INACTIVATION KINETICS AND REDUCTION OF BACILLUS COAGULANS SPORE BY THE COMBINATION OF HIGH PRESSURE AND MODERATE HEAT

Abstract

The combination effect of high pressure (400, 500 and 600 MPa) and moderate heat (70 and 80C) on the inactivation kinetics and reduction of Bacillus coagulans spore in phosphate buffer and ultra‐high temperature (UHT) whole milk was investigated. The pressure come‐up time and corresponding logarithmic reduction of spore inactivation were considered during pressure‐thermal treatment. B. coagulans spore had a much higher resistance to pressure in UHT whole milk than in phosphate buffer. Survival data were modeled using the linear, Weibull and log‐logistic models to obtain relevant kinetic parameters. The tailing phenomenon occurred in all survival curves, indicating the linear model was not adequate for describing these curves. The mean square error and regression coefficient suggested that the log‐logistic model produced best fits to all survival curves, followed by the Weibull model. PRACTICAL APPLICATIONS It becomes increasingly apparent that high‐pressure treatment combined with moderate heat treatment for low acid and acid products is often required for effective bacterial spores' inactivation. Consequently, the prediction model of microbial survival curves is essential. Bacillus coagulans is a slightly pressure‐resistant and relatively heat‐resistant spoilage bacterium of considerable concern during the processing of acid foods. Spore inactivation effect during the pressure come‐up time is sometimes considerable and should not beignored. The use of mathematical models to predict inactivation for spores could help the food industry further to develop optimum process conditions.

Inactivation of Byssochlamys nivea ascospores in strawberry puree by high pressure, power ultrasound and thermal processing

“…The Weibull n values (shape factors) were between 0.46 and 0.66 (≤ 1), indicating an upward concavity. These results are in agreement with past reports with other microorganisms, also obtaining non-linear inactivation and showing the Weibull model capable of predicting the inactivation results (Evelyn and Silva, 2015a;Serment-Moreno et al, 2014;van Boekel, 2009;Wang et al, 2009). The inactivation of Talaromyces avellaneus mold ascospores by 500-600 MPa HPP at 17-60°C, also seemed to follow a nonlinear pattern.…”

Strong and Consistently Synergistic Inactivation of Spores of Spoilage-AssociatedBacillusandGeobacillusspp. by High Pressure and Heat Compared with Inactivation by Heat Alone

“…As discussed above, the latter approach has its limitations because significant contribution to lethality can occur during the CUT and depressurization phases and because, in reality, HPT equipment design limitations mean that maintaining isothermal conditions during the hold phase is difficult, particularly for longer hold times. The suggestion in some studies (24,27) that tailing in spore HPT inactivation curves may be indicative of pressure-resistant subpopulations or pressure adaptation could rather be interpreted in terms of a reduction in temperature, and subsequent thermal lethality, during the hold phase in the (typically) nonadiabatic HPT system; however, despite the advantages of the F T z approach, it is important to note that the approach ideally requires knowledge of z T under pressure, and the acknowledged technical difficulties in gaining this knowledge may limit the approach. In this study, we elected to assume that thermal-only z T values do not change under HPT conditions.…”

Modeling the inactivation of Neosartorya fischeri ascospores in apple juice by high pressure, power ultrasound and thermal processing

“…These results are in agreement with past reports with other microorganisms. When using HPP technology, non-linear inactivation of spores is observed and Weibull can often predict the inactivation results well ( van Boekel, 2009;Buzrul, Alpas, & Bozoglu, 2005;Evelyn & Silva, 2015c;Serment-Moreno, Barbosa-C anovas, Torres, & Welti-Chanes, 2014;Wang, Li, Zeng, Huang, Ruan, Zhu, et al, 2009). The inactivation of T. avellaneus mould ascospores by 500e600 MPa HPP at 17e60 C, the only kinetic modeling reported with the mould ascospores, also seemed to follow a non-linear pattern.…”