高温高压提取茶汤加工普洱茶膏的研究

普洱茶膏是云南独特的速饮茶叶产品,但目前采用大锅熬制的工艺提取茶汤,导致产品的香气低、滋味淡薄,亟需改进提取方法。本文应用高压灭菌锅和响应面设计,开展高温高压(121℃、103kPa)提取茶汤加工茶膏研究。优化发现在浸提温度为113℃,茶水比1∶41g/mL,时间14min的条件下,提取茶汤的茶多酚、氨基酸、水浸出物含量最高,分别为20.89%±0.81%、3.82%±0.35%和37.89%±5.35%。按优化条件提取茶汤、减压浓缩、干燥加工制成茶膏有效成分含量与感官评审得分均优于大锅熬制加工的茶膏。本研究表明高温高压提取茶汤可以改进茶膏品质,在速饮茶叶产品加工中具有一定的应用前景。      

高温高压提取茶汤加工普洱茶膏的研究

普洱茶膏是云南独特的速饮茶叶产品,但目前采用大锅熬制的工艺提取茶汤,导致产品的香气低、滋味淡薄,亟需改进提取方法。本文应用高压灭菌锅和响应面设计,开展高温高压(121℃、103kPa)提取茶汤加工茶膏研究。优化发现在浸提温度为113℃,茶水比1∶41g/mL,时间14min的条件下,提取茶汤的茶多酚、氨基酸、水浸出物含量最高,分别为20.89%±0.81%、3.82%±0.35%和37.89%±5.35%。按优化条件提取茶汤、减压浓缩、干燥加工制成茶膏有效成分含量与感官评审得分均优于大锅熬制加工的茶膏。本研究表明高温高压提取茶汤可以改进茶膏品质,在速饮茶叶产品加工中具有一定的应用前景。     

酶在普洱茶膏加工工艺中的应用

本文以氨基酸、茶多糖、茶多酚含量变化为指标,研究不同酶处理对普洱茶膏中呈味物质含量的影响,优化酶的作用条件,并对优化后的茶膏进行感官评定。结果表明:在相同酶浓度条件下,风味蛋白酶水解茶叶蛋白能力显著强于中性蛋白酶(p<0.01),在两种酶添加量都为45 U/g时,茶汤氨基酸增长率都达到最高,分别为28.49%、15.19%;在复配蛋白酶浓度为27 U/g,中性蛋白酶与风味蛋白酶比例为1∶2时,两种蛋白酶协同效果最佳,极显著高于同浓度单一酶作用效果(p<0.01),茶汤氨基酸增长率达到22.07%;不同糖酶水解茶叶糖类能力强弱排序为:植物水解酶>果胶酶>纤维素酶,三者差异显著(p<0.05),在植物水解酶添加量为0.6%时,茶汤中茶多糖增长率高达82.45%;多酚氧化酶对茶汤中茶多酚的转化影响很小,茶汤中茶多酚下降范围在0.32%至4.55%。优化后的茶膏感官品质有了较大提升,优化工艺合理、可行。      

低成本吸附材料对水中氯氟氢菊酯农药的吸附研究

对两种低成本吸附材料米糠和豆渣吸附氯氟氰菊酯进行条件优化。结果表明:米糠吸附氯氟氢菊酯的最优条件为:米糠的投放量为15 g/L、粒径大小为60目、pH为9、温度为40℃、溶液中农药的初始浓度为1.00 mg/L。在最优条件下米糠对氯氟氢菊酯的吸附率可达76.54%。豆渣吸附氯氟氢菊酯的最优条件为:豆渣的投放量为15 g/L、粒径大小为100目、pH为5、温度为40℃、溶液中农药的初始浓度为1.25 mg/L。在最优条件下豆渣对氯氟氢菊酯的吸附率可达85.67%。     

新型生物质炭吸附剂对地下水中氟的去除作用

本文选用花生壳、栗子壳、核桃壳、橘子皮等生物质原料在不同温度下制备得生物质炭。通过对不同条件制备的生物质炭的除氟效果的比较,结果发现,以花生壳为原料在650℃热解所得生物质炭除氟效果最好。并对花生壳生物质炭进行了表面结构表征。在此基础上,研究了吸附时间、生物质炭投加量、pH值、氟离子初始浓度等因素对花生壳生物质炭除氟效果的影响。结果表明,最佳炭投加量为1 g/100 mL,最佳pH为5.5~6,吸附60 min左右达吸附平衡,此时去除率达到82.25%,吸附量容量达0.82 mg/g;随着氟离子初始浓度的增加生物质炭对氟的去除率成下降趋势,吸附容量随含氟量浓度的增加成上升趋势。花生壳生物质炭对氟离子的吸附等温线模拟结果表明,Freundlich型和Langmuir型均较为符合。该花生壳生物质炭对地下水氟的最大吸附容量为1.11 mg/g。该研究为农业废弃物资源化利用以及地下水氟污染治理提供了一条新的思路。     

