プロピレンオキサイドガス殺菌条件の選択指針

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Gaseous propylene oxide (PO) sterilization should produce a high effect associated with a low PO residue. This deals with the selection of conditions for sterilization of Bacillus subtilis var. niger 4380 spores and casein.The water content (Wa, %), which is the most important factor in gaseous sterilization, in both cases was expressible by the following equation over the equilibrating relative humidity (ERH) range 10 to 95% at 30℃ : 1n a_w = -A/Wa^s (1)where a_w is the water activity (=ERH/100), and A and s are constants. The activation energy (E, cal/mole) for death is the same for spores equilibrated at 10%, 44% and 75%RH at 30℃, and the empirical constant β in the Arrhenius equation is proportional to the natural logarithm of Wa of these spores, i.e., β=7.062×10^<10> 1n(0.2891 Wa). The relation between disinfectant rate constant (k, hr^<-1>), temperatue in sterilizing process (Ts, °K) and Wa of spores at 30℃ was expressible by the equation : k = βexp(-E/RTs) (2)where, R is the gas constant (1.987 cal/mole・deg).The effect Ts and ERH on the PO adsorption on casein was complicated, but it was found that the ability of casein to adsorb PO increased exponentially with increasing of Wa of casein, and the desorption of water from casein was remarkable at higher Ts than 303°K. The relation between the amount of PO adsorbed on casein (Pad, ppm), Ts and ERH could not therefore be establiched. The maximal Pad (the maximal PO residue, Pr, ppm) was defined on the basis of the safety of casein sterilized with PO. The relation between Wa of casein equilibrated at various ERH at 30℃ and Pr (calculated from the equation : Pad=m exp(α_1t)-m exp (α_2t), where, m, α_<1,2> and t are the constant (ppm), constant (hr^<-1>) and exposure time (hr), respectively) was expressible by the equation : Pr = aWa^n + b (3)where, a, b and n are constants.By calculating the Pr associated with combinations of ERH and Ts which produce the same sterilizing effect from equations (1), (2) and (3), the best conditions for gaseous PO sterilization can be selected.
社団法人日本生物工学会の論文
1981-03-25

プロピレンオキサイドガス殺菌条件の選択指針

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