Selection of Mycotoxin Non-producing Aspergillus Strains and the Characteristics of GABA Enriched Doenjang (Soybean Paste)

Abstract

To date, edible fungi such as Aspergillus flavus var. oryzae (A. oryzae) and black Aspergillus (Aspergillus niger aggregates) has been considered as safe. However, it has been recently reported that some strains have a mycotoxin biosynthetic capability. Based on this reason, a re-evaluation of the mycotoxin biosynthetic capability is required to determine the safety of edible fungi.

In the present study, comprehensive evaluation on the potential mycotoxin producing strains of Aspergillus strains which are frequently used in traditional Korean fermented foods was preformed. In return, mycotoxin non-producing Aspergillus strains were selected, which will contribute to the development of the fermented foods with enhanced safety levels.

Then, we have newly developed γ-aminobutyric acid (GABA) enriched fermented soybean paste by serial fermentation using mycotoxin non-producing A. oryzae FMB S46471 and GABA producing L. brevis GABA 100. Furthermore the soybean paste developed in present study included low salt contents as L. brevis GABA 100 could inhibit the growth of spoilage bacteria.

Furthermore the production of biogenic amines (BAs) as well as GABA in the fermented soybean pastes with enhanced functional benefits of GABA were characterized since concerns that the production of GABA may be accompanied by the increase in the production of BAs were raised.

In conclusion the present result showed that the newly developed fermented soybean paste using A. oryzae and L. brevis produced considerable levels of GABA whereas the level of BAs was relatively lower than the conventionally fermented soybean pastes. Taken together, this study will contribute to the development of the fermented foods with enhanced safety and provide useful information on the development of GABA enriched fermented foods.