科研之友
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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. D(121.1 degrees C) and z values for these spores, as determined in the saline solution, were 8.8 minutes and 12.8 degrees C, respectively. D(121.1 degrees C) and z values determined in the corn-soy mix were 14.2 minutes and 23.7 degrees C, respectively. The micrographs indicated that the spores have homogeneous shape and size, with length and diameter of 2 and 1 mu m, 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.
- 出版日期2010-12
