Dairy Cows > Milk: Composition and Processing > Flashcards

Milk: Composition and Processing Flashcards

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1
Q

how large is the dairy processing industry

A
  • second largest in canada, second only to the meet processing industry
  • but they swing back and forth
  • 18-20% of the food market in canada
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2
Q

what are challenges of the dairy industry

A
  • market for dairy products is mature, growth in consumption is sow ( compared to other products)
  • consumer concerns ( fat and choleserol)
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3
Q

new innovations in the dairy industry

A
  • new food ingredients from milk ( whey proteins)
  • microfiltered products ( processed by heat 76c for 18 seconds in canada and 85c for 30s in japan)
  • flavoured products ( strawberry and banana flavours, newest development
  • low lactose products ( most people can digest lactose as babies but it changes into adulthood
  • functional milks ( omega -3, Ca++, probiotics)
  • butter variations, butter- vegetable oil blends
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4
Q

fluid milk

A
  • 40% of production in canada
  • table milks and creams
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5
Q

industrial milk

A
  • 60% of production ( milk product)
  • manufactored products ( cultured, cheddar-type cheeses, evaporated/condensed products, dehydrated and confectionary)
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6
Q

dairy products

A
  • vary from ready to eat to ingredients of foods
  • we do not call them dairy, but there are a lot of food products including dairy ingredients
  • dairy foods and their wide applications
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7
Q

table milks

A
  • skim milk 1% 2% 3.25% ( homo)
  • reduced in fat content relative to whole milk ( 3.8%) - fluctuating numbers
  • new products - low lactose, purfiltre( filtered milk = claims that is tastes better)
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8
Q

creams

A
  • many different types
  • 10-45% fat ( cream milk, half and half, cereal cream, whipping cream (35%) heavy cream 40%)
  • elevated fat content relative to whole milk
  • depending on the amount of fat you need/want
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9
Q

flavoured products

A
  • sugar, flavour, colour stabilizer added pre- pasteurization
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10
Q

UHT products

A
  • shelf - stabke without refrigeration
  • not as common
  • lasts way longer than 6 months
  • stored on shelf or room temperature
  • good for emergency
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11
Q

lactose - reduced products

A

milk is batch treated with B - galactosidase to convert lactose to galactose and glucose ( 70% + conversion)
- sometimes its lactose reduced, but still contains some)

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12
Q

evaporated (condensed) milks

A
  • milk is evaporated to one-half original volume ( after adjustment of butterfat), subsequently filled into cans, retorted
  • kill all microbes - the last very long ( sterilized)
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13
Q

sweetened condensed milk

A
  • milk is evaporated, sugar is added to level of intermediate-moisture food, product is pasteurized, filled into cans under stringently hygenic conidtions
  • kills all microbs - they last very long ( sterilized)
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14
Q

cultured products

A

hard and semi hard cheeses
ricotta cheese

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15
Q

hard and semi hard cheese

A

milk is midly cultured ( flavour, enzymes), treated with rennin( chymosin) to precipitate casein which is heated, salted drained, pressed, aged ( with or without additional culture)

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16
Q

ricotta cheese

A
  • processed differently then regular cheese
  • ## cheddar cheese whey is heated in the presence of Ca +, acid to precipitate whey proteins, drained, salted, formed
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17
Q

products derived from milk

A
  • cream cheese and cottage cheese
  • sour cream
  • cultured buttermilk
  • whey protein concentrates and itolates
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18
Q

cream cheese

A
  • milk is partially coagulated with a less amount of rennet, heated then centrifuged, result is curd is mixed with cream
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19
Q

cottage cheese

A
  • its not aged its just protein that creates the texture
  • milk is cultured with a lactic acid bacterium ( streptococcus lactis)
  • lactic acid produced from lactose reduces pH to 4.6, casein precipitates and is heated, salted, drained
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20
Q

sour cream

A

cream is cultured, precipitation casen forms viscous gel
- gravity separation, takes hours and microbs go sour

