名优绿茶品质劣变机理及贮藏保险技术

对名优绿茶贮藏过程中品质变化机理及不同场合的保鲜技术方法进行了论述.名优绿茶贮藏过程品质陈化劣变是茶叶内含成分发生一系列的化学变化的结果,这种变化的大小直接受茶叶含水量、温度、氧气、光线等条件的影响.名优绿茶贮藏保鲜,首先,茶叶必须充分干燥;大批量名优绿茶采用茶叶专用低温冷藏库保鲜(0℃～8℃);销售小包装茶叶采用真空或除氧剂除氧密封包装比较理想;茶叶专用低温冷藏库保鲜与真空或除氧剂除氧密封包装综合应用,可以达到理想的保鲜效果.     

茶叶保鲜技术及质变成因的比较研究

试验对炒青绿茶的贮藏保鲜技术进行了比较研究。结果表明，温度主要是通过减缓茶叶氨基酸的陈化速度而起保鲜作用的；保鲜剂对延缓茶多酚、氨基酸的陈化速度作用明显，并且还提出了当前市售保鲜剂的最佳保鲜期限为3个月，在使用保鲜剂进行茶叶贮藏过程中，应当明确了解保鲜剂的保鲜期限并运用合理的贮藏方法。光照、不同包装材料等因素在茶叶贮藏过程中对茶叶品质成分（茶多酚、氨基酸、咖啡碱）的变化影响均较大。     

大米品质快速检测及贮藏保鲜新技术研究进展

大米作为我国大部分居民的主食,在饮食结构中占有非常重要的地位。大米在贮藏过程中易发生陈化、霉变、虫害等问题,如何快速检测大米品质的变化,并采取有效的贮藏保鲜技术对保障大米食用价值具有十分重要的意义。从大米品质快速检测与贮藏保鲜技术两个方面,概述了理化方法、近红外光谱等快速检测技术与微波加热、纳米保鲜膜等保鲜技术的研究与应用情况,指出了这些技术存在的问题,并对将来的发展方向进行了展望。其中,在大米品质快速检测方面,有待进一步开发方便、快捷的检测试剂与装置;在大米贮藏保鲜技术方面,则可探讨复合型保鲜技术与分子生物学技术对大米保鲜的效果。     

海参贮藏保鲜机理及保鲜技术研究进展

海参具有丰富的营养价值和食疗养生功能。在市场流通和贮藏过程中,海参自溶和微生物生长易导致品质劣化,造成巨大的经济损失。明确海参贮藏保鲜过程中内源酶和微生物的作用机理,是阐释海参品质变化的核心,对设计开发新型海参贮藏保鲜技术具有理论指导意义,是关乎海参产业发展的关键技术问题。本文概述海参贮藏保鲜机理,归纳海参相关保鲜技术,提出深入研究的建议,并对未来发展趋势予以展望,以期为海参行业高质量发展提供更强有力的理论支撑。     

茶叶保鲜新技术的探讨

对茶叶的贮藏保鲜条件、包装材料、保鲜新技术等作了全面的论述,以期为茶叶的贮藏和茶饮料的生产理论依据     

电磁场辅助低温处理对肉品质影响的研究进展

低温贮藏是肉及肉制品最常规的保鲜方法。肉制品在冷藏、冷冻及解冻过程中,因微生物侵染、汁液流失、蛋白质变性等原因导致肉的品质下降。为防止肉制品在贮藏、销售中的品质劣变,近年来研究人员对电场、磁场辅助低温对肉制品的保鲜技术进行相关研究。该文详细阐述目前电磁场辅助低温处理在肉制品保鲜上的应用现状,以及该技术面临的挑战和问题,初步探究电场、磁场以及电场-磁场组合技术在肉制品保鲜领域的应用前景,旨在为肉制品低温保鲜技术的发展与突破提供参考。     

物理方法在鲜切苹果保鲜中的应用研究进展

鲜切苹果具有新鲜、方便等优点,深受消费者的青睐。但鲜切时造成的机械损伤会破坏苹果天然的组织结 构,极易出现褐变、果实软化、腐烂等问题。传统的化学保鲜方法已不能满足消费者对食品安全高质量的要求,而 物理保鲜技术因其处理条件易于控制、保鲜效果好、安全性高的优势,在果蔬贮藏保鲜中应用广泛。本文综述了光 电方法、高压技术、气调贮藏技术、温度调控和其他物理技术在提高鲜切苹果贮藏品质方面的研究进展,分析了这 些技术通过钝化酶活性、抑制酶促褐变、杀灭微生物的方式以保持和提高鲜切苹果感官品质方面的可能机理。随着 这些技术的应用和发展,鲜切苹果的贮藏保鲜品质将得到保障。     

