Fats and oils

By students of Sir Dr. M.S. GOSAVI COLLEGE OF PHARMACEUTICAL EDUCATION AND RESEARCH, NASHIK.

1. FATS AND OILS CONTINUOUS ASSESSMENT-01 GROUP NO-13

2. 97 98 100 99 101 102 103 104 DHANASHREE SANDHAN AVNI SHARMA PRERNA SAWALE SHRADDHA SHIMPI VAISHALI SAVANT PRATIK SHENDE SAKSHI SHIRSATH RENUKA SAWANT

3. INTRODUCTION NOMENCLATURE HYDROLYSIS HYDROGENATION HYDROGENOLYSIS SAPONIFICATION RANCIDIFICATION DRYING OILS ACID VALUE SAPONIFICATION VALUE ESTER VALUE IODINE VALUE ACETYL VALUE REICHERT MEISSL VALUE Various chemical reactions of fats and oils Analysis of fats and oils CONTENTS

4. Fats and oils are major part of lipid present in adipose tissue of mammals. Fats and oil are made up of molecules known as triglycerides. Which are the esters of three fatty acid chains and the alcohol , glycerol. If the glycerol is esterifies at all –OH sites by some fatty acid (i.e.R1,R2,R3) attach with carboxylic acid ( basically from 12-20 carbons) , the resulting ester is called triglyceride. A triglyceride existing in solid state at 25ᵒC is called fats while that exists in liquid state at 25 degree celcius  is called oils.   Naturally occurring fats and oils are complex mixture of mixed triglyceride. Fats contain triglyceride with long and saturated fatty acid chains and usually obtained from animal sources.  Oils contain triglyceride with a short and unsaturated fatty acid chain and usually obtain from plant origin . Examples- lard(pig fat), tallow(beef), coconut oil, castor oil, olive oil, soyabean oil etc. A crude fat along with glyceryl ester contains some amount of free fatty acids and 1-2% of unsaponifiable matter like sterols. INTRODUCTION

5. PHYSICAL PROPERTIES - INTRODUCTION

6. A fat is product of fatty acid and bonded to a backbone structure, which is often a glycerol which consists of a three carbon chain. A triglyceride is specific type of fat formed by combination of three fatty acids with a glycerol backbone. The nomenclature of fatty acid is confusing with many different names being used for identical substance. A fatty acid is unsaturated if there is atleast one double bond between the carbon atoms in the fatty acid. A fatty acid with only one double bond is called monounsaturated fatty acid. A fatty acid with two or more double bond is called polyunsaturated fatty acid. A fatty acid with no double bond between carbon atom in the main carbon chain of fatty acid is called saturated fatty acid. The term ‘omega’ refers to position of double bond in relation to methyl group on end of fatty acid. Trans fatty acid are unsaturated fatty acid with unsaturated bond between carbon atoms of fatty acid arranged in trans configuration instead of more common cis configuration. NOMENCLATURE

7. For saturated fatty acid suffix ‘ anoic acid’ is used. For unsaturated fatty acid suffix ‘ enoic acid’ is used. NOMENCLATURE

8. Sodium hydroxide causes hydrolysis of fats and it results in the cleavage of ester linkage of fats to give glycerol and sodium salt of long chain fatty acid known as soaps. It can also be done by heating fat with water under pressure. Common soaps are the mixtures of sodium salts of ‘C’ atoms (12 atoms)and higher fatty acids. Soap molecules have both lipophilic (lipid loving) and hydrophilic (water loving ) groups. The lipophilic group dissolve oils while hydrophilic portion dissolves water. Soap molecules on dissolution in water forms micelles. Hydrolysis reaction can be done by 3 ways- HYDROLYSIS BY WATER BY ENZYMES BY ACIDS

9. By water - Fat undergoes hydrolysis in presence of water at 443K and 6 to 8 atm pressure . Zinc oxide is used as catalyst. By enzyme - It can be done by adding enzyme lipase to an emulsion of fat in water. By acids - Mineral acids causes 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 acid as a product of hydrolysis of fats while alkaline hydrolysis of fatsgives glycerol and soap which are used as cleansing agent. HYDROLYSIS

