Determination of polyphenolic content and antioxidant activity of kudingcha made from Ilex kudingcha C.J. Tseng

The total polyphenol content and the antioxidant activity of kudingcha made from Ilex kudingcha C.J. Tseng were determined by Folin–Ciocalteu reagent, and DPPH, FRAP, and TEAC methods, respectively. The crude extract (CE) of kudingcha and its four fractions of chloroform (CfF), ethyl acetate (EaF), n-butanol (nBF), and water (WtF) were prepared and subjected to antioxidant evaluation and analysis by high performance liquid chromatography. The extracts of kudingcha contained large amounts of caffeoylquinic acid (CQA) derivatives, including 3-CQA, 5-CQA, 3,4-diCQA, 3,5-diCQA, and 4,5-diCQA, and showed potent antioxidant activity. The antioxidant activities of CE and its fractions decreased in the order of EaF > nBF > CE > WtF > CfF, according to the DPPH assay and FRAP assay, which were the same, with the exception of the rank order of CfF and WtF, as the TEAC assay. Furthermore, a satisfactory correlation between total polyphenol content and antioxidant activity was observed.     

糖化酶的研究概况

糖化酶是世界上生产量最大应用范围最广的酶类，介绍了糖化酶的结构组成、特性、生产、提取、活力检测以及提高酶活力的研究。     

芹菜中黄酮化合物的研究

以2个品种芹菜的叶、茎为材料,通过微波提取黄酮化合物,并通过芦丁标准曲线法对提取液黄酮化合物含量测定,通过DPPH法对提取液的抗氧活性进行测定。结果表明芹菜叶及茎中黄酮化合物含量及抗氧活性差异很大。黄酮化合物含量香芹叶>西芹叶>西芹茎,抗氧活性香芹叶>西芹叶>西芹茎。可见其抗氧活性与黄酮类化合物含量有直接的关系。     

不同菌种发酵对纳豆激酶活性及黏液成分影响

采用5株不同来源的纳豆菌JLTH-075、JLGZL-018、JLTH-157、JLCC-243、JLLY-214,通过纳豆发酵实验,研究不同菌株对纳豆激酶活力、黏液营养物质的影响,评价其发酵性能,为纳豆工业生产用菌筛选提供借鉴。结果表明,菌株JLGZL-018生产的纳豆激酶活性最高,为4 167 IU/g;其生产的纳豆黏液成分中总蛋白、可溶性总糖含量最高,分别为（17.38±0.54）%、（5.21±0.13）%;水解氨基酸总量适中,为（5.24±0.27） g/100 g,7种必需氨基酸含量最高,为（0.87±0.08） g/100 g;游离氨基酸各成分与其他4株菌无显著差别。菌株JLGZL-018综合发酵性能较好,具有开发应用潜力。     

杨梅素及其类似物抗氧化与乙酰胆碱酯酶抑制活性研究

目的:探讨杨梅素、杨梅苷及二氢杨梅素的抗氧化和乙酰胆碱酯酶抑制活性。方法:采用DPPH自由基清除和乙酰胆碱酯酶抑制高通量筛选模型进行研究。结果:杨梅素、杨梅苷和二氢杨梅素清除DPPH自由基的IC50值分别为18.34、28.89、10.70μg/mL,三种化合物的抗氧化活性均强于阳性药芦丁(IC50=31.32μg/mL),其中二氢杨梅素还强于VC(IC50=14.69μg/mL);在质量浓度为0.25mg/mL时,杨梅素、杨梅苷和二氢杨梅素对乙酰胆碱酯酶的抑制率分别为:30.66%±4.05%、38.48%±1.98%、78.81%±2.23%,其中二氢杨梅素对乙酰胆碱酯酶抑制作用较显著,其IC50值为1546±47.05μmol/L。结论:杨梅素、杨梅苷、二氢杨梅素均具有显著的DPPH自由基清除能力,本文首次报道二氢杨梅素具有较好的乙酰胆碱酯酶抑制活性,值得进一步深入研究。     

毛竹春笋提取物抗氧化活性研究

分别对毛竹春笋甲醇、己烷、氯仿、乙酸乙酯和水提取物的抗氧化活性和总多酚含量进行了测定.结果表明,乙酸乙酯提取物具有最强的抗氧化活性(DPPH和ABTS)和最高的总多酚含量.5种提取物的抗氧化活性与其总多酚化合物含量有显著的相关性.GC-MS图谱分析表明乙酸乙酯萃取物包含多种多酚化合物,HPLC图谱证实多酚化合物主要有邻苯三酚、邻苯二酚、阿魏酸和p-香豆酸等.     

