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The differences between broad bean koji fermented in laboratory and factory conditions by an efficient Aspergillus oryzae

Summary

This study compared how two types of A. oryzae fungi ferment broad beans to make koji, a starter ingredient for Chinese broad bean paste. Researchers tested the same fungi in small laboratory batches and large factory batches to see if what works in the lab also works in industry. They found that the factory’s larger scale and different environment actually had a bigger impact on the final product than which specific fungus strain was used, though the PN strain was still efficient overall.

Background

Broad bean koji fermentation is an essential process for producing broad bean paste-meju, a traditional Chinese condiment. Aspergillus oryzae is widely used in sauce fermentation, but the differences between laboratory and factory-scale production conditions remain unclear.

Objective

This study compared the fermentation efficiency of A. oryzae PNM003 (PN) with the widely used strain HN 3.042 (HN) under both laboratory and factory (large-scale) conditions to evaluate the factory adaptability of the efficient strain and assess how fermentation conditions and strains affect koji quality.

Results

Factory koji had higher fungal counts than laboratory koji. PN koji showed higher protease activity and higher content of total acids, amino acid nitrogen, and amino acids in laboratory conditions, but similar indexes to HN koji in factory conditions. Fermentation environment had a greater influence than starter strain on bacterial composition, with more volatile flavor compounds metabolized in factory conditions, especially esters and alcohols.

Conclusion

Fermentation conditions had a greater influence than fermentation starter for broad bean koji quality. While PN was an efficient strain, its advantages were more pronounced in laboratory conditions. The study demonstrates that environmental factors are critical for koji fermentation outcomes.
  • Published in:Frontiers in Microbiology,
  • Study Type:Experimental Comparison Study,
  • Source: PMID: 37032872, DOI: 10.3389/fmicb.2023.1139406
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