Extraction and quality evaluation of yellowfin tuna bone powder

Abstract

Commercial processing of tuna either as canned tuna or tuna loins generates considerable quantities of waste and a sizeable quantity of this waste constitutes bones. Yellowfin tuna bone was prepared by three methods viz., by using 0.5% KOH, 1% KOH and 0.5% NaOH and the proximate analysis, elemental composition and fatty acid composition were evaluated in comparison to control prepared without the addition of alkali. The powder was found rich in calcium (19 400 to 26 300 mg 100 g-1) and phosphorus (7797 to 8291 mg 100 g-1) with calciumphosphorus ratio ranging between 2.5 and 3.3:1. The proportion of polyunsaturated fatty acids (PUFA), particularly, docosahexaenoic acid (DHA) content was distinctly higher in tuna bone powder prepared after boiling in 0.5% KOH. Palmitic acid, oleic acid and DHA were the common saturated fatty acid, monounsaturated fatty acid and polyunsaturated fatty acid respectively. Heavy metals like Cd and Hg were not detected in the developed bone powder.