Epimerisation of tea polyphenols in tea drinks

The present study was carried out to quantify green tea epicatechin (GTE) derivatives and to investigate the origin of epicatechin epimers present in 18 selected canned or bottled tea drinks. The major GTEs present in tea are (?)‐epigallocatechin gallate (EGCG), (?)‐epigallocatechin (EGC), (?)‐epicatechin gallate (ECG) and (?)‐epicatechin (EC). HPLC analysis showed that the content of total GTEs was lower (16.4–268.3 mg l^?1) in the canned and bottled tea drinks than in tea traditionally prepared as a beverage in a cup or teapot (3–5 g l^?1). The major finding was that they contained higher levels of epicatechin epimers, namely (?)‐gallocatechin gallate (GCG), (?)‐gallocatechin (GC), catechin gallate (CG) and (?)‐catechin (C), than of GTEs, ranging from 7.6 to 331.8 mg l^?1. To investigate the origin of these epimers, GTEs were extracted from longjing green tea and autoclaved at various temperatures for 10–60 min. It was found that at least 50% of GTEs were epimerised to their corresponding epimers when autoclaved at 120 °C for 20 min. It is concluded that epicatechin epimers in tea drinks are not originally present in green tea leaf but are instead derived from thermal conversion of GTEs. Copyright © 2003 Society of Chemical Industry     

天麻藤茶红茶复合饮料工艺优化及其抗氧化活性研究

以天麻、藤茶、红茶为主要原料,研究天麻浸提液、藤茶浸提液、红茶浸提液、白砂糖和柠檬酸添加量对天麻藤茶红茶复合饮料感官品质的影响,以感官评分为指标,采用响应面法优化天麻藤茶红茶复合饮料工艺,并对其营养成分和抗氧化活性进行测定。结果表明,最优工艺条件:天麻浸提液添加量12%,藤茶浸提液添加量45%,红茶浸提液添加量5%,白砂糖添加量6%,柠檬酸添加量0.06%。该条件下复合饮料总黄酮(0.127±0.0083)mg/g,总酚(0.131±0.0079)mg/g,可溶性糖(23.709±0.295)mg/g,还原力(3.524±0.031)mg/mL,羟基自由基清除率32.1%±1.86%,DPPH自由基清除率89.4%±2.07%,表明该复合饮料抗氧化能力良好。本试验制得复合饮料口感好、色泽均匀、呈淡黄色,具有天麻藤茶红茶复合饮料独特的香气。     

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.     

离子选择性电极法测定两种茶饮料中的氟含量

使用氟离子选择性电极测定两种茶饮料中的氟,通过加入TISAB缓冲溶液控制测定条件,采用标准曲线法测定了"康师傅"绿茶和红茶中的氟含量。进行了回收率的测定,并对搅拌状态、有无TISAB以及溶液p H大小的影响进行了实验分析。结果表明,红茶中的氟含量为0.9602mg/L,加标回收率为95.79%~102.88%;绿茶中的氟含量为1.135mg/L,加标回收率为97.04%~101.06%。实验操作简单方便,回收率高,能满足对茶饮品的测定。     

奶茶泡腾片固体饮料的研制

以脱脂奶粉和红茶粉为主要原料,研制出一种新型奶茶泡腾片固体饮料。通过单因素和正交优化试验,得到奶茶粉的最佳工艺配方为脱脂奶粉8%,红茶粉1.5%,复配稳定剂0.3%(单甘脂0.2%、卡拉胶0.1%),白砂糖5%。经优化后,奶茶泡腾片的最佳工艺配方为奶茶粉8%,三氯蔗糖0.8%,柠檬酸与碳酸氢钠质量比1︰1。在该工艺下制备得到的奶茶泡腾片平均崩解时间为235 s,平均pH 4.77,所得饮料呈棕褐色,酸甜可口,富有牛奶和红茶的香气。     

