Objective In order to reduce the loss of collagen caused by enzymatic unhairing in the pretreatment of cowhide edible processing, the protease-glycosidase composite enzymatic unhairing was carried out, and the best unhairing process and edible quality change were discussed.
Methods The content of soluble protein, glycosaminoglycans (GAGs), collagen and depilation rate in the enzymatic hydrolysate were determined as evaluation indexes. The enzyme activity ratio, enzymatic hydrolysis temperature, enzymatic hydrolysis pH, enzyme concentration and enzymatic hydrolysis time were set for single factor experiment. The response surface optimization experiment was carried out on the significant factors, and the changes of edible quality were evaluated by shear force, color difference and texture parameters.
Results The optimum condition was as follows: (xylanase: neutral protease) enzyme activity ratio 7∶3, enzymatic hydrolysis temperature 50 ℃, enzymatic hydrolysis pH 7.0, enzymatic hydrolysis concentration 800 U/mL, enzymatic hydrolysis time 4 h, the comprehensive score reached 89.674% ± 0.477%; compared with the neutral protease treatment, the content of collagen in the enzymatic hydrolysate was significantly reduced by about 68.78% (P<0.01). Scanning electron microscopy and HE staining showed that there were holes in the hair follicles after enzymatic hydrolysis. With the increase of brightness value, hardness, adhesiveness and chewiness decreased significantly (P<0.05), elasticity increased, and shear force decreased by about 35.2%.
Conclusion The composite enzymatic method has a thorough degree of hair removal and low loss of collagen components, which can effectively improve the color, tenderness, and some texture of cowhide, providing reference for the development and utilization of brown cowhide series products.
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