柑橘采后贮藏保鲜技术研究进展

柑橘采后贮藏期间易发生侵染性病害问题为其产业造成了巨大的经济损失,因此研究柑橘的贮藏保鲜技术对减少其采后损失具有重要的意义。该文围绕柑橘采后贮藏所涉及的物理、化学、生物以及协同保鲜等相关技术的研究成果进行综述,进一步探讨了目前柑橘采后贮藏存在的问题。前期的研究结果表明,热处理是一种简易高效、安全且具有发展前景的保鲜技术,天然可食性涂膜是未来研究热点,协同保鲜结合生物防治剂因其能显著增强保鲜效果亦备受关注,此外,明确保鲜效果成因的机理有助于从根本上提升柑橘保鲜技术。综上,柑橘采后保鲜技术应在满足食用安全性的同时保证柑橘良好的质量品质,而将电子信息化技术应用于柑橘采后保鲜领域在工业信息化时代亦显得尤为重要。     

兰州百合采后贮藏保鲜研究进展

目的兰州百合营养丰富,采后易褐变,造成经济损失严重。通过对兰州百合采后贮藏保鲜研究进行综述,以期为兰州百合品质提升和减损增效提供一定的参考。方法在查阅国内外相关文献的基础上,紧密结合产业发展,综合分析兰州百合的传统保鲜、物理保鲜和化学保鲜方法。结果窖藏、沙藏、预冷、低温、气调、臭氧、紫外照射、二氧化氯、1-甲基环丙烯(1-MCP)和涂膜保鲜均可有效地保持兰州百合的贮藏品质,生物保鲜研究仍有待进一步加强。结论兰州百合贮藏过程中的褐变机制亟需明确,贮藏保鲜技术仍需挖掘,不同保鲜技术的复合应用前景广阔。     

树莓果实贮藏保鲜技术研究进展

树莓果实因具有较高的营养和功能价值,受到越来越多消费者的青睐,在我国有良好的发展前景。但树莓完全成熟后呼吸速率较大且果皮极薄,组织结构脆弱,极易受到机械损伤及微生物入侵而发生腐烂,常温下货架期只有1～2 d,因此树莓的贮藏保鲜仍是世界性难题。该文从不同采前因素对树莓贮藏品质的影响、树莓采后保鲜技术、树莓全产业链保鲜措施等方面,系统全面地阐述了国内外关于树莓贮藏保鲜的研究。关于树莓贮藏保鲜技术的发展还存在着树莓采后品质劣变规律研究不深入、精准保鲜技术缺乏、保鲜技术匹配度不高等问题。今后应对保鲜机制进行深入研究,同时加强全产业链精准保鲜技术的研发,以期为树莓的贮运保鲜提供参考。     

蜂蜜茉莉普洱茶饮料工艺的研究

研究了以普洱茶和茉莉花茶为主要原料制备的茶饮料的工艺流程.结果表明,浸提普洱茶和茉莉花茶的最佳工艺参数为:浸提时间15min,茶水质量比1:65,浸提温度85℃,浸提pH值为5.0,离心速度7000r/min,椴树蜜的添加量0.6%,VC的添加量为0.05%,饮料的糖度约为3.9°Bx,135℃瞬时灭菌5s.该饮料最大程度地保留了普洱茶和茉莉花茶的香味,又减少沉淀,茶汤色泽呈红色,澄清透明.     

高效液相色谱-二极管阵列法检测四川绿茶、黄茶、黑茶、红茶和青茶中甲基化儿茶素含量

采用高效液相色谱-二极管阵列检测法(HPLC-DAD)对四川省雅安、成都、乐山、宜宾、绵阳23家企业生产的绿茶、黄茶、黑茶、红茶和青茶中48个茶样的(-)-表没食子儿茶素-3-O(3-O-甲基)没食子酸酯(EGCG3″Me)含量进行了比较研究。结果表明:青茶EGCG3″Me含量最高,在3.14~6.08 mg/g之间,平均值为4.40 mg/g;黑茶EGCG3″Me含量在0~1.72 mg/g,平均值为0.35 mg/g;绿茶和黄茶中EGCG3″Me含量较低;绿茶中含量在0~0.39 mg/g之间,平均值为0.10 mg/g;黄茶中含量在0~0.09 mg/g之间,平均值为0.05 mg/g;红茶中未检出。各茶类间EGCG3″Me含量差异显著,主要原因在于加工所用鲜叶原料(品种、采摘标准等)及加工工艺等不同。建议易过敏人群应适当饮用青茶。     

