Fats and Oils PDF

Class- Second year B. Pharmacy Semester: B. Pharm third semester Subject- Pharmaceutical Organic Chemistry -II Subject Code- BP301T UNIT-III- Fats and Oil Prepared by: Dr. Popat Mohite Associate Professor Department of Pha...

Class- Second year B. Pharmacy Semester: B. Pharm third semester Subject- Pharmaceutical Organic Chemistry -II Subject Code- BP301T UNIT-III- Fats and Oil Prepared by: Dr. Popat Mohite Associate Professor Department of Pharmaceutical Chemistry St. John Institute of Pharmacy and Research, Palghar 1 Lipids: ✓ Lipids are fatty, waxy, or oily compounds that are soluble in organic solvents and insoluble in polar solvents such as water. ✓ Lipids include: Fats and oils (triglycerides) Phospholipids Fats and Oils Fats and oils are composed of molecules known as triglycerides, which are esters composed of three fatty acid units linked to glycerol. Fats and oils are those lipids which are saponifiable. While steroids are non-saponifiable. Natural fats and oils are triesters of glycerol with long chain carboxylic acids (10 to 20 carbons) called as Triglycerides ✓ Fats and oils are called triglycerides because they are esters composed of three fatty acid units joined to glycerol, a trihydroxy alcohol: ✓ A wax is a simple lipid which is an ester of a long-chain alcohol and a fatty acid. The alcohol may contain from 12-34 carbon atoms. Types: a) Simple triglycerides: If all three OH groups on the glycerol molecule are esterified with the same fatty acid, the resulting ester is called a simple triglyceride. Although simple triglycerides have been synthesized in the laboratory, they rarely occur in nature. b) Mixed triglycerides: If all three OH groups on the glycerol molecule are esterified with the two or three different fatty acids, the resulting ester is called a mixed triglyceride. Instead, a typical triglyceride obtained from naturally occurring fats and oils contains two or three different fatty acid components and is thus termed a mixed triglyceride. Example 1: 2  Example 2: O H2C O C (CH2)14 CH3 O HC O C (CH2)16 CH3 O H2C O C (CH2)7 CH CH (CH2)7 CH3 Glyceryl palmitosterooleate Simple triglyceride Mixed triglyceride A triglyceride is called a fat if it is a solid at 25°C; it is called oil if it is a liquid at that temperature. These differences in melting points reflect differences in the degree of unsaturation and number of carbon atoms in the constituent fatty acids. Triglycerides obtained from animal sources are usually solids, while those of plant origin are generally oils. Therefore, we commonly speak of animal fats and vegetable oils. Some common fatty acids: Saturated fatty acids: Examples of saturated fatty acids Common name Chemical structure C:D[ Caprylic acid CH3(CH2)6COOH 8:0 Capric acid CH3(CH2)8COOH 10:0 Lauric acid CH3(CH2)10COOH 12:0 Myristic acid CH3(CH2)12COOH 14:0 Palmitic acid CH3(CH2)14COOH 16:0 Stearic acid CH3(CH2)16COOH 18:0 Arachidic acid CH3(CH2)18COOH 20:0 Behenic acid CH3(CH2)20COOH 22:0 Lignoceric acid CH3(CH2)22COOH 24:0 Cerotic acid CH3(CH ) COOH 3 2 24 26:0 Unsaturated fatty acids: Common name Chemical structure C:D Myristoleic acid CH3(CH2)3CH=CH(CH2)7COOH 14:1 Palmitoleic acid CH3(CH2)5CH=CH(CH2)7COOH 16:1 Sapienic acid CH3(CH2)8CH=CH(CH2)4COOH 16:1 Oleic acid CH3(CH2)7CH=CH(CH2)7COOH 18:1 Elaidic acid CH3(CH2)7CH=CH(CH2)7COOH 18:1 Vaccenic acid CH3(CH2)5CH=CH(CH2)9COOH 18:1 Linoleic acid CH3(CH2)4CH=CHCH2CH=CH(CH2)7COOH 18:2 Linoelaidic acid CH3(CH2)4CH=CHCH2CH=CH(CH2)7COOH 18:2 α-Linolenic acid CH3CH2CH=CHCH2CH=CHCH2CH=CH(CH2)7COOH 18:3 Arachidonic acid CH3(CH2)4CH=CHCH2CH=CHCH2CH=CHCH2CH=CH(C 20:4 H2)3COOH Saturated fats can stack themselves in a closely packed arrangement, so they can solidify easily and are typically solid at room temperature. For example, animal fats tallow and lard are high in saturated fatty acid content and are solids. Olive and linseed oils on the other hand are unsaturated and liquid. Fats serve both as energy sources for the body, and as stores for energy in excess of what the body needs immediately. Fats are broken down in the healthy body to release their constituents, glycerol and fatty acids. Glycerol itself can be converted to glucose by the liver and so become a source of energy. Differentiate between fats and oils: Sr. Fats Oils No 1. Fats are solids or semisolids at room Oils are liquids at room temperature temperature 2. Fats contains large amount of saturated Oils contains large amount of fatty acids unsaturated