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Chemistry 1- Vegetable oils, emulsions and hydrogenation (Vegetable oils…
Chemistry 1- Vegetable oils, emulsions and hydrogenation
Vegetable oils obtained from plants
Important ingredient in many foods, can be hardened through a chemical process
Can be used as fuels such as biodiesel
Emulsifiers- food additives- stop oil and water mixtures in food from seperating
Vegetable oils- natural oils found in seeds nuts and some fruits- can be extracted
Plant material crushed and pressed to squeeze oil out- olive oil
Some oil more difficult to extract as it has to be dissolved in a solvent
Once oil dissolved- solvent removed by distillation and impurities eg water are removed to leave pure vegetable oil- sunflower oil
Molecules of vegetable oil consist of glycerol and fatty acids
Vegetable oil- higher boiling point than water- food can be cooked or fried at higher temperatures
Vegetable oil makes food taste different and can be cooked faster
Vegetable oils- source of energy- releases more energy when eaten- causes health problems
Fatty acids in some oils are saturated- only have single bonds between carbon atoms
Saturated oils solid at room temperature- vegetable fats- lard
Fatty acids in some oils unsaturated- double bonds between some carbon atoms
Unsaturated oils tend to be liquid at room temperature- useful for frying food
Two types of unsaturated oils- monunsaturated fats- one double bond in each fatty acid, polyunsaturated fats- many double bonds
Unsaturated- healthier
Emulsion- vegetable oil does not dissolve in water- if shaken together droplets of one liquid spread throughout the other this is more viscous (thicker) and is called an emulsion
Two types of emulsion: oil droplets in water (milk, ice cream, salad cream, mayonnaise), water droplets in oil (butter, margarine, skin cream, moisturising lotion)
Emulsion left to stand- layer of oil will form on top of water
Emulsifiers stabilise emulsions stopping them seperating
Emulsifiers two different ends
Hydrophilic end- water loving- forms chemical bonds with water
Hydrophobic- water hating- forms bonds with oils
Hydrophillic head sissolves in water and hydrophobic tail dissolves in oil so they dont seperate
Unsaturated vegetable oils an be detected by bromine water due to their double bond carbon atoms- becomes colourless
Bromine water can also determine how unsaturated something is- the more unsaturated- the more it can decolourise
Unsaturated vegatable oils can be hardened by reacting them with hydrogen this is called hydrogeneration
Oils reacted with hydrogen at 60 degrees- nickle catalyst speeds it up- double bonds converted to single- unsaturated turns to saturated