不同年份甜型玫瑰香葡萄酒品质差异研究

研究了戎子酒庄不同年份甜型玫瑰香葡萄酒中的香气成分和花色苷的种类及含量,采用静态顶空气相色谱质谱联用仪和高效液相色谱仪检测出2010年葡萄酒中的香气成分21种、花色苷6种;2012年葡萄酒中的香气成分20种、花色苷6种;2013年葡萄酒中的香气成分21种、花色苷8种,2015年葡萄酒中的香气成分19种、花色苷6种;2016年葡萄酒中的香气成分17种、花色苷8种。结果分析得出,不同年份甜型玫瑰香葡萄酒中香气成分和花色苷组成及含量存在显著差异,其与葡萄酒的生产年份有一定相关性。     

HS-SPME-GC-MS测定中国四大名醋的香气成分

采用顶空固相微萃取气相色谱质谱联用仪对山西老陈醋、江苏镇江香醋、福建永春老醋、阆中保宁醋不同品牌和年份的8个 醋样进行香气物质检测分析。 结果表明,8个醋样含有酸类10种、酯类14种、醇类4种、酚类6种、醛类10种、酮类4种、吡嗪类5种、呋喃类 4种、其他类11种;四大名醋的香气成分种类繁多且差异明显,其具有各自的独有香气成分,其中山西老陈醋6种,镇江香醋5种,永春 老醋2种,保宁醋4种。 山西老陈醋的吡嗪类成分中2,3,5,6-四甲基吡嗪含量最高,平均580.75 μg/L;镇江香醋B2的乙偶姻中含量最高 为562.6 μg/L。 本研究为进一步研究各类食醋原料、微生物和香气成分之间的关系打下良好基础。     

糯米酒和糯米醋中香气物质分析

应用气相色谱-质谱联用技术对糯米酒和糯米醋中香气成分进行分析。结果表明:采用GC-MS方法分析糯米酒和糯米醋的香气成分,糯米酒中检测出22种香气成分,占总峰面积的90.70%;糯米醋中检测出23种香气成分,占总峰面积的88.56%。糯米酒与糯米醋含有相同的香气成分,主要为醇、酸、酯和酰胺类物质,且以醇类和酯类为主。糯米酒和糯米醋有各自特有的香气成分,糯米酒中含腈和呋喃,而糯米醋中含酮类物质。分析了糯米酒和糯米醋香气物质的变化情况。     

顶空固相微萃取- 气质联用分析四川麸醋的香气成分

研究四川麸醋的香气成分。采用顶空固相微萃取- 气质联用对市售三个厂家的6 个不同品种的四川麸醋的挥发性成分进行测定,并结合香气阈值与相对气味活度值对共有成分对总体香气的贡献进行评价。结果共检出75种挥发性成分,主要为酸类、酯类、醇类、酮类、醛类、呋喃类、吡嗪类等,其中12 种为共有成分;确定 其主体香气成分为乙酸乙酯、2,3- 丁二酮、壬醛、乙酸、癸醛、苯甲醛;此外,糠醛和2- 甲氧基-4- 甲基苯酚对总体香气也有重要贡献。这些成分一起构成了四川麸醋的主体香气。     

基于直接强度法的GC-O嗅闻分析不同醋龄镇江香醋香气活性成分

采用基于直接强度法的气相色谱嗅闻(GC-O)结合气相色谱质谱联用(GC-MS)分析4个醋龄镇江香醋香气活性成分。结果表明:在4个醋龄镇江香醋中共检测到50种香气活性成分,主要是酸、醇、酯、醛、酮和杂环化合物以及部分未能鉴定的香气活性成分。不同醋龄镇江香醋香气轮廓差异非常明显,新醋和经陈酿的镇江香醋风味轮廓差异显著,而经过较长时间陈酿的镇江香醋香气轮廓非常相似。大多数杂环化合物随镇江香醋醋龄的增加,香气强度显著增加。杂环化合物的差异是不同醋龄镇江香醋风味特征差异的主要原因之一。除食醋的主要呈味物质乙酸外,3-甲基丁酸、3-甲基丁醛、2,3-丁二酮、三甲基吡嗪以及一种未能鉴定的组分是不同醋龄镇江香醋香气最基本的组成成分。     

