# From Charcuterie to Plant-Based: Harnessing Penicillium nalgiovense for Innovative Soybean Co-Culture Fermentation

## TL;DR

This study explores using the fungus Penicillium nalgiovense with other microbes to improve the flavor of soybeans through fermentation.

## Contribution

The novel contribution is identifying specific microbial combinations that enhance soybean flavor by altering amino acids, lipids, and volatile compounds.

## Key findings

- PN monoculture increased free amino acids to 1324 mg/100 g, and PN-LP increased it further to 1487 mg/100 g.
- PN-KM increased polyunsaturated fatty acids like linoleic and α-linolenic acid significantly.
- Fermentation reduced hexanal levels and increased savory and floral compounds, as shown by electronic tongue profiling.

## Abstract

Improving the flavour of soybean-based ingredients remains challenging as soybeans naturally contain compounds that generate green and beany notes. This study evaluated how the surface-growing food-grade fungus Penicillium nalgiovense (PN), alone and together with selected yeasts and lactic acid bacteria, alters the chemistry and sensory attributes of soybeans during solid-state fermentation. PN showed strong proteolytic activity in the monoculture fermentation, producing the highest accumulation of free amino acids (1324 mg/100 g), while its combination with Lactiplantibacillus plantarum (LP) further increased this to 1487 mg/100 g due to acid-assisted protease action. Sugar and organic acid profiles reflected distinct metabolic roles among the strains; for example, PNLP and PN-Debaryomyces hansenii (DH) depleted sucrose and glucose completely by 72 h, whereas DH retained substantial sucrose. Fermentation also altered the lipid profiles, where PN-Kluyveromyces marxianus (KM) showed the highest increase in polyunsaturated fatty acids, with linoleic and α-linolenic acid increasing more than twofold and threefold, respectively. Volatile analysis showed a significant decrease in hexanal (from 18.3 µg/g in control to <2.0 µg/g post fermentation) and an increase in esters, floral alcohols, and savoury compounds depending on the microbial pairing. Electronic tongue profiling showed that PN-fermented samples produced the strongest savoury taste signals. Overall, the work highlights how specific PN-yeast or PN-LAB combinations can be used to modulate flavour development in fermented soy-based substrates.