dairy products

Question 1

how do you ferment milk

Answer 1

adding bacterial culture in raw/heat treated milk

Question 2

purpose of fermenting milk

Answer 2

increase taste and increase digestibility

Question 3

how do you get tangy and thick texture

Answer 3

converting lactose into lactic acid

Question 4

lactate acts as

Answer 4

preservative lowering pH, inhibiting growth of MO

Question 5

types of fermented milk

Answer 5

• yoghurt
• kefir
• buttermilk
• soured milk

Question 6

characteristics of fermented milk

Answer 6

• taste- fermented milk has sour, tangy flavour
• texture - thicker than regular milk
• probiotics - contain live bacteria to aid digestion

Question 7

division and types of fermented milk beverage

Answer 7

1. according to type of raw material
2. type of fermentation
3. by consistency
4. according to adding (plain, flavoured, fruity, etc)

Question 8

starter culture for yoghurt

Answer 8

lactobacillus bulgaricus
strep thermophilus

Question 9

what is LAB

Answer 9

lactic acid bacteria

Question 10

starter culture for buttermilk

Answer 10

lactobacillus lactic subsp lactis

Question 11

starter culture for soured cream

Answer 11

lactobacillus lactic subsp lactis

Question 12

starter culture for kefir

Answer 12

lactobacillus kefiri

Question 13

LAB can be categories into 2 main groups

Answer 13

1. mesophilic LAB (20-30oC)
2. themrophilic LAB (37-45oC)

Question 14

characteristics of LAB

Answer 14

• contain 1/+ more typical bacteria

Question 15

therapeutic role of LAB

Answer 15

• form acid slowly
  probiotics

Question 16

yoghurt types

Answer 16

• set (gel) yoghurt
• stirred yoghurt (gel broken before cooling)
• fluid yoghurt - low viscosity

Question 17

production of soft gel

Answer 17

increase in lactic acid, decreases pH
milk to form soft gel
characteristic of yoghurt

Question 18

process of yoghurt

Answer 18

1. adjust milk composition
2. pastuerise milk (85oC for 30min) high temp denatures whey to form stable gel - pasteurised before starter culture
3. homogenise
4. cool milk (42oC)
5. inoculate with starter culture
6. hold - milk held at 42oC until pH 4.5 reached -> fermentation progresses -> soft gel forms
7. cool -> cooled to 7oC to stop fermentation process
8. add flavours and fruits and package

Question 19

kefir

Answer 19

• lactic acid alcoholic beverage originating from caucasus
• kefir grains for produciotn
• product of lactic acid + alcoholic fermentation (LAB converts lactose into glucose + yeast further converts into alcohol)

Question 20

cream

Answer 20

• concentrated milk fat which fat globules protected by a membrane
• cream differs according to: proportion of milk fat and methods of pasteurising and sterilising
• 38-45oC damage to fat globules is minimal
• separator temp 38-65oC
• <45oC rancid taste

Question 21

purpose of homogenisation in cream

Answer 21

decrease size of fat globule

Question 22

sterilisation

Answer 22

140oC for 2s
fast
shelf life 3-6m
cooling cream <5oC

Question 23

butter

Answer 23

mostly milk fat
produced by process of whipping cream

Question 24

process of butter

Answer 24

1. heating 35-55oC
2. milk separation
3. cream 2-30% MF
4. pasteurisation (90-95oC)
5. starter culture
6. whipping cream
7. washing
8. kneading
9. salting
10. dyeing
11. packaging