Optimization of Enzymatic Hydrolysis Technology of Melanin from Sepia esculenta

In order to obtain high-quality Sepia esculenta melanin,the best process for enzymatic hydrolysis of Sepia esculenta melanin was studied by enzymatic hydrolysis. Based on the degree of hydrolysis,the optimum enzyme was selected from neutral protease,acid protease,alkaline protease,flavor protease and papain. Also response surface methodology was employed to study the effects of enzymatic temperature,enzyme addition and enzymatic hydrolysis time on the degree of hydrolysis of Sepia esculenta melanin to optimize enzymatic hydrolysis technology on the base of single experiment. The melanin structure was characterized by infrared spectroscopy,ultraviolet-visible spectrophotometry and scanning electron microscopy respectively. The experiment results indicated that the optimized enzymatic hydrolysis condition for Sepia esculenta melanin by flavoring protease was:ratio of material to water 2%,enzymatic temperature 51℃,primary pH7.0,enzyme addition 3750 U/g,and hydrolysis for 6.5 h. Under these conditions,the hydrolysis degree(DH)was(19.53±0.05)%,and the yield of melanin was 17.02%. Infrared spectroscopy showed that the extracted melanin had a typical anthracene ring structure;the absorbance of melanin was significantly increased after enzymatic hydrolysis by ultraviolet-visible spectrophotometry;the average particle size of melanin was significantly reduced by scanning electron microscopy,and the particle size was more uniform. It can be seen that the enzymatic hydrolysis of flavor protease can effectively improve the purity of Sepia esculenta melanin. This study can provide technical guidance and theoretical basis for the extraction and high value application of gold sepia melanin.