FCH341: Milk Composition and Proteins Lecture Quiz
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Questions and Answers

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?

    <p>It is rich in phosphorous</p> Signup and view all the answers

    Why is freshly drawn milk considered amphoteric to litmus paper?

    <p>Because it turns red litmus to blue and blue litmus to red</p> Signup and view all the answers

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

    <p>Casein</p> Signup and view all the answers

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

    <p>Kappa casein</p> Signup and view all the answers

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

    <p>Kappa casein</p> Signup and view all the answers

    What causes the precipitation of casein?

    <p>Addition of acid to milk</p> Signup and view all the answers

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

    <p>β-lactoglobulin</p> Signup and view all the answers

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

    <p>β-lactoglobulin</p> Signup and view all the answers

    What is not affected by renneting?

    <p>$\alpha$-lactalbumin</p> 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?

    <p>$\alpha$-lactalbumin</p> Signup and view all the answers

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

    <p>$\kappa$-casein</p> Signup and view all the answers

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

    <p>Bacterial contamination and perished components</p> Signup and view all the answers

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

    <p>Veterinary product residues</p> Signup and view all the answers

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

    <p>Perished components, dust, and dung</p> Signup and view all the answers

    When does contamination typically occur during milk production?

    <p>During and after milking</p> Signup and view all the answers

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

    <p>Biological hazards</p> Signup and view all the answers

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

    <p>Insects and animal hair</p> Signup and view all the answers

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

    <p>To reduce the bacterial content in milk</p> Signup and view all the answers

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

    <p>Exceeds 10,000,000 cfu/ml</p> Signup and view all the answers

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

    <p>Manure, mud, feeds, and bedding</p> Signup and view all the answers

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

    <p>Cleaning of the teat with a sanitizing solution followed by thorough drying</p> Signup and view all the answers

    Which requirement should teat disinfectants meet according to Video 1?

    <p>Have germicidal efficacy and prevent new intramammary infections</p> Signup and view all the answers

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

    <p>To reduce the bacterial content in milk</p> Signup and view all the answers

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

    <p>Streptococci, staphylococci, coliforms, and other Gram-negative bacteria</p> Signup and view all the answers

    What should teat disinfectants not do according to Video 1?

    <p>Irritate the cow or the user</p> Signup and view all the answers

    What type of bacteria are commonly found on teat surfaces?

    <p>Thermoduric and psychrotrophic strains of bacteria</p> Signup and view all the answers

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

    <p>Cleaning of the teat with a sanitizing solution followed by thorough drying with a clean towel</p> Signup and view all the answers

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