fatty acids e.g. Stearic and Palmitic acids e.g. Oleic acid, Linoleic acid 3. Fats melt at high temperature Melt at low temperature 4. Fats do not contain double bonds Oils have double bonds 5. Fats are more stable Oils are less stable 6. Fats are animal fats Oils are vegetable fats 7 Example- Lard Example- Paraffin Oil 4 General methods of extraction: Fats may be recovered from oil-bearing tissues by three general methods, with varying degrees of mechanical simplicity: a) rendering, b) pressing with mechanical presses, and c) extracting with volatile solvents. Physical Properties of Fats and Oils Pure fats and oils are colorless, odorless, and tasteless. The characteristic colors, odors, and flavors that we associate with some of them are imparted by foreign substances that are lipid soluble and have been absorbed by these lipids. They are insoluble in water but soluble in organic solvents such as ether and chloroform. They have low specific gravity than water and so float on the surface of water when mixed with it. Fats and oils are lighter than water, having densities of about 0.8 g/cm3. They are poor conductors of heat and electricity and therefore serve as excellent insulators for the body, slowing the loss of heat through the skin. They readily form emulsions when agitated with water in presence of soap, gelation or emulsifiers. For example, the yellow color of butter is due to the presence of the pigment carotene; the taste of butter comes from two compounds diacetyl and 3-hydroxy-2-butanone produced by bacteria in the ripening cream from which the butter is made. Chemical structure There are many different kinds of fats, but each is a variation on the same chemical structure. All fats are derivatives of fatty acids and glycerol. Most fats are glycerides, particularly triglycerides (triesters of glycerol). One chain of fatty acid is bonded to each of the three -OH groups of the glycerol by the 5  reaction of the carboxyl end of the fatty acid (-COOH) with the alcohol; i.e. three chains per molecule. Water is eliminated and the carbons are linked by an -O- bond through dehydration synthesis. This process is called esterification and fats are therefore esters. As a simple visual illustration, if the kinks and angles of these chains were straightened out, the molecule would have the shape of a capital letter E. The fatty acids would each be a horizontal line; the glycerol "backbone" would be the vertical line that joins thehorizontal lines. Fats therefore have "ester" bonds. The properties of any specific fat molecule depend on the particular fatty acids that constitute it. Fatty acids form a family of compounds that are composed of increasing numbers of carbon atoms linked into a zig-zag chain (hydrogen atoms to the side). The more carbon atoms there are in any fatty acid, the longer its chain will be. Long chains are more susceptible to intermolecular forces of attraction (in this case, van der Waals forces), and so the longer ones melt at a higher temperature (melting point). Fig. 1. Structure of a triglyceride and saturated, monounsaturated and polyunsaturated fatty acids. 6 Classification of Fatty acids: Fatty acids are classified according to the presence and number of double bonds in their carbon chain. a) Saturated fatty acids (SFA) – Non-Essential Fatty acids ✓ Saturated fatty acids (SFA) contain no double bonds ✓ Example- butyric acid, Myristic acid, palmitic acid, stearic acid b) Monounsaturated fatty acids (MUFA)- Essential Fatty acids ✓ monounsaturated fatty acids (MUFA) contain one ✓ Example- Oleic acid c) Polyunsaturated fatty acids (PUFA)- Essential Fatty acids ✓ polyunsaturated fatty acids (PUFA) contain more than one double bond ✓ Example- Linoleic acid, Arachidonic acid Both length and saturation of fatty acids affect the arrangement of the membrane in our body cells and thereby its fluidity. Shorter chain fatty acids and ones with greater unsaturation are less stiff and less viscous, making the membranes more flexible. This influences a range of important biological functions. Importance for living organisms 1) Fats are also sources of essential fatty acids, an important dietary requirement. 2) They provide energy as noted above. 3) Vitamins A, D, E, and K are fat-soluble, meaning they can only be digested, absorbed, and transported in conjunction with fats. Fats play a vital role in maintaining healthy skin and hair, insulating body organs against shock, maintaining body temperature, and promoting healthy cell function. 