Food and Nutritions Basis Protein

Result:

Table showing the time and the number of additions for change in appearance on the egg white under 5 given conditions

Diagram showing the visual appearance and the coagulation after the addition of 1M Acetic Acid and 5M NaCl to the egg white

In part A experiment, we were required to study the denaturation of egg white by placing the separated egg white into boiling tubes of different conditions respectively. The majority of protein found in egg white is Ovalbumin. In case 1 and case 2 , the diluted egg white was placed in the a water bath at 60oC and 80oC respectively over a period of time. Both of the boiling tubes were observed to have coagulations eventually. The coagulations are due to protein inside the egg white lost their specific tertiary structure. As bonds inside the proteins were disrupted and reformed in different ways. When the proteins uncoil, they tend to interact with each other to form coagulum and hence lose their biological properties .This explains the changes that we observe as we watch an egg being cooked. However in case 2, the temperature of the water bath was higher than that in case 1, the higher the temperature, the higher the kinetic energy and fraction of molecules w and hence the faster the rate of denaturation. This explains why case 2 require less time for the coagulation.

In case 3, the diluted egg white was

In case 4,

In case 5, since the boiling tube didn't have any heat treatment or any addition of chemicals, without any interference , the proteins in the egg white of this boiling tube would not encounter denaturation and thus no observable change.

Albumins are one of the groups of globular proteins that are soluble in water but form insoluble coagulates when heated.

B) Egg custard

In part B experiment, we were required to make an egg custard to examine the phase transitions that occur in denature of egg and milk as affected by temperature change. The preparation process involved mainly the heat treatment

Since Milk usually contains 80% of casein micelles and 20% of whey proteins and egg contains mainly Ovalbumin proteins.

C) Denaturation of milk

Result:

Chemicals

Control 5M Sodium Chloride solution 1M Acetic acid

pH

Time for the formation of the precipitate 1176 1143 57

Table showing the result of the final pH, time for the appearance of the precipitate and after the addition of the above chemicals

The proteins that do this are called caseins, there are four different types and they make up about 80% of the weight of the total protein in the milk. The outer layer