Selective elution of tea catechins and caffeine from polyvinylpolypyrrolidone

Desorption of catechins and caffeine from polyvinylpolypyrrolidone (PVPP) was comprehensively investigated. The result showed that caffeine could easily be desorbed from PVPP by the tested solvents except n‐hexane, while catechins could only be thoroughly done by dimethyl sulphoxide (DMSO) and N, N‐dimethylformamide (DMF). Excellent desorption efficiency of DMSO and DMF might be attributed to their high dipole moments and H‐bond potentials. Addition of ethanol was recommended considering the elution efficiency and fluidity, but ethanol volume should be <40% (v/v) for DMSO or 20% (v/v) for DMF. Desorption would get to equilibrium within 1 h and followed the pseudo‐second‐order model. Caffeine and catechins could be separately desorbed through two‐stage elution procedure, that is, water or 20% aqueous ethanol for desorbing caffeine and part of nongalloylated catechins and DMSO/ethanol (8/2, v/v) for eluting the remaining catechins. Highly purified catechins (~95%) with high level (~70%) galloylated catechins would be achieved when the desorption procedure was applied in column chromatograph.     

A strategy for reducing CO2 emissions from buildings with the Kaya identity – A Swiss energy system analysis and a case study

Within the general context of Greenhouse Gas (GHG) emissions reduction, decomposition analysis allows the quantification of the contribution of different factors to changes in emissions as well as the assessment of the effectiveness of policy and technology measures. The Kaya identity has been widely used for that purpose in order to disaggregate carbon emissions into various driving forces. In this paper, it is applied for the analysis of emissions resulting from energy use at three different scales. First, a decomposition analysis of the carbon emissions for the complete Swiss energy system is presented using the future projections from the Swiss Energy Strategy 2050. The Kaya identity is then applied to the Swiss building sector after it is adapted with factors that are more relatable to building parameters, such as floor area instead of Gross Domestic Product (GDP). Finally, the last level of analysis is a small scale community energy system for a unique Swiss village that aims to significantly reduce its emissions. An energy strategy is developed and its effectiveness is assessed with the adapted Kaya identity and benchmarked against the Swiss average values. The presented method demonstrates how the performance of buildings under various retrofitting scenarios can be benchmarked against future emission targets.     

柑橘萜油微胶囊的开发与制备

以β-环糊精+阿拉伯胶+玉米糖浆为壁材,采用喷雾干燥对柑橘萜油进行微胶囊化,通过正交试验,确定出包裹柑橘萜油的最佳工艺条件为:进风温度200℃,出风温度75℃,芯材∶壁材质量比为1∶50,β-环糊精∶阿拉伯胶∶玉米糖浆质量比为2∶3∶5。并测定了柑橘萜油微胶囊在溶液中的释放性能,为该微胶囊的应用提供了很好的理论指导。     

3种淀粉对鸡肉糜盐溶蛋白特性影响及其配方研究

为获得鸡肉蛋白较好的凝胶特性,从而改善其肉糜的加工品质,探讨玉米淀粉、马铃薯淀粉和磷酸酯淀粉3种常用淀粉与鸡肉盐溶蛋白相互作用对鸡肉糜加工基本特性的影响。以盐溶蛋白析出质量浓度、活性自由巯基含量和相对疏水性为指标,分别研究单因素条件下3种淀粉对鸡肉盐溶蛋白特性的影响,并通过二次通用旋转试验筛选出在5%淀粉添加总量条件下3种淀粉在鸡肉糜中的最佳组合配方。单因素试验表明:所选3种淀粉均对鸡肉盐溶蛋白特性有着复杂影响。3种淀粉最佳配方为:玉米淀粉1.6%、马铃薯1.6%、磷酸酯淀粉1.8%,此时鸡肉糜中盐溶蛋白基本特性参量指标预计为:盐溶蛋白质量浓度24.3mg/mL,活性自由巯基含量0.004μmol/mg,相对疏水性值22.86。     

不同等级金牡丹乌龙茶品质和矿质元素差异分析

以不同等级金牡丹乌龙茶为试材,测定了不同等级金牡丹乌龙茶的感官审评得分、品质指标（茶多酚、咖啡碱、8种儿茶素、可溶性糖、游离氨基酸、茶氨酸、水浸出物和总黄酮）和8种矿质元素含量。等级越高的金牡丹乌龙茶水浸出物含量越高,特等奖水浸出物含量比一等奖和优质奖分别高1.07%和1.75%,且差异均达到显著水平（P<0.05）。咖啡碱、可溶性糖和总黄酮含量均为低等级显著高于高等级（P<0.05）。三个等级的茶多酚含量之间没有显著差异（P>0.05）。特等奖的酚氨比要显著低于一等奖和优质奖（P<0.05）。优质奖的茶氨酸含量要显著低于特等奖和一等奖（P<0.05）。线性回归分析表明,游离氨基酸和总黄酮与审评得分呈显著线性负相关（P<0.05）,可溶性糖与审评得分呈极显著线性负相关（P<0.01）,而水浸出物与审评得分呈极显著线性正相关（P<0.01）。不同等级金牡丹乌龙茶除Mn和Fe外,大多数矿质元素之间不存在显著差异（P>0.05）。限制性主坐标分析表明,品质指标结合限制性主坐标分析可以很好的区分金牡丹乌龙茶等级差异,R值达1.00。但矿质元素结合限制性主坐标分析并不能很好的区分不同等级金牡丹乌龙茶的品质差异。研究结果为金牡丹乌龙茶品质鉴定提供相关参考依据。     