食醋特征香气成分分析研究

采用顶空固相微萃取与气相色谱-质谱联用对醋的香气成分进行了分析鉴定,得到了65种香气成分,主要成分为醇、酯、酸、醛、酮和杂环类化合物;根据风味贡献率理论,初步确定了8种香气成分为醋的特征香气。     

不同年份、不同葡萄品种葡萄酒品质特征分析研究

为比较不同年份、不同葡萄品种葡萄酒间理化性质及香气成分的差异,对葡萄酒的理化指标及香气物质进行分析测定。结果表明:干白葡萄酒的p H,干浸出物含量、色度、总酚含量显著低于干红葡萄酒,色调显著高于干红葡萄酒(p0.05);从两种葡萄酒中共鉴定出54种香气成分,鉴定出两种葡萄酒共有香气成分14种,其中酯类物质种类最多,且相对含量最高,为主要呈香物质。不同年份、不同葡萄品种葡萄酒间理化指标、香气种类、主要香气成分及相对含量均有差异。     

红枣醋不同发酵阶段香气成分的变化

采用顶空固相微萃取结合气质联用法,研究了液态发酵枣醋在不同发酵阶段产物(初始枣汁、枣酒醪和枣醋)的香气成分。从三种产物中分别分离鉴定出56、56、54种香气成分,各占总香气成分的94.57%、97.37%、98.86%,主要是烃类、酸类、酯类、醇类、醛酮类以及少量其他化合物。三种产物香气成分的种类总数差别不大,但种类构成比例和相对含量差异较大。在酒精发酵阶段,烃类、酮类物质明显增加,酸类、醛类物质有所增加,酯类、醇类物质基本不变;在醋酸发酵阶段,烃类、醇类、酮类物质降低,酸类、酯类物质显著升高。枣醋的香气成分主要来源于酸类和酯类物质,少量的烃类、醇类、酮醛类等物质也是枣醋香气成分不可或缺的一部分,这些香气成分共同赋予枣醋特殊的风味和品质。     

白云边年份酒香气成分分析

目的建立白酒中挥发性成分的定量分析方法,分析6种市售白云边年份酒的挥发性香气成分,确定重要香气贡献物质,揭示香气成分与酒样年份之间的关系。方法以固相微萃取为前处理手段,运用气相色谱及质谱联用技术、气相色谱-嗅闻技术,初步确定了酒样中的香气成分,采用标准加入法和外标法建立了白酒中挥发性成分的定量分析方法。结果对28种香气成分进行了定量分析。方法的检测限为0.05~78.26μg/L,相对标准偏差为5.7%~12.8%,大部分物质的回收率在80%~120%之间。根据香气活力值进一步筛选出了17种有香气贡献的物质,其中有12种物质对所有酒样均有重要的香气贡献。结论不同年份的酒样,所含挥发性物质种类相似,但各物质含量差异较大,且香气贡献成分对不同酒样的贡献程度也有很大差异。有12种物质的含量和香气活力值基本上随着酒龄的增加而递增。     

强化酯类合成,提升食醋品质

<正>食醋中的香气物质是反映不同食醋特征的重要成分之一,对醋的品质起着重要作用。据文献报道,已确认的食醋中!!!!!的香气成分有醇类、酯类、醛类、酚类、酸类、酮类和双乙酰7大类共103种。它们在醋中的含量极少,但却能赋予食醋特殊的芳香气味。食醋中的各类香气成分,主要来源于酿醋原料及发酵过程的生物代谢。发酵工艺、配料、曲种不同,其产品的香气成分及感官鉴定结果就截然不同。其中,酯类物质是食醋中很重要的香气成分之一。食醋中的酯类主要是乙酸丁酯、乙酸乙酯、乳酸乙酯     

Arsenic(III) oxidation by iron(VI) (ferrate) and subsequent removal of arsenic(V) by iron(III) coagulation

