Proteins Flashcards
What type of nutrient is proteins?
Macronutrient
What is the structure of proteins?
Large molecules
Individual units called amino acids
Chemical bonds
What happens during denaturation?
The chemical bonds in a protein are broken down making the protein unfold and change shape
What are the causes of denaturation?
Heat (frying or boiling an egg)
Acids (lemon juice and cream)
Air bubbles (whisked sponge mixture)
Mechanical agitation (whisking egg white)
What happens during coagulation
Denatured proteins take up more space
They knock together and join to form larger groups
They trap and hold water from foods between them
They are used to hold ingredients together
E.g eggs in quiche
Changes caused by coagulation
E.g egg
Transparent to opaque white
Liquid to solid
If over cooked it becomes rubbery
Gluten formation
It is a protein
Contains gluten in and gliadin which combine when liquid is added
Gives dough plasticity so it can be stretched and shaped
Makes it elastic, when it’s stretched, it’s shrinks
Why does gluten cause elasticity?
The gluten molecules are coiled so as you knead and stretch the dough, they straighten out and gradually return to their original shape.
What are foams?
They are used to create light textures foods such as mousses and meringues
How are foams formed?
Gasses, often air, are trapped inside a liquid to form a gas-in-liquid foam.
What happens when a meringue is made?
Egg white is a liquid of proteins and water.
When it is whisked, air bubbles are trapped to make a gas-in-liquid foam.
White protein molecules denature and coagulate
They then surround the air bubbles so the foam is stabilised.
If there is egg yolk or fat, the foam will not form.
If it is over whisked, the coagulated proteins bond too tightly so they squeeze out the water they were holding.
When it is heated, the protein molecules coagulate making the meringue solid.
What are the 3 functions of proteins?
To make the body grow, repaire and give it energy
What are the different types of proteins?
LBV: don’t contain all the essential amino acids - lentils
HBV: contain all the essential amino acids - meat
Protein complementation: 2 LBV - beans on toast
Protein alternatives: protein products that are alternatives to mean - tofu
What are the symptoms of deficiency?
Children won’t grow properly. May lose some hair. Easily develop infections. Skin and nails will be in poor condition. Not be able to digests food properly.
What are the effects of excess of protein
Proteins contain nitrogen which is harmful to the body when there is too much so it is removed in the urine. If the diet contains too much protein, the liver and kidneys have to work harder which person under stress and can be harmed.