4) Fat also serves as a useful buffer against a host of diseases. When a particular substance, whether chemical or biotic, reaches unsafe levels in the bloodstream, the body can effectively dilute or at least maintain equilibrium of the offending substances by storing it in new fat tissue. 5) This helps to protect vital organs, until such time as the offending substances can be metabolized or removed from the body by such means as excretion, urination, accidental or intentional bloodletting, sebum excretion, and hair growth. 7  Various chemical reactions of fats and oils: ✓ Chemical reactions in fats and oils are based on functional groups in it. ✓ i.e., Ester group and unsaturated double bond Reactions: 1) Hydrolysis (Saponification) 2) Hydrogenation (Hardening of fats and oil) 3) Hydrogenolysis 4) Saponification (Alkaline hydrolysis or soap formation) 5) Rancidification (Oxidation or hydrolysis) 6) Drying (Oxidation and polymerization) 1. Hydrolysis The hydrolysis of fats and oils in the presence of a base (KOH / NaOH) makes soap and is known as saponification. Ester + base Soap + alcohol Double bonds present in unsaturated triglycerides can be hydrogenated to convert oils (liquid) into margarine (solid). Hydrolysis can also be done by heating fat with water under pressure. Alkaline hydrolysis of fats produces salts of fatty acids called as soaps and hence this reaction is also known as saponification. a) Soft soap- hydrolysis by Potassium hydroxide b) Hard soap- Hydrolysis by Sodium Hydroxide Common soaps are the mixture of sodium salts of ‘C’ atoms (12 atoms) and higher fatty acids. Soap molecules have both lipophillic (lipid loving) and hydrophilic (water loving) group. 8  The lipophilic group dissolves oils while hydrophilic portion dissolves water. Soap molecules on dissolution in water forms micelle. Hydrolysis can be done in three ways- a) Hydrolysis by water: Fats undergoes hydrolysis in presence of water at 443K and 6-8 atmospheric pressure. Zinc oxide is used as catalyst. b) Hydrolysis by enzymes: Hydrolysis of fats and oils can be done by adding enzyme lipase to an emulsion of fat in water. c) Hydrolysis by acids: Mineral acids cause hydrolysis of fats. For this mixture of sulphonic acids which are obtained by sulphonation of mixture of oleic acid and benzene. The above three ways gives glycerol and fatty acids as a product of hydrolysis of fats while alkaline hydrolysis of fats gives glycerol and soap which are used as cleansing agent. The cleansing property of soap depends upon the ability to form emulsion with fat soluble materials. Applications: 1) In fire extinguishers 2) Cleansing, lubricating agents in laundry 9 2. Hydrogenation (Hardening or reduction): Oils have large amount of unsaturated portion in the form of glycerides. When hydrogen is passed through oils under pressure and by using Nickel catalyst at high temperature oils gets converted into solid fats. This process is known as hardening of oils. By hydrogenation, unsaturated acid part of oil gets reduced into saturated part and hence liquid oil gets converted into semi-solid fat. Vegetable oil + H2 Ni Vegetable Ghee Hydrogenation is carried out in a closed container in the presence of finely powdered catalyst (0.05 - 0.2% of nickel) at temperature as high as 150-200oC. The catalyst is usually removed by filtration. During hydrogenation process a proportion of the cis double bonds are isomerized to trans double bonds and there is also migration of double bonds. The hydrogenation process has made it possible to extend the food uses of a number of vegetable oils and marine oils whose melting points are too low. Partial hydrogenation of vegetable oil is used for manufacture of vegetable ghee (Dalda) Complete hydrogenation produces hard brittle fat. m.p -170c m.p 550c Oil is converted into fats 10 3. Hydrogenolysis: This is a cleavage reaction in which fat or oil molecule is treated with excess of hydrogen under pressure in presence of copper-chromium catalyst (CuCr2O4). In this reaction fat or oil gets splits up into glycerol and higher aliphatic alcohols. Long chain alcohols are used in manufacturing of Detergents. 4. Saponification: ✓ Saponification is a process that involves conversion of fat, oil or lipid into soap and glycerol by the action of heat in the presence of aqueous alkali (e.g. NaOH). ✓ Soaps are salts of fatty acidsand fatty acids are monocarboxylic acids that have long carbon chains (at least 10) e.g. sodium palmitate. 