Plant Oils and their Uses

Vegetable oils
1. Some fruits, seeds and nuts are rich in oils that can be extracted
  1. The plant material can be and the oil is removed by pressing
    1. This is how olive oil is obtained
    2. Other oils may be more difficult to extract so they are dissolved in water and distilled, then purified to remove any water or other impurities
      1. This is how sunflower oil is obtained
  2. Vegetable oils are important foods and fuels as they provide lots of energy and nutrients
2. Vegetable oils have higher boiling points than water so can be used to cook foods at higher temperatures than by boiling
  1. This produces quicker cooking and different flavours but increases the energy that the food releases when eaten
Emulsions
1. Oils do not dissolve in water but they can be used to make emulsions
  1. Emulsions are thicker than oil or water and have many uses that depend on their special properties
    1. They provide better texture, coating ability and appearance for example in salad dressings, ice creams, cosmetics and paints
      1. Emulsions are made using water, oil and an emulsifier
        Emulsifier contain two parts- a hydrophilic head and hydrophobic tail
        The hydrophilic part stays attracted to the water whilst the hydrophobic part stays in the oil so they do not separate
Saturated and unsaturated oils
1. Unsaturated oils have a carbon=carbon double bond which turns bromine water from orange to colourless
2. Vegetable oils that are unsaturated can be hardened by reacting them with hydrogen in the presence of a nickel catalyst at about 60 degrees celsius
  1. Hydrogen adds to the carbon-carbon double bonds
    1. The hydrogenated oils have melting points so they are solids at room temperature, making them useful as spreads and in cakes and pastries

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Plant Oils and their Uses

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	Created by seth.bragg almost 11 years ago