课件：chap2-保证食品安全的食品加工.ppt

Chemical disinfectants can be used to kill different microorganisms. For instance, for water, disinfectants such as chlorine, chlorine dioxide, chloramines and iodine can be used. Chemical disinfection can also be used for fruits and vegetables, surfaces and equipment. In this lecture we will discuss chlorination of water as an example. Disinfection of surfaces and equipment will be discussed in the presentation on cleaning and sanitation. 化学消毒可杀灭多种微生物。例如，氯、二氧化氯、氯胺和碘酒等消毒剂可用于水的化学消毒。水果和蔬菜、物质表面和设备也能采用化学消毒。本讲我们以氯水为例展开讨论。在清洁和卫生中讨论物质表面和设备的消毒。 、 Usually, the resistance of different pathogens to different disinfectants is expressed in terms of the C.t value needed to reduce microorganisms by 99%. 不同致病菌对各种消毒剂的抵抗力通常用C.t值表示。 C.t值指微生物数减少99% 。 E.coli is generally the most sensitive. Viruses differ in their sensitivity. Parasites are the most resistant. 大肠杆菌对氯最敏感，各种病毒对氯的敏感性不同，寄生虫对氯的抵抗力最强。 The efficacy of the disinfection process depends on the purity of the water because the disinfectant may be neutralized by organic matter and readily oxidizable compounds in water. Microorganisms that are aggregated or absorbed by a particular material may also be partly protected from disinfection. It is therefore important to treat the water before disinfection to produce a water with a median turbidity not exceeding 1 nephelometric turbidity unit (NTU) and not exceeding 5 NTU in any single sample. 消毒功效取决于水的纯度，因为，消毒剂有可能被水中的有机物质和易氧化的化合物中和。被特殊物质聚集或吸附的微生物较难消毒。因此，消毒前对水进行适当处理，使水的半混浊度不超过1浊度的浊度单位（NTU），在任一纯样品中不超过5NTU是很重要的， Reduction of water activity is an important technology to control microbiological hazards. The underlying principle is that microorganisms need water to grow. In their natural state, many foodstuffs contain sufficient water to support the growth of microorganisms. By decreasing the amount of water in food or its availability to microorganisms, growth of microorganisms can be prevented. 减少水分活度是控制微生物危害的重要方法。其根本原理就是微生物生长需要水分。在自然状态下，许多食品原料都含有充分的水供微生物生长之需。减少食品中水分含量或微生物生长所需的有效水分，就能防止