Fermentation Process Evaluation of a Sustainable and Innovative Miso Made from Alternative Legumes

Miso is a traditional Japanese seasoning produced by fermenting soybean. However, in Portugal, most soybean is imported. This study focused on producing sustainable and innovative misos using legumes traditionally consumed in Portugal—chickpea, lupin, and cowpea—and assessing their fermentation. Each legume was blended with 3% or 12% NaCl and inoculated with a selected microbial consortium comprising Aspergillus oryzae (koji), Debaryomyces hansenii, Zygosaccharomyces rouxii, Candida versatilis, Lactiplantibacillus plantarum, Leuconostoc mesenteroides, and Tetragenococcus halophilus. Fermentation was carried out at 20 ± 1 °C for 18 months. During this period, microbial viability, pH, total soluble solids, soluble protein, phenolic compounds, reducing sugars, and organic acids were monitored. Soybean misos were also produced and analysed at the beginning and end of fermentation for comparison. Chickpea misos showed the highest accumulation of soluble protein, phenolic compounds, reducing sugars, and organic acids. In contrast, cowpea misos exhibited the lowest levels of these soluble fractions. Lupin misos displayed the most pronounced salt-dependent behaviour. Compared to the alternative legume-based misos, soybean misos did not exhibit distinct final characteristics. These findings highlight the potential of these legumes as alternative substrates for miso production, supporting the development of sustainable, innovative, lower-salt foods with strong cultural and regional relevance.