Lipids Those components that are soluble in organic
Lipids Those components that are soluble in organic solvents such as ether, hexane, chloroform, but are insoluble in water. The term “Lipids” embraces a variety of chemical substances includes triglycerides, diglycerides, monoglycerides, phospholipids, free fatty acids, sterols, fat soluble vitamins and others.
Importance of Triglycerides v Provide the most concentrated source of energy v Supply essential fatty acids v Make food more palatable v Contribute to the feeling of satiety v Act as carriers for fat soluble vitamins
Chemical composition of Triglycerides 1 - one glycerol unit 2 - Three fatty acids units
Classification of Fatty Acids - Saturated fatty acids - Unsaturated fatty acids Cis configuration Trans configuration
Physical Characteristics of Fats & oils 1) Degree of unsaturation 2) Length of carbon chains in fatty acids 3) Isomeric forms of fatty acids 4) Molecular configuration of triglycerides
Kinds of Fats in Our Diet v Monounsaturated fats v Polyunsaturated fats v Saturated fats v Trans fats
Daily Needs of Lipids No more than 30% of total calories intake should come from lipids. Life stage Age (year) Total cal. /day Cal. (Lipids) Children 4 -6 7 -10 1800 2000 540 600 Adult males 11 -14 15 -18 19 -24 2500 3000 2900 750 900 870 Adult females 11 -24 2200 660
Reactions of Fats & Oils (1) Hydrolysis of fats (2) Oxidation of fats v Autoxidation v Oxidation at higher temperature (3) Polymerization of fat (4) Reaction during heating and cooking
* Acid Value Acid value is a measure of the extent to which the glycerides have been decomposed by lipase action. Milligrams of potassium hydroxide required to neutralize the free fatty acid in 1 gram of the fat.
* Peroxide Value The peroxide value is a measure of peroxides contained in the oil. ROOH + KI (excess) ROH + KOH + I 2 + Starch + 2 Na. S 2 O 3 2 Na. I + Starch+Na 2 S 4 O 6 The amount of sodium thiosulfate required to titrate the reaction is related to the concentration of peroxides in the original sample.
* Saponification Number The saponification number is defined as the mg of KOH required to saponify one gram of fat.
* Iodine Number The iodine value is expressed as the grams of iodine absorbed per 100 g of lipids. One of the methods for determining the iodine value of lipids is "Hanus Method". + IBr (excess) R-CHI-CHBr-R + IBr (remaining) + 2 KI I 2 + starch + 2 Na 2 S 2 O 3 KBr + KI + I 2 2 Na. I + starch + Na 2 S 4 O 6
* Refractive index is a physical property for a pure substance and for oils. The refractive index increases with increasing the chain length of the fatty acid and increasing unsaturation.
Definition Proteins polymers of smaller units called amino acids, which link together in a variety of differing combinations to perform differing functions. More than 20 different amino acids are present in nature. The general formula for the amino acid: R-HCNH 2 -COOH
Functions of Proteins v All enzymes are proteins in nature; v Maintain acid-base balance; v Maintain fluid balance; v They are needed for growth and cell maintenance; v Some have transportation function.
Kinds of Proteins 1 -Complete proteins 2 - Incomplete proteins Daily needs of Protein Life stage Age (year) Total calories/day Cal. (protein) Children 4 -6 7 -10 1800 2000 180 200 Adult males 11 -14 15 -18 19 -24 2500 3000 2900 250 300 290 Adult females 11 -24 2200 220
Determination of crude proteins The kjeldahl method is the standard of nitrogen determination. The method consists of three basic steps: Ø Digestion of the sample Ø Distillation of the ammonia Ø Quantification of the ammonia
Moisture Importance of studying moisture in food: v Legal and Labeling Requirements v Economic v Microbial Stability v Food Quality v Food Processing Operations.
Ash The ash content is a measure of total amount of minerals present within a food. Ash determination Methods Three main types of analytical procedure used to determine the ash content of foods: v v v Dry ashing Wet ashing Low tempreture plasma dry ashing.
