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Comparative Evaluation of Quality and Metabolite Profiles in Meju Using Starter Cultures of Bacillus velezensis and Aspergillus oryzae

Summary

This research explores improving the production of Meju, a traditional Korean fermented soybean product used in making popular condiments like soy sauce and soybean paste. The study found a better way to use beneficial microorganisms in the fermentation process by keeping them separate rather than mixing them together. This discovery has practical implications for food production and safety. Impacts on everyday life: • Improved quality and safety of traditional fermented food products • More efficient and controlled production of fermented soybean products • Better preservation of beneficial compounds in fermented foods • Potential for standardizing traditional food production methods • Enhanced consistency in taste and quality of fermented food products

Background

Meju is a traditional Korean fermented soybean product used in making soybean paste (Doenjang), soy sauce (Ganjang), and red pepper paste (Gochujang). The quality of Meju depends on the selection of raw materials and fermenting microorganisms, which influence its characteristic metabolites, taste, and aroma. Various fungi and bacteria are involved in the fermentation process, with Aspergillus oryzae being widely used as a starter culture. However, concerns exist about biogenic amines and biohazards during fermentation.

Objective

To develop fast-stable processing techniques for Meju production using Aspergillus oryzae and Bacillus velezensis as starter cultures, and to analyze the relationship between properties and metabolites in Meju samples fermented by these microorganisms either alone or in combination.

Results

The amino-type nitrogen content increased from 180-228 mg% to 226-776 mg% during fermentation, with higher levels in individually inoculated samples (Group C) compared to co-inoculated samples (Group D). Meju fermented with both B. velezensis and A. oryzae showed higher levels of metabolites including glucose, myo-inositol, glycerol, and fatty acids (palmitic, stearic, oleic, and linoleic acids) compared to Meju fermented with A. oryzae alone. The growth of fungi was affected by bacterial presence in co-inoculated samples.

Conclusion

The study demonstrated that high-quality Meju with optimal amino-type nitrogen content can be manufactured using separate inoculation of fungi and bacteria over one day. The inoculation method using both fungal and bacterial starters proved effective for Meju manufacturing, contributing to fungal survival and improved fermentation outcomes. The separate inoculation method showed better results than co-inoculation for maintaining beneficial metabolite profiles.
  • Published in:Foods,
  • Study Type:Experimental Research,
  • Source: 10.3390/foods11010068
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