Fermentation-Induced Changes in Nutritional, Antinutritional, and Microbial Characteristics of Calabash Fruit (Crescentia cujete L.) Seeds

This study evaluated the fermentation of calabash fruit (Crescentia cujete L.) seeds over 0, 24, 48, and 72 h to produce a daddawa-type condiment. Samples were analysed for proximate composition, antinutritional factors, morphological characteristics, and microbial profiles. Fermentation significantly (p < 0.05) reduced moisture content from 16.37% to 7.67%, carbohydrates from 34.73% to 22.93%, and crude fibre from 7.13% to 3.10%, while protein increased from 12.39% to 21.99%, fat from 24.86% to 28.69%, and ash from 4.02% to 7.62%. Antinutritional factors were also markedly reduced, with phytate decreasing from 2.23 mg/g to 0.24 mg/g, tannins from 0.17 mg/g to 0.03 mg/g, trypsin inhibitors from 3.14 mg/g to 0.17 mg/g, and saponins from 16.86 mg/g to 3.21 mg/g. Morphological analysis revealed fragmented clusters with intergranular pores, and functional amine groups responsible for the characteristic pungent aroma were detected. Bacterial isolates were identified as Bacillus and Lysinibacillus spp., with DNA sequencing confirming Bacillus spp. as the dominant fermenting organisms. These findings demonstrate that fermentation improves the nutritional quality, reduces antinutritional factors, and enhances the functional and culinary potential of calabash fruit seeds as a condiment.