FCH341: Milk Composition and Proteins Lecture Quiz

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What is the main characteristic of proteins in milk?

They contain one amino group and one carboxyl group in the molecule (correct)
They are classified into casein and whey protein
They are made up of approximately 20 different amino acids
They are amphoteric to litmus paper

What is the dominant class of proteins in milk?

Rennin enzyme
Casein (correct)
Albumin
Globulin

How are casein proteins precipitated from skim-milk?

By heating to 20°C
By using diluted acids at pH 4.6 (correct)
By adding rennin enzyme
By adding heavy metals

What are the characteristics of casein?

It is rich in phosphorous (D) Signup and view all the answers

Why is freshly drawn milk considered amphoteric to litmus paper?

Because it turns red litmus to blue and blue litmus to red (A) Signup and view all the answers

Which type of protein is precipitated from skim-milk at pH 4.6?

Casein (D) Signup and view all the answers

What acts as a stabilizing factor for the casein complex in colloidal suspension?

Kappa casein (D) Signup and view all the answers

What is responsible for the 'hairy' appearance of the micelle surface?

Kappa casein (A) Signup and view all the answers

What causes the precipitation of casein?

Addition of acid to milk (D) Signup and view all the answers

What protein constitutes about 50% of whey proteins formed in the udder?

β-lactoglobulin (B) Signup and view all the answers

What is responsible for the release of sulphurous compounds such as hydrogen sulphide at high temperatures?

β-lactoglobulin (C) Signup and view all the answers

What is not affected by renneting?

$\alpha$-lactalbumin (C) Signup and view all the answers

What protein may be considered to be the typical whey protein and is present in milk from all mammals?

$\alpha$-lactalbumin (A) Signup and view all the answers

What prevents the approach and interactions of the casein molecules due to its highly charged C-terminal?

$\kappa$-casein (C) Signup and view all the answers

Which of the following is considered a biological hazard in raw milk?

Bacterial contamination and perished components (C) Signup and view all the answers

What is the most common source of chemical contamination in milk?

Veterinary product residues (C) Signup and view all the answers

What are the key sources of milk contamination from physical hazards?

Perished components, dust, and dung (D) Signup and view all the answers

When does contamination typically occur during milk production?

During and after milking (C) Signup and view all the answers

Which type of hazard includes allergens as a potential source of contamination?

Biological hazards (B) Signup and view all the answers

What is the primary cause of physical contamination in raw milk?

Insects and animal hair (E) Signup and view all the answers

What is the primary reason for discarding the foremilk in healthy cows?

To reduce the bacterial content in milk (D) Signup and view all the answers

In diseased cows with mastitis, what is the potential bacterial count in milk from infected quarters?

Exceeds 10,000,000 cfu/ml (D) Signup and view all the answers

What contributes to the contamination of the surface of teats and udders in cows?

Manure, mud, feeds, and bedding (C) Signup and view all the answers

What is an effective method to reduce the numbers of bacteria in milk contributed from soiled teats?

Cleaning of the teat with a sanitizing solution followed by thorough drying (B) Signup and view all the answers

Which requirement should teat disinfectants meet according to Video 1?

Have germicidal efficacy and prevent new intramammary infections (B) Signup and view all the answers

What is the primary reason for discarding foremilk in healthy cows according to the text?

To reduce the bacterial content in milk (B) Signup and view all the answers

What are common organisms associated with bedding materials that contaminate the surface of teats and udders?

Streptococci, staphylococci, coliforms, and other Gram-negative bacteria (C) Signup and view all the answers

What should teat disinfectants not do according to Video 1?

Irritate the cow or the user (B) Signup and view all the answers

What type of bacteria are commonly found on teat surfaces?

Thermoduric and psychrotrophic strains of bacteria (C) Signup and view all the answers

What is an effective method to reduce bacterial numbers in milk contributed from soiled teats?

Cleaning of the teat with a sanitizing solution followed by thorough drying with a clean towel (A) Signup and view all the answers

Main characteristic of milk proteins

Milk proteins contain one amino group and one carboxyl group in the molecule.

Dominant milk protein class

Casein.