不同年份干红葡萄酒单宁结构特性与涩感强度的关系

为探究不同年份干红葡萄酒单宁的含量和结构与涩感强度之间的关系,以内蒙古产区不同年份的赤霞珠和蛇龙珠葡萄酒为材料,测定其总单宁、游离态黄烷-3-醇单体含量及缩合单宁结构组分,并对涩感强度进行评价。结果表明：新酒的总单宁含量和游离态黄烷-3-醇单体总量均高于陈酿酒,且新酒的儿茶素和表儿茶素没食子酸酯含量较高,陈酿酒的表棓儿茶素和棓酸儿茶素含量较高。在缩合单宁的结构特性中,新酒的原花青素占比较高,陈酿酒的原翠雀素占比较高,且陈酿8～9年酒样的单宁结构趋于稳定。葡萄酒中各组分与涩感强度间的主成分分析表明：总单宁、平均聚合度、单体表棓儿茶素没食子酸酯、延伸单元表儿茶素、表儿茶素没食子酸酯及没食子酰化程度对涩感影响较大,总酸、pH值、酒度、总酚、花色苷及游离态单体对涩感影响则较小。     

‘赤霞珠’种子成熟过程中缩合单宁的变化及其与颜色参数的相关性

以不同发育时期‘赤霞珠’葡萄种子为试材，探究种子成熟过程中可溶性和非可溶性缩合单宁及其结构单元含量的变化规律，结合种子表面颜色参数的变化，建立缩合单宁与种子表皮颜色参数之间的关系，为种子成熟度判断提供依据。结果表明，随着葡萄果实成熟，种子中可溶性缩合单宁呈现先增后降的变化趋势，其峰值出现在转色启动后1周左右，而非可溶性缩合单宁含量呈不断增加趋势。表儿茶素是种子缩合单宁的主要延伸单元，而表儿茶素没食子酸酯是主要的末端单元，它们的含量随种子成熟而呈现增加的态势；可溶性缩合单宁的平均聚合度在6.50～10.71，而非可溶性缩合单宁平均聚合度介于10.84～45.78，种子非可溶性缩合单宁含量变化与颜色指数a^*值呈显著正相关，而与L^*和b^*值呈显著负相关。     

不同等级干红葡萄酒中酚类物质的比较分析

对三个不同等级9个干红葡萄酒样品中的总酚、单宁、无色多酚和花色苷等酚类物质进行了比较分析。结果表明,干红葡萄酒的等级越高其中总酚、单宁、总花色苷、基本花色苷、二甲花翠素单葡萄糖苷(Mv-3-Glu)、无色多酚总量、酸性酚、中性酚、没食子酸、儿茶素和表儿茶素的含量越高。其它多酚物质组成与葡萄酒的等级没有显著关联性。     

蔗汁澄清过程各种酚类含量变化的研究

以蔗汁中的总酚、黄烷醇类酚、缩合单宁、7种单体酚为研究对象,考察甘蔗制糖亚硫酸法澄清工艺各操作单元对各种酚类物质含量的影响以及酚类物质与糖汁色值的关系,并对实验数据进行配对T双尾检验。结果表明:蔗汁加磷预灰并经一次加热后,脱色率达37.29%;硫熏中和的脱色率为56.32%;硫熏中和可减少18.71%的总酚、17.76%的黄烷醇类酚、44.05%的缩合单宁;沉降可减少41.67%的黄烷醇类酚、36.51%的缩合单宁;总酚、黄烷醇类酚、缩合单宁的含量与色值有着明显的相关性;加磷预灰、硫熏中和、沉降操作单元对降低单体酚含量有显著性作用,加磷预灰可减少100%的咖啡酸和29.31%的绿原酸;硫熏中和可减少100%的绿原酸和表儿茶素;沉降可减少38.74%的没食子酸和11.02%的阿魏酸;澄清过程不能减少柚皮苷,其他6种单体酚均减少含量。     

