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。     

耐酸性木聚糖酶在清酒酿造中的作用

从华根霉 (RhizopuschinensisY92 )发酵液中通过离子交换色谱和凝胶过滤色谱分离纯化获得一种耐酸性木聚糖酶R ,将它和另外 2种耐酸性木聚糖酶 :米曲霉 (AspergillusoryzaeRIB12 8)木聚糖酶B和白曲菌 (AspergilluskawachiiIFO43 0 8)木聚糖酶C分别应用于清酒酿造中 ,结果表明 ,木聚糖酶B可以促进米细胞的溶解 ,对于原料米的利用率有明显的提高 ,而木聚糖酶C和木聚糖酶R的作用则不太明显     

Rhizopus chinensis 12#发酵产生纤溶酶的分离提纯

分离自南方小酒药的华根霉12#(Rhizopuschinensis12#)以豆粕和麸皮为原料固体发酵可产生多种纤溶活性组分.采用饱和度40%～70%的硫酸铵溶液分步盐析、OctylSepharoseFastFlow疏水层析、Q SepharoseHighPerformance离子交换层析和SephacrylS 100凝胶层析方法对活性组分进行分离提纯,得到电泳纯的纤溶酶.SDS PAGE方法测定该酶相对分子质量为18000,凝胶过滤方法测定相对分子质量为16600,表明该酶由单亚基组成.     

Determining consumer purchase intentions: the importance of dry matter, size, and price of kiwifruit

Abstract: Knowledge of the relative importance of food quality attributes in determining consumer purchase intention is critical for robust assessment of economic opportunities for industry growth. The aim of this study is to demonstrate how conjoint analysis methodology that incorporates tasting of fruit can be used to collect such information. Three hundred Japanese consumers took part in research designed to measure the importance of dry matter (DM), size, and price of kiwifruit (Actinidia deliciosa “Hayward” and Actinidia chinensis “Hort16A”) for purchase intention. Measurement of consumer liking for kiwifruit of different DM content was a key first step. Liking increased as DM increased and was accompanied by increased purchase likelihood/choice probability for kiwifruit. The size of kiwifruit presented to consumers varied from “small” to “extra large.” Consumers liked “mid‐sized” kiwifruit over “small” or “extra‐large” kiwifruit. Despite these differences in liking, size was of little importance in determining purchase likelihood/choice probability for kiwifruit. Price was a very important factor in determining purchase likelihood/choice probability but was less important than DM content. As price increased, purchase likelihood/choice probability decreased. Beneath these general findings, heterogeneity existed. Some consumers placed more/less importance on the focal purchase drivers than suggested by the aggregate model. Overall, the results suggest that incentive schemes already implemented by industry should consider rewarding high‐DM fruit more than fruit size. Practical Application: This research has contributed to the New Zealand kiwifruit industry gaining a better understanding of the relative importance consumers place on DM, size, and price of kiwifruit and has resulted in changes to grower incentive schemes. The research approach presented forces consumer to tradeoff attributes of kiwifruit against each other and decide on how important two key quality attributes—DM and size—are relative to each other and relative to price. The application of conjoint analysis in this article can be transferred to other fruits, food, and beverages and help guide consumer‐led innovation.     

蚕豆辣酱的研制

以蚕豆和辣酱为主要原料,利用米曲霉AS3.042、黑曲霉AS3.350、根霉Q303等多种菌种的协同作用,在温度先高后低的条件下固态发酵,所得产品与单一菌种发酵相比,酱香、酯香浓郁,鲜味有明显的提高,氨基酸氮提高了30.2%、全氮提高了11.2%。     

满山香子多糖的膜分离研究

研究以满山香子为原料提取多糖的过程及工艺。利用超滤膜分离装置进行满山香子多糖的分离,对影响超滤的工艺条件,如压力、温度、时间进行考察,确定最佳的提取条件:满山香子∶水=1∶20,提取温度80℃,提取时间2h。提取物的多糖含量5.65%,超滤后的提取物中多糖含量达到80.29%,提取物得率为1.19%。     

