Food science 🧪

• Conduction


  Heat travels through solid materials
• Convection


  Heat is conducted from molecule to molecule in a liquid or a solid<|>This happens when heat travels through either air or water<|>A convection current is the movement of the heat<|>Warm rises, cool descends
• Radiation


  Heat waves directly heat the food without touching it<|>A microwave uses electromagnetic waves to cause water molecules in the food to vibrate and heat up
• Why we cook food

  • Enable ingredients to work together
  • To kill pathogenic bacteria
  • Make it easier to chew or swallow
  • More digestible
  • Reduces bulk
  • Provides a variety
• Why we cook food

  • Meats, fish
  • Different methods give different results
  • Meat and starchy carbohydrates
  • Meat, softened vegetables
  • Vegetables
  • Spinach
  • Flour to thicken a sauce
• Raising agents


  • Mechanical
  • Physical
  • Biological
  • Chemical
• Mechanical raising agent


  When air is added to the recipe mechanically. The air rises and makes a risen airy final product when heated.
• Physical raising agent


  Large quantities of water are added to the products while they are made. The heat of the oven turns the liquid into steam which means that the liquid evaporates, and the egg coagulates to set the products shape.
• Biological raising agent


  Yeast will also create CO2, but it needs certain conditions (moisture, warmth, oxygen, food, time) to work in.
• Chemical raising agent


  Creates CO2, which creates a light, airy texture required in cakes and other baked products.
• What eggs do to make food better

  • Aeration- when air becomes trapped in the egg to make it light and fluffy
  • Binding- using a substance to bind dry ingredients together to make a dough or paste
  • Coating- putting the food in a layer of egg
  • Glazing- putting a thin layer on the surface of the food to make it crispier and golden when cooking
  • Emulsifying- egg yolk stops any water and oils separating
  • Thickening- making mixture thicker by adding egg
  • Enriching- giving the food more flavour and nutrients
  • Garnish- sliced boiled eggs
• What eggs do in pasta

  Proteins form strands of gluten to bind the ingredients together<|>The egg is also a good source of water for the gluten<|>Gives the pasta its structure and strength<|>They also give fat that enriches the dough to give it a smooth, silky finish
• Fats


  • Butter
  • Ghee
  • Lard
  • Suet
  • Spreads
  • Margarine
• Butter


  Made by separating whole milk or cream into fat and buttermilk. The fat is compressed and chilled into blocks of butter. It can be used directly as a condiment or melted for frying or coating.
• Ghee


  It is made from cow milk butter, treated with a low heat until the water evaporates, leaving milk solids behind. The solids are skimmed off or strained if needed.
• Lard


  Made from 100% animal fat (usually pork) that has been separated from the meat. Most lard is made through a process called rendering, whereby the fatty parts of the pig and are cooked slowly until the fat is melted.
• Suet


  Made from the fat of cows and sheep. Specifically the crumbles that collect around the kidney. The fat is removed from the meat, clarified, chopped, and then boiled in water, which removes any impurities.
• Spreads


  Main ingredient is a liquid oil such as sunflower, canola, or rice bran oil. The liquid oils needs to be mixed with about 20% hard oil.
• Margarine


  Typically made from water and vegetable oils, such as soybean, corn and olive oils. Consists of emulsifying a blend of oils and fats from vegetable and animal sources, which can be modified using fractionination.
• Types of oils


  • Vegetable oil
  • Olive oil
  • Sunflower oil
  • Walnut
  • Corn
  • Rapeseed
• General pointers about oils

  Oil will give off smoke when it's hot and eventually ignites<|>The temperature varies when it reaches this point<|>The smoke point<|>Oils are a liquid at room temperature and fats are a solid
• Caramelisation


  Happens to sugars and is partly responsible for the colour and browning of foods<|>They turn into a Carmel<|>Burnt sugar is around 180 degrees<|>Sugar used in cooking is called sucrose
• Dextrinisation


  Starchy carbohydrate foods also brown when heated. Dry heat produces dextrinisation which are brown in colour and produce a distinct sweet flavour. A chemical change occurs in the starch molecule cause by a breakdown of sugar within it
• Gelatinisation


  Happens when starch and liquid are heated. The liquid enters the starch granules and they swell, the more water that enters the more they swell, are they expand the mixture becomes more viscous and thick.<|>If you heat cornflour and water it makes thick sauce, if you continue to heat it the water is forced out, meaning the sauce will break down and this is called retrogradation.
• Maillard reaction


  Requires dry heat which causes non enzymes browning. You can smell these changes when food is roasted, baked or grilled. The amino acids in the food change when they are heated causing the surface to brown and to change flavour and texture.
• Emulsification


  Sometimes we need to have water and oil permanently mixed together. For this we create and emulsion. If we add egg then they can combine and mix instead of the ingredients separating. The molecules arrange themselves to make sure they don't separate
• Science behind a cake

  • Using self raising flour- ingredients react together in the batter to create carbon dioxide, which blows up the air bubble
  • When baking the cake, you use radiation as it is put in the oven
  • As the batter temperature rises, the gases in the air cells expand the stretchy gluten from the flour
  • Sifting the dry ingredients makes sure there are no lumps and so the batter and product is smooth
  • To make the cream you have to whisk double cream until it's light and fluffy, if you whisk too much then you are in danger of making butter and the cream separating
• Function of ingredients


  • Flour- provides bulk and volume in baked products
  • Fat- gives food products flavour, colour and texture
  • Sugar- adds flavour, colour and texture to food
  • Baking powder- with moisture and heat will produce carbon dioxide bubbles causing a cake to rise
  • Yeast- given food, moisture, warmth and time, yeast produces carbon dioxide bubbles enabling bread dough to rise
• What went wrong in this dish?

  • Lumpy roux - Too much flour, butter hasn't been mixed and so it is clumpy
  • Sunken cake - Too much liquid, oven opened during baking, not enough rising agents