响应面优化低糖滇红奶茶的配方

目的 通过响应面法优化低糖滇红奶茶的配方。方法 以滇红茶、全脂奶粉、零卡糖为主要原料,通过单因素分析结合响应面实验设计优化滇红奶茶配方,并分析产品的理化及卫生指标。结果 优化配方为：滇红茶汁50%、全脂奶粉15%、零卡糖10%、乳化剂0.22%、稳定剂0.2%,此时感官评分为87.83。滇红奶茶浅棕色稳定性好、质地均匀、浓稠恰当、细腻滑润无杂质,甜味适中茶香味与奶香香味协调无异味,经测定蛋白质含量(5.99±0.06)%、脂肪含量(3.38±0.02)%、茶多酚含量(320.6±2.25) mg/kg,微生物指标符合国家标准。结论 本研究开发了一种低糖健康的滇红奶茶,为滇红茶的深加工提供一定的实验依据。     

薏米奶茶固体饮料的制备

以薏米和茶叶为主要原料,研究了其有效成分的提取工艺。提取液经浓缩,再配以其它辅料,加工制成有特殊风味的薏米奶茶固体饮料。     

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.     

红茶奶粉的研制

介绍用鲜牛奶、红茶、砂糖及阿期巴甜为原料研制的具有西式奶茶风味的固体乳饮料。经1∶16水稀释成奶茶,牛奶含量达40%以上,甜度以蔗糖计为6.0%。其中每加工1000kg牛奶需投入碎红茶37.5kg。产品经真空浓缩、喷雾干燥制成。     

黑豆黑芝麻复合饮料的研制

为开发一款营养健康的谷物复合饮料,以黑豆、黑芝麻为主要原料,通过单因素实验、正交试验,以感官评价为指标以获得产品的最佳配方和工艺,并对产品进行理化和微生物检测.结果表明:黑豆豆浆预制工艺为黑豆浸泡时间为8h,黑豆煮制25min后,按黑豆:水=1:9打浆;黑芝麻浆预制工艺为黑芝麻:水=1:5打浆;该饮料的最佳配方为:黑豆...     

超滤法生产罐装红茶饮料的研究

采用超滤法除去红茶汁中的鞣质，辅以砂糖、果汁等生产罐装红茶饮料，呈透明状态；同时，茶中的营养成分、风味物质得到保留。证明了超滤法生产罐装红茶饮料的可行性。     

市售茶饮料中主要功效成分分析

目的研究市售茶饮料中主要品质成分含量情况,并分析其差异原因。方法采用酒石酸铁比色法测定茶多酚(teapolyphenols,TP);采用水合茚三酮比色法测定游离氨基酸总量;采用高效液相色谱法(high performance liquid chromatography, HPLC)法检测6种儿茶素以及咖啡碱(caffeine, CAF)含量。结果目前市售茶饮料以调味茶饮料居多,不同种类、不同品牌茶饮料中的茶多酚、儿茶素、CAF以及游离氨基酸含量具有明显差异。结论绿茶饮料各种主要品质成分含量较高,其次为乌龙茶饮料,红茶饮料较低。CAF含量全部样品符合国家标, TP含量仅有一款红茶饮料低于国家标准,其余均符合国家标。     

Copper, zinc, tin and lead in canned evaporated milk, produced in Lithuania: the initial content and its change at storage

The study has been carried out to elucidate what contents of heavy metals were typical for canned milk products - evaporated (TS 25.5-28.5%) sterilized milk and condensed sweetened milk, produced in Lithuania in the period 1983-1997. The influence of storage time upon the level of Sn, Pb, Cu and Zn in the products has also been determined. The results show that the most considerable changes occurred in Cu concentration, which gradually decreased from the maximum level in 1983-1985 (2.23±0.18mg/kg) to the minimum level in the latest years (0.44±0.01 mg/kg). Such variation of copper content in canned milks can be closely connected with its changes in raw milk. Zinc content in canned milk products also was in good agreement with raw milk. The content of tin and lead in the canned products many times exceeded their concentration in raw milk and ranged from 28±2 and 0.093±0.005 to 114±4 and 0.29±0.01 mg/kg, respectively. It has been determined that the dependence of the concentration of tin and lead on the storage time of concentrated (or evaporated) sterilized milk is nearest to the parabolic, and in sweetened condensed milk to the exponential function, whereas the small increase of copper and zinc concentrations can be described by straight-line function. The functional dependence obtained enables one to predict the Sn and Pb level in canned evaporated milk products after storage and to foresee the safe initial concentration of these metals in freshly produced evaporated milk, assigned for storage.     