10. Oils have large amount of unsaturated portion in the form of glycerides . When hydrogen is passed through oils under pressure and by using catalyst at high temperature oils gets converted into solid fats.It is also known as hardening of oils. Hydrogenation is effectively done by adding small amount of finely divided Nickel or Raney nickel as a catalyst. By hydrogenation, unsaturated acid part of oil get reduced into saturated part and hence liquid oil get converted into semi solid fat. In actual, hydrogenation is not carried out completely but is stopped as fat of desired consistency and viscosity is obtained.The fats looks like ghee in appearance and is known as vanaspati ghee. Fully hydrogenated fats are very hard and cannot be digested easily in intestine. It also involves various complicated problems like isomerization , selective reduction, etc and these problems can be overcome by arresting the reaction before all unsaturated fats get completely saturated with hydrogen. HYDROGENATION

11. This is an cleavage reaction in which fat and oil molecule is treated with excess of hydrogen under pressure in presence of Copper-Chromium catalyst. •This reaction gives glycerol and long chain primary alcohol. Sometimes, active hydrogen can be obtained by action of metallic sodium with a water insoluble alcohol like 2-hexanol. HYDROGENOLYSIS

12. It is a reaction in which triglyceride is hydrolyzed with a strong base like  NaOH  to form soap. Saponification  is a process in which a soap and salts are obtained from triglyceride in presence of   NaOH . If NaOH is used for hydrolysis  hard soap are obtained from saturated fats. While, If KOH is used for hydrolysis soft soap are obtained from unsaturated fats/oils. SAPONIFICATION

13. SAPONIFICATION

14. On long storage and in contact with air, moisture and sunlight , oils and fats undergo decomposition and starts smelling unpleasant. This process is known as  rancidification . Oil is said to be rancid oil. Rancidity occurs by following causes: RANCIDIFICATION 1)Oxidation of unsaturated acids 2)Enzymatic hydrolysis 3)Beta oxidation of saturated fatty acids

15. 1)Oxidation of unsaturated acids- In presence of light and moisture Small amount of unsaturated acid present in fats/oils get  oxidised  by air Form peroxides and further breakdown into  aldehydes  having unpleasant smell and taste Saturated fatty acids do not get rancid. It can be checked by adding small quantity of  phenolic  substances which act as antioxidants. RANCIDIFICATION

16. 2)Enzymatic hydrolysis- Due to presence of microorganisms Fats get  hydrolysed  by enzymes called lipases Produce fatty acids having sour taste and unpleasant  odour Example : Butter gets rancid due to production of butyric acid. RANCIDIFICATION

17. 3)Beta oxidation of saturated fatty acids- Fats having saturated fatty acids undergo   ketone   rancidity. Saturated acids undergo beta oxidation to form  keto  acids which gives carbon dioxide to form  ketones having pungent unpleasant  odour . RANCIDIFICATION

18. Some   glycerides  of unsaturated acids having two or more double bonds absorb oxygen from air and get  polymerised  to form hard transparent coating which is used in making paints and oil cloth. This phenomenon is called drying and oils as drying oils. For example: Linseed oil, Tung oil,  Perilla  are drying oil If given acid contains conjugate system of double bonds then drying takes place much more rapidly as compared to fats containing non conjugated double bonds. It involves addition of oxygen to unsaturated bonds and causes some amount of  polymerisation . Drying can be achieved faster by addition of driers like salts of manganese, lead, Cobalt salts of short chain acids, etc Oils, depending on their exposure to light and air can be classified as DRYING OILS

19. A)Non-Drying oils- On exposure to light and long storage gets rancid. It mostly consists of triolein . Gets decomposed into glycerol and fatty acids (saturated and non saturated). Unsaturated acids get  oxidised  into  aldehyes  and acids with lesser carbon atoms in the molecule. Saturated acids get decomposed by enzymes to form  ketones . For example, olive oil and almond oil. B ) Drying oils- They are either natural or symmetric saturated fatty acids. They form a solid elastic film. A good drying oil dries within 4-5 hours. For example: Linseed oil, walnut oil, poppyseed oil, perilla oil, etc DRYING OILS

20. C)Semi- drying oils- Have high level of  linoleic  acid and low content of  linolenic  acid as compared to non- drying oils. ● For example: Sunflower oil, cotton seed oil, etc ➢ Drying oils are used as medium for paints, varnishes and lacquers. ➢ Paints are suspended along of some pigments or organic  colouring matter in linseed oil  to which some turpentine oil has been added as thinner. ➢ These paints when applied on wooden surface , they  qiuckly  dry up forming a tough organic film which protects surface. DRYING OILS

21. Definition- The acid value is defined as the  number of  milligrams of potassium hydroxide required to neutralize  the free fatty acids present in one gram of fat .It is a relative measure of rancidity as free fatty acid are normally formed during decomposition of oil glycerides . The value is also expressed as percent of free fatty acids calculated as oleic acid. Principle- The acid value is determined by directly titrating the oil/fats in an alcoholic medium against standard potassium hydroxide /sodium hydroxide solution. ACID VALUE