虾类原肌球蛋白提取和活性的保持

蛋白质分离纯化的主要目的是研究其结构和理化性质,因此在分离纯化过程中应尽量保持原有的结构和性质。本文主要综述了甲壳类动物的主要过敏原-原肌球蛋白(Tropomyosin,TM)的结构,以及影响其结构稳定性的因素。同时讨论了分离纯化的方法及条件对原肌球蛋白结构和过敏原活性的影响,为提取高纯度且保留原有结构和活性的原肌球蛋白提供参考。     

Evaluation of the Chemical Composition and Antioxidant Activity of the Peel Oil of Citrus nobilis

Peel oil of Citrus nobilis (Lour) was analyzed for determining its chemical composition. Fourteen identified components accounted for 99.1% (GC) and 100.0% (FID) of the total oil. Major component of the oil was limonene (76.8%-GC and 86.2%-FID). Essential oil was also evaluated for its antioxidant activity in four complementary test systems namely; β-carotene/linoleic acid, DPPH radical scavenging, reducing power and metal chelating activities. In the first system, antioxidant activity increased with the increasing concentration. At 20.0 mg.ml^?1 concentration, antioxidant property of the oil was 96.8% ± 0.2 and as strong as the positive controls BHT and α-tocopherol. Scavenging effect of the oil was superior to the positive controls BHT and α-tocopherol at 1.5 mg.ml^?1 concentration (96.4% ± 0.1). Reducing power and chelating effect of the essential oil increased with the increasing concentration.     

油茶籽粕蛋白功能特性及其酶解产物抗氧化活性研究

采用碱溶酸沉法提取油茶籽粕中的蛋白质,运用正交试验优化提取的最佳条件,并分析油茶籽粕蛋白功能特性及其木瓜蛋白酶水解物的抗氧化活性。结果表明,在pH 10、料液比1∶30(m/V)、提取时间3h、提取温度50℃的最佳条件下,油茶籽粕蛋白的得率为4.99%。油茶籽粕蛋白等电点在pH 5左右。乳化能力、乳化稳定性和起泡能力随p H增加呈先降后升的趋势,与蛋白溶解度密切相关。木瓜蛋白酶能有效提高油茶籽粕蛋白溶解性,其蛋白水解物对DPPH·自由基和羟基自由基均具有很好的清除能力(清除率85%),对铜离子的螯合能力大于对铁离子的螯合能力。     

Effect of temperature and air velocity on drying kinetics, antioxidant capacity, total phenolic content, colour, texture and microstructure of apple (var. Granny Smith) slices

The aim of this work was to study the effect of temperature and air velocity on the drying kinetics and quality attributes of apple (var. Granny Smith) slices during drying. Experiments were conducted at 40, 60 and 80 °C, as well as at air velocities of 0.5, 1.0 and 1.5 m s⁻¹. Effective moisture diffusivity increased with temperature and air velocity, reaching a value of 15.30 × 10⁻⁹ m² s⁻¹ at maximum temperature and air velocity under study. The rehydration ratio changed with varying both air velocity and temperature indicating tissue damage due to processing. The colour difference, ΔE, showed the best results at 80 °C. The DPPH-radical scavenging activity at 40 °C and 0.5 m s⁻¹ showed the highest antioxidant activity, closest to that of the fresh sample. Although ΔE decreased with temperature, antioxidant activity barely varied and even increased at high air velocities, revealing an antioxidant capacity of the browning products. The total phenolics decreased with temperature, but at high air velocity retardation of thermal degradation was observed. Firmness was also determined and explained using glass transition concept and microstructure analysis.