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Food Science and Technology QUESTION #5906
Question 1
The whey protein \(\beta\)-lactoglobulin (\(\beta\)-Lg) upon heating above \(70^{\circ}\text{C}\) causes which important effect?
  • It contributes to the yellow color of milk
  • It unfolds and binds to \(\kappa\)-casein via disulfide bonding (\(\text{Cys}_{121}\)), altering rennetability and improving heat stability✔️
  • It is the primary source of calcium in milk
  • It inhibits bacterial growth in raw milk
Correct Answer Explanation
\(\beta\)-Lactoglobulin (\(\approx 3.2\;\text{g/L}\) in bovine milk) denatures above \(70^{\circ}\text{C}\), exposing free sulfhydryl groups (\(\text{Cys}_{121}\)) that form disulfide bonds with \(\kappa\)-casein. This complex reduces rennet coagulation efficiency but enhances heat stability of the casein micelle.