Physicochemical and functional properties of rainbow trout (Oncorhynchus mykiss) skin gelatin in comparison to commercial bovine gelatin

• Gelatin was extracted from the skin of rainbow trout. • Morphological and structural properties were investigated. • Rainbow trout skin gelatin (RTSG) had poor functional properties. • RTSG cannot be used in food where high gel strength is required. • RTSG can be used for the clarification process in wine, beer or fruit juice. Gelatin from rainbow trout skin was extracted, and its physicochemical, structural, and morphological properties were compared with commercially available bovine gelatin. The average yield of rainbow trout skin gelatin (RTSG) was 2.5% on a wet basis. RTSG had a low protein content (71%) and moisture level (9%). The imino acid (proline and hydroxyproline) content of RTSG was quite lower (12%) as compared to BG (18%). RTSG had lower gel strength (104 g), which falls under the medium bloom category (100–200 g). The low gel strength of RTSG is due to lower hydroxyproline content than commercial bovine gelatin. RTSG scanning electron microscopy results revealed a rough and coarser gel structure, which is in line with the low gel strength. FTIR spectra of both RTSG and BG gelatin showed major bands in the amide regions. Overall, the present results revealed that rainbow trout skin gelatin with poor gelling properties does not match commercial bovine gelatin and cannot be used in food where high gel strength is required. However, it may find new applications and can be applied to such food products where fast dissolution is required in the mouth or can be used for the clarification process in wine, beer, or fruit juice.