12种广西地区茶叶的水提物活性成分测定及其抗氧化活性研究

对12种广西地区茶叶的水提取物活性成分及其抗氧化活性进行测定并比较分析。采用热水浴提取法制备茶叶水提物,测定水提物中的总黄酮、总多酚、总糖、儿茶素和表儿茶素含量,通过DPPH自由基、ABTS+自由基的清除率和铁离子还原能力评价茶叶水提物的体外抗氧化活性,并对茶叶水提物的活性成分和抗氧化活性之间的相关性进行比较分析。绿茶和白茶的总多酚含量相对较高,其中三江春总多酚含量最高;红茶的总黄酮含量高于绿茶和白茶,其中梅红的总黄酮含量最高;绿茶总糖的含量相对较高,其中最高的为小叶种香茶。绿茶中三江早春侗坡仙茗和昭平乌牛早的儿茶素含量显著高于其它样品,红茶除三江梅红外其余样品均未检出,绿茶和白茶的表儿茶素较红茶高。绿茶和白茶对DPPH自由基、ABTS+自由基的清除率和铁离子还原能力均较红茶高。总多酚、总糖和表儿茶素与体外抗氧化活性呈正相关,且相关性较高。而总黄酮和儿茶素与体外抗氧化活性的相关性较差,并呈现负相关。综合表明广西地区12种茶叶中,绿茶中总多酚和儿茶素、表儿茶素含量相对较高,且抗氧化活性较好;红茶中总黄酮含量较高,但总多酚、儿茶素含量、抗氧化活性均低于绿茶和白茶。     

以云南铁观音为原料的速溶茶加工研究

铁观音是云南近年来发展迅速的一种茶叶产品,随着种植面积与产量的增加,急需要进行精深加工研究开发。以云南腾冲产的铁观音为原料,通过单因素、正交设计优化浸提条件,以及浓缩和干燥工艺考查,建立料液比1∶10(g/mL)、60%乙醇浸提36 h、过滤后茶渣以料液比1∶5(g/mL)沸水浸提30 min、40℃减压浓缩、100℃喷雾干燥的铁观音速溶茶加工工艺。加工产品速溶性强、花香浓郁、滋味醇厚,得率为28.47%,茶多酚、儿茶素(catechins,C)、表儿茶素(epicatechin,EC)、表没食子酸儿茶素(epigallocatechin,EGC)、表儿茶素没食子酸酯(epicatechin gallate,ECG)、表没食子儿茶素没食子酸酯(epigallocatechin gallate,EGCG)含量分别为34.03%、0.45%、2.25%、9.49%、2.14%和14.16%。研究开发一种具有市场潜力的深加工茶叶产品,为云南铁观音茶叶发展提供技术支持。     

单宁抗氧化活性与结构关系的理论研究

用表儿茶素EC和表棓儿茶素EGC作为缩合类单宁的模型分子,缩酚酸DA和鞣花酸EA为水解类单宁模型分子,采用计算化学研究了单宁的抗氧化活性与分子结构的关系.利用Gauss程序包中B3LYP/6-31G(d)方法优化中性及自由基分子结构,各优化结构均在B3LYP/6-311G(d,p)水平上计算单点能.基于抗氧化剂捕捉自由基的两种机理,即直接抽氢机理和伴随电子转移的质子转移机理,分别采用O-H 键解离能BDE和绝热电离势IP两种理论参数表征单宁模型化合物的抗氧化活性.计算结果表明,在直接抽氢机制中,单宁模型化合物抗氧化活性顺序为:EGC (311.88 kJ/mol) >EC (335.39 kJ/mol) > DA (338.07 kJ/mol) > EA (357.36 kJ/mol).在电子转移的抽氢机制中,单宁抗氧化顺序为:EGC (165.53 kcal/mol) > EC (166.56 kcal/mol) > DA (175.29 kcal/mol) > EA (176.34 kcal/mol),两种机制预测的活性顺序与大部分实验报道较为吻合.有利于增强抗氧化活性的结构因素是联苯三酚结构和苯环上的供电子基团.从分子水平推测,含EGC结构的缩合类单宁具有最强的抗氧化活性,而鞣花单宁和含EC结构的缩合类单宁具有相对较低的抗氧化活性.     

