儿茶素的两种浸提工艺的优化及比较

浸提是儿茶素生产的重要步骤,对总收率和后续的分离提纯有直接的影响。本文以茶多酚、儿茶素、咖啡碱的得率为指标,比较浸提温度、时间、液固比、浸提次数对热水浸提和80％的醇水溶液浸提两种方法的不同影响获得两种浸提方法的适宜工艺条件。在此基础上,对两种方法的生产总成本进行了技术经济分析,表明醇水浸提法生产成本与水浸提法之比约为1．15,两种方法适合于不同产品要求的生产。     

国内外抗氧剂动态

本文了抗氧剂在食品中的作用机理，世界各国批准应用的抗氧剂的名单，复配型抗氧剂的优化抗氧化作用以及我国上前应用抗氧剂的情况。     

茶叶中有效成分综合提取的研究

以绿茶为原料，采用ZJL大孔离了交换树脂和ZJX大孔吸附树脂从茶叶的浸提液中提取茶氨酸、咖啡因、茶多酚和茶多糖。通过对树脂的静态、动态吸附性能的实验研究，确定了咖啡因、茶氨酸、茶多酚及茶多糖联合分离提取的工艺。研究结果表明：该工艺能有效的从茶叶中提取咖啡因、茶氨酸和茶多酚，提取的咖啡因纯度达83．23％，提取率为1．9％，茶氨酸纯度达85．43％，提取率为0．94％，提取的茶多酚纯度达95．62％，提取率为12．35％，且茶多酚中的咖啡因含量低于0．7％，茶多糖的纯度达51％，提取率为1．1％。     

不同菌种发酵绿茶对其茶多酚及咖啡碱含量影响的研究

分别以保加利亚乳杆菌、嗜热链球菌、嗜酸乳杆菌三种菌种为生产菌株,以脱脂乳为培养基,茶汁添加量分别为20%、30%、40%。在37℃恒温条件下经6、12、18、24、36、48h发酵后,以紫外分光光度法测定其中茶多酚以及咖啡碱的含量。当茶汁添加量为30%,以保加利亚乳杆菌发酵12～18h时,培养基中茶多酚含量的增加速率最快。当茶汁添加量为30%,以嗜酸乳杆菌发酵12～18h时,咖啡碱含量达最大值。      

绿茶中三种主要成份的快速定量

利用滋味成分在紫外光200—400范围内有吸收性质,选择一定波长,直接测定茶汤的吸光度,同时以常规法测定值为基准,用统计方法建立了多酚类、氨基酸和咖啡碱的定量公式。该方法操作简便、效率高,能适应在短期间进行绿茶品质管理和茶叶品质数据化及标准化的需要。     

茶叶加工中品质关键组分的变化与调控机制

茶树起源于中国,茶叶是世界三大饮品之一.茶叶中富含茶多酚、蛋白质及氨基酸、生物碱、芳香族化合物、糖类、类脂化合物、维生素、无机物、叶绿素、酶等多种化合物.它们经过非发酵、微发酵、半发酵、全发酵及后发酵工艺,萎凋、杀青、揉捻、发酵、干燥等处理后,由于温度、压力、酶及微生物的作用,儿茶素在多酚氧化酶、过氧化物酶等的氧化聚合下分别形成茶黄素、茶红素、茶褐素等茶色素;β-D-糖苷类等香气前驱体在β-葡萄糖苷酶、β-樱草糖苷酶的作用下水解生成相应的醇类等香气物质;蛋白质水解成氨基酸,并形成不同的手性对映体,所以赋予茶叶特有的颜色、香气、滋味、外形以及其抑菌、抗病毒、抗氧化、防衰老、增强机体免疫、防癌抗癌、预防心脑血管疾病等功效,进而形成绿茶、白茶、黄茶、青茶、红茶、黑茶六大茶系.本文从茶叶成品色、香、味等关键组分入手,阐述其在加工过程中的变化规律和关键技术调控的相关性及存在问题,并探讨它们的形成机理,为提高茶叶品质提供理论依据.     

