绿豆淀粉/PVA复合膜的制备及性能研究

采用流延法,制备一种含绿豆淀粉与聚乙烯醇(PVA)复合膜,并对其性能进行评价。采用单因素实验研究了绿豆淀粉与PVA比例、交联剂、增塑剂等因素对膜性能的影响,并利用正交实验法对绿豆淀粉与PVA质量比、增塑剂用量和交联剂用量进行的优化。结果表明,以绿豆淀粉∶PVA质量比、甘油和乙二醛的质量分数分别为7∶3(g/g)、20%、8%制备的膜的拉伸强度、断裂伸长率、透光率最佳,分别为(17.3±0.25)MPa、112%±2.15%、28.2%±0.23%。      

黄瓜黄酮类化合物的抗氧化作用

以70%乙醇为溶剂提取黄瓜黄酮类化合物,并对其黄酮含量进行测定;采用水杨酸比色法测定黄瓜中黄酮类化合物对羟基自由基的清除效果.结果表明:黄瓜中含有黄酮类化合物;且黄瓜中黄酮类化合物对羟基自由基有明显的清除效果,清除率达63.95%.     

The effect of acid and glucoamylase hydrolysis on partial physicochemical properties and characteristics of Dioscorea alata Linn. starch

Dioscorea alata Linn. (D. AL) rich in starch was widely used as food and medicine. This work aimed to compare the effect of acid and glucoamylase on the starch of different reaction time. The physicochemical properties of the native and hydrolyzed starches, such as swelling power (SP), starch solubility (SOL), and paste clarity were also determined in this study. The native and modified starches by acid and glucoamylase were compared and characterized by scanning electron microscope (SEM) and secondary derivative FT‐IR spectroscopy. The morphological characteristics of native D. AL starch granules revealed by SEM varied from round to oval or elliptic with smooth surface. SEM showed that glucoamylase primarily attacked the exterior of starch granules and permeate into the interior by the cracks formed on the surface. Owing to acid hydrolysis, the starch granules were depressed and transformed to bread‐like in shape and then broke into irregular lumps with particles adhered. From secondary derivative FT‐IR spectrum, the intensities of the two peaks from acid and enzyme hydrolysis starches at 1137 and 1066/cm were stronger than native starch. Some new peaks appeared due to hydrolysis. The digested starches exhibited a lower SOL and SP than native starch in water as the temperature increasing. The light transmittance of the digested starches was significantly higher than that of native starch paste and decreased with increase in storage period.     

一点红提取物体外抗氧化活性研究

目的:研究一点红提取物体外抗氧化活性。方法:通过水提醇沉、有机溶剂萃取、大孔树脂吸附纯化,得到六种不同部位的样品。以抗坏血酸和2,6-二叔丁基-4-甲基苯酚为对照,测定样品对羟基自由基和二苯基苦基苯肼自由基的清除能力,对Fe3+的还原能力,抑制油脂的氧化能力。结论:上述样品均具有一定的抗氧化活性,其中大孔树脂纯化的50%乙醇洗脱部位活性最好,但总体上弱于抗坏血酸和2,6-二叔丁基-4-甲基苯酚。     

罗布麻纤维的抑菌性及远红外性能

对罗布麻纤维的抑菌性进行了测试,罗布麻纤维对大肠杆菌的抑菌率为98%,对白色念珠菌的抑菌率为93%,结果表明罗布麻纤维对革兰氏阴性菌及真菌具有良好的抑菌性,且罗布麻中抑菌性物质的极性相对于水较弱。经远红外性能检测罗布麻纤维法向全发射率为87%,表明罗布麻具有发射远红外线的功能,发射的远红外线可以活化细胞、促进血液循环、增强组织再生能力及抑菌保暖等保健功效。     

落葵种子蛋白质提取工艺的研究

采用碱提酸沉的方法提取落葵种子蛋白,研究pH值、浸提温度、浸提时间和固液比对落葵子蛋白质提取率的影响。通过正交试验,确定较佳工艺条件为:pH值10、温度50℃、浸提时间1.5 h、固液比1∶15,该条件下蛋白质提取率为82.15%。     

芒果叶多糖的提取及含量测定

为生产各种食用品、化妆品、医药药品等多糖新产品提供重要原料,研究芒果叶多糖的提取条件和含量的测定。采用水提醇析的方法提取了芒果叶中多糖,采用硫酸-苯酚法进行了糖含量测定。结果显示,多糖在484 nm有最大吸收峰,求得其回归方程为A=0.126 9C-2.076 27×10-3,相关系数r=0.999 5;平均回收率为96.14%,RSD=1.094%(n=5)。芒果叶中多糖含量为1.516%。     

In vitro anti‐HSV‐2 activity and mechanism of action of proanthocyanidin A‐1 from Vaccinium vitis‐idaea

The aim of this study was to investigate the in vitro anti‐HSV‐2 activity and mechanism of action of proanthocyanidin A‐1, a compound isolated from Vaccinium vitis‐idaea Linn (Ericaceae). The results demonstrated that proanthocyanidin A‐1 exhibited anti‐HSV‐2 activity. The IC₅₀ value for the XTT assay was 73.3 ± 14.5 µM and the IC₅₀ and IC₉₀ values for the plaque reduction assay were 41.9 ± 2.0 and 62.8 ± 6.3 µM respectively. Proanthocyanidin A‐1 showed no cell cytotoxic effect at concentrations that blocked HSV‐2 infection, with a CC₅₀ value of 282.1 ± 27.5 µM . The mechanism studies demonstrated that proanthocyanidin A‐1 did not reduce viral infectivity but inhibited viral attachment and penetration and affected the late stage(s) of HSV‐2 infection. It was concluded that proanthocyanidin A‐1 suppressed HSV‐2 infection through many modes of action and thus merits further investigation. Copyright © 2004 Society of Chemical Industry     

Antibacterial and antioxidant activities of the essential oil and methanol extracts of Bidens frondosa Linn

Antibacterial and antioxidant potential of essential oil, extract and its fractions of Bidens frondosa Linn were evaluated. Sixty‐one components representing 95.41% of the total oil were identified. The essential oil (7.5 μL disc^?1), methanol extract and its different organic subfractions (0.5 μg disc^?1) of B. frondosa displayed a great potential of antibacterial activity against Staphylococcus aureus (ATCC 6538 and KCTC 1916), Listeria monocytogenes ATCC 19116, Bacillus subtilis ATCC 6633, Pseudomonas aeruginosa KCTC 2004, Salmonella enteritidis KCTC 12021 and Enterobacter aerogenes KCTC 2190. Antioxidant activity was evaluated by using 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) assay. The free radical scavenging activity of ethyl acetate (EtOAc) fraction was superior to all other fractions (IC₅₀ = 11.96 μg mL^?1), which was higher than synthetic antioxidant butylated hydroxyanisole, (IC₅₀ = 18.27 μg mL^?1). Furthermore, the amount of total phenolic compounds was determined and its content in EtOAc fraction was the highest as compared to methanol extract or other fractions. The results indicate that the oil and extracts of B. frondosa could serve as an important bio‐resource of antimicrobial agents and antioxidants for using in the food industries.     

夏枯草研究概述

夏枯草（Prunella vulgaris Linn）为临床常用中药,具有许多生物活性及药理作用。本文系统的介绍了夏枯草的化学成分、药理作用及其栽培研究等方面的研究进展。