Effects of defatting and tannic acid incorporation during extraction on properties and fishy odour of gelatin from seabass skin

Gelatins from seabass skin without and with defatting, extracted in the absence and presence of tannic acid at various concentrations (0-0.4 g/kg), were characterised. Gelatins from skin without defatting had higher gel strength (p < 0.05) with coincidentally higher band intensity of α- and β-chains, compared with those extracted from defatted skin. Gelatins from defatted skin had lower fishy odour with concomitantly lower thiobarbituric acid reactive substances and peroxide value. Lower abundance of volatile compounds, including aldehydes, ketones and alcohols was found in gelatin extracted from defatted skin. The addition of tannic acid during gelatin extraction could lower lipid oxidation, fishy odour as well as the formation of volatile compounds, especially hexanal and heptanal, in the resulting gelatins, regardless of defatting. Therefore, gelatin with reduced fishy odour could be prepared from seabass skin, in which 0.2 g/kg tannic acid was incorporated during extraction.