酸枣叶缩合单宁的分离鉴定及其对黑色素生成的抑制机制

目的:研究酸枣叶缩合单宁的结构特征及其对酪氨酸酶的效应和黑色素生成的抑制机制。方法:利用Sephadex LH-20凝胶柱色谱技术分离制备酸枣叶缩合单宁纯化物,采用硫醇降解结合高效液相色谱-电喷雾电离质谱（Thiolysis-HPLC-ESI-MS）解析酸枣叶缩合单宁的结构单元组成,运用酶动力学、紫外光谱、荧光猝灭等方法系统研究酸枣叶缩合单宁对酪氨酸酶的抑制作用机理,应用CCK-8法、多巴氧化法、NaOH裂解法和实时荧光定量PCR检测酸枣叶缩合单宁对小鼠黑色素瘤细胞（B16F10）的增殖、酪氨酸酶活性、黑色素合成及其相关基因表达水平的影响。结果:构成酸枣叶缩合单宁的主要结构单元是（表）儿茶素和（表）棓儿茶素;酸枣叶缩合单宁具有较强的酪氨酸酶单酚酶和二酚酶抑制活性,是二酚酶可逆的混合型抑制剂;酸枣叶缩合单宁可有效抑制B16F10细胞的增殖、酪氨酸酶活性、黑色素生成量以及酪氨酸酶（TYR）、酪氨酸酶相关蛋白-1（TRP-1）、小眼畸形相关转录因子（MITF）等基因的表达。结论:通过在酶水平和细胞水平的综合分析,阐明酸枣叶缩合单宁对B16F10细胞黑色素合成的分子抑制机制,为后期酸枣叶缩合单宁开发为新的美白化妆品添加剂和果蔬保鲜剂提供理论依据。     

贺兰山东麓不同陈酿年份赤霞珠干红葡萄酒中酚类物质对涩感质量的影响

为了探究赤霞珠干红葡萄酒陈酿过程中酚类物质的变化规律及其与涩感质量变化之间的联系。选取宁夏贺兰山东麓同一酒庄10个垂直年份的赤霞珠干红葡萄酒,分析总酚、总单宁、总花色苷含量,利用超高效液相色谱-电喷雾多级质谱(ultra high performance liquid chromatography-electrospray ionization multi-stage mass spectrometry,UHPLC-ESI-MSn)法分析了该系列葡萄酒中的儿茶素、表儿茶素、表棓儿茶素、表儿茶素没食子酸酯、原花青素B1、B2的含量,通过二级质谱分析鉴定了(表)儿茶素三聚体,并对样品涩感质量进行了感官分析。通过相关分析建立酚类物质与涩感质量的相关性。结果表明,随着葡萄酒年份的增加总酚、总单宁和总花色苷的含量呈逐渐减少的趋势。在陈酿过程中葡萄酒的口感呈现干涩下降绒涩上升的趋势。不同质量的涩感强度与总酚及总单宁的含量没有显著的相关性(p 0. 05)。干涩强度与葡萄酒中儿茶素、表儿茶素、表棓儿茶素及原花青素B1、B2含量显著正相关(p 0. 05)与(表)儿茶素三聚体含量极显著正相关(p 0. 01),绒涩与这些物质没有显著相关性。     

