From waste to nutrient: Proximate composition, morphological and elemental analysis of Tigertooth croaker (Otolithes ruber) fish bone

Fish processing generates a large amount of waste including bones, the disposal of which contribute to environmental pollution. Fish bones, rich in calcium and phosphorous can be repurposed using suitable technology to support a circular economy by minimizing waste and promoting sustainability. Processing waste specially the bone from Tigertooth croaker (Otolithes ruber) fish was analysed for chemical composition, morphology and elemental composition and distribution. The moisture (28.18±0.25%), fat (6.98±0.12%) and ash content (49.9±0.13%) of the fish bone indicates absorbance of water by the porous particles, lipid retention during processing stages and higher ash values for mineral richness. The protein and carbohydrate content of the bone was 13.18±0.19% and 1.76 ±0.11% respectively. The morphology of the fish bone under field emission gun scanning electron microscopy with Energy-dispersive X-ray analysis detector reported the roughness, agglomerate particles, particle size (100-1000 nm) and major essential minerals (calcium, phosphorus, sodium and magnesium) distribution and composition. The bone had the maximum Ca:P ratio of 2.65 and minimum of 1.60, which makes it ideal for artificial bone integration also. Two distinct transitions of phases were observed in fish bone under elemental mapping. The results indicated that Tigertooth croaker fish bone is nutritious and could significantly fulfil human health needs. The outcomes of this research aim to establish the possibility of effectively utilizing the Tigertooth croaker bone as a nutrient source and mitigate environmental impacts due to fish processing waste disposal.