Ultrafiltration isolation,physicochemical characterization,and antidiabetic activities analysis of polysaccharides from green tea,oolong tea,and black tea

Both fermentation degree and preparation method of polysaccharides could influence the bioactivity of tea polysaccharides. The aim of this study was to compare the physicochemical characterization and biological activities of the polysaccharides isolated by ultrafiltration method from three kinds of tea (green tea, oolong tea, and black tea). The bioactivities of tea polysaccharide fractions were compared from four aspects, including antioxidant activities, antiglycation activities, α-glucosidase inhibitory capability, and hypoglycemic effects on L6 myotubes. Results showed that six polysaccharides (GTPS1, GTPS2, OTPS1, OTPS2, BTPS1, and BTPS2) had different contents of neutral sugar and uronic acid, and they showed different morphologies. Six polysaccharides were composed of the seven monosaccharides with different molar ratios. BTPS1 exhibited the highest DPPH scavenging activity and hydroxyl radical scavenging activity (P < 0.05), and BTPS1 also showed the strongest antiglycation inhibitory effects (P < 0.05). BTPS1 and BTPS2 showed strong inhibitory capacity on α-glucosidase and hypoglycemic effects in L6 skeletal muscle cells. The result suggested that the degree of fermentation of tea could improve their bioactivities (BTPS > OTPS >GTPS), and TPS1 with smaller molecular weight distribution showed higher bioactivities than TPS2. This study can provide a scientific foundation for the application of tea polysaccharides and related functional products.     

Coffee,cocoa, and tea

Abstract

This review deals with the chemistry of the odoriferous constituents of the volatile part of the flavors of coffee, cocoa, and tea. A general survey of the analytical studies which have been conducted on these aromas is presented. A list of identified compounds mentions the year of their first discovery and the reference of the corresponding publication. Comments are given on the structure, the origin, and the organoleptic properties of some typical constituents. In the last section the organoleptic characteristics of the three beverages are discussed on the basis of their distribution among the various functional classes.     

Effects of tea leaf waste of green tea,oolong tea,and black tea addition on sudangrass silage quality and in vitro gas production

This study evaluated the fermentation characteristics and in vitro gas production of sudangrass (Sorghum sudanese) silage with tea leaf waste of green tea, oolong tea and black tea added. All types of tea leaf waste contain large amounts of nitrogen (N) and tannins, and a small amount of low‐water‐soluble carbohydrates. Sudangrass was preserved without (control) and with green tea waste (GTW), oolong tea waste (OTW) or black tea waste (BTW) at rates of 50, 100 and 200 g kg^?1 fresh matter in laboratory silos. The pH and butyric acid levels were significantly lower in GTW at all rates and in OTW at the 200 g kg^?1 rate, whereas those levels were high in the control and BTW‐treated silage. Lactic acid level was appreciably higher in GTW‐ and OTW‐treated silage than the control and BTW‐treated silage. The addition of all types of tea waste increased the total N and tannins of the silage, whereas the acid detergent insoluble N was increased in the OTW‐ and BTW‐treated silage. GTW treatment increased gas production within a 96‐h period compared with the control, whereas OTW and BTW additions at 200 g kg^?1 rates caused lower gas production. It is concluded that the fermentation characteristics and feed value of the silage incorporating with tea leaf wastes are different for these types of tea leaf. Among the three kinds of tea waste, GTW is the most valuable material as a silage additive. Copyright © 2004 Society of Chemical Industry     

茶叶籽油、油茶籽油与茶树油的区别

茶叶籽油、油茶籽油和茶树油是不同的物质,它们很容易混淆.介绍了茶树和油茶树的生长特性、植物学分类和分布情况,并对茶叶籽和油荼籽、茶叶籽油和油茶籽油的成分和异同之处进行了分析比较,还介绍了茶树油的来源、性质和用途,以便正确区分它们.     

K and Ca content of fresh green tea, black tea, and tea residue determined by X-ray fluorescence analysis

Summary X-Ray fluoresence (XRF) can be successfully used for the qualitative and quantitative elemental analysis of various agricultural products. Its simplicity, high throughput and the possibility of automation make it useful for screening large numbers of samples. The K and Ca content of 138 samples of fresh green tea, black tea and black tea residues were determined by applying the XRF system. Such a method of mineral analysis of food products is not very common. Tea from different teagrowing areas of Turkey, green tea of different shooting periods, black tea processed at different tea plants and tea residues from these black tea were analysed. The K content of green tea, processed black tea and tea residues after brewing were found to have ranges of 19,049–26,254 mg/kg, 21,904–26,883 mg/kg and 9,468–13,778 mg/kg, respectively. In the same samples the Ca content was determined as 3,580–4,799 mg/kg, 3,370–4,823 mg/kg, and 3,743–5,733 mg/kg, respectively. These findings were compared with the results of atomic emission techniques and it was concluded that the XRF system could be effectively used for quantitative analysis of the K and Ca content of tea samples.