基于多元统计分析的不同安溪铁观音茶产品的化学品质

对6 款3 个批次不同风格的安溪铁观音茶进行感官审评分析,并使用气相色谱-质谱联用法、多元统计分析的主成分分析、偏最小二乘法和层次聚类分析等方法,对其化学品质进行研究。结果表明：6 款产品在感官审评上具有一定差异;含水率、游离氨基酸、黄酮类物质是造成不同茶产品滋味差异的关键成分,清香型茶产品A、B具有较高含水率、游离氨基酸,滋味呈“清醇、鲜醇”;浓香型茶产品C、D的含水率、游离氨基酸、黄酮类物质含量居中,滋味呈“醇和、较醇厚”;浓香型产品E、F具有较高含量的黄酮类物质,滋味呈“醇厚、浓醇”;这些滋味成分差异主要受焙火工艺影响。吲哚、茉莉内酯、己酸叶醇酯是决定不同茶产品香气特征的关键成分,清香型产品A、B的吲哚、茉莉内酯、己酸叶醇酯相对含量较高,香气呈“清高”,产品A比产品B具有更多含“青气”的酯类香气物质;浓香型茶产品C、D的吲哚、茉莉内酯香气成分含量最低,香气呈“较浓郁”,产品D的吲哚、茉莉内酯、己酸叶醇酯均稍高于产品C,因而香气更好;浓香型茶产品E、F的吲哚、茉莉内酯香气成分含量居中,烘焙程度稍高,因而香气“浓郁”具有“花果香”,产品F具有更多醛类香气,可能是产品F香气“馥郁”、“花果香”的原因;香气成分差异主要受产品原料以及焙火工艺影响。本研究期望通过化学品质的数据化,为安溪铁观音产品的精制生产、品质管理、风味创新提供一定理论依据。     

基于非靶向代谢组学方法探究德昂酸茶与普洱茶（熟茶）之间的成分差异

为了探究使用云南大叶种茶树制作不同种类的发酵茶德昂酸茶和普洱茶（熟茶）（以下简称“普洱熟茶”）之间的代谢产物差异,采用超高效液相色谱-四极杆飞行时间质谱技术,对德昂酸茶和普洱熟茶进行非靶向代谢组学研究。结果发现,德昂酸茶和普洱熟茶虽原料相同但因其加工方式不同,而存在较大的代谢物差异。通过主成分分析和正交偏最小二乘判别分析可以显著区分不同发酵工艺茶叶中的代谢产物,共检测出21 类268 种显著性差异代谢产物,占所有代谢物的63.81%,主要包括49 种氨基酸类、39 种脂肪酸、36 种核苷酸类、29 种有机酸、18 种糖类。其中,麦角硫因、3,4-二甲氧基苯乙酸、3-羟基扁桃酸、氯化乙酰胆碱、2-羟基-4-甲基戊酸、米格列醇、L-脯氨酸、4,6-二氧代庚酸、丙二醇、原花青素B2、N-乙酰甘氨酸等差异代谢产物对于不同发酵工艺的茶叶不同滋味品质的形成可能具有重要贡献。京都基因与基因组百科全书代谢通路分析发现,德昂酸茶和普洱熟茶的氨基酸和核苷酸类物质代谢水平具有显著差异,涉及氨基酸代谢和核苷酸类代谢相关的通路对不同发酵工艺茶叶的滋味品质有重要影响。该研究从植物代谢组学角度揭示德昂酸茶和普洱熟茶的代谢产物差异性。     

Quantitative assessment of risk associated with dietary intake of mycotoxin ochratoxin A on the adult inhabitants in Shanghai city of P.R. China

Mycotoxin ochratoxin A (OTA) is considered to be a possible risk factor for adverse effects in humans. In the present study, quantitative assessment of risk associated with dietary intake of OTA was performed based on consumption habits of the representative adult inhabitants in Shanghai city of P. R. China. Firstly, a total of 400 food samples randomly collected from different locations of Shanghai were analyzed by the previously established isotope dilution LC–MS/MS method. Then, 265 participants of 70 males and 195 females as representative inhabitants were invited to answer the designed questionnaire about the quantity and frequency of foods including four major varieties of grapes, cereals, beans and dried fruits as well as their derived products. Finally, all data were simulated by the point evaluation and model evaluation for the risk assessment of OTA contamination. Results from the point evaluation indicated that mean value of daily intake (DI) of OTA was 1.147 ng/kg body weight/day, which was lower than all the reference standards. However, DI value (8.566 ng/kg body weight/day) in the high percentile (97.5th) was obviously higher than the PTDI (5 ng/kg body weight/day) proposed by Scientific Committee on Food. Among the different groups of foods, OTA in cereals and derived products made the largest contribution to the potential healthy risk. The mean DI value and 97.5th percentile were 1.093 and 7.962 ng/kg body weight/day, respectively, indicating that more than 90% of the risk was due to the contamination of OTA in cereals and derived products. On the other hand, similar results were obtained by the Monte Carlo assessment model. Thus, from the currently available data and analyzed results on the adult inhabitants, regarding OTA contamination issues on food safety administration of Shanghai, there was no significant attention which should be paid on food consumption in Shanghai, besides cereals and derived products with very little possibility as the risk factors.