Effect of Extraction Parameters on the Properties of Gelatin from King Weakfish (Macrodon ancylodon) Bones

Fish bones are important sources of collagen and are usually discarded by the processing industries. A response surface methodology was utilized to optimize the extraction process of gelatin from king weakfish (Macrodon ancylodon) bones submitted to alkali pre-treatment. The experimental responses were gel strength and gelatin yield, while the studied variables were sodium hydroxide concentration (2 and 4 g/100 g), maceration time (48 and 72 h) and extraction temperature (60 degrees C and 80 degrees C). An increase in extraction temperature carried out a significant (p <= 0.05) reduction in gelatin gel strength. The increase in the NaOH concentration during maceration increased the process yield. Extraction temperature, NaOH concentration and their interaction had a pronounced effect on process yield. High extraction temperatures resulted in higher yields, but reduced the strength of gelatin gel.