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 CaCl 2 , 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.