低温猪肉火腿肠降盐工艺探究

为探究低温猪肉火腿肠的有效降盐工艺,在加工过程中,对腌制前的肉糜进行超高压处理,而后采用优化低盐腌制配方腌制,以感官评分、质构特性、肉糜乳化稳定性、色差、凝胶保水性、蒸煮损失及风味物质分析等为考察指标,确定降盐工艺参数。优化得到的工艺条件为:腌制前肉糜的超高压条件为200 MPa保压10 min,低盐腌制配方为0. 12%Na Cl,1%KCl,1%乳酸钾,1%抗坏血酸钙,0. 9%L-赖氨酸,0. 9%L-精氨酸,0. 25%生姜粉。该工艺中的低盐优化配方将产品中的钠含量降至118 mg/100 g,符合国标关于低盐声称的标准(≤120mg/100g),超高压处理有效促进低盐凝胶体系的构建,弥补低盐对产品品质的不良影响,2种工艺结合使用,使最终产品具有良好的品质。     

低氟砖茶与传统砖茶品质的比较分析

为满足国家标准规定砖茶允许含氟量≤300mg/kg的要求,选用一芽四五叶原料生产低氟砖茶（氟含量285mg/kg）,以传统砖茶（氟含量850mg/kg）为对照,分别进行了感官品质、主要成分及儿茶素和氨基酸组分比较分析。结果表明:低氟砖茶感官品质优于传统砖茶;低氟砖茶主要成分水浸出物、茶多酚、可溶性糖、咖啡碱、茶黄素、茶红素、茶褐素比传统砖茶增加了48.33%、79.22%、44.44%、89.55%、42.86%、26.28%、42.96%;氨基酸组分除甲硫氨酸和脯氨酸外,其他氨基酸高于传统砖茶,儿茶素组分除L-CG外,其他儿茶素含量高于传统砖茶。结果显示通过提高原料嫩度生产低氟砖茶是可行的。      

改性竹炭对南极磷虾酶解液的除氟效果

利用竹炭为原料,得到除氟效果较好的除氟剂,用以去除南极磷虾酶解液中的氟。用Fe2(SO4)3溶液作为竹炭的改性剂,使得竹炭载铁,对比竹炭改性前后的除氟效果,并研究了竹炭颗粒度、p H值、时间、温度及吸附剂投入量5个参数对吸附效果的影响,得到最佳除氟条件。通过对吸附等温模型、热力学参数和吸附动力学模型的分析,结合参数以及模型,分析了改性竹炭的除氟原理。结果表明,改性竹炭除氟效果远高于未改性的竹炭,改性竹炭在南极磷虾酶解液中的最佳吸附条件为:吸附剂投放量0.01 g/m L,吸附温度40℃,吸附时间1 h,吸附剂颗粒度40~60目,除氟率达到73%,酶解液氟离子质量浓度由18.7 mg/L降至5.1 mg/L,氟质量浓度在安全食用范围内。     

茶叶氟富集与控制研究进展

我国个别茶类氟含量较高,已成为影响茶产业发展的重要因素。近年来,有关茶树品种、土壤、大气、水源、肥料等因素对茶树氟富集影响,以及对不同茶叶中氟含量和浸出规律已展开研究。降低人体对茶叶摄入氟含量的措施主要有选育低氟茶树品种、改善栽培环境、增加采摘鲜叶嫩度,以及改变加工技术、饮茶方式等。各种降氟措施各有利弊,采用单一的降氟措施具有一定的局限性。通过对茶叶氟富集与控制研究的梳理,以期为茶叶降氟措施的深入研究和低氟茶的开发提供思路。     

赤泥为原料制备除氟剂的实验研究

赤泥是一种具有污染性且产量巨大的废弃物,实验以广西平果铝厂的拜耳法赤泥为主要原料,加入一定量的添加剂Na_2SiO_3·9H_2O、CaO、碳粉等,将赤泥制成球状并进行焙烧处理.采用XRD分析方法对所得样品进行物相分析,研究了赤泥除氟剂的吸附时间、焙烧温度、焙烧时间、溶液pH值对除氟性能的影响.结果表明：采用焙烧温度700℃、焙烧时间1h条件下活化的赤泥除氟剂,溶液中氟离子的浓度可从19 mg/L下降到0.37 mg/L,吸附容量达到0.47 mg/g,氟去除率达98％,同时受制备条件及pH值的影响很大.     

