How low can we go? Effect of moisture content on lactic acid fermentation of air-classified faba bean protein concentrate

Abstract

Application of air-classified faba bean protein concentrates in foods is limited by raffinose family oligosaccharides (RFOs) and beany flavours. Fermentation with lactic acid bacteria (LAB) can degrade RFOs and off-flavours while generating masking aromas. However, combining air classification with fermentation is inefficient due to the need for drying, increasing water and energy use. Therefore, drier fermentation conditions are desirable. This study evaluated the impact of varying the moisture content during the fermentation of air-classified faba bean protein concentrate with Pediococcus pentosaceus VMCU76F. Doughs with moisture contents of 0.75, 1.0, 1.5, 2.0 $g·{\left(gd.m.\right)}^{-1}$ were made and incubated at 30 °C for 48 h. Titratable acidity, pH, viable cell counts, RFOs, and volatile organic compounds were measured at 0, 6, 24, 48 h. Lower moisture did not significantly affect maximum number of cells but reduced the acidification and RFO degradation rates. Fermentation below 1.0 $g·{\left(gd.m.\right)}^{-1}$ increased fatty aldehydes, fatty alcohols, ketones, and furans associated to beany aromas, while higher moisture reduced these off-flavours. Moisture contents above 1.0 $g·{\left(gd.m.\right)}^{-1}$ promoted fruity and dairy aromas from amino acid degradation and the citrate cycle. Although all conditions led to RFO degradation, higher moisture improved acidification rates and volatile profile modulation. Optimizing this novel process involves balancing fermentation speed, aroma development, and energy sustainability.