Protein full

Essential Amino acid

Cannot be made by the body and must be taken from the food we eat e.g. valine

Non essential amino acids

Can be made in the body so not essential in our food e.g. Alanine

Sources

Animal; meat(Actin) egg(Albumin) cheese (casein). Plant; wheat(gluten)

Primary protein structure

The sequence or order of amino acids in the polypeptide chains. They are linked by peptide links. Refers to the number of amino acids in each polypeptide chain

Secondary protein structure

Further linking of amino acid definite shape normally spiral by cross link 2 types disulphide links 2 sulphur atoms bonding. Hydrogen bond one hydrogen in one chain bonds with an oxygen atom in another chain

Tertiary protein structure

Pattern of folding gives a three dimensional compressed unit, fibrous or globular protein structure

Fibrous proteins

Polypeptide links are straight, coiled, zigzag

Globular proteins

Polypeptide chains are spherical

Properties of protein

denatured, mechanical action, elasticity, solubility, Maillard, gel formation, foam formation

Denaturation

Change in nature of protein, unfolding of protein chains ,irreversible loss in structure and shape causes are heat eg eggs coagulating. And chemicals eg lemon juice with milk coagulates

Mechanical action (agitation) part of denatured

Whisking an egg white cause the protein chain to unfold resulting in partial coagulation, foam forms. Moist heat(boiling) tenderising meat Dry heat(grilling) tougher meat whisking egg whites (mechanical action) meringues

Elasticity

Proteins like gluten are elastic. Presence of gluten allows bread to rise. Yeast dough is elastic, traps Co2

Solubility

Proteins are generally insoluble in water. Except egg white, soluble in cold water. Collagen, soluble in warm water. Moist heat,stewing

Millard reaction

Non enzymic browning of food when dry heat is applied. a reaction between amino acids and carbohydrates resulting in browning of food, roast beef, potatoes, toast

Gel formation

The protein collagen present in the bones and skin of meet is converted to gelatine on heating. Gelatine absorb large amounts of water, when heated, protein chains uncoil and water becomes trapped.

A Sol

A Sol ( a solution with evenly dispersed particles) is formed which on cooling forms a gel

A Gel

a semi solid thickened solution with a 3D network in which water molecules can be trapped. E.g. setting cheesecake

Foam formation

Whisking an egg white causes the protein chain to unfold and air bubbles form, entrap air creating temporary foam. Heat is generated due which coagulates the egg albumin. Egg white slightly sets. Foam will collapse in time unless heated so it sets to form permanent foam. E.g. making meringues

Biological Value

A measure of quantity of a protein in food and determined by the number of essential amino acids present. Two types

High biological protein

Contains all essential amino acids from animals except soya beans

Elements

Carbon (C) Oxygen (O) Nitrogen (N) Hydrogen (H)

Supplementary value/complimentary role

Two foods eaten together but their opposite one is high in one essential protein but not other and the other food is opposite so when eaten together you get all amino acids needed eg beans on toast, beans high in methionine and toast high in lysin

Low biological protein

Normally lack some essential amino acids normally plant sources

Daily RI of protein + energy value

Depends on body weight + rate of growth, adults need 1g per 1kg of body weight, more needed during childhood ,adolescente and pregnancy. 1g of protein = 4kcal (17kj)

Digestion of protein absorption and utilisation

Amino acid absorb at ileum of small intestine, it has finger like projections called villi . Amino acid absorbed by diffusion and enter blood stream

Utilisation amino acid replace and repare body cell , form new cells , antibodies and hormones. Excess protein are delaminated in liver for heat and energy

Deamination digestion of protein

Process of how excess protein turned to energy and heat broken down by liver , amino group converted to ammonia then urea and e created by kidneys as waste in urine. Carboxyl group is oxidised and used as heat and energy

Draw digestion table , organ/gland, secretion , enzymes, substrate and product . Stomach, pancreas and small intestine

.