Characteristics of Gelatin Film Produced from Common Carp Scales (Cyprinus carpio) by Investigating the Effect of Effective Parameters in Extraction Process

In this study, gelatin from common carp scales (Cyprinus carpio) was produced using alkaline, acidic and thermal methods. Then, the physical factors, barrier properties and its appearance characteristics were optimized by changing effective factors in the initial gelatin extraction process. In order to optimize the film, the response surface methodology included a central composite design for extraction process, a series of effective factors in extraction including sodium hydroxide concentration, alkaline pre-treatment, hydrochloric acid concentration and extraction temperature as independent variables were investigated. The dependent variables including tensile properties, water solubility and water vapor permeability were investigated. The results of screening based on mechanical strength and solubility resulted in the selection of 4 factors of 9 factors. In the screening stage, four variables including two factor of the pH of extraction and the duration of the alkaline treatment that had the greatest effect on the tensile strength, and two factor including concentrations of acid treatments and the extraction temperature that had the most effect on the solubility of the films were selected for the the main experiments with gelatin extraction. Other variables that did not have a significant impact on the mechanical properties and film solubility were in their most common form. The main experiments of gelatin extraction included 30 treatments. Solubility showed significant changes (p <0.05). The lowest solubility was 25.08% for treatment No. 9 with alkaline treatment for 195 minutes, acid treatment with 0.3 molar concentration and extraction at 63 ° C. The lowest permeability was for treatment No. 15 with alkaline treatment for 140 minutes, acidic treatment with a concentration of 0.18 molar and extraction at 76 ° C (p <0.05). Finally, it was determined that by changing some of the extraction factors, the properties of gelatin film obtained from common carp scales could be optimized.