Food Science and Processing 2024 Lecture 10 PDF

3 Fats Dr. Mohamed Elsaadany 24  Fats Fats belong to a larger group of compounds called lipids, which include both fats and oils and cholesterol etc Fat formed by the reaction between fatty acids and Glycerol forming Ester called triglycerides If 3 Fa...

3 Fats Dr. Mohamed Elsaadany 24  Fats Fats belong to a larger group of compounds called lipids, which include both fats and oils and cholesterol etc Fat formed by the reaction between fatty acids and Glycerol forming Ester called triglycerides If 3 Fatty acids are chemical chains that contain carbon, hydrogen, and oxygen atoms Fatty acids that have as many hydrogen atoms as they can hold are called saturated fatty acids Fatty acids that have fewer hydrogen atoms than they can hold are called unsaturated fatty acids 25 Dr. Mohamed Elsaadany 25  Properties of Fats and Oils Solubility However, in the presence of a suitable substance known as an emulsifying agent, it’s possible to form a stable mixture of fat and water The Emulsion may be a Fat – in – Or a Water – in – Fats and oils are soluble in organic solvents such as petrol and carbon Plasticity Some of the fatty acids forming the triglyceride will stay solid for longer than – Has a wide range of plasticity and will spread whereas most 26 26 Dr. Mohamed Elsaadany 26  Properties of Fats and Oils Effect of Heat Melting Point Most fats melt at temperatures of 30°/40°C Melting point for oil is below normal air temperature – The more double bonds, the lower Smoke Point When a fat or oil is heated to a certain temperature it starts to decompose, producing a Most fats and oils start to smoke at 200°C Smoke Point for lard = 185°C Corn Oil = 232°C Smoke is useful to measure when assessing the suitability of a fat or oil for frying 27 27 Dr. Mohamed Elsaadany 27  Properties of Fats and Oils Saponification Hydrogenation Hydrogenation is used to add hydrogen to the oil to break the Hydrogenated fat makes TRANS fats which increases likelihood of cancer and CIS 2 Trans 29 29 Dr. Mohamed Elsaadany 29  Rancidity Oxidative Rancidity Oxygen molecules join across the double bond of the triglyceride molecule Aldehydes and Ketones – gives Hydrolytic Rancidity Enzymes known as lipase hydrolyse fats, breaking them down into glycerol and Fat + Water Glycerol + Fatty Acids Short Chains = More rancid 30 30 Dr. Mohamed Elsaadany 30  How to prevent Rancidity Do not store oil in iron containers use glass Anti- 31 31 Dr. Mohamed Elsaadany 31  Uses in Food Preparation Frying Fast cooking method – bad for health as it increases fat content, but Frying occurs at 180°C Shortening It’s an effect that fat has on a product – increases the crumbly texture of Creaming and Aerating Adding air bubbles Lighter colour Increases volume – 32 32 Dr. Mohamed Elsaadany 32  Fat sources Vegetable Oils 70% of all oils in the world are vegetable oils Margarine The vegetable fat being used is first hydrogenated to give it some hardness (plasticity), and is then Butter Churning of pasteurised cream, this causes the cream to become more viscous forming a solid 33 33 Dr. Mohamed Elsaadany 33