Effect of Calcium Lactate, 4-Hexyl Resorcinol and Vacuum Packing on Physico-chemical, Sensory and Microbiological Qualities of Minimally Processed Litchi (Litchi chinensis Sonn.)

Litchi (Litchi chinensis Sonn.) fruits are very susceptible to pericarp browning which adversely affects consumer acceptability even though the aril portion remains in excellent condition. Litchi arils (litchis) were treated with a solution containing 0–2% (w/v) calcium lactate (CL), 0–0.02% (w/v) 4‐hexyl resorcinol (4‐HR) and 1% potassium sorbate. The pH of solution was adjusted to 4.0 with citric acid. Treated litchis were packed in polystyrene trays, over‐wrapped with polypropylene film, vacuum‐packed (0, 47409.3, 94831.9 Pa) and stored at 4 ± 2 °C. Drip losses, pH, total soluble solids (TSS), sensory attributes and microbiological quality of stored samples were estimated. A four‐factor, three‐level experimental design (D₆ Hokes design) with 19 experiments was chosen. Mathematical models were developed to analyse and predict the effect of CL, 4‐HR, in‐package vacuum and storage time on the responses. TSS, pH and sensory scores decreased significantly (P 0.01), whereas drip losses and microbial count increased significantly (P 0.01) with time. Drip loss was significantly (P 0.1) reduced by addition of CL. 4‐HR prevented browning and changes in colour score during storage were significantly less. Vacuum in packages exerted significant (P 0.01) effect over pH, TSS, sensory and microbiological qualities of minimally processed litchis.     

外源紫杉醇作用下南方红豆杉细胞凋亡及其动力学研究

利用光学显微照相技术、细胞总DNA琼脂糖凝胶电泳和TUNEL标记等手段 ,研究了外源紫杉醇(Taxol)作用下南方红豆杉细胞的凋亡及其动力学。研究结果表明 ,外源紫杉醇能显著提高南方红豆杉细胞凋亡的速率和发生率 ,表明高浓度紫杉醇不利于细胞的生长。凋亡动力学研究对指导大规模植物细胞培养生产紫杉醇具有重要意义     

高效液相色谱法测定南、北五味子中木脂素含量

建立了用高效液相色谱法测定南、北五味子中5种木脂素成分(五味子醇甲、五味子醇乙、五味子酯甲、五味子甲素和五味子乙素)的分析方法。以甲醇和水为流动相,采用梯度洗脱,对21个不同产地的南、北五味子样本进行了色谱分离,并利用标准物质、保留时间和紫外光谱对木脂素进行定性。结果表明,样品中各组分的色谱峰基本达到基线分离,该方法重复性好、灵敏度高,为评价南、北五味子中的木脂素活性成分提供了一种可靠的分析方法。     

野生金雀花营养成分研究

对金雀花的基本营养成分作了较为全面的分析测定.结果表明:金雀花鲜品粗蛋白含量为4.20%,氨基酸种类齐全,并含有VB1、VB2、尼克酸、VC、VE及胡萝卜素等多种维生素,矿质元素含量丰富,还含有适量的纤维素、碳水化合物、酸及果胶等营养成分;重金属、硝酸盐、亚硝酸盐含量均未超过国家标准.因此,金雀花营养成分种类齐全,含量丰富,具有较高的营养价值.     

甲嘧磺隆对两种滩涂动物的急性致毒试验

本文生要研究了甲嘧磺隆对鲈鱼、蛏两种主要的滩涂养殖生物进行了急性毒性研究,为甲嘧磺隆用于滩涂防治互花米草提供科学依据。结果表明：处理96h后对于鲈鱼和蛏的半致死浓度（LC50）分别为151．322和374．450mg／L,甲嘧磺隆对两种实验动物急性毒性属于低毒,对于两种滩涂养殖动物在急性毒性方面没有明显影响。     

