Effect of Pretreatments and Defatting of Seabass Skins on Properties and Fishy Odor of Gelatin

Abstract

The impact of different pretreatments and defatting processes of seabass skins on fishy odor and other properties of gelatin was investigated. Skin pretreated with 0.05 M citric acid, followed by defatting using 30% isopropanol (G-Ci-Def) had the lowest residual phospholipid content (P < 0.05). Nevertheless, G-Ci-Def had a lower yield and gel strength, compared to those from skins pretreated with acetic acid (G-Ac) or citric acid (G-Ci) (P < 0.05). All gelatins contained α-chains as the predominant component as indicated by SDS-PAGE. G-Ci-Def showed the highest L* value and the lowest a*, b*, ΔE* and ΔC* values, compared to the other gelatins (P < 0.05). All gelatins were sponge or coral-like in structure but varied in patterns as evaluated by scanning electron microscopy. The lower fishy odor associated with lower amounts of most volatile compounds was found in G-Ci-Def, compared to other gelatins. Therefore, gelatin with negligible fishy odor could be prepared from citric acid pretreated and isopropanol defatted skin. Practical Applications Seabass skins are potential raw materials for production of collagen, gelatin and bioactive protein hydrolysates. Pretreatment and defatting of seabass skin plays a significant role in the reduction of lipids, especially membrane phospholipids. Pretreatment using citric acid and defatting using isopropanol of skin prior to gelatin extraction could lower lipid oxidation, volatile compounds, and fishy odor. Gelatin prepared could be widely used in foods with minimal effect on sensory attributes.