1. Different processes in cooking

2. Gelatinisation  Moist and heat on starch. Grains soften and swell. Absorb water, there is some rupture and liquid thickens. Irreversible. E.g. custard / roux sauce / cooking cakes / rice / macaroni/ boiled rice, etc.

3. Coagulation  Heat acting on protein provoke denature. Coagulation begins at 60 ºC cannot be reversed.  Overheating causes protein to shrink. E.g. syneresis when scrambled egg is overcooked or baked egg custard is overcooked.  Hardens, sets: chemical structure changes.  E.g. boiled egg / egg custard / roast meat / baked bread / quiche / skin on boiled milk / coating on fried fish.

4. Fermentation  Yeast produces carbon dioxide and alcohol (ethanol) with food produces sugar (glucose).  Needs: moisture, warmth  Enzymes bring about fermentation process named (e.g. maltase / invertase / zymase)  Amylase, in flour, changes starch to maltose.  Maltase, in yeast, changes maltose to glucose.  Zymase, in yeast, changes glucose to carbon dioxide and alcohol.  e.g. bread making

5. Pasteurisation  Heat destroys harmful bacteria and souring bacteria or those causing tuberculosis.  Does not prevent decay, keeps longer.  72 ºC / 162 ºF for 15 seconds  HTST or Flash 145 ºC for 30 minutes.  Cool rapidly to prevent bacterial growth to below 10 ºC  e.g. milk

6. Hydrogenation  H 2 added makes fat solid from liquid oil.  E.g. sunflower / soya  Unsaturated fats can take up hydrogen to become saturated fats.  Uses a nickel catalyst.  Can be stopped at any time to achieve degree of hardness required  Hard margarine more saturated, soft / spreading margarine less saturated.  e.g. margarine, cooking fats

7. Creaming  E.g. Victoria sandwich cake, queen cakes, Eve’s pudding etc.  Equal quantities of fat and sugar. Mix with wooden spoon/electric mixer until light and fluffy, traps air to help raise the mixture.  Butter or soft margarine, good colour and flavor.  Caster sugar, finer grains, easier to cream.

8. Basting  E.g. roast beef, grilled steak etc.  Pour/spoon, hot fat over surface of food, from time to time to prevent drying or burning  Adds flavour of fat and extractives.

9. Making a roux  E.g. base for sauce, soup, cheese sauce  Equal quantities of fat and flour, usually margarine /butter  For colour and flavor.  Melt fat, do not brown, stir in flour, wooden spoon.  Resembles a paste, cook over gentle heat for 1 minute, stir constantly to prevent sticking or burning.  Starch absorbs fat looks ‘sandy’/like marzipan  Changes taking place when a roux sauce is made:  Fat melts, flour stirred into fat. Fat is absorbed by starch grains and mixed to a paste.  Gentle heat cooks starch until sandy appearance. Liquid added and absorbed by cooked starch. Add gradually to prevent formation of lumps, add liquid off heat to prevent lumps.  Becomes thin liquid when milk has been added.  When heated starch grains soften, swell, absorb liquid.  Boil to cook starch, some starch grains rupture/ burst and starch gelatinises and sauce thickens.

10. Sautéing  E.g. mushrooms, potatoes, onions toss.  Small/thin pieces of food or cooked food in small amount of hot fat.

11. Making a stock  E.g. vegetable, chicken, beef, fish.  Boil bones/small pieces of food for a long time.  Strain to gain flavour/extractives to add to soup/sauces /casseroles.  Instead of water can use commercial stock cube.

12. Raising agents  Principles of raising agents:  Gases expand when heated, mixture enlarges / expands / swells.  Steam has a larger volume than water hot gases rise, push up mixture, heat sets risen shape, protein in other ingredients coagulates.  E.g. egg, gluten in flour etc.