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21
Q

cultured buttermilk

A
  • bi product of making butter
  • skim milk is cultured to develop flavour, acidity
  • originally it was a fluid part of butter making process
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22
Q

whey protein concentrates and isolates

A
  • water drainage from cheese making - why proteins are recovered and used for other products (protein powder)
  • whey is concented by membrane filtration - concentrate is then dried
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23
Q

other dairy products derived from milk

A
  • butter
  • butter oil / clarififed butter
  • ice cream
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24
Q

butter

A
  • cream is chilled ( with or without mild culturing )
    churned; converts oil in water emulsion to water- in- oil emulsion, which is drained, salted and moulded
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25
butter oil/ clarified butter
- cream is rendered to remove non fat consituents
26
ice cream
- mixture of milk, cream, milk solids, sugar, flavour, stabilizers is aerated/frozen in scraped- surface heat exchangers
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caseinates
casein is precipitated by addition of HCL, neutralized, evaporated and dried
28
casamino acids
- as above except hydrolyzed by acid/ enzyme prior to neutralization
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dehydrated products
- skim milk powder, buttermilk powder, whey powder and whey protein concentrates - liquid product is vacuum evaporated, spray dried in a high temperature/ high velocity airstream, may be agglomerated to improve dispersability - they are mostly used as food ingredients in the processed foods, such as dressings and canned soup
30
milk as defined in the law
B .08.003 Milk or whole milk - shall be the normal lacteal secretion obtained from the mammary glland of the cow, genus Bos - shall contain added vitamin D is such an amount that a reasonable daily intake of the milk contains not less that 300 international units and not more than 400 international units of vitamin D
31
what can be classified as milk
only cows - any other milk type will have the animal on the lable
32
what is milk
- nutrition for infanc=ts - contains all necessary nutrients - milk is solely made for the purpose as food - milk is a complex mixture - there is more than 1000 molecular species - there are many factors that can are affected from the complexity
33
the post colostrum mammary secretion of cows compotition
87.3% water 3.9% milkfat 8.8% non-fat solids ( solids- not - fat; SNF) most variable component is fat
34
what makes up SNF
- 4.6% lactose - 3.25% proteins - 0.65% minerals - 0.18% acids, enzymes, gasses and vitamins
35
structure of milk
- milk is in liquid form - remarkably high solid fluid
36
three aspects of milk as liquid
- oil in water emulsion - colloid suspension - solution
37
lactose
- milk contains considerable amounts of sugar - lactose is essentially unique to milk 4-o-B-D galactopyranosyl-D-glucopyranose - energy source for young animals
38
chemical properties of lactose impact the chemical and physical properties of milk and milk products
sweetness: sweetnss is much lower than sucrose smoothness: sandy mouth from ice cream, evaporated milk ( sugar/ice crystals = beating process is important) color: caramelization, maillard reaction fermentation substrate: lactic acid formation
39
what does lactose stimulate
- stimulates intestinal absorption of calcium - lactose containing oligosaccharides in milk have a pre-biotic effect on lactobacillus bifidus, which becomes the predominant microbe of the intestinal flora of breast fede infants
40
lactose intolerance
- hydrolyzed to galactose and glucose in the small intestine by B-galactosidase (lactase) - is not hydrolyzed in the small intestine, fermented in large intestine - acidic products irritate the lining of the colon, leading to an increased movement of contents - diarrhea is caused by this increased movement and by fluid retention - gaseous products of fermentation cause bloating and cramping - uncommon in childen under 6 and becomes more increased with age - incidence and degree of lactose intolerance vary among ethnic groups - lactase helps to hydrolize lactase in small intestine
41
milk fat
- energy supplier in milk triglycerides ( account for 98.3% of milk fat, combination of fatty acids on glycerol) - other lipids ( phospholipids, cholesterole)
42
which fatty acids are in milk fat
long chain ( 89% supplied from rumen through the blood) - short chain ( 11% made in secretory cells) - saturdated and unsaturated saturated : about 2/3 of fatty acids unsaturated: mostly cis configuration
43
what causes the smell in dairy barns
- butyric - caproic - caprylic - capric
44
how is milk fat present
- present in milk in the form of membrane bound globules ( in a membrane made of phospholipids) - can be concentrated by settling or centrifugation ( skimming) - oxidation of fat is a source of off-flavours - cholesterol is a componenent of the globular membrane - milk is a source of fat- soluable vitamines ( A D E K) - low energy conductivity and high specific heat
