Presentation on theme: "Oils and Fats Major Component (%95-99) Minor Components (%1-5)"— Presentation transcript:
1 Oils and Fats Major Component (%95-99) Minor Components (%1-5) TriglyceridesMinor Components (%1-5)Triglyceride DerivativesGlycerolFree Fatty AcidsMono- and DiglyceridesNon-Triglyceride DerivativesPhospholipidsSterolsPigmentsVitaminsAntioxidantsOxidation ProductsTrace MetalsHydrocarbons
2 Triglyceride Structure OC- R1triacylglycerol=- R2- R3HCH2COHglycerolHCH2CHO -CO- R13 fatty acids+- R3- R2+3H20OROne chiral carbon with 1-3 acyl groupssimpler stereochemistry than sugars - Cmore possible substituentsacyl
3 Triglycerides differ from each other in regard to Number of Carbon Atoms in fatty acid chainsNumber of double bondsIsomerizationDistribution of FA on glycerol backbone
4 Analytical Methods Saponification Value Iodine Value Gas Chromatographic Analysis for Fatty AcidsLiquid Chromatography
5 Saponification ValueSaponification - hydrolysis of ester under alkaline condition.The saponification value of an oil or fat is defined as the number of mg of potassium hydroxide (KOH) required to neutralize the fatty acids resulting from the complete hydrolysis of 1 g of the sample.
6 Saponification Value Determination Saponification # --mgs of KOH required to saponify 1 g of fat.1. 5 g in 250 ml Erlenmeyer.2. 50 ml KOH (0.5 N) in Erlenmeyer.3. Boil for saponification.4. Titrate with HCl (0.5 N) using phenolphthalein.Conduct blank determination.B - ml of HCl required by Blank.S - ml of HCl required by Sample.N- Factor of 0.5 N HCL.
7 Saponification Value 3 + 3 K+OH - O - R C H2C H2C OH O HC + HC KO - triacylglycerolHCH2COHglycerolHCH2CCO- RKO -+ 3 K+OH -3+Potassium saltSimilarly;RCOOH KOH RCOO-K GlycerolMG KOH RCOOK GlycerolDG KOH 2RCOOK Glycerol
8 Saponification Value 1 mol TG 3 mol KOH required 1 g TG X mol KOH requiredMWKOH: 56 g = mg1 g TG : 1 g / MWTG (g/mol) mol1 mol TG 3x mg KOH required1 g TG / MWTG X mg KOH required
9 Saponification Value What is the MWTG ? O O O - R1 - R1 C - R C H2C C
10 Saponification Value Which one’s MW should be taken? O O O - R1 - R1 C HCH2COC- R1- R2HCH2COC- RHCH2C
11 Saponification Value The Answer is the Weighted Average MW O O O - R1 HCH2COC- R1- R2HCH2COC- RHCH2C
12 Saponification Value Calculation of AMWTG Oil consists of only type Simple TriglycerideOC- RHCH2C
13 Average Moleculer Weight of FAs in Oil (AMWFA) Saponification ValueCalculation of AMWTGOil consists of Simple and Mixed type Triglyceride with two fatty acids R1 (%90 w/w) and R2 (%10 w/w)OC- R1HCH2COC- R1- R2HCH2COC- R2HCH2COC- R1- R2HCH2CAverage Moleculer Weight of FAs in Oil (AMWFA)
14 Saponification Value Generalized Calculation of AMWTG Oil consists of Simple and Mixed type Triglyceride with N fatty acidsFA xiR1 x1R2 x2. .RN xN
16 GC Analysis for Fatty Acids 1. Extract fat.2. Saponify (hydrolysis under basic condition).3. Prepare methyl ester (CH3ONa).4. Chromatography methyl ester.5. Determine peak areas of fatty acids.Fatty acids are identified by retention time.6. Compare with response curve of standard.
19 Iodine NumberThe iodine value of an oil or fat is defined as the mass of iodine absorbed by 100 g of the sample.The unsaturated fatty acid residues of the glycerides react with iodine, and thus the iodine value indicates the degree of unsaturation of the fatty acid residues of the glycerides.It is constant for a particular oil or fat, but depends on the method used. Animal fats (butter, dripping, lard) Iodine ValueNon-drying oils (olive, almond) Iodine ValueSemi-drying oils (cottonseed, sesame, soya) Iodine ValueDrying oils (linseed, sunflower) Iodine ValueThe iodine value is often most useful in identifying the source of an oil. Generally, the higher iodine values indicate oils and the lower values fats. Iodine values are normally determined using Wigs or Hanus methods.
20 Determination of Iodine Number Iodine Value = (ml of Na2S2O3 volume for blank - ml of Na2S2O3 volume for sample) N of Na2S2O3 0.127g/meq 100Weight of Sample (g)Excess unreacted ICl