Optimization Of Gelatin Extraction From Silver Carp Skin And Textural, Rheological, And Sensory Characteristics Of Extracted Gelatin
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Gelatin is an important multifunctional biopolymer, being the only protein widely used in foods, drugs and cosmetics; to improve elasticity, consistency, and stability. Although pork skin is still the most commonly used raw material for gelatin production, fish skin has been looked at as an alternative raw material, eliminating religious concerns shared by the Jewish and Muslim communities and providing an alternative way of using the waste from the fish processing industry. Silver carp, an Asian carp subspecies, accounts for over 2.5% of the world’s total fish production with over 4 million tonnes annual production. The objective of this study was to optimize gelatin extraction from silver carp skin and to determine its textural, rheological, and sensory properties in comparison with commercially available gelatins from different sources. For the optimization part of the project, a two-step optimization procedure was used. First, those extraction parameters that significantly affect the quality of gelatin extracted were elucidated and second, the optimum levels of those parameters giving the best possible gelatin were determined. The optimum extraction conditions were 50 °C for water extraction with a 4:1 (v/w) water/skin ratio and a 0.1 N HCl acid pretreatment for 45 min. The predicted values for the most important gelatin parameters for these extraction conditions were 630 g gel strength, 6.3 cP viscosity, and 80.8% recovery of the gelatin in the original skin. The gelatin extracted from silver carp skin under optimum conditions was found to be similar to fish gelatins currently being exploited commercially and superior in some aspects such as viscosity. The textural, rheological, and sensory measurements were strongly correlated with physiochemical parameters measured for various gelatin samples extracted from different raw materials. The rheological measurements were found to successfully discriminate between different gelatins. For the gelatin industry and future research studies, rheological measurements might be useful for routinely characterizing gelatin gels. Other fish species should also be studied as a raw material for gelatin production and a cost analysis might be useful to demonstrate the potential opportunities for further processing of waste from the fish processing industry into value-added products.