Comprehensive Metabolite Profiling and Microbial Communities of Doenjang (Fermented Soy Paste) and Ganjang (Fermented Soy Sauce): A Comparative Study

Abstract

<i>Doenjang</i> and <i>ganjang</i> are secondary fermented soybean products from <i>meju</i> (primary fermented product) following a complex fermentation process that separates the products into solid (<i>doenjang</i>) and liquid (<i>ganjang</i>) states. We performed a comparative study on gas chromatography mass spectrometry-(GC-MS) and liquid chromatography mass spectrometry-(LC-MS) based metabolite profiling with fungal and bacterial microbial community analysis of <i>doenjang</i> and <i>ganjang</i> during fermentation. Metabolite profiling and microbial community data showed distinct patterns, depending on the fermentation process. The relative levels of metabolic patterns were similar and most of the microorganisms produced halophilic or halotolerant microbes during the fermentation period in <i>doenjang</i> and <i>ganjang</i>. In the <i>doenjang</i> end products, isoflavones, soyasaponins, and amino acids were largely distributed and <i>Debaryomyces</i> and <i>Staphylococcus</i> were dominant, whereas the biogenic amine and phenylpropanoid contents were highly distributed in the <i>ganjang</i> end products, with higher levels of <i>Meyerozyma</i> and <i>Tetragenococcus</i>. Our results demonstrate that the quality of <i>doenjang</i> and <i>ganjang</i> is predominantly influenced by the microbiome and by metabolite changes during fermentation. Moreover, the present study provides a platform for comparing samples in different states.