We investigated the stoichiometry, kinetics, and mechanism of arsenite [As(III)] oxidation by ferrate [Fe(VI)] and performed arsenic removal tests using Fe(VI) as both an oxidant and a coagulant. As(III) was oxidized to As(V) (arsenate) by Fe(VI), with a stoichiometry of 3:2 [As(III):Fe(VI)]. Kinetic studies showed that the reaction of As(III) with Fe(VI) was first-order with respect to both reactants, and its observed second-order rate constant at 25 degrees C decreased nonlinearly from (3.54 +/- 0.24) x 10(5) to (1.23 +/- 0.01) x 10(3) M(-1) s(-1) with an increase of pH from 8.4 to 12.9. A reaction mechanism by oxygen transfer has been proposed for the oxidation of As(III) by Fe(VI). Arsenic removal tests with river water showed that, with minimum 2.0 mg L(-1) Fe(VI), the arsenic concentration can be lowered from an initial 517 to below 50 microg L(-1), which is the regulation level for As in Bangladesh. From this result, Fe(VI) was demonstrated to be very effective in the removal of arsenic species from water at a relatively low dose level (2.0 mg L(-1)). In addition, the combined use of a small amount of Fe(VI) (below 0.5 mg L(-1)) and Fe(III) as a major coagulant was found to be a practical and effective method for arsenic removal.     

Iron(VI) and iron(V) oxidation of copper(I) cyanide

Copper(Il) cyanide (Cu(CN)4(3-)) in the gold mine industry presentsthe biggest concern in cyanide management because it is much more stable than free cyanide. Cu(CN)4(3-) is highlytoxic to aquatic life; therefore, environmentally friendly techniques are required for the removal of Cu(CN)4(3-) from gold mine effluent. The oxidation of Cu(CN)4(3-) by iron-(VI) (FeVIO4(2-), Fe(VI)) and iron(V) (FeVO4(3-), Fe(V)) was studied using stopped-flow and premix pulse radiolysis techniques. The stoichiometry with Fe(VI) was determined to be 5HFeO(4-) + Cu(CN)4(3-) + 8H2O - > 5Fe(OH)3 + Cu2+ + 4CNO- +3/202 + 6OH-. The rate law for the oxidation of Cu(CN)4(3-) by Fe(VI) was found to be first-order with each reactant. The rates decreased with increasing pH and were mostly related to a decrease in concentration of reactive protonated Fe(VI) species, HFeO4-. A mechanism is proposed that agrees with the observed reaction stoichiometry and rate law. The rate constant for the oxidation of Cu(CN)4(3-) by Fe(V) was determined at pH 12.0 as 1.35 +/- 0.02 x 10(7) M(-1) s(-1), which is approximately 3 orders of magnitude larger than Fe(VI). Results indicate that Fe(VI) is highly efficient for removal of cyanides in gold mill effluent.     

Mind the (yield) gap(s)

This paper explores the origin of the notion of ??yield gap?? and its use as a framing device for agricultural policy in sub-Saharan Africa. The argument is that while the yield gap of policy discourse provides a simple and powerful framing device, it is most often used without the discipline or caveats associated with the best examples of its use in crop production ecology and microeconomics. This argument is developed by examining how yield gap is used in a selection of recent and influential agricultural policy documents. The message for policy makers and others is clear: ??mind the (yield) gap(s)??, for they are seldom what they appear.     

Supercritical fluid extraction (SFE) of 4(5)-methylimidazole (4-MeI) and 2-acetyl-4(5)-(1,2,3,4)-tetrahydroxybutyl-imidazole (THI) from ground-coffee with high-performance liquid chromatographic-electrospray mass spectrometric quantification (HPLC/ESI-MS).

Two polar analytes, 4(5)-methylimidazole (4-MeI) and 2-acetyl-4(5)-(1,2,3,4)-tetrahydroxybutyl-imidazole (THI), were extracted with supercritical carbon dioxide (CO2) modified with aqueous methanol. The method was applied to a roasted coffee powder with good recovery rates. Method efficiency was compared with that of solid-phase extraction using SCX Disc cartridges and validated for spiked solid matrix. The analytes were determined using isocratic liquid chromatography-mass spectrometry (LC/MS) on an Atlantis HILIC Silica column (150 x 2.1 mm, 3 microm) with 80% methanol and 20% 0.01 mol l-1 ammonium formate as the mobile phase. The limit of quantification was around 1.5 pg for 4-MeI and 2.0 pg for THI. The linearity of the calibration curves was satisfactory as indicated by correlation coefficients of >0.999. The coefficient of variation for the intra-day and inter-day precisions was <4% (n = 6). Accuracy was in the range 98-101%; recovery rates were > or = 98 and > or = 99% for THI and 4-MeI, respectively. Several samples of Arabica coffee from various locations and commercially available 'off-the-shelf' coffee products (Arabica/Robusta mixtures) were analysed to test the method.     