5. Rancidification: Rancidification is the process of complete or incomplete oxidation or hydrolysis of fats and oils when exposed to air, light, or moisture or by bacterial action, resulting in unpleasant taste and odor. Rancidity reactions may be due to hydrolytic rancidity: hydrolysis of ester bonds due to moisture, warm temp and bacterial enzymes. 11  Oxidative rancidity: oxidation of unsaturated fatty acids forming lipid peroxides, aldehydes and ketones. Rancidity occurs by the followingways- a) Oxidative rancification: It involves oxidation of carbon carbon double bond in fats and oils to produce volatile carboxylic acids. In presence of light and moisture, small amount of unsaturated acids present in fats/oils gets oxidized by air to form peroxides which further break down into aldehydes having unpleasant smell and taste. Saturated fatty acids do not get rancid. This problem can be checked by adding small quantity of phenolic substances which act as antioxidant. b) Enzymatic hydrolytic rancification: 12  Due to presence of micro-organisms fats gets hydrolyzed by enzymes to produce fatty acids having sour taste and unpleasant odor. For example, butter gets rancid due to production of butyric acid in this manner. Antioxidants are added in many fats and oil products to retard rancification c) β-oxidation of saturated fatty acids: fats having saturated fatty acids undergo ketone rancidity. Saturated acids undergo β-oxidation to form keto acids which gives carbon dioxide to form ketones having unpleasant odor. Prevention of Rancification: 1) Addition of antioxidants 2) Avoid exposure to light, moisture and high temperature 6. Drying oils (Polymerization): When highly unsaturated oils are exposed to air, they undergo oxidation and polymerization to form thin waterproof film. such oils are called as drying oils and the process is called as Drying of oils. Drying oils area key component of oil paint and some varnishes. Some commonly used drying oils include linseed oil, tung oil, poppy seed oil, perilla oil, and walnut oil. Drying oils (wild rose oil, linseed oil, wheat oil) contain more than 50% of polyunsaturated acids. They are quickly absorbed and leave no greasy layer on oily skin. Their light consistency makes them a good make-up primer. Process of drying: ✓ The "drying", hardening, or, more properly, curing of oils is the result of autoxidation, the addition of oxygen to an organic compound and the subsequent crosslinking. ✓ This process begins with an oxygen molecule (O2) in the air inserting into carbon- hydrogen (C-H) bonds adjacent to one of the double bonds within the unsaturated fatty acid. ✓ The resulting hydroperoxides are susceptible to crosslinking reactions. Bonds form 13  between neighboring fatty acid chains, resulting in a polymer network, often visible by formation of a skin-like film on samples. ✓ This polymerization results in stable films that, while somewhat elastic, do not flow or deform readily. Diene-containing fatty acid derivatives, such as those derived from linoleic acid, are especially prone to this reaction because they generate pentadienyl radicals. Monounsaturated fatty acids, such as oleic acid, are slower to undergo drying because the allylic radical intermediates are less stable. ✓ The oil hardens through a chemical reaction in which the components crosslink (and hence, polymerize) by the action of oxygen (not through the evaporation of water or other solvents) Oils depending upon their exposure to light and air can be classified as- a) Non-drying oils: These oils on exposure to light and long storage get rancid. Oils get decomposed into glycerol and fatty acids (saturated and unsaturated). The unsaturated acids get oxidized into aldehydes and acids with lesser carbon atoms in the molecule. The saturated acidsget decomposed by enzymes to form ketones. For example, olive oil, almond oil, Babassu oil, Baobab oil, Coconut oil, Peanut oil and Tiger Nut Oil. b) Drying oils: They form a solid elastic film. A good drying oil dries within 4-5 hours. For example, Linseed oil. c) Semi-drying oils: It is the oil which partially hardens when exposed to air. This is as opposed to a drying oil, which hardens completely, or a non-drying oil, which does not harden at all. ✓ Oils with an iodine number of 115-130 are considered semi-drying. ✓ Semi-drying oils contain 20%- 50% of polyunsaturated acids. ✓ They include: sweet almond oil, apricot seed oil, Cottonseed oil, Sesame oil and Grape seed oil. 14 15  Analysis of fats and oil Purity and composition of oil depends upon the degree of unsaturation, acidity on hydrolysis, and its molecular weight. A variety of physical tests have been performed on fats and oils to determine their composition and quality. Some of the common tests are as follows and these tests are also known as analytical constants. 