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Die Bestimmung des K- und Ca-Gehaltes von frischem Tee, schwarzem Tee und Teerückstand durch die X-Ray-Fluoreszenz-Technik

Zusammenfassung Mit der X-Ray Fluoreszenztechnik können die qualitativen und quantitativen Bestimmungen der Mineralstoffe in verschiedenen Produkten erfolgreich durchgeführt werden. Mit dieser Methode wurde der Ca- und K-Gehalt von 138 Proben untersucht, und zwar frischer Tee, schwarzer Tee und Teerückstand. Diese Methode ist in der Lebensmitteltechnologie, insbesondere bei der Mineralstoffbestimmung nicht üblich. Die Teeproben stammten aus verschiedenen Teeanbaugebieten der Türkei. In dieser Arbeit wurden die Wirkung der Sproßperiode, der Verarbeitungstechnik und des Anbaugebietes auf den Ca- und K-Gehalt der Teeproben untersucht. Der durchschnittliche K-Gehalt betrug: in frischem Tee 19049–26254 mg/kg, in schwarzem Tee 21904–26883 mg/kg, in Teerückstand 9468–13778 mg/kg; der Ca-Gehalt 3580–4799 mg/kg, 3370–4823 mg/kg und 3473–5733 mg/kg.

     

Antioxidant activities of crude tea polyphenols, polysaccharides and proteins of selenium-enriched tea and regular green tea

The crude tea polyphenols, polysaccharides and proteins of regular green tea and Se-enriched green tea were investigated in vitro for antioxidant activities by auto-oxidation test (AAPH) and α,α-diphenyl-β-picrylhydrazyl (DPPH) radical scavenging method. Results showed that crude tea polyphenols of Se-enriched green tea provided the highest antioxidant activity by DPPH assay and the antioxidant activity was decreased in the order: crude tea polyphenols > crude tea proteins > tea polysaccharides. The crude protein of Se-enriched green tea was found to exhibit the highest antioxidant activity by AAPH method and the antioxidant activity was decreased in the order: crude tea proteins > tea polyphenols > tea polysaccharides. Tea polyphenols and tea polysaccharides of Se-enriched green tea presented significantly higher antioxidant activities than that of regular green tea. No significant difference of antioxidant activities was found between crude tea proteins of Se-enriched green tea and regular green tea. The combinations of Se with tea polyphenols and tea polysaccharides were responsible for the higher antioxidant activities of Se-enriched green tea than regular green tea.     

Pu-erh tea, green tea, and black tea suppresses hyperlipidemia, hyperleptinemia and fatty acid synthase through activating AMPK in rats fed a high-fructose diet

Although green tea extract has been reported to suppress hyperlipidemia, it is unclear how tea extracts prepared from green, oolong, black and pu-erh teas modulate fatty acid synthase expression in rats fed on a high-fructose diet. In this animal study, we evaluated the hypolipidemic and hypoleptinemia effect of these four different tea leaves fed to male Wistar rats for 12 weeks. The results showed that a fructose-rich diet significantly elevated serum triacylglycerols, cholesterol, insulin, and leptin concentrations, as compared with those in the control group. Interestingly, consuming tea leaves for 12 weeks almost normalized the serum triacylglycerols concentrations. Again, rats fed with fructose/green tea and fructose/pu-erh tea showed the greatest reduction in serum TG, cholesterol, insulin and leptin levels. In contrast, serum cholesterol and insulin concentrations of the fructose/oolong tea-fed rats did not normalize. The relative epididymal adipose tissue weight was lower in all rats supplemented with tea leaves than those fed with fructose alone. There was molecular evidence of improved lipid homeostasis according to fatty acid synthase (FAS) protein expression. Furthermore, supplementation of green, black, and pu-erh tea leaves significantly decreased hepatic FAS mRNA and protein levels, and increased AMPK phosphorylation, compared with those of rats fed with fructose only. These findings suggest that the intake of green, black, and pu-erh tea leaves ameliorated the fructose-induced hyperlipidemia and hyperleptinemia state in part through the suppression of FAS protein levels and increased AMPK phosphorylation.     

发展名茶名牌开发茶业经济增长点

茶叶市场供过于求，竞争日趋激烈，部分焦点是质量、价格和品牌。发展名茶名牌，以带动２１世纪茶业经济可持续发展。