鸡脚脱脂除杂蛋白预处理工艺

摘要:

以脱脂率、胶原蛋白损失和除杂蛋白效果为指标，研究超声波辅助下对鸡脚进行脱脂除杂蛋白的预处理工艺，为从鸡脚中提取胶原蛋白提供基础。索氏提取法测定鸡脚处理前后脂肪含量，计算脱脂率；高效液相色谱法测定处鸡脚理前后羟脯氨酸、脯氨酸、甘氨酸含量，计算胶原蛋白损失和评价除杂蛋白效果。首先考察了V(石油醚):V(乙醇)=1:1/NaCl溶液法、碱性脂肪酶溶液法、NaOH溶液法对脱脂率的影响。对料液比及超声时间/次数进行优化，得出采用V(石油醚):V(乙醇)=1:1/NaCl溶液法脱脂率最高，其次为碱性脂肪酶溶液法、氢氧化钠溶液法，而NaOH溶液法胶原蛋白损失最大。进一步设计V(石油醚):V(乙醇)=1:1与碱性脂肪酶溶液结合的两步法，优化两步的料液比及超声次数/时间，获得较佳工艺为：第一步，V(石油醚):V(乙醇)=1:1，料液比1:4（g/mL），超声萃取3次，每次用新的溶剂超声10 min；第二步，质量分数为2.5%的脂肪酶溶液（含0.05 mol/L NaOH，pH 8），料液比1:2（g/mL），超声处理40 min；脱脂率96.48%，胶原蛋白损失率9.31%，处理后鸡脚中羟脯氨酸、脯氨酸、甘氨酸占比与从鸡脚中热水提取的明胶相似，表明除杂蛋白选择性较好。

Abstract:

The technology of degreasing and removing miscellaneous protein in chicken feet by ultrasonic extraction was studied using degreasing rate, collagen loss and effect of removing miscellaneous protein as evaluation index. The hydroxyproline, proline and glycine of chicken feet after and before treatment were determined by HPLC. The effects of V(petroleum ether)∶V(ethanol)=1∶1/NaCl solution method, alkaline lipase solution method and NaOH solution method on the degreasing rate were investigated. Furthermore, the solid-liquid ratio and ultrasonic time/times were optimized. It was found that V(petroleum ether)∶V(ethanol)=1∶1/NaCl solution method showed the highest degreasing rate, followed by alkaline lipase solution method, while NaOH solution method showed the highest collagen loss. Then, a two-step treatment method of V(petroleum ether)∶V(ethanol)=1∶1/ alkaline lipase solution was designed and the optimized process was as follows: in the first step, V(petroleum ether)∶V(ethanol)=1∶1, solid-liquid ratio 1∶4 (g/mL), ultrasonic extraction for 3 times, each time using the new solvent ultrasonic 10 min; in the second step, 0.05 mol/L NaOH solution with mass fraction of 2.5% lipase (pH=8), solid-liquid ratio 1∶2 (g/mL), consecutive ultrasonic time 40 min. Under these optimum conditions, the degreasing rate was 96.48%, and the collagen loss was 9.31%. Besides, the proportions of hydroxyproline, proline and glycine in chicken feet by the two-step treatment method were similar to those in the gelatine extracted by hot water from the chicken feet after degreasing.