45
size of fat globules
- more than 95% of total milk lipids forms globules ( fat is enveloped with membrane) - diameter : 0.1 to 15 um - membrane 8-10 nm - secretory cell membrane - phospholipids and proteins - fat globule is covered in lipid bilayer that has both hydrophilic and hydrophobis properties
46
hardness depends on fatty acid contents
- faster separation at low temperature ( cold agglutination: bridging globules with IgM = apparent size increase
47
whipping
- air bubbles have surface tension - air is surrounded by fat globules - has to be at low temperatures
48
fat content of milk is affect by
- fat content of milk is affected by genetic, physiological and environmental factors - breed - individual animal - stage of lactation - milking frequency - season - feed - health of cow - milk of mammalian species ranges in fat content from 2-22%
49
function of milk fat in food
- lubrication: mouth feel - flavour: buttery flavour, rancidity - taste - reservoir of other flavour compounds - shortening effects: spreadabilit of butter - energy provider - nutrients
50
Milk protein
- 95% of the nitrogen in milk is in the form of protein - protein exists in both particulate ( casein, 80%) and soluble ( serum, whey 20%) forms
51
casein
- heat stable; precipitates from milk near pH 4.6 or after treatment with rennin/ chymosin - several associated caseins ( a- B- and k- caseins - casein complex) - a- and b- caseins are phosphoproteins - casein is present in milk in the form of colloidal particles ( micelles) - micelles are stabalized by k-casein and colloidal calcium phosphate ( CCP) - trapping lipases and proteinases, thus damage in micelles results in smell and taste defects
52
structure of milk micelle
a and b casein are hydrophobic k casein partially hydrophobic and hydrophilic Ca- phosphate - a/ b casein/ ca+ phosphate are in the center - they are surrounded by k casein tails are removed by enzyme reaction = deactivated and stick together = creating cheese
53
milk micelle
casein micelle aggregation = removal of tails on casien micelle - when the surface of micelle is reactive - collision of micelles lead to aggregation
54
what changes the reactivity of the surface
- chymosin treatment - acid - heat - aging
55
whey ( serum proteins)
- are dissolved in the whey ( serum phase) - enzymes, antibodies, mineral binding proteins - a-lactalbumin, b-lactalbumin, blood serum albumin, immunoglobulins - globular, heat sensative proteins - useful physico chemical properties - gelation, emulsification, water/oil holding - easily denatured by heat - release H2S cooked milk flavour
56
mineral constituents
- minerals (ash) ( K Na Ca Mg P) - milk salts ( Ca, Mg, Na, K salts of phosphate citrate, acetate, chloride and carbonate - soluable and insolable forms ( all essential minerals - as a nutritious food, milk is considered as complete food
57
processing of fluid milk products
- milk entering the processing plant is weighed, sampled and stored 4.5C or lower for up to 3 days - from storage, milk is clarified, standardized, vitaminzed homogenized pasteurized packaged and stored
58
clarification
milk is centrifuged to remove extraneous particulate matter- udder cells, white blood cells, dirt etc
59
standardization
- adjustment of fat content - part or all of the butterfat is removed ( as cream) from milk by centrifugation
60
vitaminization
- addition of Vitamine A and D to milk to compensate for losses due to fat removal and variations due to feed and season
61
homogenization
the relatively large butter fat globules are disintegrated by shearing and impact
62
pasturization
- heat treatment to destroy pathogens and extend shelf life - in practice 80C for 30 sec - in canada 72C for 15 seconds - target organism is coxiella burnetti - UHT milk - 140C 4 sec shelf stable product - its mandatory in canada to retail milk - elsewhere it depends on their legislation
63
cooling
to storage temperature
64
packaging
- cartons, polyethylene film, bottles - air and light tightness, wieght- rigidity, recyclable - reusable, shape, printability
65
storage
at less than 4.5 C
66
flavour defects
- odour, foretaste, aftertaste - should leave clean, sweet pleasant condition after tasting
67
causes of flavour defects
- lipolytic or hydrolytic rancidity - milkfat hydrolysis by lipoprotein lipase ( production of short chain fatty acids ) - oxidation ( milk fat oxidation, radicle reactions, photo oxidation ) - cooked - transmitted flavour - microbial
68
processor perspective
- quality at the plant is maintained through temperature control, cleanliness HACCP - safety of milk and dairy products is assured through the application of heat ( pasteurization) - 72C for 15 seconds targetting coxiella burnetti
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the safety and quality of milk
- adequacy of pasturization is assessed by determining the presence or absence of alkaline phosphatase activity - sanitization, pasturization, testing, process control, documentation, traceability and refrigeration - quality is ultimately in the hands of the retailer and consumer ( refrigeration
69
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