HPLC-DAD-Q-TOF-MS在线筛选鉴定牛蒡中的抗氧化成分

建立高效液相色谱-飞行时间质谱联用在线筛选并鉴定牛蒡提取物中抗氧化活性成分的方法。样品经在线色谱柱分离后进行分流,一路与稳定的1,1-二苯基-2-三硝基苯肼-甲醇溶液混合,实现在线筛选自由基清除剂;另一路进入二极管阵列检测器-串联三重四极杆飞行时间质谱,用于化合物的快速鉴别。负离子模式下,通过高分辨率质谱获得的相对分子质量结合化合物的紫外吸收特征,参考相关文献和部分对照品验证,从牛蒡乙酸乙酯相中筛选并鉴定出咖啡酸及衍生物19 种。本方法可实现快速定向筛选和鉴定食品及中药等复杂体系中的抗氧化活性成分。     

复合酶法制备椰子种皮油的研究

采用复合酶法从椰子种皮中提取高品质椰子种皮油。研究了椰子种皮原浆的预处理、复合酶组成、酶解温度和酶解时间对椰子种皮提油率和油品质量的影响。结果表明,复合酶法提取椰子种皮油的最佳工艺条件为:在100℃将椰子种皮原浆预煮2 h,加入20%的水,再添加0.1%木瓜蛋白酶、0.1%纤维素酶和0.2%果胶酶(均以椰子种皮原浆质量计),50℃酶解15 h。在最佳工艺条件下,椰子种皮提油率为16.8%;所得椰子种皮油品质良好,酸值(KOH)为2.19 mg/g,总酚酸含量为0.49 mg/mL,各项指标均比市售干法椰子种皮油显著提高。     

Optimization of eigenvalue selection in Chinese liquors discrimination based on electronic nose

An eigenvalue selection optimization method for Chinese liquors discrimination using electronic nose (e-nose) was proposed in this paper. Experiments on 13 Chinese liquors were conducted and e-nose responses were recorded. Eigenvalues of e-nose responses were selected and used in principal component analysis (PCA). The Chinese liquors were partially discriminated. The e-nose responses were analyzed by stochastic resonance method and systematic output signal-to-noise ratio eigenvalues were selected for PCA analysis. Experimental results demonstrated that the eigenvalue optimization improved the Chinese liquors discrimination results. This discussed method provided a promising way for food quality and safety examinations based on artificial olfactory system.     

耐酒精高产L-乳酸菌株的筛选及发酵培养基优化

为提高L-乳酸产量,降低L-乳酸的生产成本,该研究经过筛选、驯化获得一株耐酒精且高产L-乳酸的菌株鼠李糖乳杆菌AK-0779。使用玉米酒糟代替部分酵母粉作为菌株AK-0779发酵培养基的氮源。在单因素实验基础上,对葡萄糖添加量、酵母粉添加量和玉米酒糟添加量进行三因素三水平响应面优化试验。结果表明,最适发酵培养基为：葡萄糖添加量9.80%,玉米酒糟添加量0.98%,酵母粉添加量1.72%,L-乳酸产量为78.91 g/L,糖酸转换率为80.52%。与酵母粉完全充当氮源产L-乳酸82.36 g/L相比,产量无显著差异,说明玉米酒糟能有效代替部分酵母粉作为发酵培养基的氮源,降低L-乳酸生产成本。     

Ridgetail White Prawns,Exopalaemon carinicauda,Storage Time Rapid Determination Using Electronic Nose

Ridgetail white prawns, Exopalaemon carinicauda, storage time rapid determination method based on electronic nose was investigated in this paper. Prawns were stored at 4 °C for 9 days. Each day, electronic nose responses, and total volatile basic nitrogen index were measured during the storage period. Total volatile basic nitrogen index provided a freshness standard according to China standard protocols. Signal-to-noise ratio spectrum calculated by stochastic resonance discriminates prawn samples under different storage days successfully. Prawns' storage time determination model was developed based on signal-to-noise ratio eigenvalues. Validating experiments demonstrated that this model predicted prawn storage time with an accuracy of 90 %. Prawn freshness critical value ?82.77066 was also obtained by referring to total volatile basic nitrogen index and the developed model. This method is promising in seafood freshness evaluation.     

Effects of Different Pretreatments to Fresh Fruit on Chemical and Thermal Characteristics of Crude Palm Oil

This study selected 5 methods, including boiling, hot air drying, high‐pressurized steam, freezing, and microwave radiation to pretreat fresh oil palm fruit before solvent extraction of the oil. Using fresh fruit as a control, the pretreatment methods were compared for the effects on the activity of the 2 main enzymes in the fruit and some physicochemical properties of the crude palm oil. The results indicated, although all the 5 pretreatments could inactivate lipase and peroxidase in the treated flesh significantly (P < 0.05), the high‐pressurized steam was the most effective. There were also differences in the unsaturated fatty acid contents of the 6 oils. The crude oil from frozen fruit contained significantly more vitamin E (37829.33 ppm) than previously reported. Microwave radiation was shown to significantly decrease the free fatty acid content and the peroxide value, while increasing the oxidative stability index. Thermal behaviors of the oils were significantly different to each other with the exception a few parameters (P < 0.05).     

气相-离子迁移谱结合化学计量学方法快速区分不同年份酿造白酒

目的:建立了气相色谱-离子迁移谱(Gas chromatography-ion mobility spectroscopy,GC-IMS)技术结合化学计量学分析快速区分不同年份酱香型白酒的方法.方法:采用GC-IMS技术对多批次不同年份的酱香型酿造白酒样本中挥发性有机物进行分析,通过对比挥发性有机物含量差异快速生成指纹...     

基于特高压背景的江苏电网电压控制

在特高压交直流背景下,为全面分析特高压交直流电网的建设给江苏电网安全稳定运行带来的影响,重点选取江苏电网无功电压薄弱和区外交直流受电比例较高区域,针对严重故障方式,进行电网电压稳定研究计算,分析存在的无功电压问题。提出针对提高江苏电网本身动态无功储备能力的措施,以及利用直流本身特性来实现直流系统相互支援协调的措施,以期为江苏电网动态无功及电压控制提供参考。     

WZ12-1导管架设计中新技术新方法的应用

针对ＷＺ１２－１导管架在位分析和施工分析的特点,在设计中采用了一些新技术新方法,比较准确地模拟了结构的受力方式,解决了设计上的难点,优化了结构,节省了钢材,为今后的工程设计取得了有益的经验。     

向家坝地下洞室群施工通风效果三维数值模拟

金沙江向家坝水电站右岸地下厂房洞室群结构复杂、规模庞大、施工通风散烟难度大。为优化施工期的通风方案,改善实际通风效果,运用基于流体力学理论的三维数值模拟,对其不同通风方式下的通风流场形态进行了深入研究,定量分析了混合式通风布置、串联风机布置和风机安放位置的选择以及通风竖井等因素对改善其施工通风效果的作用,提出了洞内串联风机安放位置直接影响通风效果、负压通风机应距新鲜风源点较近等建议。