Combined Effect of Heat and Alkali in Sterilizing Sugarcane Bagasse

Abstract

— Bacterial spores contained in sugarcane bagasse were subjected to various combinations of heat exposure and alkali concentration and the rate of destruction determined for each set of conditions. A series of survival, thermal death time and alkaline destruction curves revealed a different mode of death by heat exposure than alkali treatment. Addition of alkali into the heating menstruum caused the death rates of bacterial spores to be much greater than with heat alone at a given temperature. Exposure of the spores to a temperature of 75°C for 130 min was required to reduce the spore population by 90% with heat treatment alone. Incorporation of a 1% NaOH solution into the heating menstruum effected the same degree of destruction of the spores within a 2 min period at the same temperature. From a series of thermal destruction and alkaline destruction curves, an empirical equation expressing the relationship between the death rate of bacterial spores, and the intensity of temperature and the concentration of alkali was established. The equation reveals that the death rate of bacterial spores is affected in an exponential manner by temperature and in a direct relationship by alkali concentration. Using the equation, sterilization time for various combinations of temperature and alkali concentration was determined and the overall correlation index between the experimental data and computed value was 0.877.

The role of heat exchangers in the contamination of milk with Bacillus cereus in dairy processing plants

“…For B cereus isolated from sugarcane bagasse, exposure of spores for less than 1 min to 80°C with 1% NaOH in the heating menstruum was required to reduce the spore population by 90%. 16 Stadho~ders'~ observed for three strains of B cereus a decrease in numbers from lo5 to less than 10 per ml within 10 min in a 1% NaOH solution at 80°C. However, in all swab samples B cereus was shown to be present, mainly as spores determined after a heat activation step of 10 min at 80"C, in levels of less than 1 cm-2.…”

Heterogeneity and the modelling of bacterial spore death: the case of continuously decreasing death rate

“…This was the approach used to apply the general model of innate heterogeneity to the data of Han et al (2). For such non-logarithmic-survival curves, a skewed initial distribution of the rates of destruction is required if the innate heterogeneity model is to describe satisfactorily the data.…”

“…Deviations of the IH-GM and HAM/IH-MPM models, fitted by least squares, from the data points(2) Sums of squares of deviations as calculated by the least squares analysisaOThe least squares analysis (6, 7) minimises the sums of squares of deviations to give the 'best fit' parameter estimates for the model under consideration.F o r the authors' parameter estimates, seeTable 2.…”

Combined effects of microorganism control and the concept of their evaluation methods

“…7) . These dependencies were examined in the analysis of the simultaneous mode of the combination treatment method presented at the beginning of this section (Han et al 1971;Swartling and Lindgren 1968;Tsuchido 1977;Tsuchido and Shibasaki 1980;Tsuchido 2020;Yamamoto et al 1989) .…”