Changes in Microbiological and General Quality Characteristics of Gamma Irradiated Kanjang and Shoyu

감마선을 조사한 간장의 미생물 및 일반품질 특성

  • Song, Tae-Ho (School of Food Technology, Woosong University) ;
  • Kim, Dong-Ho (Team for Radiation Food Science and Biotechnology, Korea Atomic Energy Research Institute) ;
  • Park, Byoung-Jun (Team for Radiation Food Science and Biotechnology, Korea Atomic Energy Research Institute) ;
  • Shin, Myung-Gon (School of Food Technology, Woosong University) ;
  • Byun, Myung-Woo (Team for Radiation Food Science and Biotechnology, Korea Atomic Energy Research Institute)
  • 송태호 (우송대학교 식품생명공학부) ;
  • 김동호 (한국원자력연구소 방사선식품.생명공학연구팀) ;
  • 박병준 (한국원자력연구소 방사선식품.생명공학연구팀) ;
  • 신명곤 (우송대학교 식품생명공학부) ;
  • 변명우 (한국원자력연구소 방사선식품.생명공학연구팀)
  • Published : 2001.06.30

Abstract

The effect of gamma-irradiation on the microbiological and general qualities of Kanjang (fermented soy sauce, Korean type) and Shoyu (fermented soy sauce, Japanese type) was studied. Samples were prepared, irradiated at 5, 10 and 20 kGy, and then stored at $25^{\circ}C$ for 18 weeks. The results showed that the Bacillus spp. was inactivated by 3 log cycles with the irradiation dose of 10 kGy and the number of Bacillus cells that survived from 10 to 20 kGy of gamma irradiation was decreased gradually during storage. Yeasts and Lactobacillus were nearly eliminated at 5 to 10 kGy of irradiation. The $D_{10}$ values of Bacillus, yeast and Lactobacillus in Shoyu were 2.67 kGy, 0.81 kGy and 1.30 kGy, in Kanjang were 2.75 kGy, 0.99 kGy and 1.47 kGy, respectively. The general quality of gamma irradiated Shoyu and Kanjang, such as total nitrogen, amino nitrogen, protease activity and pH were more stable than that of control during storage periods. Decolorization was observed just after irradiation, but the color was recovered during storage. The sensory evaluations showed that irradiated samples were more acceptable. Therefore, it was considered that gamma irradiation was effective for maintaining better quality of Shoyu and Kanjang during storage.

Keywords

Kanjang;Shoyu;gamma irradiation