葡萄酒缩合单宁测定方法的比较研究

目的：对比葡萄酒中测定缩合单宁的甲基纤维素沉淀法(MCP法)和蛋白质沉淀法(A-H法),以寻找一种快速准确的测定方法。方法：采用两种方法测定不同类型、产地、品种葡萄酒的缩合单宁,考察其测定值和变异系数;采用液相色谱-质谱联用法(HPLC-MS法)测定缩合单宁含量,采用吸光度法(A280)测定总酚含量,并与上述两种方法的结果对照。结果：(1)MCP法和A-H法均只适用于红葡萄酒缩合单宁测定,MCP法精度略高但差异不显著。(2)MCP法测定值平均为A-H法的9.13倍,但二者存在较好的线性关系(R2=0.6029)。MCP法与HPLC-MS法线性关系良好(R2=0.7733),A-H法较差(R2=0.4843)。(3)MCP法与总酚存在良好的线性关系(R2=0.9095),A-H法与总酚无显著线性关系(R2=0.2872)。结论：两种方法均能反映红葡萄酒缩合单宁含量,但MCP法与HPLC-MS法、总酚具有更高的一致性,如采用A280测定总酚,应采用MCP法测定缩合单宁。     

柿果成熟过程中总酚和缩合单宁含量的变化

本实验通过Folin-Ciocalteu法、香草醛-盐酸法测定不同类型12 个柿品种果实生长发育进程中总酚和缩合单宁含量的变化,并运用正交试验法对香草醛-盐酸法进行优化。结果表明：香草醛-盐酸法优化参数为：显色液为2.0 g/100 mL香草醛甲醇与15%盐酸甲醇液,显色0.5 h。柿果实的生长发育进程中,总酚和缩合单宁含量变化规律相似,花后35～50 d达到最高水平,随后逐渐降低,但不同类型柿间总含量及变化幅度存在着较大的差异;其中,日本完全甜柿（J-PCNA）、中国完全甜柿（C-PCNA）、不完全甜柿（PVNA）、不完全涩柿（PVA）、完全涩柿（PCA）同类型各品种间总酚和缩合单宁变化趋势相似,含量相近,总酚、缩合单宁含量基本符合规律PCA＞C-PCNA＞PVA＞PVNA＞J-PCNA。     

橄榄果实单宁的抗氧化能力研究

对橄榄果实中的总酚含量与可溶缩合单宁含量进行了测定,并利用二苯基苦基苯肼自由基(DPPH)和铁离子还原/抗氧化能力测定(FRAP)法,研究了橄榄果实中单宁的自由基清除能力及抗氧化活性。结果表明:橄榄果实中总酚含量较高[(572.35±39.72)mg/g(干重)],用正丁醇-HCl法测得缩合单宁的含量为(1.47±0.02)mg/g(干重),用DPPH法和FRAP法研究其自由基清除能力及抗氧化活性表明,橄榄果实单宁具有较高的自由基清除能力(IC_(50)为48.45μg/mL),及较强的抗氧化能力(2.955 mmol AAE/g)。     

Changes in tannin content,polymerisation and protein precipitation capacity in oak (Quercus incana) leaves with maturity

Changes in the content of total phenolics, condensed tannins, proanthocyanidins and flavan-4-ols, the degree of polymerisation, the protein precipitation capacity, the protein-precipitable phenolic content and the specific activity (protein: tannin in the complex) were determined in Quercus incana leaves with maturity. Total phenolic content and protein precipitation capacity decreased whereas the levels of condensed tannins, proanthocyanidins, flavan-4-ols and degree of polymerisation increased with maturation. The protein-precipitable phenolic content was highest in young leaves and decreased as leaves matured. The specific activity decreased slightly. The results suggest that young leaves would be more toxic to livestock than mature leaves.     

Effect of drying conditions on tannin,fibre and lignin levels in mature oak (Quercus incana) leaves

Oak (Quercus incana Roxb) leaves are rich in tannins and produce adverse effects when fed to livestock. The effects of shade and sun drying and oven drying at 60°C and 90°C for different lengths of time (24 to 72 h) on total phenolics, condensed tannins, protein precipitation capacity, degree of polymerisation, specific activity (protein bound per unit tannins), fibre-linked proanthocyanidins, acid and neutral detergent fibres and lignin levels in mature oak leaves were studied. Removal/inactivation of tannins was not observed on wilting or drying under several conditions. Similarly the drying conditions had no effect on fibre composition. The adverse effects on feeding fresh or dried oak leaves are expected to be of similar magnitude.     