Reduction of Tc(VII) by Fe(II) sorbed on Al (hydr)oxides

Under oxic conditions, Tc exists as the soluble, weakly sorbing pertechnetate [TcO4-] anion. The reduced form of technetium, Tc(IV), is stable in anoxic environments and is sparingly soluble as TcO2 x nH2O(s). Here we investigate the heterogeneous reduction of Tc(VII) by Fe(II) adsorbed on Al (hydr)oxides [diaspore (alpha-AlOOH) and corundum (alpha-Al2O3)]. Experiments were performed to study the kinetics of Tc(VII) reduction, examine changes in Fe surface speciation during Tc(VII) reduction (M?ssbauer spectroscopy), and identify the nature of Tc(IV)-containing reaction products (X-ray absorption spectroscopy). We found that Tc(VII) was completely reduced by adsorbed Fe(II) within 11 (diaspore suspension) and 4 days (corundum suspension). M?ssbauer measurements revealed thatthe Fe(II) signal became less intense with Tc(VII) reduction and was accompanied by an increase in the intensity of the Fe(III) doublet and magnetically ordered Fe(III) sextet signals. Tc-EXAFS spectroscopy revealed that the final heterogeneous redox product on corundum was similar to Tc(IV) oxyhydroxide, TcO2 x nH2O.     

优质农业生产管理指导手册

优质农业生产管理体系(GAP)概念提出的目的在于确保烟叶生产的持续、健康发展,可以将GAP定义为:在保护、维持或增强土壤、水源、空气、动植物生命和环境的同时,在确保农业生产可持续发展的条件下,推行一系列农业措施,生产出一定产量和质量的优质农作物.     

优质农业生产管理指导手册(二)

4病虫害综合防治 病虫害综合防治(IPM)是烟叶生产的一项系统体系,利用病虫害预测预报系统,提供最好的病虫害综合防治决策,重点是协调应用一切可行的办法.病虫害综合防治并不意味着完全排除使用农药,而是在使用其它办法不能使病虫害的种群数保持在可接受的范围时适当使用农药.施用农药的地方应确保安全,并遵守一切法律法规.     

优质农业生产管理指导手册(三)

7 烘烤（调制）和烤房管理 烟叶的正确烘烤和烤房管理对优化烟叶的产量、质量和产值来说是非常关键的因素。烟叶烘烤是保持烟叶产量、质量的最后一道环节。烟叶质量会因烘烤不当而降低，而正确进行烘烤能确保烟叶质量的稳定。然而，若将劣质的鲜烟叶或烟株放入烤房，则不可能提高最终的烟叶质量。     

Reactivity of Pb(II) at the Mn(III,IV) (oxyhydr)oxide--water interface

In this study, the reactivity of lead (Pb(II)) on naturally occurring Mn(III,IV) (oxyhydr)oxide minerals was evaluated using kinetic, thermodynamic, and spectroscopic investigations. Aqueous Pb(II) was more strongly adsorbed to birnessite (delta-MnO1.7) than to manganite (gamma-MnOOH) under all experimental conditions. The isoteric heat of Pb adsorption (delta HT) or birnessite was 94 kJ mol-1 at a surface loading of 1.1 mmol g-1, and decreased with increasing adsorption density. This indicated that adsorption was an endothermic process and that birnessite possessed heterogeneous sites of reactivity for Pb. X-ray absorption fine structure (XAFS) spectra revealed that Pb was adsorbed as inner-sphere complexes on both birnessite and manganite with no evidence to suggest oxidation as an operative sorption mechanism. Lead appeared to coordinate to vacancy sites in the birnessite layer structure with concurrent release of Mn to solution, which resulted in a greater number of second shell Mn scatterers in Pb-birnessite when compared to Pb-manganite samples. The difference in Pb coordination apparently explained the contrasting desorption behavior between the two Mn minerals. These results have significant implications for Pb partitioning in soil environments containing solid-phase Mn(III,IV) (oxyhydr)oxides.