Dry heat inactivation of Bacillus cereus in rice

Abstract

Houška M., Kýhos K., Landfeld A., Průchová J., Schlemmerová L., Šmuhařová H., Špelina V., Novotná P. (2007): Dry heat inactivation of Bacillus cereus in rice. Czech J. Food Sci., 25: 208-213.The aim of this work was to validate the method of decontamination of rice at the temperature of 120°C (determined as optimal in previous experiments). Bacillus cereus was selected as the marker micro-organism for the monitoring of decontamination. The spores of Bacillus cereus are moderately heat resistant. In order to show the efficacy of our decontamination process, we artificially contaminated the rice under study with B. cereus. Decontamination was carried out in a homogenising steriliser about 20 h after contamination. The sample was first heated to 90°C and held at this temperature for 70 minutes. Then the temperature was increased to 120°C and held for 3 hours. Five samples were taken for microbiological analyses as follows: before the experiment, on reaching 120°C, and then after 1, 2, and 3 h of decontamination. Decontamination of rice from vegetative forms and spores of B. cereus present at the level of 400 CFu/ml was effected by heating to 120°C and holding for 1 hour.

Impacts of broadband and selected infrared wavelength treatments on inactivation of microbes on rough rice

“…For instance, B. cereus spores can survive temperature as high as 95°C for 2 min or 85°C for 32 min (Byrne et al, ). However, Houska et al () found that treatment at 120°C for 1 hr can significantly inactivate heat resistant bacterial spores.…”

Incidence and toxigenic profile of Bacillus cereus in some fishes

“…This my duo to the fact that the cooking process may effect on the count of aerobic spore forming bacteria, its ability to form active spore or toxins. (Parry and Gilbert, 1980), (Houška et al, 2007) and (Desai and Varadaraj, 2010).…”

Bacillus Spores in the Food Industry: A Review on Resistance and Response to Novel Inactivation Technologies

“…Generally, this involves either a moderate heat treatment (<75 °C) designed to kill pathogenic vegetative cells, termed pasteurization, or a higher heat treatment (>5 min at 121 °C at the coldest spot), termed sterilization, canning, or retorting, to enhance the shelf‐life and safety of the food items, and this includes the inactivation of spores of Bacillus and Clostridium species (Oomes and others ). A dry heat operation in which rice was heated to 120°C in a sterilizer for 1 h has been validated as a method of inactivating B. cereus spores (Houska and others ). In thermal processing, the term D ‐value is used to define the time required at any specific temperature to inactivate 90% of the bacterial population of concern.…”