华南理工大学：《食品分析》课程PPT教学课件（Food Analysis）Chapter 6 Lipids

Measurement of Lipids

Measurement of Lipids

Contents 1.Introduction(definition,characteristics) 2.Function of lipids in foods 3.Determination of fats in food 4.Quality evaluation of edible oils

Contents 1. Introduction (definition ,characteristics) 2. Function of lipids in foods 3. Determination of fats in food 4. Quality evaluation of edible oils

Introduction Lipids 1)The term lipid is used to denote fats and fatlike substances and is synonymous with the terms lipoids or lipins. 2) It includes a great varieties.The main component is triglycerides(>95%),others include phospholipids. wax,fatty acids,cholesterin etc. 3)Lipids are usually defined as food components that are insoluble in water but soluble in organic solvents 4) Essential structural component of living cells (along with proteins and carbohydrates). 5)exist in the free form(such as fats or oil),or associated combined with carbohydrates,or protein in food)

Introduction Lipids 1) The term lipid is used to denote fats and fatlike substances and is synonymous with the terms lipoids or lipins. 2) It includes a great varieties. The main component is triglycerides(>95%), others include phospholipids, wax, fatty acids, cholesterin etc. 3) Lipids are usually defined as food components that are insoluble in water but soluble in organic solvents. 4) Essential structural component of living cells (along with proteins and carbohydrates). 5) exist in the free form(such as fats or oil),or associated ( combined with carbohydrates,or protein in food)

Characteristics of lipids 1.Insoluble in water,but soluble in organic solvents such as ethyl oxide(乙瞇)，petroleum ether(石油醚) chloroform(氯仿)，acetone(丙酮). 2.Most of lipids contain ester bond,and main section is fatty acid ester. 3.Be produced by organism,and can be used by organism(different from mineral oil) 4. Except the phospholipids(磷脂)，sphingomyelin(鞘 磷脂)，etc

Characteristics of lipids 1. Insoluble in water, but soluble in organic solvents , such as ethyl oxide(乙醚),petroleum ether(石油醚), chloroform(氯仿),acetone (丙酮). 2. Most of lipids contain ester bond, and main section is fatty acid ester. 3. Be produced by organism, and can be used by organism(different from mineral oil). 4. Except the phospholipids(磷脂), sphingomyelin(鞘 磷脂), etc

Function of lipids in foods 1.Provide caloric. 2.Provide essential fatty acids(linolenic acid亚庥酸， linoleic acid亚油酸) 3.Carrier of fat-soluble vitamin(VE,VA.VD) 4.Provide glossy appearance,smooth taste. 5.Provide savory in the fry food. Lipids content is one of indexes of evaluating food quality and food nutrition,food processing and storage

Function of lipids in foods 1.Provide caloric. 2. Provide essential fatty acids(linolenic acid亚麻酸, linoleic acid亚油酸) 3.Carrier of fat-soluble vitamin(VE,VA,VD) 4. Provide glossy appearance, smooth taste. 5. Provide savory in the fry food. Lipids content is one of indexes of evaluating food quality , and food nutrition, food processing and storage

Determination of fats in food >Soxhlet extractor method >Extraction of crude fats ethyl ether in acid(酸性乙瞇提取法) Extraction of crude fats by ethyl ether in Akai(碱性乙醚提取法)（罗兹一哥特里法） >Babcock Method and Gerber method(巴布科氏法和盖勃氏法) >Extraction of fats by Chloroform-Methanol(氯仿-甲醇抽提法)

Determination of fats in food ➢ Soxhlet extractor method ➢ Extraction of crude fats ethyl ether in acid(酸性乙醚提取法） ➢ Extraction of crude fats by ethyl ether in Alkali (碱性乙醚提取法）（罗兹－哥特里法） ➢ Babcock Method and Gerber method(巴布科氏法和盖勃氏法) ➢ Extraction of fats by Chloroform-Methanol (氯仿－甲醇抽提法）

索氏提取法 Principle 冷凝器 样品 乙醚或石油醚 蒸去溶剂 粗脂肪 提取管 虹吸管 联接管 提取瓶 图1索氏抽提器

索氏提取法 样品 乙醚或石油醚 蒸去溶剂 粗脂肪 Principle

Procedure: 1)Preparation of sample: Solid sample-grinding Semi-solid sample or liquid sample-adding sand- dried-grinding 2)Preparation of filter paper tube 3)Put sample ready into the filter paper tube. 冷凝罗 4)Extract the fats with solvents 5)Weighting 提取管 虹吸管 6)Calculation 联接管 提取瓶 图1索氏抽提器

Procedure: 1)Preparation of sample: Solid sample –grinding Semi-solid sample or liquid sample– adding sand– dried—grinding 2) Preparation of filter paper tube 3) Put sample ready into the filter paper tube. 4) Extract the fats with solvents 5) Weighting 6) Calculation

Attention 1) Crude fats include phospholipids,pigments,wax, volatile oil,etc. 2) Sample should contain greater amount of free fats,little associated fats. 3) Samples should be dried(decrease the efficiency. increase nonfat substance) 4) If more dextrin or saccharide is included in sample,it should be remove by water 5) Ethyl ether should be purified:no water,no peroxide,no alcohol. 6) It should be heated in water bath,be careful of firing

Attention 1) Crude fats include : phospholipids, pigments,wax, volatile oil, etc. 2) Sample should contain greater amount of free fats, little associated fats. 3) Samples should be dried(decrease the efficiency, increase nonfat substance) 4) If more dextrin or saccharide is included in sample, it should be remove by water 5) Ethyl ether should be purified: no water, no peroxide, no alcohol. 6) It should be heated in water bath, be careful of firing

Determination of fats in food Soxhlet extractor method Principle 冷凝器 Ethyl ether or sample Petroleum ether Distill Crude fat 提取管 虹吸管 联接管 提取瓶 图1索氏抽提器

Determination of fats in food Soxhlet extractor method sample Distill Crude fat Ethyl ether or Petroleum ether Principle