中华绿螂抗氧化肽的提取及其抗氧化性

利用响应面法和超滤法对中华绿螂中抗氧化肽的木瓜蛋白酶水解提取工艺条件进行优化。在单因素试验基础上,利用响应面法分析建立二次回归模型。以酶与底物浓度比值([E]/[S])、酶解温度、酶解p H和酶解时间为自变量,DPPH自由基清除率为响应值,研究各因素及其交互作用对自由基清除率的影响。根据响应曲面图及其等高线图,确认木瓜蛋白酶水解中华绿螂制备抗氧化肽的最优工艺条件:底物浓度6%、pH 4.11、酶解温度40℃、酶解时间3.09 h。在此条件下,中华绿螂抗氧化肽对DPPH自由基清除率为97.64%。所得回归模型高度显著(p<0.0001),与理论预测值基本吻合。根据超滤试验可知,超滤膜截留分子质量3000~1000 Da时抗氧化性最佳,超滤所得可溶性蛋白酶解物的抗氧化性为94.96%。     

Analysis and characterization of aroma‐active compounds of Schizandra chinensis (omija) leaves

Volatile components from leaves of Schizandra chinensis (omija), a native plant of Korea, were extracted by simultaneous distillation–extraction (SDE) and analyzed by gas chromatography–mass spectrometry (GC‐MS) using two types of capillary column with different polarities (DB‐5MS and DB‐Wax). The GC‐MS analysis of volatile compounds obtained by SDE revealed that germacrene D is the most abundant compound (22.6%) in omija leaves, followed by β‐elemene (17.4%), (E)‐2‐hexenal (8.7%), and (E)‐β‐ocimene (7.2%). Aroma‐active compounds were determined by gas chromatography–olfactometry (GC‐O) using the aroma‐extract‐dilution analysis method. (E,Z)‐2,6‐Nonadienal (cucumber) was the most intense aroma‐active compound due to its higher flavor‐dilution factor (243–729) than any other compound. (Z)‐3‐Hexenal (green/apple), (E)‐2‐hexenal (green/fruity), and (E)‐β‐ocimene (wither green/grass) were also identified as important aroma‐active compounds by GC‐O. In addition, the volatile compounds were extracted by solid‐phase microextraction (SPME), and the quantitative analysis of the SPME samples gave slightly different results, depending on the type of SPME fiber, compared with those from SDE, However, the aroma‐active compounds identified in SPME were similar to those in SDE. Copyright © 2004 Society of Chemical Industry     

Purification and biochemical characterization of an intracellular lipase by Rhizopus chinensis under solid‐state fermentation and its potential application in the production of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)

BACKGROUND: Purification and characterization of an intracellular lipase produced by Rhizopus chinenesis cultured in solid‐state fermentation was investigated. The potential application in concentrating eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) from fish oil by the pure enzyme was also studied. RESULTS: Through four successive purification steps, the enzyme was purified to homogeneity with an apparent molecular mass of 36 kDa. The lipase was active for pH between 7.0 and 9.0 and temperatures 20–45 °C. Lipase activity was slightly increased in the presence of Ca²⁺ and Mg²⁺, but strongly inhibited by Hg²⁺ and SDS. The pure enzyme was most active on medium chain p‐nitrophenol esters, with the highest activity towards pNP‐caprylate (C8). The enzyme is a non‐specific lipase, because it cleaved not only the 1,3‐positioned ester bonds but also the 2‐positioned bond in triolein. High EPA (17.6%) and DHA (32.9%) contents were achieved using the pure lipase (100 U) within 10 h. CONCLUSION: The enzymatic activity of the lipase on a wide variety of substrates and its stability in the presence of some organic solvents suggest that the lipase should be investigated for a range of commercial applications. The pure lipase was proved to possess potential ability for the production and concentration of EPA and DHA from fish oil. Copyright © 2008 Society of Chemical Industry