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huyueming321铜虫 (小有名气)
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[求助]
高水分含量下微生物更容易杀死的原因 已有1人参与
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微生物在水分活度越低越难杀死，求谈论这方面的原因？是不是高水分含量下微生物更容易杀死？热处理时 我在文献中有看到低水分时渗透压使微生物迅速失水体积变小，然后细胞膜变厚，膜通透性和流动性降低。热处理时跟这些变化有关系吗，这样对不对？大家有其他解释吗或者文献？ The protection of the microbial cells at low water activity can be mainly due to the osmotic pressure that induced rapid water loss from the cell. Thus result in cell shrinkage, which probably causes a thickening in the cell membrane, followed by reduced membrane permeability and fluidity, and the increase of water activity will result an opposite effect.这是我写的原文，大家看合不合适？ |
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【答案】应助回帖
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感谢参与，应助指数 +1
huyueming321: 金币+5, ★有帮助 2015-06-24 14:55:53
感谢参与，应助指数 +1
huyueming321: 金币+5, ★有帮助 2015-06-24 14:55:53
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC238580/ Title: Survival of Bacteria and Fungi in Relation to Water Activity and the Solvent Properties of Water in Biopolymer Gels Survival of bacteria (Rhizobium, Agrobacterium, and Arthrobacter spp.), fungal spores (Penicillium sp.), and yeasts (Saccharomyces sp.) was studied in relation to water activity (aw) and the presence of nutritive solutes. The cells were entrapped in polysaccharide gels, as is done to immobilize cells or enzymes, and then dehydrated. The number of living cells (1010 g of dry polymer−1) remained constant for periods of storage of >3 years at 28°C when the inocula were kept at an aw of <0.069. At aw values between 0.069 and 0.83 the number of survivors diminished more and more rapidly as the aw was raised. For a given aw and organism, there were large differences in survival rate as a function of the nutritive solutes used to culture the microorganisms. Low-molecular-weight compounds (with three or five carbon atoms) had a deleterious effect on survival, whereas compounds of higher molecular weight (C6 to C12) had a protecting effect. Thus, the aw alone was not a sufficient explanation for the deterioration of the inocula. Survival seemed to be more directly related to some properties of the water in the biopolymer. New concepts such as the discontinuity of properties of water and the point of mobilization of solutes, already proposed by Duckworth and Kelly (J. Food Technol. 8:105-113, 1973) and Seow (J. Sci. Food Agric., 26:535-536, 1975), have been taken into consideration to explain the interactions of water with the biopolymer and their specific effects on the microorganisms. |
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