《食品微生物学》课程教学资源（PPT课件讲稿）微生物引起的食品变质

Chapter 10 Food deterioration caused by microbes

Chapter 10 Food deterioration caused by microbes

SectionA Grain deterioration 1. Formation of grain microbial flora micron ertain ecologic 1.1 major sources of grain micobes Soil, water, air, transportation, processing storage appliances 1.2 existent position of grain microbes Mainly on the surface, some in the cortex layer

SectionA Grain deterioration 1.Formation of grain microbial flora ⚫ flora: groups of microbes existed in a certain ecological conditions 1.1 major sources of grain micobes ⚫ Soil, water, air, transportation, processing, storage ,appliances 1.2 existent position of grain microbes ⚫ Mainly on the surface , some in the cortex layer

2. Major microbial groups in the grain and heir detrimental effects 21 bacterial Newly cropped grain has the largest amount of bacteria Don't endanger the grain quality under conventional storage condition

2. Major microbial groups in the grain and their detrimental effects 2.1 bacterial ⚫ Newly cropped grain has the largest amount of bacteria. ⚫ Don’t endanger the grain quality under conventional storage condition

actinomyces Mostly indwell grains carry the mud Mainly endanger those grains with high Water content 2.3 yeasts Little quantity in the grains Endanger the grains with high water content and stored in a sealed condition

2.2 actinomyces ⚫ Mostly indwell grains carry the mud ⚫ Mainly endanger those grains with high water content 2.3 yeasts ⚫ Little quantity in the grains ⚫ Endanger the grains with high water content and stored in a sealed condition

2.4 moulds Major groups are aspergllus, penicillium,镰刀菌 The major detrimental microbes in the grain

2.4 moulds ⚫ Major groups are aspergillus, peniicillium,镰刀菌 ⚫ The major detrimental microbes in the grain

Environmental condition Ecological types ypical moulds water activity 0.8 干生型 灰绿曲莓( Aspergillus glaugus)局限 曲霉( Aspergillus restrictus 黄曲霉( Aspergi1 us flavus) 0.8~0.9 中生型 棕曲霉( Aspergi1 us ochraceus) 大多数青霉( Penicill ium sp.) >0.9 湿生型 黑根赛( Rhizopus nigricans) 高大毛莓 temperature(℃) 40℃ 高温型 烟曲霉( Aspergillus fumigatus) )content(%) 0 ma102 content(21%)好氧型 大多数青霉( Penicillium sp.) 大多数曲霉( Aspergillus sp.) LowO2 content(<1%)耐低氧型 灰绿曲霉( Aspergillus glaugus)

Environmental condition Ecological types Typical moulds water activity 0.9 湿生型 黑根霉（Rhizopus nigricans） 高大毛霉 temperature（℃） 40℃ 高温型 烟曲霉（Aspergillus fumigatus） O2 content（％） Normal O2 content（21％） 好氧型 大多数青霉（Penicillium sp.） 大多数曲霉（Aspergillus sp.） Low O2 content （< 1％） 耐低氧型 灰绿曲霉（Aspergillus glaugus）

3. Basic changing rules of grain microbial Flora lunder traditional storage 3. 1 bacterial amount 5 The total amount 细菌总量 80 口一附生细菌 rapidly dropped 芽孢菌 The amount of spore-bearing bacteria keeps 20 stable 012345678储藏时间0 常规储粮中细菌数量的变化

3.Basic changing rules of grain microbial flora under traditional storage 3.1 bacterial amount ⚫ The total amount rapidly dropped ⚫ The amount of spore-bearing bacteria keeps stable 常规储粮中细菌数量的变化 0 20 40 60 80 100 120 0 1 2 3 4 5 6 7 8 储藏9 时间10 细菌量 细菌总量 附生细菌 芽孢菌

3.2 moulds 3.2.1 surface(external)moulds The total moulds amount has a 霉菌总量 一田间型霉菌 tendency to drop 亠一储藏型霉菌 Field-type dropped Storage-type moulds keep stable 012345678储藏时间 常规储粮中粮食外部 霉菌数量的变化

⚫ The total moulds amount has a tendency to drop ⚫ Field-type dropped ⚫ Storage-type moulds keep stable 常规储粮中粮食外部 霉菌数量的变化 0 20 40 60 80 100 120 0 1 2 3 4 5 6 7 8 储藏9 时间10 霉菌量 霉菌总量 田间型霉菌 储藏型霉菌 3.2 moulds 3.2.1、 surface (external) moulds

3.2 moulds 霉菌总量 D田间型霉菌 一储藏型霉菌 Similar to the 244 changing rules of surface moulds, but 2345678储藏时间 within a small 常规储粮中粮食内部 霉菌数量的变化 extent

3.2 moulds 3.2.2 moulds dwell inside the grain ⚫ Similar to the changing rules of surface moulds, but within a small extent 常规储粮中粮食内部 霉菌数量的变化 0 20 40 60 80 100 120 0 1 2 3 4 5 6 7 8 储藏9 时间10 霉菌感染率 霉菌总量 田间型霉菌 储藏型霉菌

4 basic rules when stored grain get mouldy 4.1 grain deterioration under poor storage condition The grain will deteriorate rapidly when its water content and the pile temperature ids suitable for microbe growth

4、basic rules when stored grain get mouldy 4.1 grain deterioration under poor storage condition The grain will deteriorate rapidly when its water content and the pile temperature ids suitable for microbe growth