fat and oil chemistry and occurrence.pptx

Fat andoil

1. FAT AND OIL Occurrence and chemistry

2. Fat and oils Oils and fats form an important part of a healthy diet. Structurally they are esters of glycerol with three fatty acids (called either triacylglycerols or triglycerides). It is these fatty acids that give the functionality to fats. Fats provides 8 kcal per 1 gram. Fats provides much energy as compared Some people think that fats and oils are different things. But in reality, they share a common chemical structure and similar properties. The difference is that those that stay solid at room temperatures are called fats while those that stay liquid at room temperatures are called oils. Chemically, each fat or oil molecule consists of three long strings of fatty acid molecules combined with a glycerol molecule. Fats and oils may originate from plants, land or marine animals. Fats and oils may contain small amounts of other minor components that are naturally present. As fats and oils are produced by organisms as a way to store energy, they are found in a wide range of plants and animals.

3. Oils are commonly obtained from oil producing plants like corn, peanuts, soya beans, vegetable seeds, olives, palm kernels, whilst fats are more commonly obtained from animal sources like milk (butter), beef (tallow), pork (lard), etc. Fats and oils can also be obtained from marine sources like fish.

4. Occurrence of fat and oils In food chemistry, fats and oils are naturally occurring substances found in both plant and animal sources. They play essential roles in nutrition, food texture, and flavor. Here’s a breakdown of the occurrence of fats and oils: 1. Animal Sources Dairy products: Milk, butter, and cream are rich in fats, especially saturated fats.Meat : Animal fat from beef, pork, chicken, and other meats are significant sources of both saturated and unsaturated fats.Fish oils: These contain essential omega-3 fatty acids, which are beneficial for heart health.Egg yolks: Rich in fats, mainly in the form of lecithin and cholesterol.

5. 2. Plant Sources Vegetable oils: Extracted from seeds and fruits of various plants, such as olive oil (from olives), sunflower oil (from sunflower seeds), canola oil (from rapeseed), and soybean oil (from soybeans). These are typically rich in unsaturated fats.Nuts and seeds: Almonds, walnuts, flaxseeds, and chia seeds are rich in healthy fats like omega-3 and omega-6 fatty acids.Avocados : High in monounsaturated fats, especially oleic acid, beneficial for heart health.Coconut oil: Derived from coconuts and is high in medium-chain triglycerides (MCTs) and saturated fats.

6. 3.mArine sources Fish liver oils: Cod liver oil and other fish liver oils are high in omega-3 fatty acids and vitamins A and D.Algae : Certain algae are used to produce oils rich in omega-3 fatty acids, often used as a vegan alternative to fish oils.4. 4.processed Fats and oils :Margarine: A processed spread made from vegetable oils, often containing a blend of saturated and unsaturated fats.Hydrogenated fats: These are chemically altered vegetable oils, used in processed foods to create a solid form, which can result in trans fats (now largely avoided due to health concerns).Shortening: A fat product derived from vegetable oils or animal fats, used in baking

7. 5. Functional Roles in Food : Flavor: Fats and oils enhance the flavor of foods, making them more palatable. Texture and mouthfeel: Fats contribute to the creamy, smooth texture in foods like butter, sauces, and ice cream Nutrient absorption: They are essential for the absorption of fat-soluble vitamins (A, D, E, and K). Energy: Fats are a dense source of energy, providing 9 kcal per gram.Understanding the different sources and types of fats and oils helps explain their occurrence and significance in the context of food chemistry.

8. CHEMISTRY OF FAT AND OILS Fats and oils are crucial components in food chemistry, providing energy, flavor, texture, and essential nutrients. Chemically, they are triglycerides, which are esters formed from glycerol and three fatty acid molecules. Here’s an overview of their chemistry: 1. Structure of Fats and OilsTriglycerides : Fats and oils are composed of triglycerides, which consist of a glycerol backbone bonded to three fatty acids via ester linkages.Fatty Acids: These are long hydrocarbon chains with a carboxyl group (-COOH) at one end. Fatty acids can be:Saturated : No double bonds between carbon atoms (e.g., stearic acid). Saturated fats are typically solid at room temperature.Unsaturated : One or more double bonds between carbon atoms (e.g., oleic acid). Unsaturated fats are typically liquid at room temperature.Monounsaturated fatty acids (MUFAs): One double bond (e.g., oleic acid).Polyunsaturated fatty acids (PUFAs): More than one double bond (e.g., linoleic acid).

9. 2. Physical PropertiesMelting Point : The degree of saturation affects the melting point. Saturated fats have higher melting points and are solid at room temperature, while unsaturated fats (with cis double bonds) tend to be liquid due to the kinks in the chain.Polymorphism : Fats can crystallize into different forms, known as polymorphs (alpha, beta prime, and beta forms), affecting texture and stability in food products. 3. Chemical ReactionsHydrolysis : Triglycerides can undergo hydrolysis in the presence of water and an acid or base catalyst, producing glycerol and free fatty acids. This process can lead to rancidity.Hydrogenation : Unsaturated fats can be hydrogenated to convert double bonds to single bonds, increasing saturation and raising the melting point (e.g., converting oils to margarine).Oxidation: Unsaturated fats are prone to oxidation, especially at the double bonds, leading to the formation of peroxides and free radicals. This results in rancidity, affecting flavor and nutritional quality.Interestification : Rearranging the fatty acids on the glycerol backbone can modify the physical properties of fats, useful in creating custom fat blends for food products.

10. 4. Nutritional AspectsEnergy Source: Fats provide 9 kcal per gram, making them a concentrated energy source.Essential Fatty Acids: Some PUFAs, such as omega-3 ( α- linolenic acid) and omega-6 (linoleic acid), cannot be synthesized by the body and must be obtained through the diet.Cholesterol and Trans Fats: Excessive consumption of saturated fats and trans fats (formed during partial hydrogenation) is linked to cardiovascular diseases. 5. Functional Properties in FoodFlavor Carrier : Fats dissolve and retain flavor compounds, enhancing the taste of food.Texture : Fats contribute to the creamy, smooth texture of foods such as ice cream and butter. They also affect the flakiness of pastries.Emulsification : Fats can form emulsions, where oil and water phases are dispersed in each other. Emulsifiers like lecithin stabilize these mixtures.

11. 6. Food Processing and ApplicationsFractionation : Separating fats into solid and liquid fractions to create specific products like cocoa butter or frying oils.Deep -Frying: Fats with high smoke points (e.g., refined oils) are ideal for frying because they maintain stability at high temperatures.Margarine and Shortenings: Hydrogenated and interesterified fats are used to make margarine and shortenings, providing specific textural and functional properties in baking 7. Health ImplicationsSaturated vs . Unsaturated Fats : Diets high in saturated fats and trans fats are linked to heart disease, while unsaturated fats, particularly omega-3 and omega-6 fatty acids, are beneficial for heart health.In conclusion, the chemistry of fats and oils is integral to their role in food. Their structure, reactions, and interactions influence food quality, stability, and nutrition, making them essential in food science and culinary applications

12. Thank you Hisana thesni 1 st year msc food science and technology