δ-Tocomonoenol: A new vitamin E from kiwi (Actinidia chinensis) fruits

A new vitamin E, δ-tocomonoenol, has been isolated from Actinidia chinensis (kiwi) fruits. The new structure, 2,8-dimethyl-2-(4,8,12-trimethyltridec-11-enyl)chroman-6-ol, has been elucidated on the basis of EIMS, 1D, and 2D NMR spectral data. GC–MS analysis of peels and pulps of kiwi showed that the new compound, together with δ-tocopherol, is mainly present in the fruit peel, whilst α-tocopherol is present in a similar amount in both matrices. The compound was tested for its radical-scavenging and antioxidant capabilities, by measuring its ability to scavenge DPPH (2,2′-diphenyl-1-picrylhydrazyl radical) and anion superoxide radical, and inhibit the formation of methyl linoleate conjugated diene hydroperoxides and TBARS (thiobarbituric acid reactive species).     

Effects of spontaneous and inoculated fermentation on the volatile profile of lychee (Litchi chinensis Sonn) fermented beverages

The aim of this study was to evaluate the contribution of yeast to the volatile profile of beverages obtained by the fermentation of lychee must through inoculated (Saccharomyces cerevisiae strains UFLA CA116 , UFLA CA1183 and UFLA CA1174 ) and spontaneous fermentation. Higher alcohols and esters were the primary volatiles detected by SPME/GC–MS. A Principal Component Analysis indicated similarities between UFLA CA116 and UFLA CA1183 and between UFLA CA1174 and spontaneous fermentation. Changing the yeast strain used in the fermentation process has the potential to modulate the volatile profile of fermented beverages. The beverage produced by the inoculation of yeast CA1183 showed the most complex aroma profile compared to the other beverages.     

糯米糍荔枝叶片矿质养分含量充足范围的确定

对深圳市4个典型丰产园糯米糍荔枝叶片7种矿质养分(氮、磷、钾、钙、镁、锌和硼)含量的统计分析表明:采样地点和生育时期均对叶片营养元素含量有显著的影响。四个关键生育时期(末次秋梢老熟期、花芽形态分化期、谢花期和果实成熟期)的单株样与混合(多株)样的供试矿质养分含量之间大部分没有显著差异。本研究根据丰产园糯米糍荔枝叶片混合样的分析结果提出了7种矿质养分的充足含量范围。     

ICP-OES法快速测定白头翁中21种矿物元素

采用微波消解结合电感耦合等离子体发射光谱法(ICP-OES)对白头翁中21种元素含量进行了测定。所采用方法线性关系良好,r≥0.999 0,各元素检出限均低于0.003 6 mg/L,加标回收率为88%~105%,RSD均小于3.6%,具有良好的准确度和精密度。结果表明,白头翁中矿物元素含量丰富、重金属元素含量低于国家最低标准,符合安全用药标准。试验方法简单、快速、可靠、灵敏度高,可同时测定多种元素,满足样品分析要求。该研究结果可为开发利用白头翁药用资源提供基础资料。     

基于FWO法与CR法的中蒙边境森林草原交错区沟塘草甸羊草热解动力学分析

以内蒙古自治区阿尔山市内沟塘草甸为研究区域,选取典型草本羊草为研究对象,运用热重分析法以通氧速率10、20、30 mL/min,在升温速率分别为40、80 ℃/min的条件下进行热失重行为研究。使用TG-DTG曲线分析样品的热解过程,利用Coats-Redfern（CR）积分法和Flynn-Wall-Ozawa（FWO）积分法对样品的快速热解阶段进行动力学分析,得出在不同氧气浓度下样品的热解活化能和指前因子并求得相应参数。结果表明羊草热解过程分为：失水阶段、快速热解阶段、炭化阶段。其中快速热解阶段为350～450 ℃,此阶段中升温速率越快,温度滞后现象越明显;通氧速率越快,温度超前现象越明显。热解过程及动力学参数分析表明,Flynn-Wall-Ozawa法更适用于羊草热解过程,引发火灾危险程度的通氧速率为：30 mL/min＞20 mL/min＞10 mL/min。