13. Air  Gives a light texture, no change in colour or flavour must be introduced before cooking.  Expands on heating, sieving flour. Air trapped between grains of flour.  Creaming fat and sugar traps air as tiny bubbles rubbing in fat and flour air trapped as mixture falls.  Whisking egg white, meringues, ovalbumin stretches, entangles 7 × own volume of air.  Whisking whole egg and sugar traps less air – due to fat in egg yolk used in cakes.  e.g. Swiss roll etc.  Folding and rolling flaky pastry / puff pastry, air trapped between layers, sealed to prevent air loss expands on heating, pushes layers apart etc.

14. Carbon dioxide  Bicarbonate of soda with moist heat, gives off carbon dioxide, residue of sodium carbonate, washing soda, yellow colour, bitter flavor, used in dishes where this would be hidden – e.g. gingerbread etc.  Bicarbonate of soda and cream of tartar, moist heat, produces CO 2, colourless and tasteless residue, Rochelle salt (potasium sodium tartrate) e.g. scones  Bicarbonate of soda and sour milk, as above, acid + alkali, baking powder contains correct proportion of bicarbonate and cream of tartar.  e.g. suet pastry, scones, cakes etc.  Self-raising flour: plain flour + baking powder, as above, yeast feeds on sugar  Moisture, warmth, ferments sugar, produces alcohol and CO 2 continues under favourable conditions.  Heat of oven kills yeast and fermentation stops. e.g. bread etc.

15. Steam  Used in mixtures with a high proportion of liquid.  e.g. choux pastry, Yorkshire puddings, etc.  Hot oven, water changes to steam, larger volume than water, mixture rises etc.

16. Kneading  Develops gluten protein in flour and forms elastic dough.  Stretches during rising, traps carbon dioxide, smooth dough.  Distributes yeast, aerates dough, stimulates action of yeast, breaks down large bubbles of gas for even texture of finished dough, use knuckles / heel of hand for large amounts, fingertips for small pieces.

17. Proving  Warm place, just before baking, after dough has been shaped.  Too much heat kills yeast, dough will not rise.  Left for some time in cold place / refrigerator does not kill yeast, only slows down process, but can prove overnight in refrigerator.  Replaces carbon dioxide, lost during kneading, dough doubles in size.  Avoid over-proving, dough will collapse, cannot recover.

18. Choice of flour for bread making  Strong / hard flour (high gluten content) from spring wheat:  e.g. Canadian, more than 10% protein, allows dough to stretch, plain flour, yeast is raising agent.  Wholemeal flour, adds color, ‘nutty’ flavour, B vitamins, NSP, has less gluten, gives closer texture, more difficult for yeast to raise.

19. Changes when bread is baked  Rapid rising: enzymes work quicker with heat, more carbon dioxide produced, warmth encourages fermentation, alcohol produced, water changes to steam, more raising action, gluten stretches, gases expand when heated,  Heat kills yeast, no further carbon dioxide produced, gases continue to expand with continued heat, gluten coagulates, around bubbles of gas.  At 73 °C gluten is protein, alcohol evaporates (vaporises below boiling point of water) carbon dioxide diffuses out.  Heat causes gases to rise on expansion, starch gelatinizes, action of moist heat on starch, crust forms on outside, dry heat on starch, crust lifts off as gases continue to expand, ‘oven spring’, browns on outside, dextrinisation of starch, caramelisation of sugar (Maillard browning)

20. Changes when bread is baked  Rises: warmth of oven encourages fermentation, carbon dioxide produced, alcohol evaporates, water evaporates (pushes up dough), yeast is killed, no more carbon dioxide produced, gas in dough expands on heating.  Protein gluten coagulates, shape sets, starch dextrinises, gluten stretches, forms crust, browns, crust lifts off, ‘oven spring’,  Framework formed as carbon dioxide continues to expand after shape has set, air replaces gas which has escaped, open texture.  Starch gelatinizes. Maillard browning (reaction between protein and sugar). Caramelisation of sugar.