Home ec -Lipids

• Lipids supply the body heat of 37 degrees and are a concentrated source of energy to help with exercise and maintain body heat.
• Lipids protect the delicate organs of the body such as the kidneys and insulate the nerve fibres.
• Lipids supply the body heat of 37 degrees and are a concentrated source of energy to help with exercise and maintain body heat.
• Lipids protect the delicate organs of the body such as the kidneys and insulate the nerve fibres.
• The digestion of lipids involves the pancreas secreting pancreatic juice containing lipase, which breaks down lipids into fatty acids and glycerol in the duodenum.
• Cis fatty acids are polyunsaturated fatty acids where the hydrogen atoms on either side of the double bond are both above or both below the carbon chain.
• Trans fatty acids are polyunsaturated fatty acids where the hydrogen atoms on either side of the double bond are on opposite sides of the carbon chain.
• Saturated fatty acids have no double bonds between the carbon atoms and each carbon is fully saturated with atoms.
• Monounsaturated fatty acids have one double bond between the carbon atoms and are generally soft/liquid at room temperature.
• Polyunsaturated fatty acids have more than one double bond between the carbon atoms and are generally soft/liquid at room temperature.
• Rancidity is the spoilage of lipids, with two types: oxidative rancidity, which occurs when oxygen combines with a carbon atom at the double bond, resulting in an unpleasant rancid smell, and hydrolytic rancidity, which occurs when enzymes or bacteria hydrolyse lipids, changing them to fatty acids and glycerol, resulting in an unpleasant smell or taste.
• Emulsification is the ability of lipids to form an emulsion.
• Saturated fatty acids have all carbon atoms fully saturated with hydrogen atoms, no double bonds between the carbon atoms, and generally come from animal sources such as butter and stearic acid.
• Monounsaturated fatty acids have one double bond between the carbon atoms, generally come from plant sources such as oleic acid, and are considered good fats that lower total blood cholesterol and LDL levels.
• Polyunsaturated fatty acids have all carbon atoms not saturated with hydrogen, one or more double bonds between carbon atoms, generally come from plant sources such as walnuts, seeds, and oily fish, and include the essential fatty acids such as linoleic, linolenic, and arachidonic.
• Saturates contribute to CHD and raise total blood cholesterol and LDL levels.
• Monounsaturates are good fats that lower total blood cholesterol and LDL levels.
• Trans fatty acids are associated with CHD and may raise LDL and lower HDL cholesterol levels.
• Hydrogenation is a process where an unsaturated fatty acid can have hydrogen added in the presence of a nickel catalyst, converting the oil into fats.
• Plasticity in lipids relates to whether a lipid is solid, liquid or spreadable, and is determined by the degree of saturation.
• Omega 3 fatty acids in the diet can reduce the risk of coronary heart disease by raising HDL cholesterol levels and lowering LDL cholesterol levels, and prevent blood clots by decreasing the thickness of blood.
• Oxidative rancidity is more common and occurs when oxygen combines with a carbon atom at the double bond, resulting in an unpleasant rancid smell.
• Hydrolytic rancidity occurs when enzymes or bacteria hydrolyse lipids, changing them to fatty acids and glycerol, resulting in an unpleasant smell or taste.
• Cis fatty acids have all carbon atoms on either side of the double bond above or below the carbon chain, examples include olive oil and cod liver oil.
• Trans fatty acids have all carbon atoms on either side of the double bond on opposite sides of the carbon chain, examples include crackers and crisps.
• Biological functions of lipids include contributing to the structure of cell membranes, acting as energy storage, and serving as a precursor to hormones.
• Emulsion: A colloidal solution formed when two liquids that do not usually mix such as oil and water are forced to do so.
• There are two types of emulsions: water in oil emulsions and oil in water emulsions.
• Water in oil emulsions: Water droplets are dispersed in the oil, examples include butter or margarine.
• Oil in water emulsions: Oil droplets are dispersed in the water, examples include milk and mayonnaise.
• Emulsifiers in food production: Emulsifiers are used to stabilize emulsions.
• Oxidative rancidity: More common, occurs when oxygen combines with a carbon atom at the double bond, resulting in an unpleasant rancid smell.
• Hydrolytic rancidity: Occurs when enzymes or bacteria hydrolyse (break down) lipids, changing them to fatty acids and glycerol, resulting in an unpleasant smell or taste.
• Hydrolytic rancidity can occur in the freezer due to enzymes.
• Fatty acids in the diet: Saturates contribute to CHD and raise total blood cholesterol and LDL levels, monounsaturates are good fats that lower total blood cholesterol and LDL levels, and trans fatty acids are associated with CHD and may raise LDL and lower HDL cholesterol levels.
• Cis fatty acids are polyunsaturated fatty acids with the first double bond between the third and fourth carbon atoms, examples include sunflower oil and olive oil.
• Trans fatty acids are polyunsaturated fatty acids with the first double bond on the opposite side of the carbon chain, examples include crisps, cakes, and biscuits.
• Omega 3 fatty acids are unsaturated fatty acids with the first double bond between the third and fourth carbon atoms, examples include fish, nuts, seeds, and soya beans.
• Digestion of lipids: Lipids are digested in the small intestine by intestinal juice and lipase, resulting in fatty acids and glycerol.
• Function of omega 3 fatty acids in the diet: Omega 3 fatty acids reduce the risk of coronary heart disease by raising HDL cholesterol levels and lowering LDL cholesterol levels, prevent blood clots by decreasing the thickness of blood, and are found in oil fish such as salmon, nuts, and seeds.