食品添加剂 防腐剂 PPT课件.ppt

(第二章防腐剂)
Chapter 2 Preservatives
Contents:
Definition of preservatives**
Mechanisms of preservatives**机理
Varieties of preservatives**种类
Classification of preservatives **分类
Introduction to the preservatives used often in food
acid and its sodium salt**苯甲酸
Sorbic acid and its potassium salt**山梨酸
and calcium propionate**丙酸
-hydroxybenzoates ** (sum)对羟基苯甲酸酯
* Nisin ** 乳酸链球菌素
* fresh-keeping preservatives for fruits and vegetables **
2. 6 Attention to the application of food preservatives **
2. 7 Development tendency of food preservatives ** (Questions for discussion)
preservatives
Examples of foods which easily undergo spoilage as the result of microbial action
meat products
cheese
bread
spices
Fruit juice
aquatic products
Methods for preserving foods
(1) Physical methods:
* Drying in the sun
* low-temperature storage (freezing/frozen storage)冷冻冷藏
* pickling/salting, sugaring 腌制
* soaking with wine 腌制、浸酒
* fermentation 发酵
Traditional physical methods:
 New Physical Methods:
* Canning packaging 罐藏
* vacuum/gas packaging 真空、气体
* high hydrostatic pressure (sterilization) 高压
* irradiation sterilization 辐照
* electron sterilization 电子辐照
(2) Chemical Methods:preservatives
1. Definition()
Food preservatives may be defined as substances which can kill anisms or prevent the growth of anisms. 抑制或杀死微生物的物质
Or in simple words, preservatives are substances used in foods which have antimicrobial effects. 抗菌效果
Mechanisms of preservatives
(1) Food spoilage caused by micro- organisms (three types) 食品腐败三种形式
 Food spoilage caused by the action of bacteria. 细菌的作用
 Food spoilage caused by the action of molds 霉菌的作用
* alcohol fermentation, 酒精
* acetic acid fermentation,醋酸
* lactic acid fermentation,乳酸
* butylic acid
Food fermentation: 发酵