茶饮料生产中茶乳酪的形成及解决方法

主要介绍了茶饮料中茶乳酪的形成原因、基本构成物质及解决方法。     

茶叶中茶多酚的微波辅助提取

介绍了以绿茶茶末为原料，以乙醇为介质，用微波加热法提取茶多酚，并对溶剂浓度、微波功率、提取时间等条件对产品提取率的影瞻进行了探讨，获得最佳的提取条件．结果表明，料液比(w／v)1：9，时间25s，微波浸提2次，茶多本分浸提率达85．8％．该方法与传统提取方法相比，提取率高，省溶剂，提高了提取效率．     

三类茶中茶氨酸、咖啡碱及多酚类的比较分析

采用高效液相色谱等方法比较分析了绿茶类的西湖龙井和碧螺春、红茶类的祈门红茶和立顿红茶、黑茶类的普洱茶Ⅰ（特级标准样）和普洱茶Ⅱ（临沧出产）中茶氨酸、游离氨基酸、咖啡碱、多酚类和没食子酸等物质的含量；研究了绿茶、红茶和普洱茶中茶氨酸与咖啡碱的比例关系、儿茶素的组成特征及含量，探讨了上述物质作为茶叶品质控制和鉴定的综合指标参数以及相关生理功效方面的组效关系的研究意义。     

茶多酚类抗氧化剂的改性

综述了将茶多酚由水溶性改性为脂溶性的溶剂法、乳化法、分子修饰法,并对三种方法在实际应用中的前景进行评述。     

茉莉花茶中茶多酚的提取分离纯化及其抗氧化性能研究

本实验采用溶剂法浸提茉莉花茶中茶多酚,研究发现,相对最优的工艺条件为:温度70℃,乙醇溶液浓度60%,提取次数1次,提取时间60min。在此浸提工艺下提取到茶多酚粗提物后用石油醚、氯仿和乙酸乙酯萃取,得乙酸乙酯相过聚酰胺柱分离纯化,将得到的不同洗脱组分过高效液相色谱检测发现:30%乙醇洗脱组分含表儿茶素没食子酸酯(ECG)最高,60%乙醇洗脱组分中含有表没食子儿茶素没食子酸酯(EGCG),95%乙醇洗脱组分主要是儿茶素没食子酸酯(CG)。继而对不同组分进行抗氧化活性研究得出:60%洗脱组分对油脂的抗氧化活性最高;30%洗脱组分与60%洗脱组分对DPPH自由基50%清除率的浓度分别为0.1723mg/ml、0.1693mg/ml。     

不同极性抗氧化剂在猪油和猪油乳浊液中的抗氧化活性

四种食品抗氧化剂—维生素E(VE或α-生育酚)、茶多酚(TP)、二丁基羟基甲苯(BHT)、特丁基对本二酚(TBHQ)分别添加到猪油、猪油+司班80和猪油+司班80+水为基质的七种不同的体系中,置于(65±1)℃的条件下贮存,每三天对其过氧化值(POV)进行分析,并比较四种不同极性抗氧化剂分别在这七种体系中的抗氧化活性结果表明:在纯猪油体系中TBHQ活性最强,抗氧化效果最好,其次为BHT,再其次为TP,而VE的活性最弱在含有乳化剂和水的猪油体系及只含有乳化剂的猪油体系中,BHT的活性最强体系中的＊,’“起到催化氧化的作用,可加速其氧化,而柠檬酸则可有效钝化卜’”催化氧化活性,大大提高猪油的氧化稳定性     

Antioxidant activity prediction and classification of some teas using artificial neural networks

In order to characterise and to classify some teas a simple, rapid and economical method based on composition, antioxidant activity and artificial neural networks (ANNs) is proposed. For these purpose two types of ANN based applications have been developed: one for predicting the antioxidant activity and a second one for establishing the class of the teas. The complex relationship between the total antioxidant activity (AA) depending on the total flavonoids content (F), total catechins content (C) and total methyl-xanthines content (MX) of commercial teas was revealed by the first designed feed-forward ANN. Secondly, using a probabilistic ANN, successful tea classification in various classes (green tea, black tea and express black tea) was also performed.     

脂溶性儿茶素类化合物的制备研究进展

儿茶素类化合物是一类具有多种生理活性的多酚类抗氧化剂,本文综述了国内外利用分子修饰法制备脂溶性儿茶素类化合物的进展。化学法主要利用酰氯在化学催化剂作用下反应制备脂溶性儿茶素,但是酰化反应发生的位点有所不同,总的来说酰基供体碳链长度一般大于等于8;酶法主要利用脂肪酶使脂肪酸或脂肪酸酯通过直接酯化或酯交换反应制备脂溶性儿茶素,在儿茶素及其化合物上键合烷基,由此提高了儿茶素类化合物在油脂体系中的溶解度,拓展了其应用领域。     

