Determination of thermobacteriological parameters and size of Bacillus stearothermophilus ATCC 7953 spores

Food Science and Technology (Campinas)

Marcos Fraiha¹  Antonio Carlos De Oliveira Ferraz¹  João Domingos Biagi¹ 

[1] ,Universidade Estadual de Campinas Faculdade de Engenharia Agrícola Campinas SP ,Brasil

关键词: thermobacteriology;    feed;    D value;    z value;    spore size;    termobacteriologia;    ração;    valor D;    valor z;    dimensões do esporo;   

DOI  :  10.1590/S0101-20612010000400032

来源: SciELO

【 摘 要 】

In order to determine thermobacteriological parameters for B. stearothermophilus spores, they were diluted in a saline solution medium and in ground corn-soybean mix, distributed in TDT tube, and submitted to heat for a specific period of time. The D value (time to reduce 1 log cycle of microbial count under a certain temperature) and z value (variation of temperature to cause 10-fold change in D value) were estimated. To estimate their dimensions, the spores were visualized by using a scanning electron microscope. D121.1 ºC and z values for these spores, as determined in the saline solution, were 8.8 minutes and 12.8 ºC, respectively. D121,1 ºC and z values determined in the corn-soy mix were 14.2 minutes and 23.7 ºC, respectively. The micrographs indicated that the spores have homogeneous shape and size, with length and diameter of 2 and 1 µm, respectively. These results confirm that the spore is highly thermal-resistant, and it is a good biological indicator to evaluate the extrusion process as a feed sterilizer.

【 授权许可】

CC BY   
 All the contents of this journal, except where otherwise noted, is licensed under a Creative Commons Attribution License