In order to improve the pectin-degrading efficiency in wet processing of Arabica coffee in Yunnan, Box-Behnken design and single factor experiment were used to optimize the fermentation conditions of five pectinolytic...In order to improve the pectin-degrading efficiency in wet processing of Arabica coffee in Yunnan, Box-Behnken design and single factor experiment were used to optimize the fermentation conditions of five pectinolytic Wickerhamomyces anomalus strains from the fermentation broth of Arabica coffee in Baoshan, Yunnan during wet processing with pectase activity as an indicator. The results showed that the five strains all synthesized pectin lyase(PL), polygalacturonase(PG), and pectin methylesterase(PM).Among them, strain CAP5 had strong ability to produce PG and PL,while strain CAP4 secreted a large amount of PM. Under optimized conditions, the activity of PG, PL, and PM of the five strains came in at 250.17~411.20 U/mL, 12.98~16.55 U/mL, and 208.52~322.83 U/mL,respectively. The four factors of nitrogen source concentration,fermentation time, Mn2+ concentration, and pH value were optimized and the optimal pectinase-producing fermentation conditions for five strains were as follows: peptone 2.2 g/L, fermentation time 30 h, Mn2+ 1.5 mmol/L, and pH 4.3. After fermentation under the optimized conditions, the maximum PG activity of CAP5 amounted to 411.20 U/mL, 114.03% higher than that before optimization.Meanwhile, the PG activity of strains CAP3, CAP4, CAP8, and CAP10 increased by 86.74%, 114.55%, 65.79%, and 66.07%,respectively, and the activity of PL and PM of the five strains rose 150.35%~218.56% and 341.07%~418.52%, respectively. These findings suggested that W. anomalus strains could be used as coffee starter and had great potential for the lysis of pectin.展开更多
异氰酸酯基(NCO基)含量是聚氨酯工业中重要的指标,关系到异氰酸酯预聚体中的反应活性,直接影响聚氨酯产品性能。文章应用Mettler Toledo T90电位滴定仪进行等当点滴定,以ASTM D5155—14 Standard Test Methods for Polyurethane Raw Mat...异氰酸酯基(NCO基)含量是聚氨酯工业中重要的指标,关系到异氰酸酯预聚体中的反应活性,直接影响聚氨酯产品性能。文章应用Mettler Toledo T90电位滴定仪进行等当点滴定,以ASTM D5155—14 Standard Test Methods for Polyurethane Raw Materials:Determination of the Isocyanate Content of Aromatic Isocyanates中方法A为指导,对比GB/T 12009.4—2016《塑料聚氨酯生产用芳香族异氰酸酯第4部分:异氰酸根含量的测定》(A)的优势与不同,筛选溶剂,最终确定了样品前处理方法与滴定参数。改进的滴定方法适合不同体系异氰酸酯中NCO基含量测定,满足精度(绝对误差<0.2%)要求同时降低废液产量。自动进样盘的配合使用降低了滴定过程耗时,是一种自动化程度高的化学分析法。展开更多
文摘In order to improve the pectin-degrading efficiency in wet processing of Arabica coffee in Yunnan, Box-Behnken design and single factor experiment were used to optimize the fermentation conditions of five pectinolytic Wickerhamomyces anomalus strains from the fermentation broth of Arabica coffee in Baoshan, Yunnan during wet processing with pectase activity as an indicator. The results showed that the five strains all synthesized pectin lyase(PL), polygalacturonase(PG), and pectin methylesterase(PM).Among them, strain CAP5 had strong ability to produce PG and PL,while strain CAP4 secreted a large amount of PM. Under optimized conditions, the activity of PG, PL, and PM of the five strains came in at 250.17~411.20 U/mL, 12.98~16.55 U/mL, and 208.52~322.83 U/mL,respectively. The four factors of nitrogen source concentration,fermentation time, Mn2+ concentration, and pH value were optimized and the optimal pectinase-producing fermentation conditions for five strains were as follows: peptone 2.2 g/L, fermentation time 30 h, Mn2+ 1.5 mmol/L, and pH 4.3. After fermentation under the optimized conditions, the maximum PG activity of CAP5 amounted to 411.20 U/mL, 114.03% higher than that before optimization.Meanwhile, the PG activity of strains CAP3, CAP4, CAP8, and CAP10 increased by 86.74%, 114.55%, 65.79%, and 66.07%,respectively, and the activity of PL and PM of the five strains rose 150.35%~218.56% and 341.07%~418.52%, respectively. These findings suggested that W. anomalus strains could be used as coffee starter and had great potential for the lysis of pectin.
文摘异氰酸酯基(NCO基)含量是聚氨酯工业中重要的指标,关系到异氰酸酯预聚体中的反应活性,直接影响聚氨酯产品性能。文章应用Mettler Toledo T90电位滴定仪进行等当点滴定,以ASTM D5155—14 Standard Test Methods for Polyurethane Raw Materials:Determination of the Isocyanate Content of Aromatic Isocyanates中方法A为指导,对比GB/T 12009.4—2016《塑料聚氨酯生产用芳香族异氰酸酯第4部分:异氰酸根含量的测定》(A)的优势与不同,筛选溶剂,最终确定了样品前处理方法与滴定参数。改进的滴定方法适合不同体系异氰酸酯中NCO基含量测定,满足精度(绝对误差<0.2%)要求同时降低废液产量。自动进样盘的配合使用降低了滴定过程耗时,是一种自动化程度高的化学分析法。