1) Acid value 2) Saponification value 3) Ester value 4) Iodine value 5) Acetyl value 6) Reichert-Meissl Value (R.M. Value) 1. Acid value: The Acid value is the number, which expresses in milligrams, the amount of potassium hydroxide necessary to neutralize the free acids present in 1 gram of the substance (fats or oil). It is an measure of breakdown of triglycerols into free fatty acids Procedure: Weigh about 10g of the substance being examined, in an iodine flask. Prepare 50ml mixture of equal volumes of ethanol (95 per cent) and ether, add 0.5 ml phenolphthalein solution and Titrate it against 0.1 N aqueous potassium hydroxide (KOH) solution until the solution remains faintly pink after shaking for 30 seconds. Calculate the acid value from the following equation. Acid value = 5.61×V x N /W Where, VKOH = Volume of potassium hydroxide solution used (ml) W = the weight of the fat or oil being examined (gm). N = Normality of potassium hydroxide solution % Free Fatty Acids= Acid Value x 0.5.3 16  Significance: Acid value indicates the degree of hydrolytic rancidity of the given fat. High acid values arise in rancified oils. Edible oil should contain acid value > 1% Rancidification is the decomposition of fats and other lipids by hydrolysis and/or oxidation. Oxidation primarily occurs with unsaturated fats by a free radical-mediated process, which is responsible for producing the unpleasant and obnoxious odors and flavors. Rancidification can be reduced (but not completely eliminated) by storing the fats and oils at low temperature and away from light. High acid value ----high acid content-----oil is not ideal for health or non-edible oil Low acid value -----Low acid content------ideal for dietary health or edible oil. 2.Saponification value: Saponification value is defined as the number of milligrams of potassium hydroxide required to completely saponify 1 gram of fat or oil. In saponification reaction 1 mole of fat react with 3 moles of KOH,as fats is having 3 ester groups. It is calculated by Saponification Number = 168000 / M Where, M= molecular weight of fat Fats or oil Saponification value Milk fat 210-233 Coconut oil 250-264 Cotton seed oil 189-198 Soyabean Oil 189-195 Lard 190-202 Butter Fat and vegetable fat 220-250 17  Procedure: Weigh about 2 g of the substance being examined in an iodine flask with reflex condenser. Add 25 ml of 0.5 ethanolic potassium hydroxide solution and boil under reflux on water bath for 30 minutes. Remove the condenser and add 1 ml of phenolphthalein solution and titrate immediately with 0.5 M Hydrochloric acid. Note the reading as ‘A’. Repeat the operation omitting the substance being examined. Note the reading as ‘B’. Calculate the saponification value from the following equation, Saponification value = 56.1 × N x (B-A)/W Where, W = weight of substance (gm). B = ml of HCl used for blank titration A = ml of 0.5 N HCl used for titration Significance: 1) The saponification value is used primarily as an identification aid to detects adulteration with unsaponifiable matter. 2) It is also used to determine the extent of compounding (fats and oils added to improve oiliness) in a lubricant. 3) Saponification value is inversely proportional to the mean molecular weight of fatty acids 3. Ester value: The Ester value is the number of milligrams of potassium hydroxide required to react with esters present in 1 g of fat or oil. The difference between saponification value and acid value is called Ester value. Ester value = Saponification value – Acid value Significance: It gives an idea about number of hydroxyl groups in given fat 18 4. Iodine value: Iodine value is defined as the number of grams of iodine taken up by 100 gm of fat or oil or it is the number of grams of iodine which will combine with 100 gm of the fat or oil. ✓ It may be determined by any of the following methods. 1) Hubl’s method: Fat or oil sample is dissolved in carbon tetrachloride and is treated with excess of standard solution of ethanolic iodine in presence of mercuric chloride. Unused iodine is then calculated by titration with standard sodium thiosulphate solution. 