铁观音乌龙茶和红茶的香气化学特征分析

以铁观音茶鲜叶为材料,采用不同工艺加工成乌龙茶、红茶和绿茶,运用感官审评法评定茶样的香气品质,利用溶剂辅助风味蒸发-气相色谱-质谱/火焰离子化检测器法分析茶样中挥发性成分,研究铁观音茶香气品质及其主要挥发性组分的工艺差异。结果表明,不同工艺铁观音茶样的香气品质得分均高于90 分且呈现花香特征。铁观音茶中检测到52 种挥发性成分,其中芳樟醇类和脂肪酸酯类化合物是挥发性组分的主体。铁观音茶香气的品种特征组分有氧化芳樟醇II、氧化芳樟醇IV、芳樟醇、反-橙花叔醇、己酸-3-己烯酯、己酸-2-己烯酯、苯甲酸-3-己烯酯、苯甲酸己酯和新植二烯等。红茶工艺能促进芳樟醇及其氧化物、3-甲基丁酸-2-己烯酯、己酸-3-己烯酯、己酸-2-己烯酯、新植二烯、二氢猕猴桃内酯、β-紫罗酮和水杨酸甲酯等的形成,而乌龙茶工艺有利于脱氢芳樟醇、2,6-二甲基-3,7-辛二烯-2,6-二醇、反-橙花叔醇、辛酸-顺-3-己烯酯和苯甲酸己酯等的形成。综上所述,铁观音茶的香气化学特征与品种特有组分、加工工艺调控密切相关,可为铁观音新产品研发提供重要技术参考。     

Phenolic composition of Flacourtia indica, Opuntia megacantha and Sclerocarya birrea

The phenolic acid composition of the peel and pulp of the fruits of Flacourtia indica (Burm. f.) Merr., Opuntia megacantha (L.) Mill and Sclerocarya birrea (A. Rich.) Hochst., from Zimbabwe, were analysed using traditional colorimetric as well as HPLC methods. The total phenolics, flavanoids and condensed tannin levels varied with species. Sclerocarya birrea pulp had the highest total phenolics, flavanoids and condensed tannins, i.e., 2262 μg GAE/g, 202 μg catechin/g and 6.0% condensed tannins, respectively. Flacourtia indica pulp contained the least total phenolics, flavanoids and condensed tannins 334 μg GAE/g, 41 μg catechin/g and 1.4%, respectively. There were no significant differences in the total phenolics between the peels and the pulps of the individual fruits. However, significant differences were noted in the flavanoids and the condensed tannins between the peels and pulps of the fruits assayed. Ferulic acid, caffeic acid and vanillic acid were the dominant phenolic acids in the three fruits. There were differences between the phenolic acids in the peels and the pulps of the fruits.     

不同采收期红油香椿营养成分和抗氧化活性分析

以国内主要栽培品种红油香椿为研究对象,对同茬3 个不同采收期香椿嫩芽营养物质和抗氧化能力进行研究,旨在为其适时采收提供理论依据。结果表明：香椿嫩梢叶中的叶绿素、可溶性糖、可溶性蛋白及黄酮含量均在Ⅲ期达最大值,其含量分别为1.72、119.94、3.87、11.83 mg/g。叶中的叶绿素、氨基酸、可溶性蛋白、多酚及黄酮含量在所有的采收期均极显著高于茎（P＜0.01）,而可溶性糖在Ⅲ期、VC在Ⅰ期叶与茎中的含量差异不显著。不同采收期及不同部位香椿嫩芽的提取液质量浓度均与抗氧化能力呈显著量效关系（P＜0.05）。3 个采收期茎提取液清除1,1-二苯基-2-三硝基苯肼（1,1-diphenyl-2-picrylhydrazyl,DPPH）自由基能力均高于叶,而清除•OH能力叶强于茎。对不同采收期,在清除•OH能力和还原能力方面Ⅱ期香椿嫩芽提取液最强,在清除DPPH自由基能力方面Ⅰ期较强。综合考虑营养物质含量、抗氧化活性和食用性,Ⅱ期为最适宜的采收时间。     