Fluoridgehalt in Teebl?rttern

Zusammenfassung In 35 Teeproben verschiedener Provenienz wurde nach Veraschung und modifiziertem Destillationsverfahren quantitativ Fluorid chemisch und potentiometrisch bestimmt. Das potentiometrische Verfahren ist für Routineuntersuchungen gut geeignet. Es werden Fluoridgehalte zwischen 40 und 330 ppm nachgewiesen. Abhängigkeiten zwischen Fluoridund Aschegehalt sowie der Herkunft der Proben konnten nicht festgestellt werden. In Brühversuchen konnte die gute Löslichkeit des Fluorid aus den Teeblättern gezeigt werden. Es gelang nicht, eine Abhängigkeit zwischen der Fluorid-Löslichkeit und der Teefarbe (Gehalt an Gerbstoffen) aufzuzeigen.

---

Fluoride in the tea leaves

Summary Thirty five tea samples from various countries of origin were examinated for fluoride content. After an ashing and modified distillation procedure the fluoride war determined quantitatively by a chemical and a potentiometric procedure. The differences in values between both methods were small, for practical reasons the potentiometric method may be preferred. Fluoride levels in tea leaves ranged from 40 to 330 ppm. No relationship was found between the content of fluoride and ash and the origin of the sample. Under the experimental conditions the extraction of the fluoride from the tea leaves into the infusion is very efficient. No relationship was found between the color of the infusion and the fluoride concentration.

     

Analysis of Naturally Occurring Fluoride in Commercial Teas and Estimation of Its Daily Intake through Tea Consumption

The aim of this study was to determine the levels of fluoride in commercial teas and to estimate the contribution of tea consumption to the fluoride recommended daily allowance. A total of 558 tea products in 6 categories, green tea, black tea, oolong tea, pu'er tea, white tea, and reprocessed tea, were collected in the period from 2010 to 2013. The levels of fluoride in infusions of these teas were determined by a fluoride‐ion selective electrode. The mean fluoride level in all of the tea samples was 85.16 mg/kg. For each category of tea, the mean fluoride levels were 63.04, 99.74, 52.19, 101.67, 159.78, and 110.54 mg/kg for green tea, black tea, white tea, pu'er tea, oolong tea, and reprocessed tea, respectively. The fluoride content of tea from 4 tea zones in descending order were Southern tea zone (111.39 mg/kg) > Southwest tea zone (78.78 mg/kg) > Jiangnan tea zone (71.73 mg/kg) > Jiangbei tea zone (64.63 mg/kg). These areas produced teas with lower fluoride levels than available foreign‐produced tea (161.11 mg/kg). The mean chronic daily intake (CDI) was 0.02 mg/(kg?day) or 1.27 mg/kg. Generally, consuming tea from these 6 categories does not result in the intake of excessive amounts of fluoride for the general population.     

Human exposure assessment of fluoride from tea (Camellia sinensis L.): A UK based issue?

Fluoride concentrations in UK tea, including the leading supermarket economy labelled products, were determined. Fluoride ranged from 93 to 820 mg/kg in the products and 0.43 to 8.85 mg/L in the infusions. The UK supermarket economy teas contained elevated fluoride, ranging from 3.60 to 7.96 mg/L in a 2 minute brewing infusion, comparable to Chinese brick tea, indicating the use of mature leaves in their manufacture. Considering the dietary reference intake (DRI) of 4 mg/day of fluoride for an adult consuming 1 L of tea, prepared from an economy tea, containing 6.0 mg/L fluoride, 75–120% of the DRI fluoride is available for absorption by the human system in the presence of food, increasing to 150% when fasting. Excess fluoride in the diet can lead to detrimental health effects such as fluorosis of the teeth and skeletal fluorosis and consuming economy branded tea will lead to exposure.     

Fluoride in tea from Shandong Province,China and exposure assessment

ABSTRACT

In this study fluoride in 170 tea samples from Shandong province (China) was determined using a selective ion electrode. The fluoride concentrations ranged from 31.2 to 338 mg/kg with an average of 119 mg/kg. The mean fluoride concentrations were 164, 121, 98.7 and 96.8 mg/kg, which corresponded to Pu’erh tea, green tea, oolong tea and black tea, respectively. Moreover, 4.7% of the analysed samples exceed the legal limit of 200 mg/kg recommended by China. The estimated daily intake of fluoride via drinking tea for an adult was between 0.655 and 1.07 mg/person/day, which were lower than the provisional maximum tolerable daily intake value of 3.5 mg/person/day set by the National Health and Family Planning Commission of the People’s Republic of China. In future, maintaining a surveillance programme to monitor the trend of fluoride in tea is necessary for food safety and human health.     