Minerals are inorganic or carbon free nutrients, needed in small amounts to support human life. Importance of minerals: Minerals are important to many parts of the body: v Important part of the bones v Maintain the body s fluid balance v Control the balance between acids and bases v Part of other important compounds
Classification of Minerals Ø Major minerals Ø Minor or trace minerals Ø Ultratrace minerals
Extraction of Oils from Chips Samples Result: Sample name g Oil/pocket Kcal. /pocket Crunshy 5. 44 45. 00 Chipsy 5. 00 48. 96 Lion 8. 09 72. 81 Besly 11. 71 105. 39 Rambo 9. 00 81. 00 Pringles 71. 16 640. 44 Crispy 8. 50 76. 50
Discussion: These results appears that the amount of calories obtained by the body from one chips pocket is high comparing with the recommended daily needs, in addition to calories obtained from the remainder daily meals. Ingestion more than one pocket increases the danger on health.
Acid Value Determination Result: Sample name Acid value Crunshy 1. 6532 Chipsy 0. 8588 Lion 0. 9447 Besly 1. 5029 Rambo 0. 7085 Pringles 0. 4720 Crispy 1. 1809
Discussion The reference range of acid value is 0. 6 -0. 7 mg KOH / fat. Most of our results exceed the reference range which means that the oil containing chips sample is rancid.
Peroxide Value Determination Result: Sample name Peroxide value Crunshy 14. 20 Chipsy 6. 75 Lion 33. 30 Besly 25. 20 Rambo 204. 70 Pringles 23. 58 Crispy 25. 40
Discussion Depending on the peroxide optimum value for fresh oils, we found that the oil used in frying contain high percent of peroxides as a result of oxidation processes occurred in the oil.
Saponification Number Determination Result: Sample name Saponification no. Crunshy 176. 08 Chipsy 192. 70 Lion 188. 82 Besly 185. 70 Rambo 197. 45 Pringles 184. 80 Crispy 181. 30
Iodine Number Determination Result: Sample name Iodine no. Crunshy 54. 01 Chipsy 56. 47 Lion 113. 5 Besly 84. 3 Rambo 114. 21 Pringles 123. 7 Crispy 122. 45
Refractive Index Determination Result: Sample name Refractive index Crunshy 1. 4628 Chipsy 1. 4563 Lion 1. 4640 Besly 1. 4583 Rambo 1. 4775 Pringles 1. 4750 Crispy 1. 4724
Discussion for the previous 3 experiments: It is found that the most commonly oils used in frying are: palm oil, peanut oil and soybean oil. The reasons of using these oils are: * Cheap * Resist high temperature during fring
Crude Protein Determination Result: Sample name g protein/pocket Kcal. /pocket Crunshy 10. 04 40. 16 Chipsy 11. 55 46. 20 Lion 19. 60 78. 40 Besly 21. 70 86. 80 Pringles 75. 92 303. 68
Discussion: These results appear that the body obtain a certain amount of proteins in an inadequate amount due to the deficiency of essential amine acids needed for body health.
Water Content Determination Result: Sample name % Moisture Crunshy 53. 09 Chipsy 40. 72 Lion 58. 59 Besly 75. 09 Rambo 54. 47 Pringles 41. 04 Crispy 83. 62
Discussion As we mention before that food samples containing more than 25 % moisture may become spoil. The results show that the moisture percent is very high which means that the chips samples may be contaminated with bacteria.
Determination of Ash Result: Sample name % Ash Crunshy 44. 72 Chipsy 39. 23 Lion 61. 63 Besly 62. 73 Rambo 48. 15 Pringles 49. 15 Crispy 37. 28
Discussion The results show that the ash percent in chips samples is too small which means that minerals content is low.
Overall result: Sample Na. Cl (g) K (mg) Ca (mg) Cu (mg) Crunshy 0. 4603 247. 29 347. 20 35. 48 Chipsy 0. 4125 238. 60 402. 14 24. 75 Lion 1. 1060 59. 28 895. 43 35. 17 Besly 1. 1187 42. 58 1139. 00 28. 01 Rambo 3. 4250 1147. 85 5094. 76 139. 90 Pringles 0. 5302 390. 18 514. 88 37. 73 Crispy 0. 8280 44. 043 1535. 28 39. 19
Discussion v. The amount of sodium chloride (salt) obtained by the body from one chips pocket is too high which promotes ingestion more and more chips causing hypertention. v. Low potassium amount obtained from chips sample under the adequate amount needed per day. v. Totally depending on such fast foods lead to ingestion low amount of calcium under the adequate daily needs. v. It is possible to suffer from copper deficiency
Thank You
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