Application of white-spored mutants induced from koji molds [Aspergillus] for the production of Indonesian soy sauce (kecap)

Aspergillus was dominant in 5 koji samples collected from kecap and tauco factories in Java, Indonesia, whereas Mucorales was dominant in one sample. Although, no aflatoxin was detected in all the 6 koji samples, but two out of 24 Aspergillus strains isolated from them were identified as a producer of aflatoxins. Aspergillus sp. 2-5 isolated from the tauco koji produced aflatoxins during 2-day of cultivation on cooked soybeans. The mash prepared by the kecap koji inoculated with the tempe starter contained lower formol nitrogen (FN) than those inoculated with Aspergillus strains. The kecap koji prepared by inoculating with white-spored mutants, induced from koji molds by UV irradiation, could be distinguished from those inoculated with their original koji strains or the aflatoxin-producing strain by developing white conidia (spore) during koji making. FN contents of the kecap mashes prepared using whitespored mutants were not different from those prepared using original strains. These results show that white-spored mutant can be used as a starter for preparation of kecap koji from the standpoint of preventing aflatoxin contamination.