Eggs

Nutrients in eggs  The proteins that are present in the eggs are called ovalbumin, mucin,vitellin. It is a HBV protein and helps to growth, repair, energy and to elaborate hormones, antibodies, enzymes etc.  Fat: energy, warmth and to make an emulsion, source of fat soluble vitamins: ADEK  Vitamin A/retinol: help to mucous membranes, skin, visual purple, night vision.  Iron: formation of haemoglobin in the blood, red pigment, transports oxygen, prevention of anaemia.

Nutrients in eggs  Vitamin D/ cholecalciferol: absorption of calcium in the bones and teeth  Vitamin B 2 /riboflavin: from B group of vitamins. Helps to release the energy from carbohydrates.  Lecithin – emulsifier  Water  Phosphorus – works with calcium in the formation of bones and teeth. Also in the formation of protoplasm as a component of protein  Sulfur – formation of protoplasm as a component of protein

Storage of eggs  Cool place/refrigerator  Not too dry, water evaporates through Shell.  Away from strong smells, smell absorbed through pores in shell  Do not wash shells, removes protective cuticle on shell and bacteria can penetrate the shell.  Round end upwards, air space at top, holds yolk in place  Freeze only if separated, water freezes and breaks shell, add salt or sugar to egg whites and make a note on label  Test for freshness by placing in brine sinks if fresh because is heavier

Changes when an egg is heated  Protein coagulates: egg white at 60 °C and egg yolk at 70 °C and become less digerible.  Egg white thickens and changes from transparent to opaque, becomes firm then rubbery if overcooked.  Sulphur in egg white – indigestible if overcooked.  Yolk thickens and becomes powdery when overheated. Green ring forms around yolk (ferrous sulphate) because of the iron present in yolk.

Changes when an egg is heated  If cooked too quickly proteins shrink rapidlyand liquid squeezed out. It is an irreversible reaction.

Uses of eggs  Main meal: boiled / poached / scrambled / omelette etc. – easily digested. Quick to cook, source of HBV protein. Versatile - for sweet and savoury dishes.  Trapping air –whole eggs with sugar. Swiss roll, sponge flan.  Lightening – whisked egg white in mousse, meringue, soufflé etc.  Egg white – traps 7 × volume – ovalbumin stretches – meringue etc.  Thickening – custard, sauces, soup etc. Protein coagulates at 60°C  Emulsifying – lecithin in egg yolk is an emulsifying agent mayonnaise, rich cakes etc.  Setting – coagulation of protein setting: quiche / baked cake.

Uses of eggs  Binding: coagulation of protein. Croquettes, fish cakes, rissole, stuffing etc.  Coating: With breadcrumbs or flour forms a seal around food fish etc. Prevents absorption of fat / breaking up / protects from hot fat. Scotch eggs, fish fillets etc.  Glazing: white, yolk or whole egg on pastries or bread to give shine and browns on heating, a denaturation of protein.

Uses of eggs  Enriching – sauces, milk puddings, soups etc. Adds HBV protein. Inexpensive.  Garnishing: hard-boiled egg in salads – separated egg white and egg yolk on dressed crab.  Clarifying – whisked egg white in consommé / mint jelly etc.

FATLESS SPONGE CAKE  Recipe:  3 eggs  75g plain flour (allow SR)  75g caster sugar  Proportion:  1 egg per 25g of plain flour and 25g of caster sugar

Method of making and baking  Whisk eggs and sugar over hot water with electric hand mixer until thick and creamy.  Leaves a trail to introduce air  Sieve flour to aerate and remove lumps  Fold in flour: with a metal spoon/palette knife, to prevent air loss.  Add flour in thirds: weight of flour would press out air. Use a cutting action or figure of eight (to avoid loss of air). Continue until no dry flour seen, to give an even consistency.

Method of making and baking  Pour – into greased and floured/greased and lined tin – do not spread –  air bubbles will break – tilt to give even thickness  Bake in preheated oven so rising can begin immediately.  Sponge cake 200°C/400°F/gas mark 6, for 15–20 minutes. Until golden brown, firm to the touch, shrinks from sides of tin – (max. 2)  Cool on wire rack – to allow steam to escape

Changes during baking  Air expands, gases rise, push up cake mixture.  Protein coagulates – at 60°C.  Around air bubbles, sets in risen shape, open texture.  Sugar caramelizes. Maillard browning (action of protein and sugar)  Starch grains absorb water, from egg, swell, gelatinize.  Flour on outside dextrinises as an effect of dry heat (browns, dries on outside, forms a crust.  Steam, from egg, evaporates and helps cake to rise.

Reasons for a close texture  Insufficient whisking  Air knocked out during folding in of flour/addition of flour  Did not use a cutting action to add flour – whisked/beat in flour  Used wooden spoon or an electric mixer for adding flour  Did not use metal spoon/palette knife to incorporate flour.  Continued folding after all flour was incorporated  Not baked immediately  Oven temperature too low  Insufficient baking/undercooked

Other baked items which can be made with this recipe  Swiss roll  Sponge flan  Sponge fingers