无子刺梨红茶复合饮料配方研究及其香气成分分析

目的 以无子刺梨及红茶为主料研制无子刺梨红茶复合饮料, 确定最佳配方并探究其香气成分。方法 基于单因素实验, 以感官评分为评价指标, 通过正交实验结合模糊数学评价法对无子刺梨红茶复合饮料配方进行优化, 经顶空固相微萃取-气相色谱-质谱法(headspace solid-phase micro-extraction coupled with gas chromatography-mass spectrometry, HS-SPME-GC-MS)分析复合饮料香气成分。结果 影响复合饮料感官品质的因素排序为:无子刺梨原汁与红茶茶汤体积比>苹果酸添加量>柠檬酸添加量>白砂糖添加量, 最佳配方为: 无子刺梨原汁与红茶茶汤的体积比为1:45、白砂糖添加量为6.00%、柠檬酸添加量为0.10%、苹果酸添加量为0.01%。复合饮料包含挥发性成分31种, 邻苯二甲酸二异丁酯、壬醛、癸醛是饮料香味轮廓呈现柑橘香和红茶香韵的重要物质。结论 该复合饮料呈深褐色、酸甜适口, 具有无子刺梨的果香和红茶浓郁的茶香, 是一款适于消费者饮用的复合饮料。     

紫背天葵茶饮料的研制

本研究以紫背天葵和绿茶为主要复合原料,开发新型复合果蔬茶饮料,旨在为紫背天葵深加工提供新思路。在单因素实验的基础之上,通过正交试验优化了紫背天葵茶饮料的调配配方,并对均质条件进行了研究。实验结果表明,紫背天葵茶饮料的最佳配方为紫背天葵汁和茶水的比例1:1(体积比)、白砂糖5%、柠檬酸0.05%;稳定剂最佳组合为黄原胶0.2%、海藻酸钠0.07%、羧甲基纤维素0.08%;最佳的均质条件为均质压力30 MPa均质2次。在此工艺下,得到的紫背天葵茶饮料可溶性固形物为5.2%(以白砂糖计),总酚为12.64 mg/mL,总黄酮为0.47 μg/mL,V_C为210.16 μg/mL。     

玫瑰花、玫瑰茄、滇红茶、绿茶复合饮料的研制

以玫瑰花、红茶、绿茶、玫瑰茄为主要原料研制复合饮料。采用L2(556)正交试验和感观评定的方法确定了饮料的最佳配方及加工工艺。试验表明添加红茶4g·L-1、绿茶g·L-1、玫瑰花8g·L-1、玫瑰茄10g·L-1、白糖120g·L-1、柠檬酸0.2g·L-1,饮料感观品质最好。     

乳酸菌发酵红茶饮料主要营养成分变化

以红茶浸提液为发酵基质,接种植物乳杆菌种子液进行发酵制备乳酸菌发酵红茶饮料,对其发酵过程中pH值、总酸、蔗糖、茶多酚含量进行分析,采用分光光度法及顶空固相微萃取气质联用法（HS-SPME-GC-MS）测定其游离氨基酸及风味物质,并比较红茶浸提液发酵前后二者的变化。结果表明,乳酸菌发酵红茶饮料pH值由4.97降至3.16,总酸由0.15 g/L升至2.38 g/L,蔗糖含量由0.90 g/L降至0.34 g/L;茶多酚含量由15.1 g/L减少至10.6 g/L,游离氨基酸含量由0.921 g/100 g提升至1.175 g/100 g,发酵前后分别检出88和94种挥发性风味物质。乳酸菌发酵红茶饮料较红茶浸提液营养成分更加丰富,酸甜适宜,风味独特。     