2) Wij’s method: This method uses iodine monochloride in acetic acid in presence of iodine. ✓ Iodine monochloride readily combines with the double bonds present in fat and oil. ✓ The unreacted iodine is then calculated by the addition of potassium iodide and titration with standard solution of sodium thiosulphate using starch as indicator. ✓ Calculate the Iodine value from the following equation: Iodine value = 1. 269 × (b-a)/W Where, W = weigh of fat or oil taken. b = reading of actual titration a = reading of blank titration Significance: 1 ) Iodine value gives us an idea about the proportion of unsaturated fatty acids presents both in free and combined forms of esters. O H2C O C (CH2)7 CH CH (CH2)7 CH3 O HC O C (CH2)7 CH CH (CH2)7 CH3 O MW = 884 H2C O C (CH2)7 CH CH (CH2)7 CH3 3I 2 HgCl 2 ( 6 X 123.9 = 761.4 gm) O H2C O C (CH2)7 CHI CHI (CH2)7 CH3 O HC O C (CH2)7 CHI CHI (CH2)7 CH3 O H2C O C (CH2) 7 CHI CHI (CH2)7 CH3 19  2 ) Susceptibility of rancidity increases for the oils or fats having higher iodine values. 3 ) Iodine value helps to indicate the composition of complex mixture, as well as pure substances. Examples of Iodine Number: Fats or oil Iodine Number Coconut oil 8-10 Palm Oil 37-54 Lard 45-70 Olive oil 75-95 Peanut oil 85-100 Cottonseed oil 100-117 Fish oil 120-180 Soyabean oil 125-140 Sunflower oil 130-145 5. Acetyl value: It is defined as the number of milligrams of potassium hydroxide required to neutralize acetic acid produced by the saponification of one gram of completely acetylated fat or oil. Significance: ✓ It helps in determining the number of alcoholic groups present in oil or fat. Procedure: to the given sample add 5 ml of acetic anhydride-pyridine mixture (1:7). Add 5 ml of water. Put on a water bath for about 30 minutes then cool it. Titrate with 0.5N KOH using phenolphthalein as an indicator. Acetyl value = E ×4.3/ A Where, A = Weight of sample acetylated (gm) E = Acidity equivalent 6. Reichert-Meissl Value (R.M. Value): It is defined as the number of ml of 0.1N KOH solution required to neutralize the water soluble steam or to neutralize the distillate of 5 gm of hydrolyzed fat or oil. ✓ It is an indicator of how much volatile fatty acid can be extracted from fat through 20  saponification. ✓ It is a measure of the volatile fatty acid residues present in a given fat or oil. Procedure: To the 10 gm of sample add an excess of 0.1N NaOH solution in order to completely saponify the fat. The solution is then acidified with dil.H2SO4 and is undergo steam distillation. The distillate containing the volatile acid is then titrated with 0.1N KOH solution using phenolphthalein as an indicator. R.M. value = 1.10 (T1-T2) Where, T1 = volume of 0.1N KOH used for the titration T2 = volume of 0.1N KOH used for blank titration Significance: ✓ R.M. value is useful for testing the purity of the butter and desi ghee which may contain a high number of glycerides of butyric acid and other steam volatile fatty acid residues. ✓ For example, Adulterated butter has low R.M. value than that of pure butter. ✓ This R.M. value number is an indicator of non-fat compounds in edible fats like butter and ghee. Hence, it helps in determining the purity of ghee and butter. 21 Difference: 22  Important questions for study 1) Comment on rancidity of fats and oil with reaction and examples. Explain how rancidity of fats and oil is related to Acid value. 2) How oils are structurally distinguished from Fats? Explain the structural changes occurring during hardening process with suitable example 3) Explain the term Acid value, saponification value and iodine value of fats or oil. Write the principle and significance of determination of these values. 4) Explain the term rancidity of fats and oil along with reaction involved in it. 5) Elaborate on drying of oils along with chemical reaction involved in it. 6) Write any two differentiation points between rancidity and drying of oils. 7) Differentiate between fats and oil. 8) Explain essential and nonessential fatty acids with examples. 9) Write any four differentiation points between acetyl value and iodine value. 10) Explain saponification of oil along with chemical reaction. Justify Fatty acid soap is amphiphilic in nature. 11) What is acid value? Give its significance. Explain the procedure to determine acid value. 12) How will you determine degree of unsaturation in oil sample? What do you mean by partial hydrogenation and complete hydrogenation. 23