Food Tech Revision Notes PDF

# Macronutrients ## Macronutrient-Protein ### Key Words * Macronutrients * Needed by body * Large amounts ### Composition of proteins * Found in animal/plant foods * Made from 'building blocks' called **amino acids** * 20 amino acids ### AA (Amino Acids) ### Functions in the body * **Growth*...

# Macronutrients ## Macronutrient-Protein ### Key Words * Macronutrients * Needed by body * Large amounts ### Composition of proteins * Found in animal/plant foods * Made from 'building blocks' called **amino acids** * 20 amino acids ### AA (Amino Acids) ### Functions in the body * **Growth** * **Repair** * **Secondary source of energy** * **Needed for** * **Enzymes** (and digestion) * **Antibodies** (fight infection) ### Why amino acids are important? * 10 essential amino acids for children. * 8 essential amino acids for adults. * *Must get essential amino acids from non-essential proteins* * HBV protein - contains all essential amino acids * LBV protein - missing some essential amino acids ### Main food sources * **HBV:** Meat, poultry, fish * **LBV:** Eggs, dairy, soya beans, beans, lentils, nuts, seeds ### Protein Alternatives * Tempeh * Textured vegetable protein (TVP) * Quorn ### Effects of deficiency (too little in the body) * Poor growth in children * Hair loss * Poor skin/nails * Infections * Poor digestion * Deficiency disease: **Kwashiorkor** ### Effects of excess (too much in the body) * Stored as fat * Weight gain * Puts strain on liver/kidneys ## Macronutrient-Fats ### Key Words * Fats * Fatty acids * Triglyceride * Saturated * Unsaturated * Visible fats * Invisible fats ### Composition of fats * **Fats** * Solid at room temperature * Liquid at room temperature * **Glycerol + 3 fatty acids = Triglyceride** ### What are fatty acids? * **Saturated fatty acids:** animal sources * **Unsaturated fatty acids:** plant sources * **Essential fatty acids:** cannot be made in the body so come from the food we eat, e.g. oily fish, meat, eggs. ### Functions in the body * **Energy:** warmth * **Protects vital organs.** * **Provides fat-soluble vitamins (A, D, E, K).** ### Main food sources * **Solid animal fat:** bacon, butter, cakes, biscuits * **Visible:** oily fish * **Invisible:** milk, cream * **Liquid animal fat:** * **Visible:** butter * **Invisible:** cream * **Solid plant fat:** vegetable fat spreads * **Visible:** vegetable fat spreads * **Invisible:** chocolate, doughnuts * **Liquid plant oils:** * **Visible:** sunflower oil, olive oil * **Invisible:** nuts, avocado ### Effects of deficiency (too little in the body) * Weight loss * Bruise easily * No get vitamins A, D, E, K ### Effects of excess (too much in the body) * Weight gain * Obesity * Heart disease (CHD) ### RDA * 1g fat = 9 kcals * No more than 35% fat per day ## Macronutrient-Carbohydrates ### Key Words * Photosynthesis * Sugars * Monosaccharides * Disaccharides * Polysaccharides ### Composition of carbohydrates * **Carbon** * **Hydrogen** * **Oxygen** * Made by plants during photosynthesis ### Types of carbohydrates * **Sugars** * **Monosaccharides** (one sugar) * Glucose, Fructose, Galactose. * **Disaccharides** (2 sugars) * Sucrose, Lactose, Maltose * **Starches** * **Polysaccharides** (many sugars) * Starch, Dextrin, Pectin * Glycogen * **Fibre** ### Functions in the body * **Energy** * **Dietary fibre** * Aids Digestion * Removal of waste * **Can be broken down in the body to glucose** * Gives instant energy. ### Main food sources * **Monosaccharides** * **Glucose** * Fruits, honey, milk from mammals * **Fructose** * Apples, onions * **Galactose** * Milk from mammals * **Disaccharides** * **Maltose** * Cereals, biscuits * **Sucrose** * Drinks, sweets * **Lactose** * Milk, cheese * **Polysaccharides** * **Starch** * Pasta, potatoes * **Fibre (NSP - non starch polysaccharide** * Wholegrain bread, brown rice * **Pectin** * Fruit, eg. apples, carrots * **Dextrin** * Formed when starchy foods are baked or toasted, eg. bread, toast ### RDA * 50% of energy every day * Dietary fibre 30g per day ### Effects of excess (too much in the body) * Obesity * Raised blood sugar * Type 2 diabetes * Tooth decay ### Effects of deficiency (too little in the body) * Lack of energy/tiredness * Weight loss * Severe weakness ## Functional/chemical properties of protein * **Chemical Structure of protein:** Protein molecules are made up of long chains of **amino acids**. * **Once joined into bundles they are held together by chemical bonds.** * **Denaturation:** Chemical bonds have been broken causing protein molecules to unfold and change shape. * This happens when: * Food is heated * Mechanical agitation, e.g. whisking eggs * Adding acid, e.g. lemon juice to chilled lemon flan. ## Functional and chemical properties of fats * **Plasticity:** The ability of a fat to soften over a range of temperatures, and be spread/shaped with light pressure. * e.g. Spreading butter on toast, mixing margarine in a cake. * **Shortening:** The ability of fats to shorten the length of gluten molecules in pastry * **Aeration:** The ability of some fats to trap lots of air bubbles when beaten together with sugar. * e.g. cakes * **Emulsification:** Either keeping drops of oil or fat suspended in a liquid and preventing them from separating, or keeping drops of water suspended in an oil/fat and preventing those separating out. * e.g. Mayonnaise, Hollandaise sauce ## Dextrinisation * When food containing starch, e.g. bread, is cooked by **dry heat** it turns brown. * Due to the effect of the heat on the starch molecules, they break down into small groups of glucose molecules = **dextrin**. * Dextrin contributes to the flavour. * This process is called **dextrinisation**. * If you toast bread until it is very dark, it goes past dextrinisation. The oxygen and hydrogen are driven off by the heat as water, leaving behind **carbon**. ## Caramelisation * **Sugar (sucrose) - disaccharide (fructose + glucose)** * **Sugar is heated** → **melts** → **forms syrup** → **boils** * **As this happens, the sucrose molecules break up** * **As heating continues, hydrogen/oxygen atoms in the sugar form water which evaporates and the colour of the sugar changes from colourless/clear to golden brown, to dark brown, and eventually to black (Carbon).** * **Flavour changes from sweet (toffee/caramel) to a bitter, burnt taste.** * **To caramel, add water to sugar in a saucepan - heat gently until water evaporates and caramel forms. DO NOT STIR IT, it will crystalise** * **Texture:** Crystals of sugar → syrup → cools down to create toffee. * **Temperature of caramelising sugar is 160˚C - 170˚C**