PHFS Exam 3 > Milk Grading and Processing > Flashcards

Milk Grading and Processing Flashcards

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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
casein proteins fractions
- caseins as1-casein - 40% - caseins B-casein - 34% - caseins k-casein - 12% - caseins as2-casein - 10% - caseins y-casein - 4%
26
which milk protein is the major raw material for cheese making
caseins
27
vitamins and minerals found in large amounts in milk
- vitamin B12 (cobalamin) - vitamin B2 (riboflavin) - calcium - phosphorous
28
testing milk aroma
if off-odor retest ensure sample not too hot if off odor still persists get second opinion from plant manager
29
testing milk pH
**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**
30
testing milk titratable acidity
**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**
31
seven major parameters routinely checked by regulatory agencies for quality raw milk production
- 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
32
what nutritional composition must regulated milk have
- 87% water - >3.325% fat - >8.25% non fat solids
33
what are somatic cell counts related to
mastits
34
what SCC must regulated raw milk have
less than 750,000 SCC/mL
35
how are bacterial counts in milk measured
standard plate count (aerobic colony count)
36
bacteria counts of regulated milk
less than 100,000 CFU/mL
37
bacterial count by standard plate count
- targets general bacteria - counts overall number of aerobic bacteria in milk
38
bacteria count by preliminary incubation count
- 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
bacterial counts by lab pasteurization count
- 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
bacterial counts by coliform bacteria counts
- 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
most frequent cause of high SPC bacterial counts
poor cleaning of milking systems
42
sources of high bacterial counts
- mastitis - staph aureus, streptococcus, coliforms - soiled cows - unsanitary milking conditions - failure to cool milk rapidly to less than 4C - failure of water heater
43
normal color of milk
whitish
44
normal odor of milk
no off-odor
45
normal taste of milk
pleasantly sweet
46
normal consistency of milk
liquid but not watery
47
three major sources or causes of bad flavor and odor development in milk
- absorbed or transmitted form environment - bacterial or microbial - chemical, enzymatic, processing
48
how does absorbed or transmitted from environment affect milk flavor
feedy, barny, cowy, weedy, unclean, lacks freshness, stale, refrigerator or cooler odors
49
how does bacteria or microbes affect milk flavor
acid, bitter, malty, lacks freshness, unclean, fruity or fermented, putrid, rancid
50
how does chemical, enzymatic, processing affect milk flavor
cowy (ketosis), salty, rancid, bitter, oxidized, sunlight, foreign, astringent, medicinal, flat, cooked
51
organoleptic characteristic of typical normal milk flavor
very little distinct odor pleasantly sweet clean with no aftertaste
52
organoleptic characteristic of acid (sour) milk
sour like lemon due to **lactic acid** production by microbes due to poor refrigeration
53
organoleptic characteristic of barny milk
barn (**feces**) odor due to ventilation and unclean barn conditions or ketosis
54
organoleptic characteristic of bitter (beer taste) milk
bitter like hops in beer or coffee due to breakdown of **milk proteins** by microbial enzymes
55
organoleptic characteristic of carton/paperboard milk
resembles freshly dampened cardboard becasue milk absorbed odor of carton pack
56
organoleptic characteristic of cooked milk flavor
suggestive of boiled milk results from improper **pasteurization**
57
organoleptic characteristic of cowy flavor milk
cow breath or fecal odor due to acetone such as during ketosis or acetonemia
58
organoleptic characteristic of feed flavor milk
milk has silage, hay, grassy flavor feeding should be done after milking as milk absorbs odor poor ventilation could also cause feed flavor
59
organoleptic characteristic of flat (watery) milk flavor
loss of normal flavor of milk due to adulteration, particularly **water addition**
60
organoleptic characteristic of garlic or oniony milk flavor
cows may consume garlic weed
61
organoleptic characteristic of rancid (soapy) milk flavor
putrified fat due to release of free **fatty acid** by microbial destruction of milk fat
62
organoleptic characteristic of salty milk flavor
like salt, which is linked to late lactation or **mastitis**
63
advantages to grading milk
- standardizes milk prices - determines type of milk sold in liquid form - determines type of milk that requires further processing (cheese) before consumption
64
criteria for milk grading
- chemical constituents (water, fat, non fat) - load of bacteria count - bulk tank SCC - organoleptic features of milk
65
milk grades based on bacteria counts
- 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
what is grade B milk used for
cheese further processed products illegal to sell as milk
67
characteristics of certified milk
- 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
characteristics of grade A milk
- <750,000 SCC - <100,000 aerobic bacterial count - <10 cfu/mL zero tolerance coliform plate count - <0.02% total acidity
69
characteristics of grade B milk
- <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
pasteruization temperature
>63 C kill microbes
71
4 kinds of milk pasteruization
- 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
yogurt processing
- 40-45 C for 15 min
73
cheese processing
- 30-35 C for 15 min
74
thermization
- 57-68 C for 15 min - targets pathogenic bacteria - leaves good bacteria - does not alter structure and taste of milk
75
batch pasteruization
- low temp high time - 63 C for 30 min - alteration in milk protein, structure, and taste
76
flash pasteurization
- high temp short time - 72-74 C for 15-20 sec
77
ultra high temperature pasteurization
- 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
canned sterilization
- wet treatment of canned milk products in autoclave/specialized treatment chamber - 115-121 C for 10-20 min
79
basic steps in milk processing
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
nano pore membrane technology
reverse osmosis (RO), nanofiltration (NF), ultrafiltration (UF), microfiltration (MF)
81
milk processing - collection
- collected rom dairies - stored in storage tanks - cooled to certain temp - transferred to refrigerated tanks
82
milk processing - separation
- sediment, debris, bacteria removed from raw milk - heavier milk fat and lighter milk separated to get skim milk and cream
83
milk processing - pasteurization
- milk heated to specific temp for specific time - cooling again without allowing recontamination
84
milk processing - standardizing
- reintroducing 1%, 2%, 3.5% fat
85
milk processing - homogenizing
- 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
milk processing - packaging
- cartons for retail or used further for manufacturing other dairy products
87
cheese processing
- 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
starter bacteria for cheese making
- lactococcus lactis - streptococcus thermophilus - lactobacillus sp
89
what is rennet
enzyme cleaving casein
90
top 5 biological hazards associated with milk
listeria monocytogenes e coli salmonella infested with moulds or yeasts staphylococcus
91
milk quality assessmnet
20 GHP 12 HACCP 5 animal welfare (including avoiding milking cows with 5Ds) 7 milk quality assessment methods
92
7 milk quality assessment methods
SCC bacteria count milk composition organoleptic pH temperature
93
5Ds of milking cows
- distorted milk - drug residues in milk - devastated animal - diseased animal - discharges from animal
PHFS Exam 3
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