22. The value is a measure of the amount of fatty acid which have been liberated by hydrolysis from the glycerides due to the action of moisture , temperature and/or lipolytic enzyme lipase. Acid value is defined as the no. of mg KOH required to neutralized the free fatty acids in one gram of fats or oil. The STD for edible fats and oil indicate that the acid value must not exceed 0.6 mg KOH/1gm.  Method- 1)Weigh 10gm of sample. 2)Dissolve in sample in 50 mi equal volume of ethanol and ether.  3)Titrate the mixture using 0.1M NAOH/KOH solution with pH as indicator.  ACID VALUE =56.1* V KOH /W Where, V KOH: volume of potassium hydroxide ( mL ) W: weight of fats or oil being examined (gm) Result- High acid value indicates that given sample of fats and oils is of low quantity and stored under improper conditions. ANALYTICAL IMPORTANCE

23. Definition- The saponification value is the number of mg of potassium hydroxide required to saponify 1 gram of oil/fats. Analytical importance- The saponification value is saponified by refluxing  with a known excess of alcoholic potassium hydroxide solution . Alkali required for saponification is  determind  by titration of the excess potassium hydroxide with standard HCL. SAPONIFICATION VALUE

24. The Saponification value in an index of mean molecular weight of the fatty acid of glycerides comprising a fat. Lower the saponification value larger the molecular weight of fatty acid in the glycerides and vice versa. Method- 1) Weigh 2 gram of oil into glass flask.  2) Add 25ml of alcoholic KOH sol and boil for 1 hour under a condenser shaking the content of the flask at frequent interval. 3) Determine the access of alkali by titration with HCL using 0.5ml of indicator as phenolphthalein. 4) Set a blank test upon the same quantity of KOH at the same time and under the same condition. 5) SAPONIFICATION value = 56.1*TV*N/W.   ANALYTICAL IMPORTANCE

25. The ester value is defined as the number of milligram of KOH required to  saponify  the ester in 1 gm of sample. Formula:- Ester Value (EV) = ( BHCL – AHCL ) x 28.05/ W where, BHCL: volume ( mL ) of HCL consumed by blank AHCL: volumev ( mL ) of HCL consumed by actual test W: weight (g) of sample taken The ester value is calculated by subtracting the acid value of an oil from the saponification value. ESTER VALUE ANALYSIS

26. Definition - The number of grams of iodine taken up by 100 grams of fats or oils. Principle- It is determined by treating the given sample of fats or oil with iodine in ethanol of mercuric chloride. Unreacted iodine is then calculated. It gives the idea of degree of unsaturation present in sample. It can be calculated by two methods- IODINE VALUE ANALY SIS 1) Hubl’s method 2) Wij’s method

27. 1) Hubl’s method- Fat or oil sample is dissolved in CCL4 and is treated with excess of std solution of ethanolic iodine in presence of mercuric chloride . Unused iodine is then calculated by titration with std sodium thiosulphate solution . 2) Wij’s method- Significance of iodine value: It tells the degree of unsaturation present in fat or oil. Higher the iodine value, highly unsaturated the given fat is. It also gives an idea of drying characters of fat and oil. It also helps in determining adulteration in given sample of fat. Iodine value of non drying oil- 85 to 105 Semi- drying oils- 105 to 120 Drying oils- above 120 IODINE VALUE ANALYSIS

28. It is the mg of KOH required to acetic acid liberated by hydrolysis of 1g of acid acetylated substances. Acetyl value = 1335 (b-a)/ (1335-a) Where, a: saponification of the substance b: saponification value of acetylate substance Acetyl value = mole amount of free fatty acids Significance : It is the measure of hydroxy acid in lipids ACETYL VALUE

29. Richert Meissl (RM) Value :- It is useful in testing the purity of  butter since it contains a good concentration of volatile fatty acids (butyric acid, caproic acid,caprylic acid). P so it is defined as the ml of 0.1 N KOH required to completely  neutralized the soluble volatile fatty acid distilled from 5 g fat. e.g. :- butter (short chain fatty acids) RM value (25-30) Significance :- It is a measure of water soluble strain volatile fatty.  Acids, specially butyric and caproic acid present in oil or  fat. Butter fat contain butyric acid, glycerides and no other.  Fat contain it, so RM value is high for butter fat. RICHERT MISSL VALUE