Fats (and oils)

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  • Fats (and oils)
    • Fats and oils can be visible in some foods such as fat on meat or butter on bread. Some fats are invisible such as in milk, egg yolk, mayo and gravy
      • Foods containing large quantities usually come from animal products such as meat, meat products, cheese, cream, eggs and oily fish
      • Fat in the diet
        • high fat intake and especially  saturated fat is associated with a raised blood cholesterol level- factor in the development of CHD
        • Obesity also develops with the increased consumption of energy-dense foods and lack of activity
          • Obesity increases the risk of type 2 diabetes and heart disease
    • Functions
      • Provides a concentrated source of energy- 37KJ (9kcal) of energy per gram
      • Provides the body with a long-term energy store known as adipose tissue. Adipose tissue is stored under the skin and around some internal organs
      • Protects vital organs such as the kidneys
      • Essential component of all cell membranes in the body
      • Provides a source of fat-soluble vitamins A,D,E,K
      • Enhances flavour, texture and aroma of food
    • Structure of fats and oils
      • Chemically, fat is a triglyceride which consists of 3 fatty acid molecules combines with one glycerol molecule
        • Unsaturated fats
          • The chain of carbon atoms has some hydrogen atoms missing, resulting in a double-bond
          • The molecules are not packed together easily- movement
          • Vegetable oils- liquid at room temperature
          • Mono-unsaturated fatty acids
            • A type of sat fat and have 1 double bond
            • Avocados, cashews, peanuts
            • A good example is oleic acid. Olive oil is rich in oleic acid
            • The double bond is an area of weakness in the molecular structure of oil
          • Poly-unsaturated fatty acids
            • Have 2 or more double bonds in the carbon chain
            • Corn, soya, sunflower oils
            • The double bonds can reduce stability
            • Have more double bonds than mono so are more likely to react with oxygen- rancid when exposed to sun or air for long periods of time
          • Trans and cis fatty acids
            • Unsat fatty acids exist in these 2 structures
            • Structures are identified by the position of the hydrogen atoms to the double bonds
            • Trans- hydrogen atoms on opposite sides of the double bond
            • Cis- hydrogen atoms both on the same side of molecule
      • Fatty acids are chains of carbon and hydrogen atoms
        • Saturated fats
          • No double bonds between any of the carbon atoms in the carbon chains
          • Usually solid at room temperature are have very stable molecules which are unlikely to react with other chemicals
          • Linear shape, rigid structure
          • Red meat, butter, milk, cheese and eggs
      • The carbon atoms in the fatty acid molecule can be linked by single or double bonds
    • Omega 3 and 6
      • The number indicates the location of the first double bond at one end of the carbon chain
      • Essential fatty acids
      • 3- pumpkin seeds, soya beans, green leafy veg, walnuts
      • 6- oils made from sunflower, corn, soya, pumpkin. Also found in tuna and salmon

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