Responses of Lotus corniculatus to environmental change. 2. Effect of elevated CO2, temperature and drought on tissue digestion in relation to condensed tannin and carbohydrate accumulation

Clonal plants of three genotypes of Lotus corniculatus (cv Leo) were grown in eight controlled environments under combinations of two temperature regimes, two CO₂ concentrations and two watering regimes. Condensed tannins (proanthocyanidins), in-vitro digestibility, initial rates of gas evolution (as an indicator of the initial rates of fermentation of the substrate), volatile fatty acid evolution, and non-structural carbohydrate (NSC) levels were determined in leaves, stems and roots at full flowering. Under control conditions (average midsummer conditions in the United Kingdom) the total condensed tannin content of leaves varied six-fold between genotypes but condensed tannin contents in stems and roots were similar. Condensed tannin levels were significantly increased in leaves and stems of all three genotypes by doubling the CO₂ concentration while raising the temperature towards the optimum for growth significantly reduced condensed tannin levels. Drought stress significantly reduced condensed tannin levels in leaves and, particularly, in roots. Nutritive value was inversely related to condensed tannin levels in leaves and a negative relationship was observed between condensed tannin concentrations of more than 25–30 g kg⁻¹ dry matter and the initial rates of gas evolution when subjected to in-vitro fermentation with rumen micro-organisms. In leaves, digestibility was significantly increased by drought and by increasing temperature but reduced by high CO₂. In stems, digestibility was significantly increased by drought, but not significantly affected by increasing temperature, or by high CO₂ alone. In roots, digestibility was significantly increased by drought, and decreased by increasing temperature or CO₂. Increasing the growth temperature towards optimum growth reduced the content of NSC in all tissues with the greatest changes occurring in root tissue. Doubling the CO₂ concentration increased NSC levels in leaves and stems with starch content more than doubled under high CO₂ while, in roots, increased levels were only observed in combination with drought stress. There was a linear correlation between condensed tannin concentration and total NSC that was positive for leaves, neutral for stems and negative for roots. The relationship between carbohydrate levels and rates of gas production was negative for leaves and positive for stem and roots. © 1999 Society of Chemical Industry     

不同皮渣浸渍发酵时间对葡萄酒中缩合单宁构成及感官品质的影响

为明确不同皮渣浸渍时间对葡萄酒中缩合单宁的影响,以赤霞珠和西拉为材料,进行不同浸渍发酵时间处理,对葡萄皮和葡萄籽以及葡萄酒中缩合单宁的含量、组成、缩合单宁以及相关口感指标等进行了分析。结果表明,不同葡萄品种中缩合单宁的初始含量、聚合度及没食子酰化率都有显著差异（P<0.05）。葡萄皮中缩合单宁的平均聚合度显著高于葡萄籽（P<0.05）,而葡萄皮缩合单宁的没食子酰化率则显著低于葡萄籽缩合单宁（P<0.05）。葡萄皮和葡萄籽中缩合单宁组成的最大差异是葡萄籽缩合单宁中不含有（?）-表棓儿茶素亚单元,而且末端单元主要是由（+）-儿茶素、（?）-表儿茶素和（?）-表儿茶素没食子酸酯组成。皮渣浸渍时间对葡萄酒中缩合单宁的组成及含量都有明显影响。随着浸渍时间的延长,葡萄酒中缩合单宁的总含量呈上升趋势,而平均聚合度则呈下降趋势。不同品种的葡萄酒之间缩合单宁含量也存在显著差异（P<0.05）,这与不同葡萄品种中酚类物质的可浸提率有关。葡萄酒中葡萄皮缩合单宁的占比一直显著高于籽粒缩合单宁的占比（P<0.05）,说明葡萄皮中缩合单宁比葡萄籽缩合单宁更容易浸提到葡萄酒中。相对于苦味和酸味,不同浸渍时间处理对葡萄酒的涩味影响更为显著（P<0.05）,综合考虑酒体的丰满度和口感的平衡,皮渣浸渍时间选择14 d左右更好一些。