Lipids PDF

CHT413A: FOOD CHEMISTRY LIPIDS COMPILED BY: LOWELA C. VILLARIAS  LIPIDS ✓ Composed of structural units with pronounced hydrophobicity which makes them unique ✓ Their water insolubility separates them from carbohydrates and...

CHT413A: FOOD CHEMISTRY LIPIDS COMPILED BY: LOWELA C. VILLARIAS  LIPIDS ✓ Composed of structural units with pronounced hydrophobicity which makes them unique ✓ Their water insolubility separates them from carbohydrates and proteins ✓ Majority are fatty acid derivatives known as acyl lipids present as esters ✓ Minority groups are present in amides form ✓ Triglycerides also known as primary triacylglycerols are deposited in some animal tissues and organs and some plants ✓ Storage tissues lipid content is at 15 to 20% or even higher and serves as a source for commercial use.  LIPIDS AND FOOD Figure 2.0 Wagyu Beef are essential in food application due to its melting courtesy of Holy Grail Steak properties and sensorial contribution Co. It imparts specific mouthfeel or that juicy and tender texture, creamy and oily taste with satisfactory aroma retention Some lipids are also used as solvent to fat or oil soluble aroma and food colorants. https://robbreport.com/food- drink/dining/what-is-wagyu-beef-luxury- steak-2855767/ Lipid Classifications  COMPONENT FATTY ACIDS Saturated Fatty Acids Unsaturated Fatty Acids Dominantly composed of unbranched, Those that contain one or more double straight chain molecules with even bonds in the fatty acid chain number of atoms The greater degree on unsaturation Higher melting points than unsaturated (more double bonds) of fatty acids the ones more vulnerable it is to lipid Their ratio significantly affects the peroxidation or rancidity physical properties of fats and oils  COMPONENT FATTY ACIDS Saturated Fatty Acids Unsaturated Fatty Acids  FATTY ACID COMPOSITION OUTLINE 1. Depot fats or higher land animal fats– consist mainly of palmitic, oleic and stearic acid and high in saturated fatty acids, with 70% composed of fatty acids with 18 carbon atoms. The kind of feed animals consume greatly affects the composition of depot fats; and animal depot fats re usually characterized by 20 to 30% palmitic acid (16:0) 2. Ruminant milk fats – characterized by greater variety of component fatty acids; present in large amount are lower saturated acids with 4 to 10 carbon atoms and the major fatty acids are palmitic, oleic and stearic with several additional minor fatty acids composed of short chain fatty acids from butyric and capric. 3. Marine oils – contains wide variety of fatty acids that are high in unsaturated fatty acids especially those with long chains containing 20 to 22 carbons or more. Includes eicosapentaenoic (EPA) and docosahexaenoic acid (DHA) 4. Fruit Coat Fats – mainly consist of palmitic, oleic and at times linoleic acids 5. Seed fats – characterized by low contents of saturated fatty acids, contains palmitic, oleic, linoleic and linolenic acids  3 MAIN TYPES OF LIPIDS 1. Triglycerides Also known as natural fats and is a mixtures of mixed triglycerides Distribution of fatty acids both between and within glycerides is selective rather than random make up more than 95 percent of lipids in the diet and are commonly found in fried foods, butter, milk, cheese, and some meats. we commonly call the triglycerides in our food “fats (solid at room temperature)” and “oils (liquid at room temperature.” Naturally occurring in many foods such as avocados, olives, corn and nuts  3 MAIN TYPES OF LIPIDS 1. Triglycerides When one of the carbon atoms is esterified with a fatty acid, a monoglyceride results and two nonsuperimposable structures exist called enantiomers (also referred to as chiral as shown in Figure 2.4 and 2.5). Chiral compounds are formed in 1-monoglycerides; all 1, 2-diglycerides; 1, 3 diglycerides containing unlike substituents and all triglycerides in which the 1- and 3- positions carry different acyl groups. Racemic mixture is composed of mixture of equal amounts of enantiomers (optically inactive or does not rotate the plane of polarized light  3 MAIN TYPES OF LIPIDS II. Phospholipids Are surface active containing lipophilic and hydrophilic portions Can easily be remove from fats and oils during refining process make up only about 2 percent of dietary lipids are water-soluble and are found in both plants and animals are crucial for building the protective barrier, or membrane, around your body’s cells, are synthesized in the body to form cell and organelle membranes In blood and body fluids, phospholipids form structures in which fat is enclosed and transported throughout the bloodstream. PHOSPHOLIPIDS 3 MAIN TYPES OF LIPIDS III. Unsaponifiables include all those that are barely soluble in aqueous solution but soluble in organic solvent after undergoing the process of alkaline hydrolysis these are lipid fraction cannot be converted into soap and generally occurs 2% of the oil’s content consisted of sterols, terpenic alcohols, aliphatic alcohols, squalene and hydrocarbons STEROLS The major component of unsaponifiable fraction are the least common type of lipid found in animal fats Cholesterol is perhaps the best well-known Cholesterol is produced by the body Cholesterol is an important component of the cell membrane and is required to synthesize sex hormones, vitamin D, and bile salts  AUTOXIDATION The reaction that may occur in the unsaturated bonds present in all fats and oils represent active centers with oxygen The reaction leads to the formation of primary, secondary and tertiary oxidation products that make fat or fat-containing products unsuitable for consumption.  RANCIDITY Deterioration in flavor of fats and fatty foods brought about by the process of autoxidation Also referred to as oxidative deterioration Lipids degrade to the point of becoming unpalatable FACTORS AFFECTING OXIDATION amount of oxygen present degree of unsaturation of lipids presence of antioxidants presence of prooxidants, especially copper and some organic compounds such as heme-containing molecules and lipoxidase nature of packaging material light exposure temperature of storage  PHOTOOXIDATION also known as light induced oxidation are results from the reactivity of the singlet oxygen also known as the excited state of oxygen (1O2). Compounds that act as Singlet state oxygen is more reactive that ground Sensitizers: state oxygen and is produced in the presence of sensitizer - chlorophyll - myoglobin The presence of sensitizer converts unsaturated - riboflavin fatty acid residues to hydroperoxide - heavy metals PHOTOOXIDATION can cause light induced flavor deterioration on several fats and oil products packed in transparent containers displayed in brightly lit supermarkets where presence of sensitizers and light is both present. Studies found that milk fat and soybean oil is the most susceptible while corn oil is the least to be attacked by singlet oxygen Quenchers such as beta-carotene in olive oil and other carotenoids effectively compete for the singlet oxygen to bring it back to normal state, thus prevent or reduce photooxidation. CHEMICAL REACTIONS DURING DEEP FRYING PROCESS THANK YOU