Effect of the wavelength of infrared heaters on the inactivation of bacterial spores at various water activities

Daisuke Hamanaka, Toshitaka Uchino, Naomi Furuse, Wenxue Han, Shun ichiro Tanaka

Research output: Contribution to journalArticle

33 Citations (Scopus)

Abstract

Bacterial spores (Bacillus subtilis subsp. subtilis NBRC 16183) inoculated onto a stainless steel Petri dish and treated at nine levels of water activity (aw) for 2 days were inactivated by infrared radiation heating (IRH) using three kinds of infrared heaters with different radiation spectra. The peak wavelengths used were 950, 1100 and 1150 nm. In general, the inactivating efficacy of IRH treatment against bacterial spores with shorter wavelength heater (950 nm) was greater than that with other heaters. The decimal reduction times (D value) calculated using the linear portion of survival curves were affected by both the initial aw values and the spectra of the infrared rays. Spores at approximately 0.9, 0.7 and 0.6 aw were most resistant to IRH at wavelengths of 950, 1100 and 1150 nm, respectively. The aw values that led to maximum D values for bacterial spores increased as the wavelength was shortened. Optimum aw values were identified for the inactivation of bacterial spores by IRH. Spore resistance to IRH could also be affected by the spectral characteristics of the infrared absorption, which varied with the aw of bacterial spores.

Original languageEnglish
Pages (from-to)281-285
Number of pages5
JournalInternational Journal of Food Microbiology
Volume108
Issue number2
DOIs
Publication statusPublished - Apr 25 2006

All Science Journal Classification (ASJC) codes

  • Food Science
  • Microbiology

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