Effect of Extraction Temperatures on Physical and Chemical Properties of Gelatin from Skin of Tilapia

In this study,the tilapia skin was used as raw material to study the yield,gel strength,sds-page,and Fourier infrared spectroscopy,thermal denaturation temperature,rheological properties and other physical and chemical characteristics of gelatin extracted at different temperatures(30,40,50,60,70,80 and 90℃). In general,the extraction temperature had no significant effect on UV absorption of fish skin gelatin. With the increase of extraction temperature,the yield of gelatin in fish skin increased gradually,and the difference was not significant at the extraction temperature of 60~80℃,reaching a maximum at 90℃(62.6%±0.84%). The SDS-PAGE pattern indicated that the bands of gelatin α and β chains extracted at lower temperature were more obvious. With the increase of temperature,the band intensity decreased due to the thermal degradation of gelatin molecules. The gel strength of tilapia fish skin gelatin was the highest(884.33±26.76) g at the extraction temperature of 50℃. FTIR spectroscopy showed that fish skin gelatin extracted at different temperatures had characteristic absorption peaks in the amide region,showing slight differences in the spectra. The thermal denaturation temperatures of the gelatin extracted at different temperatures were(101.05±2.97),(104.35±3.54),(107.59±0.37),(97.80±4.21),(95.35±2.60),(92.52±3.15)and(89.66±1.23)℃,respectively. The extraction temperature affects the internal storage energy of the gelatin solution by changing the molecular weight of the gelatin,thereby affecting the rheological properties of the gelatin solution.