
68
Q

characteristics of grade A milk

A
  • <750,000 SCC
  • <100,000 aerobic bacterial count
  • <10 cfu/mL zero tolerance coliform plate count
  • <0.02% total acidity
69
Q

characteristics of grade B milk

A
  • <1,000,000 SCC
  • < 500,000 aerobic bacteria count
  • <100 zero tolerance coliform plate count
  • > 0.2% total acidity
  • <0.75 mg/O.5 L milk foreign particles
70
Q

pasteruization temperature

A

> 63 C
kill microbes

71
Q

4 kinds of milk pasteruization

A
  • ultra high temp
    • 125-140 C for 2-4 sec
    • long shelf life (>6 months)
  • canned sterilization
    • 115-120 C for 15-20 min
  • high temp short time
    • 72-74 C for 15-20 sec
    • widely used
  • low temp long time (batch)
    • 63 C for 30 minutes
72
Q

yogurt processing

A
  • 40-45 C for 15 min
73
Q

cheese processing

A
  • 30-35 C for 15 min
74
Q

thermization

A
  • 57-68 C for 15 min
  • targets pathogenic bacteria
  • leaves good bacteria
  • does not alter structure and taste of milk
75
Q

batch pasteruization

A
  • low temp high time
  • 63 C for 30 min
  • alteration in milk protein, structure, and taste
76
Q

flash pasteurization

A
  • high temp short time
  • 72-74 C for 15-20 sec
77
Q

ultra high temperature pasteurization

A
  • 135-140 C for 2-4 sec
  • targets coxiella burnetii (Q fever)
  • kills vegetative forms of bacteria and milk can survive for 9 months
78
Q

canned sterilization

A
  • wet treatment of canned milk products in autoclave/specialized treatment chamber
  • 115-121 C for 10-20 min
79
Q

basic steps in milk processing

A

separating its components

  • raw milk
    • water 87.4%
    • milk solids 12.6%
      • milk fat 3.6%
      • milk solids non fat 9%
        • minerals 0.7%
        • lactose 4.9%
        • protein 3.4%
          • casein 2.7%
          • whey protein 0.7%
80
Q

nano pore membrane technology

A

reverse osmosis (RO), nanofiltration (NF), ultrafiltration (UF), microfiltration (MF)

81
Q

milk processing - collection

A
  • collected rom dairies
  • stored in storage tanks
  • cooled to certain temp
  • transferred to refrigerated tanks
82
Q

milk processing - separation

A
  • sediment, debris, bacteria removed from raw milk
  • heavier milk fat and lighter milk separated to get skim milk and cream
83
Q

milk processing - pasteurization

A
  • milk heated to specific temp for specific time
  • cooling again without allowing recontamination
84
Q

milk processing - standardizing

A
  • reintroducing 1%, 2%, 3.5% fat
85
Q

milk processing - homogenizing

A
  • raw milk pushed through atomizer to form tiny particles to disperse fat evenly
  • stops fat from floating to top of container
  • done by breaking down the fat particles
86
Q

milk processing - packaging

A
  • cartons for retail or used further for manufacturing other dairy products
87
Q

cheese processing

A
  • standardize milk (protein to fat ratio)
  • pasteurize 63C or heat treat 30-35C
  • cool to 32C for starter bacteria
  • inoculate with starter and non starter bacteria, hold at 32C for 30 min to ripen
  • add rennet and form curd and curds not disturbed for 30 min
  • ferment until pH 6.4, cut curd, heat at 38C to separate curds from whey
  • drain whey
  • cut into blocks, piling and flipping until pH 5.1-5.5 and cut into pieces
  • sprinkle dry alt or brine (salt water solution) onto vats
  • form into blocks by placing cheese in hoops (molds)
  • store in coolers for aging (months to years)
  • package
88
Q

starter bacteria for cheese making

A
  • lactococcus lactis
  • streptococcus thermophilus
  • lactobacillus sp
89
Q

what is rennet

A

enzyme cleaving casein

90
Q

top 5 biological hazards associated with milk

A

listeria monocytogenes
e coli
salmonella
infested with moulds or yeasts
staphylococcus

91
Q

milk quality assessmnet

A

20 GHP
12 HACCP
5 animal welfare (including avoiding milking cows with 5Ds)
7 milk quality assessment methods

92
Q

7 milk quality assessment methods

A

SCC
bacteria count
milk composition
organoleptic
pH
temperature

93
Q

5Ds of milking cows

A
  • distorted milk
  • drug residues in milk
  • devastated animal
  • diseased animal
  • discharges from animal

PHFS Exam 3 (5 decks)

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