Safety evaluation on fluoride content in black tea

Fluoride content in black tea in various commodities, packages, and preparation processess was assayed and its safety evaluated. A fluoride ion selective electrode method was used to determine the fluoride content in 20 tea samples, in various black tea commodities, namely stick-shaped, granular, and canned or bottled tea beverage, originally produced in India, Sri Lanka, China, Japan and UK, and milk–tea after addition of milk and sugar. The fluoride content of 5 stick-shaped black teas was 96.9–148 mg/kg, that of 8 granular black tea was 139–223 mg/kg, and that of 3 canned or bottled beverage black tea beverages was 0.70–0.96 mg/l, respectively. Neither the bagged black tea paper nor the addition of milk and sugar affected the ionic fluoride level within the tea. These results suggest that, for heavy black tea drinkers, the fluoride intake in areas with drinking water fluoridation, and also other probable sources of fluoride, may approach or reach the level of risk from chronic fluoride intoxication.     

绿茶茶汤中黄酮醇及其苷类的测定方法以及对茶汤色度的影响

黄酮醇及其苷类物质是构成绿茶汤色的重要组分。绿茶中含有20多种黄酮醇及其苷类物质,其中以槲皮素、杨梅素、山柰素的3种苷类物质为主。文中采用高效液相色谱法研究了绿茶茶汤酸水解前后槲皮素、杨梅素、山柰素的含量变化,建立了黄酮醇及其苷类含量的检测方法。利用正交实验方法得到茶汤水解的优化条件为:5 mL的茶汤中加15 mL纯甲醇、5 mL 6 mol/L HCl,在75℃下水解时间2h,芦丁的平均水解率为82.74%。对不同贮藏期间茶汤色度与黄酮醇及其苷类的相关性进行了研究,结果表明:茶汤贮藏过程中随着茶汤的红绿度(a)和黄蓝度(b)不断升高,杨梅素苷含量逐步下降,杨梅素苷与茶汤的红绿度、黄蓝度的相关系数分别为:-0.982 1、-0.882 6,但与茶汤明亮度(L)的相关性不显著。槲皮素和山柰素及其苷类与茶汤色泽变化关系不密切。     

茶对氟化物和呕吐毒素对大鼠肝糖原分解的保护作用

目的探究茶对氟与呕吐毒素染毒大鼠肝糖原含量降低的保护作用。方法将50只Wistar大鼠分为空白组、呕吐毒素染毒组、氟染毒组、联合染毒组和饮茶干预组,染毒5周后解剖大鼠,用蒽酮比色法试剂盒检测肝糖原含量。结果氟单独染毒、呕吐毒素与氟联合染毒后肝糖原含量显著性降低(P0.05),呕吐毒素与氟联合染毒后的肝糖原含量显著性低于呕吐毒素单独染毒(P0.05),饮茶干预后的肝糖原含量显著提高(P0.05)。结论呕吐毒素和氟化物对肝糖原有损伤作用,茶对其损伤有保护性作用。     

绿茶提取液沉淀形成机理的研究

以绿茶为试验材料,从茶汤体系的物化性质和化学成分两方面探讨了茶汤沉淀形成的机理。通过对沉淀形成过程中沉淀颗粒形态变化、电解质和氢键裂解剂的作用、红外光谱变化等内容的研究,来判断茶汤形成沉淀前后的性质改变,初步判定经低温贮存后的茶汤体系介于胶体分散系和粗分散系;茶汤颗粒间的氢键、静电作用是影响茶汤沉淀形成的因素,共价键不是沉淀形成的主要因素。通过计算茶汤中各主要成分进入上清相和沉淀相的分配系数,来判断该成分进入上清相和沉淀相的趋势,结果表明:茶多酚是构成茶汤沉淀物的主体物质,其次是果胶、咖啡碱,而在沉淀相中分配系数较大的成分依次是叶绿素、没食子酸、果胶、蛋白质、花青素、咖啡碱、可可碱。     

聚乙烯聚吡咯烷酮(PVPP)吸附对茶饮料风味 品质的影响

目的 通过聚乙烯聚吡咯烷酮(PVPP)过滤吸附除去茶饮料中非生物稳定性物质来研究其对饮料风味品质的影响。方法 茶汤样品经PVPP过滤处理后, 对理化指标、感官品质及特征成分进行分析与全面评价。结果 分析表明PVPP对一般性指标和基本风味物质的影响很小, 说明PVPP处理不会对饮料造成显著影响, 但对特征性指标苦味值表没食子儿茶素没食子酸酯(EGCG)、表儿茶素没食子酸酯(ECG)和香味物质顺-3-己烯醇、苯乙醇有一定的影响。结论 研究表明PVPP能有效地除去茶饮料中的敏感多酚与蛋白, 可明显提高非生物稳定性, 合理利用PVPP调控饮料中多酚含量及构成, 有利于茶饮料风味的改善与保持。