Lab exam of consumers liquid milk

Question 1

Sensory evaluation is done by evaluating:

Answer 1

Colour - yellowish creamy white to creamy white
Flavour - slight sweet w salt taste of minerals
Consistency - homogenous

Question 2

Parameters affecting:

Answer 2

Feed (flavouring in feeds), health, residues, storage

Question 3

Flow diagram:

Answer 3

Milk recieved in dairy plant
Storage
Pre-heat treatment
Milk separatin
Milk standardization
Heat treatment
Milk homogenization
Milk pasteurization
Milk holding
Milk cooling II
Milk cooling I
Milk filling
Milk storage in cooler
Transport to market

Question 4

Methods of lab examination:

Answer 4

Alkaline phosphatase test: adequate pasteurization (white colour - pasteurized)

Peroxidase test - enzyme is inactive if milk heated to 80*C (bluegrey-unpasteurized)

Catalase test - udder healthy or not, catalase is destroyed by heating 75*C for 1 min

Question 5

Defects of drinking milk can be:

Answer 5

Flavour and smell:
- sour: lactose fermentation, acid producing bacteria
- caramel/brunt: streptococccus
- bitter: streptococcus
- blue souring: unpleasant sweet&sour
- fruit aroma: pseudomonas fragi
- slimy: capsule forming bacteria
- bubbles, coagulation & whey separation: yeast
- potato-like flavour: pseudomonas
- turnip: e. coli

Colour defects:
- yellow: flavobacterium
- pronounced white: beet, beet silage
- red: blood first days after calving, injury, micrococcus
- blue: feed, microbial, streptococcus lactis
- pink: yeasts
- brown: pseudomonas