The effectiveness of dry heat treatment and UV-C irradiation to kill the fungus models of microcyclus ulei

Abstract

This study was carried out to develop methods of treatment as well as determine the effective dose of dry heat treatment and UV-C irradiation to kill the fungus models of Microcyclus ulei on soybean grains and soybean meals without damaging its nutritional content. The fungus models used in this research were Colletotrichum gloeosporioides, Botryodiplodia theobromae, Fusarium oxysporum f.sp. niveum, and Sclerotium rolfsii. The results of this research showed that UV-C treatment until 12 and 24 hours exposure times at 15 and 30 cm from UV-C light was not effective to kill all the fungus models in PDA, probably due to the influence of NUV light from the lamp which was not pure at wavelength of UV-C. Therefore, further test on soybean would not be continued. Dry heat treatment at 55 ºC for 30 and 60 minutes had been shown effective to kill C. gloeosporioides, B. theobromae, and S. rolfsi in PDA, except F. oxysporum f.sp. niveum. Further experiments on soybean showed that 55 ºC for 30 minutes was effective to kill conidia of C. gloeosporioides, B. theobromae, and F. oxysporum f.sp. niveum, without damaging its protein content. However, dry heat treatment at 60 ºC for 60 minutes has been proved not effective to kill sclerotia of S. rolfsii. If M. ulei had the similar resistance as S. rolfsii, then it would need a higher temperature and time than used in this study. Therefore, experiments using a large amount of soybean were still needed.