Task 5: Function Properties of Protein- Denaturation and Enzyme Activity

In your own words, summarise what you have learnt about the chemical and physical properties of proteins in relation to denaturation and enzyme activity. As part of your summary comment on something that you did not know or understand before now or something that you still don’t understand and want to know more about.

 You may use the following as discussion points if you are stuck.

•  What is denaturation 
•   Chemical/physical changes that occur.
•  The experiments and how they helped your understanding.
•  The effect of enzymes on the denaturation process
•  Usefulness of denaturation in food processing.

Use diagrams, pictures or videos if these help your understanding. However, make sure you explain them!



Probably the best experiment we've done so far- Chicken Stir Fry with rice.
It looked pretty much exactly like that, yummmo!

Okay so short and sweet Denaturation can occur through many different things in food processing, the aim of our experiment was to show how denaturation affects the tenderness of chicken in a stir fry. So, to marinade or not to marinade?

Our results proved that marinading chicken before cooking it in the stir fry had better results. The chicken end up moist, tender, juicy and full of flavour, while the un-marinaded chicken was dry and tasteless-in doing it that way the vegetables soaked up all the flavour, making them soggy and leaving the chicken bland.

So what makes denaturation occur? and why were we learning this through making chicken?
Several factors  affect the denaturation process in food. Whether its temperature, acidity and agitation, salt or sugar, theres one factor that sticks out the most for me. The enzymes.

For any of you that don't know, enzymes are responsible for speeding up chemical reactions. They are also known as catalysts. Enzymes break down protein into individual amino acids. So when we were marinading our chicken, because it had pineapple juice in it(which contains the enzyme bromelin-which breaks down the proteins myosin, elastin and collagen) it helps speed up the denaturation process which was evident in our experiment results.

The second experiment helped me understand the importance of different ingredients-and how they can denature protein. When adding heat, the higher the temperature, the more quickly proteins will denature-then coagulate and clot. When the pH of a food is less than 7, proteins will denature. So by adding an acid to a protein, the acid begins attacking and breaking the bonds between amino acid strands.

The mechanical action in food handling causes protein strands to stretch, when too much mixing occurs the protein becomes denatured also. Salt can denature and coagulate protein, for example adding salt to boiled eggs so that if there is a crack in the shall, the salt water helps minimise loss of white. Last but not least, in the presence of sugar, proteins can tolerate higher temperatures by denaturating and coagulating-which was evident when we made Baked Custard Tarts.