红茶小米复合型发酵乳的研制

以牛乳、小米和红茶为主要原料,以保加利亚乳杆菌（Lactobacillus bulgaria）和嗜热链球菌（Streptococcus thermopiles）为发酵剂,经混合发酵制成一种新型固态发酵乳,并以红茶小米混合发酵乳的酸度和感官评分为评价指标,利用正交设计和模糊数学评价法确定产品最优配方为：小米浆添加量18%,红茶添加量5%,糖粉添加量12%、羟丙基甲基纤维素（HPMC）添加量1.5%。在此优化配方条件下,红茶小米发酵乳的感官评分为93.6分,酸度为78.8 °T,蛋白质含量为2.45 g/100 g,脂肪含量为2.63 g/100 g;乳酸菌数为1.72×106 CFU/g,未检出致病菌,符合相关国家标准;成品风味清新,口感醇厚,是一种营养和美味兼具的发酵乳制品。     

Magnetic effervescent tablet-assisted ionic liquid dispersive liquid–liquid microextraction of selenium for speciation in foods and beverages

A novel, simple and rapid method based on magnetic effervescent tablet-assisted ionic liquid dispersive liquid–liquid microextraction (MEA-IL-DLLME) followed by graphite furnace atomic absorption spectrometry (GFAAS) determination was established for the speciation of selenium in various food and beverage samples. In the procedure, a special magnetic effervescent tablet containing CO₂ sources (sodium carbonate and sodium dihydrogenphosphate), ionic liquids and Fe₃O₄ magnetic nanoparticles (MNPs) was used to combine extractant dispersion and magnetic recovery procedures into a single step. The parameters influencing the microextraction efficiency, such as pH of the sample solution, volume of ionic liquid, amount of MNPs, concentration of the chelating agent, salt effect and matrix effect were investigated and optimised. Under the optimised conditions, the limits of detection (LODs) for Se(IV) were 0.021 μg l^–1 and the linear dynamic range was 0.05–5.0 μg l^–1. The relative standard deviation for seven replicate measurements of 1.0 μg l^–1 of Se(IV) was 2.9%. The accuracy of the developed method was evaluated by analysis of the standard reference materials (GBW10016 tea, GBW10017 milk powder, GBW10043 Liaoning rice, GBW10046 Henan wheat, GBW10048 celery). The proposed method was successfully applied to food and beverage samples including black tea, milk powder, mushroom, soybean, bamboo shoots, energy drink, bottled water, carbonated drink and mineral water for the speciation of Se(IV) and Se(VI) with satisfactory relative recoveries (92.0–108.1%).     

Survey of bisphenol a diglycidyl ether (BADGE) in canned foods.

2,2-Bis(4-hydroxyphenyl)propane bis(2,3-epoxypropyl) ether (BADGE) is used in the manufacture of lacquers for coating the inside of food and beverage cans. In June 1996 the EC Scientific Committee for Food temporarily increased the specific migration limit applying to BADGE to 1 mg/kg pending consideration of additional toxicological data. In order to find out if there is migration of BADGE from can coatings into foods, a 'worst case' sampling exercise has been conducted to survey those canned foods where the propensity for migration of BADGE was judged to be highest. The foods surveyed include canned fish in oil, meat and milk and, altogether, BADGE was determined in 181 retail samples. Analysis for BADGE was conducted, in duplicate, by HPLC with fluorescence detection with confirmation of BADGE identity by GC/MS analysis using selected ion monitoring. BADGE was found at levels exceeding 1 mg/kg in seven of the 15 canned anchovy samples and five of the 22 sardine samples purchased during the period September 1995-July 1996. Infrared analysis of the can coatings provided strong evidence that the higher BADGE levels found were associated with use of PVC organosol lacquers, although in some cases cans coated with organosols gave low BADGE results. For canned sardine samples found to contain greater than 0.5 mg/kg BADGE in the total contents, a replicate can was opened and separate analyses performed on the drained fish and the oil. The results clearly showed that BADGE concentrations in the oil were about 20 times higher than in the drained fish. Further samples of canned sardines and anchovies were purchased in June/July 1997 and, in all cases, BADGE levels were found to be below 1 mg/kg. In the other retail canned foods, BADGE was not detectable (DL = 0.02 mg/kg) or detected at concentrations well below the temporary SML of 1 mg/kg.