functional properties

Question 1

proteins - explain denaturing

Answer 1

Denaturation is when the structure of the protein breaks apart –> Peptide bonds come apart.
- It is not easy to observe as a chemical change occurs instead of physical.

Question 2

proteins denaturing E.G.

Answer 2

Salt helps keeps the meat moist.

Question 3

proteins - explain coagulation

Answer 3

Heat, acids and enzymes can cause the separated strands of amino acids in the denatured protein to regroup with new cross bonds.
If coagulation continues for too long, over coagulation will occur, where the proteins shrink and toughen forcing liquids out from inside the protein. It is irreversible e.g. when you overbeat egg whites it reverts back to runny mass. This is called syneresis.

Question 4

protein coagulation E.G.

Answer 4

Example: Eggs = When an egg exposed to heat, the liquid albumen (egg white) gradually sets to form a white rubbery mass and the yolk becomes firm.
 temps: white = 62-65oC and yolk at 65-70oC.
Example: Cheese = the enzyme rennin is added to warm milk to coagulate the milk into curds (solid) and whey (liquid).
Example: Egg used for crumbing meat = Egg is used in the process. IT coagulates when heated and binds ingredients together.
Example: Meringue = Egg white foams when the foam goes into the oven the egg coagulates
Example: Cakes and Biscuits = made from wheat flour (gluten). Under heat gluten stretches and coagulates.
Example: Milk = When milk is heated, a skin forms on the top made of proteins (Casen and lactalbumin) and the milk will boil over.