黑曲霉固态发酵改善木薯渣品质的研究

Quality Improvement of Cassava Residue by Solid-State Fermentation with Aspergillus niger

本试验旨在研究黑曲霉固态发酵对木薯渣营养价值的影响,并探讨最佳的木薯渣发酵工艺参数。先采用单因素试验设计,根据发酵后木薯渣的营养价值,分别筛选出最佳的黑曲霉接种量、菜籽粕添加量、发酵时间、发酵温度、料水比以及初始pH。在此基础上采用正交试验设计,考察发酵时间、发酵温度、料水比以及初始pH间交互作用对木薯渣营养价值的影响。结果表明:1)每克发酵原料接种3×106个黑曲霉孢子,添加15%的菜籽粕,料水比1∶1.50,初始pH4,在36℃条件下发酵4 d效果最好。2)最优条件发酵后,与对照组相比,以干物质为基础,粗纤维含量由22.26%降低到17.71%(P<0.05),还原糖含量由1.42%提高到5.11%(P<0.05),粗蛋白质含量由8.67%提高到13.48%(P<0.05),粗脂肪含量由7.89%提高到11.72%(P<0.05),粗灰分含量由6.02%提高到7.31%(P<0.05);此外,发酵后羧甲基纤维素酶活性达到9.05 U/g,滤纸酶活性达到2.37 U/g,β-葡萄糖苷酶活性达到2.25 U/g。由此可见,利用黑曲霉固态发酵可以显著提高木薯渣的营养价值。

In this study,a solid-state fermentation （SSF） using Aspergillus niger was conducted to improve the nutritional quality of cassava residue and the optimal fermentation parameters were investigated.Firstly,a single factor experiment design was adopted to screen the optimal fungi inoculation size,rapeseed meal supplemental level,fermentation time,fermentation temperature,the ratio of substrate to moisture and initial pH according to the nutritional value of fermented cassava residue.An orthogonal experiment design was further used to investigate the effects of fermentation parameters such as fermentation time,fermentation temperature,the ratio of substrate to moisture and initial pH on the nutritional quality of cassava residue.The results showed as follows：1） inoculated 3 × 106 Aspergillus niger spore per gram fermentation materials,added 15％ rapeseed meal,controlled the ratio of substrate to water 1：1.50 and fermented with initial pH 4 at 36 ℃ for 4 days could get the optimal result.2） Fermented cassava residue under the optimized condition described above and calculated based on dry matter,the crude fiber content was decreased from 22.26％ to 17.71％ （P＜0.05） and the reducing sugar content was increased from 1.42％ to 5.11％ （P＜0.05）,crude protein content was increased from 8.67％ to 13.48％ （P＜0.05）,crude fat content was increased from 7.89％ to 11.72％ （P＜0.05）,the ash content was increased from 6.02％ to 7.31％ （P＜0.05） after SSF,Moreover,after fermentation the enzyme activities of carboxy methyl cellulase,filter paper activity and β3-glucosidase reached 9.05,2.37,2.35 U/g,respectively.Our results suggest that the SSF with Aspergillus niger offers an effective alternative to improving the nutritional value of cassava residue.