桑叶发酵工艺优化及营养价值评价

Optimization of Technology and Evaluation of Nutritional Value on Fermented Mulberry Leaves

为了提高桑叶的营养价值,进行了发酵桑叶的工艺优化研究。以发酵桑叶粗蛋白质和单宁含量为指标,以桑叶与麸皮质量比、菌种组合、接种量和发酵时间为影响因素,进行L 9(34)正交试验,以确定最佳发酵条件。根据正交试验结果进行验证试验和对比试验。结果表明:1)正交试验优化组合为,桑叶与麸皮质量比为9∶1,菌种组合为酒窖片球菌+地衣芽孢杆菌,接种量为2%,发酵时间为4 d。2)验证试验表明,优化组合发酵桑叶测得粗蛋白质含量为26.18%,单宁含量为4.73 g/kg,均优于正交试验表中最优值。3)对比试验表明,与未发酵桑叶相比,发酵桑叶粗蛋白质、粗脂肪、粗灰分、磷含量显著提高(P<0.05),单宁、中性洗涤纤维、碳水化合物含量和pH显著降低(P<0.05)。与未发酵桑叶相比,发酵桑叶精氨酸、丝氨酸、谷氨酸、天冬氨酸、总非必需氨基酸、总氨基酸含量显著降低(P<0.05),而丙氨酸含量、总必需氨基酸/总氨基酸、总必需氨基酸/总非必需氨基酸显著提高(P<0.05)。发酵桑叶的半胱氨酸+蛋氨酸、苏氨酸、亮氨酸、酪氨酸+苯丙氨酸组成均显著高于未发酵桑叶(P<0.05)。由此可见,发酵桑叶的最佳条件是:桑叶与麸皮质量比为9:1,菌种组合为酒窖片球菌+地衣芽孢杆菌,接种量为2%,发酵时间为4 d。发酵提高了桑叶的营养价值。

In order to improve the nutritional value of mulberry leaves,the optimization of technology of mulberry leaf fermentation was studied.The contents of crude protein and tannin in fermented mulberry leaves were used as indexes,the optimum fermentation conditions of fermented mulberry leaves were identified by an L 9(34)orthogonal experiment with mulberry leaves to bran mass ratio,strain combination,inoculation amount and fermentation time.The verification experiment and comparison experiment were carried out according to the results of orthogonal experiment.The results showed as follows:1)the optimal combination of orthogonal experiment was as follows,the mulberry leaves to bran mass ratio was 9∶1,the strain combination was Pediococcus cellicola+Bacillus licheniformis,the inoculation amount was 2%,and the fermentation time was 4 days.2)The verification experiment showed that the crude protein and tannin contents of the optimized combination fermentation of mulberry leaves were 26.18%and 4.73 g/kg respectively,which were better than the optimal values in the orthogonal experiment table.3)The comparison experiment showed that compared with unfermented mulberry leaves,the contents of crude protein,ether extract,ash and phosphorus in fermented mulberry leaves were significantly increased(P<0.05),and the contents of tannin,neutral detergent fiber and carbohydrate and pH were significantly decreased(P<0.05).Compared with unfermented mulberry leaves,the contents of arginine,serine,glutamic acid,aspartic acid,total non-essential amino acids and total amino acids of fermented mulberry leaves were significantly decreased(P<0.05),while the alanine content,total essential amino acids/total amino acids and total essential amino acids/total non-essential amino acids were significantly increased(P<0.05).The composition of cystine+methionine,threonine,leucine and tyrosine+phenylalanine of fermented mulberry leaves was significantly higher than that of unfermented mulberry leaves(P<0.05).In conclusion,the optimal condition for fermenting mulberry leaves is as follows,the mulberry leaves to bran mass ratio is 9∶1,the strain combination is Pediococcus cellicola+Bacillus licheniformis,the inoculation amount is 2%,and the fermentation time is 4 days.Fermentation improves the nutritional value of mulberry leaves.