Decomposition and Transformation of Aroma Compounds and Anthocyanins during Black Currant (Ribes nigrum L.) Juice Processin

ABSTRACT: Processing of black currant juice includes crushing, heating, enzyme treatment, pressing, pasteurization, clarification, and filtration. Changes in concentration of impact aroma compounds and anthocyanins during black currant juice processing in pilot plant scale were examined. Impact compounds were identified by gas chromatography-olfactometry and quantified by dynamic headspace and gas chromatography-mass spectrometer. Anthocyanins were analyzed by the pH-differential method. Identified aroma compounds comprised volatiles like esters, terpenes, terpenoids, and ketones. The reduction of aroma compounds and anthocyanins during the process was approximately 50 to 100% and 25%, respectively. The pressing step definitely had a negative effect on the concentration of aroma compounds and anthocyanins, and the heating treatments were mainly negative as well.     

不同粒度花椒籽黑种皮粉理化特性

为探讨不同粒度花椒籽黑种皮粉加工利用的差异性,本研究利用粒径测定、显微特征分析、红外光谱 分析等方法,比较了不同粒度花椒籽黑种皮粉的粒径、色度、微观结构、中红外光谱、吸附特性、活性物质 及其抗氧化活性之间的差异。结果表明：花椒籽黑种皮粗粉经超微粉碎后,粒度显著减小、色泽明显增亮, 可引起细胞壁破碎,持水力和持油力显著提高,分别提高了33.33%和44.60%,对重金属离子的吸附性显著增 强,但花椒籽黑种皮超微粉的官能团结构并未发生改变。随着粉体粒度的减小,花椒籽黑种皮超微粉中多酚和 黄酮的溶出量分别提高了15.93%和11.24%,对1,1-二苯基-2-三硝基苯肼自由基和2,2’-联氨-双-3-乙基苯并噻唑 啉-6-磺酸自由基清除能力显著增强（P＜0.05）。因此,超微粉碎可有效增加花椒籽黑种皮活性物质的溶出并提高 其抗氧化能力,从而提高了花椒籽黑种皮的有效利用率。     

填充型多相聚合物导电复合材料的PTC效应

以聚丙烯和低密度聚乙烯共混物为基体,用碳黑为填充材料制备了复合导电材料,导电性能的测试表明多相复合体系的渗滤阈值低于两相复合体系的渗滤阈值。对复合材料PTC效应的分析以及对材料的热性能测试结果表明碳黑在共混体系中的分布。同时探讨了体系碳黑含量的变化对PTC效应的影响。     

黑血糯米粉的物化性质研究

研究了黑血糯的营养成分,黑血糯淀粉的颗粒形貌和结晶性质,糊的凝沉性,冻融稳定性以及糊的粘度曲线。结果表明黑血糯的蛋白质含量高,氨基酸组成合理,结晶度高,糊化温度高,糊的凝沉性低,冻融稳定性一般。可知酸、碱可以促进黑血糯的糊化,而蔗糖则有一定的抑制作用。     

黑粒小麦麸皮中花色苷的提取及性质研究

为了对我校自主培育的黑粒小麦麸皮中花色苷进行开发利用,本试验以黑粒小麦麸皮为原料,进行了花色苷的提取条件和理化性质的研究。结果表明,用pH 1.0、40%的乙醇作提取剂,在料液比为1∶20(g/mL)、70℃条件下浸提80 min,提取效果最好,花色苷得率为14.5%;该花色苷可见光范围内的最大吸收波长为525 nm,pH对其影响明显,温度影响不大,60℃以内比较稳定。Mg2+、K+和Al3+对该花色苷有很好的增色、稳定作用,Ca2+和Fe2+对其稳定作用影响不大,Cu2+、Zn2+和Fe3+使其明显褪色。该花色苷耐氧化性、耐还原性差,耐光性好。蔗糖、柠檬酸对其有明显的褪色作用,苯甲酸钠在低质量浓度(<0.1 mg/mL)时对其基本无影响,在高质量浓度(>0.2 mg/mL)时有一定的褪色作用,盐对其有一定的增色、稳定作用。     

三波长分光光度法测定红茶及其饮料中黄酮的含量

采用三波长分光光度法测定红茶及其饮料中黄酮的含量,消除了由于红茶中黄酮光谱吸收峰不对称给定量分析造成的影响,并校正了基于干扰组分(饮料中添加剂)的吸收光谱具有线性吸收产生的基线倾斜。实验结果,回归方程为:DA=-3.221?0-4 0.06735C,相关系数r=0.9992;黄酮的浓度在1000~3000g/mL范围内,分别在波长为l1=470nm、l2=420nm、l3=370nm处测吸光度时,则DA与浓度C之间呈良好的线性关系,可按标准曲线法进行定量分析。本法的回收率为96.0%~107.0%,变异系数小于0.48%。方法的准确度与精密度均令人满意,而且操作简便易行。     

Comparison of bioactive phytochemical content and release of isothiocyanates in selected brassica sprouts

The consumption of brassica sprouts as raw vegetables provides a fair amount of glucosinolates (GLs) and active plant myrosinase, which enables the breakdown of GLs into health-promoting isothiocyanates (ITCs). This study reports the determination of the main constituents related to human health found in edible sprouts of two Brassica oleracea varieties, broccoli and Tuscan black kale, and two Raphanus sativus varieties, Daikon and Sango. Radish sprouts exhibited the highest ability to produce ITCs, with Daikon showing the greatest level of conversion of GLs into bioactive ITCs (96.5%), followed by Sango (90.0%). Tuscan black kale gave a value of 68.5%, whereas broccoli displayed the lowest with 18.7%. ITCs were not the exclusive GL breakdown products in the two B. oleracea varieties, since nitriles were also produced, thus accounting for the lower conversion observed. Measuring the release of plant ITCs is a valuable tool in predicting the potential level of exposure to these bioactive compounds after the consumption of raw brassica sprouts.     

乳状液膜法处理制浆黑液的研究现状

介绍了液膜分离技术应用于制浆黑液处理的方法和研究现状。     

黑液气化技术发展历程及趋势

碱回收炉是回收黑液中能源与化学品的主要设备,其能源利用率较低且存在爆炸危险,黑液气化技术是一种较有前景的替代方案。在回顾黑液低温与高温气化工艺发展历程的基础上,从能源和化学品回收的角度对比已实现商业化的Chemrec气流床高温气化工艺和MTCI流化床低温气化工艺。总结黑液气化技术存在的主要障碍,判断其发展的重要趋势。根据我国造纸工业现状,认为如果成功应用黑液气化技术将大幅提高黑液的能源利用率和碱回收水平。     

川北地区黑木耳中锌铁铜微量元素的测定

为了解不同产地黑木耳中金属元素含量是否与产地有关,采用火焰原子吸收分光光度法测定了绵阳、通江、青川、北川等地黑木耳中铜、铁、锌3种微量元素的含量。样品采用干法灰化和湿法消解进行处理。测定结果表明干法效果较好。同时对方法进行了准确度和精密度测定,其加标平均回收率为97%,RSD<3%。结果表明:4种黑木耳都含有丰富的人体必需的微量元素,不同产地黑木耳中同一种元素的含量不同。