Development of a new D-value testing method for heat-resistant molds using microscopical counting of ascospore germination

DOI JASI Web Site 1 Citations 25 References
  • UEDA Seiichi
    Graduate School of Human Health Science, University of Nagasaki
  • KAWARA Nozomi
    Graduate School of Human Health Science, University of Nagasaki

Bibliographic Information

Other Title
  • 耐熱性カビの子嚢胞子発芽測定による新規 D 値試験法の開発
  • タイネツセイ カビ ノ シノウ ホウシ ハツガ ソクテイ ニ ヨル シンキ Dチ シケンホウ ノ カイハツ

Search this article

Description

<p>A new testing method was developed to facilitate the D-value (decimal reduction time) determination of heat-resistant molds. For heat treatment, 500 µl of ascospore suspensions (approximately 106 ascospores/ml 0.1 M phosphate buffer) in capped test tubes were heated for 5-180 min at different temperatures. After heating, 100 µl of the ascospore suspensions were poured into a microplate with nutrient broth and the microplate incubated at 25℃ for 1 day. Percentage of germinated ascospores was counted with the aid of an inverted microscope. For comparison, surviving ascospores were also determined by the method of conventional plating incubation. Four heat-resistant strains of Neosartorya spp. and Talaromyces macrosporus were used in this examinations, three were isolated from spoiled food products and the remaining specimens from soil samples taken from a mango farm. D-values of all tested strains obtained by the spore germination counting method were almost identical to those of the plating incubation and there was no statistical significance between the two methods. Thus, we conclude that the spore germination counting technique can be applied as a new D-value testing method instead of the conventional plating incubation. This new method has advantages in simplicity, and is time- and labor- saving when compared to the conventional plating incubation method.</p>

Journal

Citations (1)*help

See more

References(25)*help

See more

Keywords

Details 詳細情報について

Report a problem

Back to top