Journal of Food Processing & Technology

Heat resistance of spores of six major Bacillus species in phosphate buffer and fermented soybean products

4^th International Conference and Exhibition on Food Processing & Technology

August 10-12, 2015 London, UK

Jae-Hyung Mah, Xuezhi Bai and Young Kyoung Park

Posters-Accepted Abstracts: J Food Process Technol

Abstract:

The aim of this study was to compare the heat resistance of Bacillus cereus spores with that of spores of dominant Bacillus species
present in fermented soybean products and thereby optimize thermal treatment conditions of fermented soybean products to
reduce risk of B. cereus contamination. For this, heat resistance of spores of six different species belonging to the genus Bacillus
including B. subtilis, B. coagulans, B. licheniformis, B. pumilus and B. brevis as well as B. cereus was measured in a phosphate buffer.
Consequently, B. cereus spores revealed the smallest D-values at all the tested temperatures of 100-112°C whereas B. licheniformis
spores had the greatest D-values at temperatures in the range of 106-112°C. The spores of the other dominant Bacillus species showed
similar or slightly smaller D-values than those of B. licheniformis at respective temperatures. Subsequently, heat resistance of spores of
six species was determined in two types of fermented soybean products, Cheonggukjang and Gochujang products. In the fermented
soybean products B. licheniformis spores revealed the greatest D-value at 112° C and one of either B. coagulans spores or B. brevis
spores exhibited the greatest D-values at temperatures in the range of 103-109°C whereas B. cereus spores showed the smallest
D-values at all the tested temperatures. Meanwhile, B. licheniformis spores had the highest z-values in both phosphate buffer and
fermented soybean products followed by B. cereus spores. These results indicate that a mild thermal treatment would allow speciesselective
inactivation of B. cereus spores, less affecting spores of the other Bacillus species.

Biography :

Jae-Hyung Mah has completed his PhD from Korea University and Postdoctoral studies from University of Wisconsin-Madison and Washington State University. He is the
Professor of Food and Biotechnology at Korea University (Sejong Campus). He has published more than 40 papers in reputed journals and has been serving as an Editorial
Board Member of several peer-reviewed journals. His researches focus on the analyses of hazardous chemicals and microorganisms in fermented foods and development
of novel protective and preservative strategies such as application of genetically designed starter culture to food fermentation and inactivation kinetics of pathogenic
microorganisms exposed to intervention treatments.