Improving Nutritional Quality of Peanut Meal through Solid-State Fermentation with Heyndrickxia coagulans

With the increasing global demand for protein sources to feed the ever-growing population, peanut meal-a by-product of peanut oil extraction-holds promise as a valuable feed ingredient for animal protein production. However, its utilization is constrained by anti-nutritional factors and limited digestibility. This study employed solid-state fermentation using Heyndrickxia coagulans (formerly Bacillus coagulans) to enhance the nutritional quality of peanut meal. Among three evaluated strains, Heyndrickxia coagulans S17 was selected for its superior fermentation performance. Optimal fermentation conditions were established: 1 g/L of CaCl₂, 45 °C, material-to-liquid ratio of 1:2.1, 14% inoculation, and 36-h fermentation. Under these conditions, crude protein, small peptides, and acid-soluble protein contents increased from 53.75%, 3.35%, and 1.80% to 60.11%, 8.93%, and 5.37%, respectively. In vitro protein digestibility improved from 54.18% to 64.91%. Additionally, aflatoxin B 1 levels decreased from 43.87 μg/kg to 9.23 μg/kg, while trypsin inhibitors and phytic acid were reduced from 2.97 mg/g to 0.56 mg/g and 14.36 g/kg to 2.57 g/kg, respectively. These findings suggest that solid-state fermentation with Heyndrickxia coagulans S17 effectively enhances the nutritional quality of peanut meal, offering a viable approach for producing high-quality protein feed and contributing to sustainable livestock nutrition.