Enzymatic assisted extraction of gelatin from Beloga (Huso huso) fish skin in response surface method (RSM)

Fish gelatin, by benefiting the lower melting point, quicker mouth melting and presenting elastic characteristics is considered as the most proper substitute for mammalians gelatin and as a Halal food item. The aim of this study was to evaluate the effects of temperature at three levels of 30, 40 and 50 ºC, enzyme at 0.055%, 0.01% and 0.1% (w/w) levels and pH at 2, 3 and 4 levels on the quality of extracted gelatin from Huso huso fish skin. Accordingly, the gel strength in form of breaking force and distance, yield and color (L*a*b*) and whiteness of resultant gelatin were determined. According to the results, the highest gelatin yields as 21.65% was related to the enzymatic assisted method at 50 ºC, 0.01% enzyme at pH=2, whereas it was obtained as 10% at the chemical extraction method. Based on the results, despite from temperature, by increasing of pH and enzyme percentage, the firmness of gelatin was increased (p<0.05). The highest firmness was recorded at 30 ºC, 0.1% enzyme at pH=4. The color data revealed that lightness (L*), redness (a*) and whiteness of enzymatic extracted gelatin powder was higher that the chemical extracted one (p<0.05). The highest lightness was observed at 40 ºC, 0.055% enzyme at pH=3. In conclusion, by application of 30 ºC and 0.1% enzyme at pH=4 the highest gelatin with the highest firmness is achievable, while using 50 ºC and 0.01% enzyme at pH=2 could results the gelatin yield.