Improved effect of autoclave processing on size reduction, chemical structure, nutritional, mechanical and in vitro digestibility properties of fish bone powder

Global fisheries production has increased up to 200 MT which resulted in 20 MT of waste. Discards or by-products from aquatic processing have remained a big challenge for waste management and their efficient use for human food. In the present study, we prepared fish bone powder (FBP) from grass carp (Ctenopharyngodon idella) using autoclave processing and compared its characteristics with simple heat treatment as well as with size reduction process. The results showed that autoclave processing with reduced particle size significantly (p < 0.05) increased ζ-potential (15.2 mV) and facilitated size reduction (5.2 µm), while only heat treatment improved the proximate composition. The collagen denaturation was followed using Fourier Transform Infrared Spectroscopy (FTIR) at 1338 cm⁻¹ peak while amide regions, such as amide I (1590–1720 cm⁻¹), amide II (1560 cm⁻¹) and amide III (1237 cm⁻¹), carbonate (870 cm⁻¹) and phosphate (565 and 1030 cm⁻¹) groups were identified in all treatments. The scanning electron microscopy showed the variation in particle size, and porous structure of FBP. Moreover, calcium and protein in vitro digestibility was significantly high in autoclave processing groups. The results of amino acid analysis at intestinal stage of in vitro model digestion depicted that the concentration of essential amino was higher than the cereal proteins. The results propose the feasibility of using autoclave processing as an alternative to the thermal treatment to prepare FBP.