Catechin contents in tea (Camellia sinensis) as affected by cultivar and environment and their relation to chlorophyll contents

The variations of the total and individual catechin contents of tea were evaluated among three cultivars grown in 10 locations; the dynamic changes of chlorophyll and catechin contents in two cultivars during young leaf development were also analysed. The results showed the variations of catechin contents among locations were larger than those among cultivars. Correlation analysis indicated that (+)-catechin was the major catechin fraction significantly correlated with climate factors and chlorophyll contents. Moreover, chlorophyll contents were significantly influenced by climate factors, with the highest correlation coefficient for daily lowest temperature. Furthermore, the rise of chlorophyll a content during young leaf development was observed alongside the increase of (−)-epicatechin, (−)-epigallocatechin and the decline of (+)-catechin, suggesting chlorophyll plays a vital role in the regulation of individual catechins.     

由中国茶叶中提取抗氧化剂的研究

本文主要论述由15种不同的中国成品茶、半成品茶、茶树老叶中提取以多酚类化合物为主的抗氧化剂,用HPLC测定其中6种已知组分的含量。以Rancimat法和POV法测定它们在猪油中抗氧化性能。结果表明,不同的加工工艺能够显著地影响茶叶抗氧化剂的得率和抗氧化性能。同时发现,它们在抗氧化过程中达到某一个阶段后,因积累了一定数量的氧化产物或新的自由基,当其氧化性的影响超过抗氧化剂的抗氧化性的影响时,将促使油脂更快地氧化(酉合)败。     

茶叶咖啡碱分离提取新技术研究

本文以中、低档绿茶为原料,研究了咖啡碱分离提取技术,结果表明:微波水提结合乙酸乙酯萃取应用于茶叶中咖啡碱的提取具有短时、高效、产品无毒性等优点。确定咖啡碱最佳萃取条件为:供试液中NaCl浓度0.2%,二倍量的乙酸乙酯萃取三次,咖啡碱萃取率达95.14%。经升华纯化后,咖啡碱得率为1.2%,纯度为98.2%;紫外光谱分析证实,该工艺分离对咖啡碱制品的化学结构无影响。     

Quantitative and Qualitative Portrait of Green Tea Catechins (Gtc) Through Hplc

Green tea (Camellia sinensis) is a prosperous source of polyphenols, especially catechins. In the current research, an effort was made to optimize the extraction conditions for maximum yield of catechins from the local green tea Qi-Men. For the purpose, three different solvents were used, i.e., aqueous ethanol (50%), aqueous methanol (50%), and water at different time intervals (20, 40, and 60 min). Green tea catechins were quantified through HPLC using a C18 column and UV detector. The antioxidant activity of green tea catechins was measured through in vitro tests including DPPH radical scavenging ability and antioxidant activity. Results showed that extraction through aqueous ethanol resulted in maximum yield of green tea catechins (17400 ± 0.19 mg/100 g green tea leaves. Moreover, epigallocatechin, epigallocatechin gallate, epicatechin gallate, and epicatechin ranged from 4.26 ± 0.09 to 6.4 ± 0.2, 12.1 ± 0.123 to 17.7 ± 0.3, 1.32 ± 0.03 to 1.81 ± 0.02, 5.48 ± 0.099 to 8.6 ± 0.2 g/100 g of dry-extract, respectively. Furthermore, highest antiradical (80.65 ± 3.69%) and antioxidant activity (67.12 ± 3.08%) were observed in catechins extracted through aqueous ethanol.     

Bioactive Compounds and Antioxidant Activity of Bunchosia glandulifera

Bunchosia glandulifera is a red-colored fruit and a source of bioactive compounds with antioxidant potential. The fruit was collected in the city of Santo Antonio Patrulha-Brazil, and the pulp contained phenolic compounds, anthocyanins, flavonoids, lycopene, β-carotene, vitamin C, and caffeine. Rutin, vitexin, and quercitrin were the phenolic compounds identified in the pulp. The concentrations of lycopene (16.39 mg/100 g fruit) and β-carotene (8.10 mg/100 g fruit) provided the fruit’s distinct color. The fruit pulp was rich in caffeine (206.35 mg/100 g) and showed antioxidant activity as determined by Ferric Reducing Antioxidant Power, 2,2′-Azinobis-(3-Ethylbenzothiazoline-6-Sulfonic acid, and 2,2 Difenil-1-Picrilhidrazil. The high antioxidant activity was due to its high levels of bioactive compounds.