Effect of Low-Pressure Carbonation on Heat Inactivation of Yeast and Bacterial Vegetative Cells

Abstract

Effect of low-pressure carbonation (LPC) on heat inactivation of yeast and bacterial vegetative cells was investigated. Microbial cell suspensions were carbonated at 0.6 MPa and 12℃ for 15 min and subsequently heated for 1 min at temperatures ranging from 50℃ to 70℃ at 1 MPa. As a control experiment, suspensions were heat treated for 1 min under atmospheric pressure without LPC. The heat inactivation effect on yeast was not significantly changed by LPC; however, the heat inactivation efficiency on several bacteria was enhanced. The promoted inactivation was also observed for heat treatment under atmospheric pressure after LPC. The enhanced inactivation was not notable by heat treatment followed by LPC. The results suggest enhanced heat inactivation against bacteria under LPC, and the increased heat inactivation of bacteria may be due to LPC-mediated sensitization to heat.

Effect of Low-pressure Carbonation on the Heat Inactivation and Cytoplasmic Acidification of Saccharomyces cerevisiae

“…Heating at 53 °C and 55 °C with LPC showed higher inactivation ratio than heating alone for 1.15 and 1.25 log order, respectively. In addition to the previous study, herein it can be firstly suggested that not only the bacteria [13], but also S. cerevisiae LPC can increase the heat sensitivity. However, the LPC-increased heat sensitivity of S. cerevisiae seemed to be different depending on the level of heating temperatures.…”

“…We previously revealed that LPC can enhance the heat inactivating effect on bacteria to 3-5 log orders at several heating temperatures [13]. However, the increased inactivation effect enhanced by LPC was smaller in S. cerevisiae compared to bacteria.…”

“…In previous study, we investigated that low-pressure carbonation (LPC) can not significantly inactivate microbial cells itself, but can increase the heat sensitivity of the microbial cells. We carbonated several microbial cell suspensions and subsequently heated for 1 min at temperatures ranging from 50 °C to 70 °C at 1 MPa compared with heating under atmospheric pressure, heating with LPC exhibited 3-5 log inactivation on several bacteria [13]. In present study, we decided to explore the most appropriate condition of heating temperature and time under the LPC in an effort to facilitate the LPC's enhancing effect on heat inactivation of S. cerevisiae.…”

The Effect of Low-Pressure Carbonation on the Heat Inactivation ofEscherichia coli

“…We reported that under LPC, the inactivation efficacy of heat treatment increased. 11) To determine whether the increased inactivation of the bacteria was caused by heat-induced sensitization to LPC or by LPC-induced sensitization to heat, the inactivation of E. coli cells as a result of heating followed by LPC was compared with that as a result of heating with LPC (Fig. 2).…”

“…Furthermore, this effect did not depend on the bacterial phenotype, such as heat resistance, gram staining, or oxygen requirements. 11) We designed the present study to clarify how lowpressure carbonation (LPC) is associated with decreases y To whom correspondence should be addressed. Fax: +81-92-642-3018; E-mail: mshimoda@agr.kyushu-u.ac.jp in the heat resistance of microorganisms.…”