PLANT OILS

UNSATURATED OILS CONTAIN C=C DOUBLE BONDS1. oils and fats contain long-chain molecules with lots of carbon atoms2. oils and fats are either saturated or unsaturated3. unsaturated oils contain double bonds between some of the carbon atoms in their carbon chains4. so, an unsaturated oil will decolourise bromine water (as the bromine opens up the double bonds and joins on)5. Monounsaturated fats contain one c=c double bond somewhere in their carbon chains. Polyunsaturated fats contain more than one c=c double bond

UNSATURATED OILS CAN BE HYDROGENATED1. unsaturated veggie oils are liquid at room temperature2. they can be hardened by reacting with hydrogen in the presence of a nickel catalyst at about 60 degrees C3. Hydrogenated oils have higher melting points than unsaturated oils so they're more solid at room temperature. This makes them useful as spreads and for baking cakes and pastries4. Margarine is usually made from partially hydrogenated veggie oils - turning all the double bonds in veggie oil to single bonds. This would make margarine too hard and difficult to spread. Hydrogenating most of them gives margarine a nice, buttery, spreadable consistency5. partially hydrogenated veggie oils are often used instead of butter in processed foods, e,g, biscuits. These oils are a lot cheaper than butter and they keep longer . This makes biscuits cheaper and gives them a longer shelf life.6. But partially hydrogenating vegetable oils means that end up with a lot of so-called trans-fats. And there's evidence to suggest that trans fats are very bad for you. 

VEGETABLE OILS IN FOODS CAN AFFECT HEALTH1. vegetable oils tend to be unsaturated, while animals fats tend to be saturated2. In general, saturated fats are less healthy than saturated fats (as a saturated fats increase the amount of cholesterol in the blood, which can block up the arteries and increase the risk of heart disease)3. Natural unsaturated fats are less as olive oil and sunflower oil reduce the amount of blood cholesterol. But because of the trans fats, partially hydrogenated veggie oils increase the amount of cholesterol in the blood. So eating a lot of food made with partially hydrogenated veggie oils can actually increase the risk of heart disease4. Cooking food in oil, whether saturated,  unsaturated of partially hydrogenated makes it more fattening. 

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