Biological valorization of Pangas fish processing waste into nutrient-rich fish silage using molasses-assisted Lactobacillus plantarum: fermentation dynamics, nutritional quality, and economic feasibility

Introduction Biological valorization of fish processing waste offers a sustainable strategy to reduce environmental load while generating value-added feed resources. This study evaluated the production of fish silage from Pangas ( Pangasianodon hypophthalmus ) processing waste using molasses-assisted Lactobacillus plantarum fermentation. Methods A two-factor factorial design was employed with molasses levels (0–25% w/w) and L. plantarum inoculum levels (0–5% v/w). Fermentation was carried out for 30 days, and parameters including fermentation dynamics, proximate composition, biochemical stability, microbiological quality, and economic feasibility were assessed. Results The optimized treatment (15% molasses + 5% L. plantarum ) yielded 0.89 kg silage per kg viscera and 0.37 kg per kg whole fish. Rapid acidification (pH < 4.5), decreasing temperature trends, and reduced water activity confirmed effective fermentation. Proximate composition showed improved crude protein, stabilized fat content, and progressive carbohydrate utilization. Free fatty acid and peroxide values remained within acceptable limits, indicating lipid stability. Total plate count ranged from 6.20 to 7.67 log CFU g -1 , reflecting active fermentation, while Escherichia coli and Salmonella were not detected. Colour parameters remained stable across treatments. Economic analysis estimated a production cost of ₹93.70/kg at laboratory scale. Discussion Molasses supplementation enhanced fermentable substrate availability, promoting efficient lactic acid fermentation and stabilization of fish silage. The optimized combination of 15% molasses and 5% L. plantarum provided the best balance between fermentation efficiency, nutritional quality, and economic feasibility. The findings support the potential of this approach as a sustainable and cost-effective method for converting fish processing waste into aquafeed ingredients.