Fortification of γ-aminobutyric acid and bioactive compounds in Cucurbita moschata by novel two-step fermentation using Bacillus subtilis and Lactobacillus plantarum

Pumpkin (Cucurbita moschata) was co-fermented using Bacillus subtilis HA and Lactobacillus plantarum EJ2014 for producing a novel food ingredient fortified with gamma-aminobutyric acid (GABA) and bioactive compounds. After the first fermentation, the broth showed pH 6.1, 0.26% acidity, 8.9 log CFU/mL viable cell counts of B. subtilis, 2.61% mucilage, and a consistency index of 5.43 Pa.s(n). After the second fermentation, the broth indicated pH 5.1 and 0.23% acidity. The viable cell counts of B. subtilis decreased to 7.7 log CFU/mL, while L. plantarum counts increased from 7.4 log CFU/mL to 9.1 log CFU/mL by the end of the co-fermentation. The final mucilage content was 0.58% and consistency index was 0.15 Pa.s(n). The co-fermented pumpkin contained 1.47% GABA, indicating that the MSG precursor was successfully utilized by the stepwise fermentation. Therefore, the co-fermented pumpkin paste could potentially be used as a novel ingredient for the food industry.