Milk and dairy products

Question 1

What are the 2 ways epithelial cells in the mammary alveoli produce milk?

Answer 1

Synthesis - of milk fat, protein, lactose

Diffusion - of water, minerals, vitamins

Question 2

What are the 3 types of milk secretion?

Answer 2

Merocrine
Holocrine
Apocrine

Question 3

What type of milk secretion do cows do?

Answer 3

Merocrine

Question 4

What type of milk secretion do goats do?

Answer 4

Holocrine and apocrine

Question 5

What acid is a natural component of milk?

Answer 5

Citric acid

Question 6

Which milk has a fat level of 0.1-0.3% and has a lower level of fat-soluble vitamins (particularly vitamin A)?

Answer 6

Skimmed milk

Question 7

What milk is 1.5-1.8% fat?

Answer 7

Semi-skimmed milk

Question 8

What milk is 3.5-4.5% fat?

Answer 8

Whole milk

Question 9

What is milk homogenisation?

Answer 9

Forcing milk through small holes at high pressure to break fat globules
(prevents creamy layer)

Question 10

What bacteria fermentationt milk to produce yoghurt?

Answer 10

Streptococcus
Lactibacillus
(By forming lactic acid)

Question 11

What can cause an increased (more alkaline) pH of milk?

Answer 11

Stress

Decreased temperature

Question 12

What can cause a decreased (more acidic) pH of milk?

Answer 12

Fermentation of lactose
Extensive lipolysis
Increasing temperature

Question 13

How does a decrease in temperature alter milk pH?

Answer 13

Decrease temperature = increased pH

Inverted relationship

Question 14

What is the average pH of milk?

Answer 14

6.4-6.8

Question 15

Salt is added to dairy products for flavour and to increase shelf-life. Why does salt allow dairy products to be kept for longer?

Answer 15

Most bacteria prefer higher water activity

Salt decreases water activity

Question 16

At what temperature does milk legally have to be kept at on the farm if it is collected daily?

Answer 16

<8 degrees C

Question 17

At what temperature does milk legally have to be kept at on the farm if it is NOT collected daily?

Answer 17

<6 degrees C

Question 18

At what temperature does milk legally have to be kept during transport?

Answer 18

<10 degrees C

Question 19

Milk is not required to be kept refrigerated if it is collected within how long after milking?

Answer 19

2 hours

Question 20

What is SCC and TVC?

Answer 20

Somatic cell count

TVC = total viable count (number of colonies per 1ml)

Question 21

Why should pregnant woman avoid non-pasteurised dairy products?

Answer 21

TB

Also leptospirosis

Question 22

Infectious agents may be found in dairy products due to contamination. At what stages in milk production can contamination occur?

Answer 22

During milking, processing or storage

Question 23

Give examples of contagious mastitis organisms

Answer 23

Staph aureus, coagulase -ve Staphs
Strep dysgalactiae and agalactiae
Corynebacterium bovis
Mycoplasma spp

Question 24

Give 3 examples of environmental mastitis pathogens

Answer 24

Streptococcus uberis
E. coli
Klebsiella spp

Question 25

Spoilage organisms can cause hydrolysis of milk. What physical changes may indicate milk spoilage?

Answer 25

Change in odour, texture, appearance, flavour

Question 26

What does the phosphatase test of milk assess?

Answer 26

Efficiency of pasteurisation

Question 27

What does peroxidase test of milk assess?

Answer 27

If hydrogen peroxide present in milk

Question 28

What does Resazurin test of milk assess?

Answer 28

If contaminated

Question 29

What does the pH and alcohol tests of milk assess?

Answer 29

If spoilage

Question 30

What is the Delvotest used to assess in milk?

Answer 30

Presence of antibacterial substances

Question 31

The Delvotest is used to assess presence of antibacterial substances, based on the inhibition of which bacteria?

Answer 31

Bacillus stearaothermophilus var calidolactis

Question 32

If wanting to check if milk is spoiled, what test should be used?

Answer 32

pH and alcohol tests

Question 33

If wanting to check if milk is contaminated, what test should be used?

Answer 33

Resazurin

Question 34

If wanting to check if there are antibacterial substances present in milk, what test should be used?

Answer 34

Delvotest

Question 35

If wanting to assess the level of pasteurisation of milk, what test should be used?

Answer 35

Phosphatase test

Question 36

The Delvotest shows what colour for a positive result, and what for negative?

Answer 36

``` Positive = purple Negative = yellow ```

Question 37

Can raw milk be sold in England?

Answer 37

Yes but not Scotland | Requires annual TB testing and other requirements