凉茶渣的黑曲霉发酵工艺和抗氧化活性研究

为促进凉茶渣在畜牧业中的资源化利用，本研究以黑曲霉为菌种固态发酵凉茶渣，首先在单因素试验条件下考察了时间、温度、含水量、浸泡液pH、氮源和碳源对凉茶渣降解率和产物pH的影响；再根据单因素试验结果和规模化生产实际需要，以4%硫酸铵为氮源，2%葡萄糖为碳源，以降解率为考察指标，通过正交试验优化发酵工艺；并通过检测超氧自由基清除率、羟基自由基清除率和1，1-二苯基-2-三硝基苯肼（DPPH）自由基清除率，评价凉茶渣在最优工艺条件下发酵前后抗氧化活性的变化。结果发现，含水量为60%，浸泡液pH为9.0，31℃发酵168 h是凉茶渣的最佳发酵工艺参数。最佳工艺条件下凉茶渣的降解率为25.23%，发酵产物pH为4.53。当凉茶渣发酵前水提液浓度为24 mg/mL时，超氧自由基清除率为43.56%，羟基自由基清除率为47.06%，DPPH自由基清除率为90.71%；当最优条件下发酵产物水提液浓度24 mg/mL时，超氧自由基清除率为30.77%，羟基自由基清除率为95.63%，DPPH自由基清除率为87.36%。本试验结果表明，黑曲霉是适宜的凉茶渣发酵菌种，且凉茶渣经过黑曲霉发酵后具有良好的抗氧化活性。

Study on the Fermentation Process of Herbal Tea Residue by Aspergillus niger and Antioxidative Activity

In order to promote the resource utilization of herbal tea residue,the solid-state fermention using Aspergillus niger was adopted in this study.The effects of six single factors,including time,temperature,water content,initial pH,nitrogen source,and carbon source,on the degradation rate of herbal tea residue and product pH after fermentation were investigated.According to the single factor experimental results and the actual situation of large-scale production,4%ammonium sulfate was used as nitrogen source,2%glucose as carbon source,through orthogonal experiments,the fermentation process was optimized with the degradation rate as the index.The antioxidant activity of herbal tea residue before and after fermentation was evaluated by measuring superoxide radical scavenging rate,hydroxyl radical scavenging rate and DPPH radical scavenging rate.It was found that the optimal parameters of fermentation were water content 60%,pH 9.0,31℃for 168 h.Under the optimum conditions,degradation rate of herbal tea residue was 25.23%,products pH was 4.53.As the concentration of water-extract of herbal tea residue before fermentation was 24 mg/mL,the scavenging rates of superoxide radical,hydroxyl radical and DPPH radical were 43.56%,47.06%and 90.71%,respectively.When the water-extract concentration of product was 24 mg/mL,the scavenging rates of superoxide radical,hydroxyl radical and DPPH radical were 30.77%,95.63%and 87.36%,respectively.The results showed that Aspergillus niger was suitable for fermentation of herbal tea residue,and herbal tea residue had good antioxidant activity after fermentation by Aspergillus niger.