鱼类腌制品加工过程微生物群落多样性研究进展

鱼类腌制品是中国的一种传统加工水产品,由于其易保存、风味特殊、营养丰富,深受大众喜爱。然而腌制加工过程中微生物种类复杂,对制品的品质有较大的影响。结合国内外最新研究阐述了传统腌制鱼和微生物发酵快速腌制鱼中的微生物群落变化、微生物多样性最新研究技术及应用,并在此基础上提出了鱼类腌制品加工过程微生物群落多样性的研究方向,为揭示影响鱼类腌制过程的微生物作用机制及生产优化控制提供理论依据。     

黑茶提取物对脓毒症模型小鼠的保护作用

研究黑茶提取物对脓毒症模型小鼠的保护作用。本实验采用腹腔注射高浓度40 mg/kg脂多糖(LPS)和盲肠结扎穿孔术(CLP)两种不同的方式建立小鼠脓毒症模型,考察黑茶提取物对脓毒症小鼠7 d存活率的影响;利用LPS诱导巨噬细胞程序性坏死实验研究黑茶提取物对小鼠脓毒症治疗作用的机制。结果显示,黑茶水提物可提高LPS和CLP诱导的脓毒症小鼠的7 d存活率,提高幅度达40%;黑茶多糖可对LPS诱导的巨噬细胞程序性坏死有一定的抑制作用,与LPS对照组相比,差异具有显著性(P0.05)。提示黑茶提取物对脓毒症模型小鼠有一定的治疗作用,其作用的机制可能与黑茶多糖抑制LPS诱导的巨噬细胞程序性坏死有关,更深入的作用机制有待进一步研究。     

黑茶提取物对脓毒症模型小鼠的保护作用北大核心CSCD

研究黑茶提取物对脓毒症模型小鼠的保护作用。本实验采用腹腔注射高浓度40 mg/kg脂多糖(LPS)和盲肠结扎穿孔术(CLP)两种不同的方式建立小鼠脓毒症模型,考察黑茶提取物对脓毒症小鼠7 d存活率的影响;利用LPS诱导巨噬细胞程序性坏死实验研究黑茶提取物对小鼠脓毒症治疗作用的机制。结果显示,黑茶水提物可提高LPS和CLP诱导的脓毒症小鼠的7 d存活率,提高幅度达40%;黑茶多糖可对LPS诱导的巨噬细胞程序性坏死有一定的抑制作用,与LPS对照组相比,差异具有显著性(P<0.05)。提示黑茶提取物对脓毒症模型小鼠有一定的治疗作用,其作用的机制可能与黑茶多糖抑制LPS诱导的巨噬细胞程序性坏死有关,更深入的作用机制有待进一步研究。     

植物中XRN家族的研究进展

XRN家族是一类5′-3′核酸外切酶家族,主要参与rRNA的成熟加工以及特异mRNA的降解过程,在动物、植物以及微生物的生长发育过程中起着重要的作用.对XRN家族在植物生长发育过程中的功能进行了综述,XRN家族在植物中主要参与rRNA加工过程、miRNA途径、外源mRNA降解过程以及乙烯信号通路.     

湖南黑茶对小鼠辐射损伤的保护作用

研究湖南黑茶对辐射损伤小鼠的保护作用。本研究采用外周血液学指标、免疫系统指标、体内抗氧化指标超氧化物歧化酶(Superoxide dismutase,SOD)及存活时间考察黑茶对辐射损伤小鼠的保护作用。结果显示,小鼠受到137Cs-γ6.5 Gy的照射后,与单纯照射组相比,黑茶能明显提高小鼠的外周血白细胞数(white blood cell,WBC)、股骨有核细胞数(the number of bone narrow nucleated cells,BMNC)、骨髓DNA含量以及脾结节数(colony forming unit-spleen,CFU-S),差异具有显著性(P0.05);小鼠受到137Cs-γ6.0 Gy后,与单纯照射组相比,黑茶可显著提高小鼠肝组织和肺组织中SOD的活力,差异具有显著性(P0.05);黑茶可使受照(8.0Gy)小鼠存活天数由8.6±1.96 d延长到11.13±2.75 d。提示黑茶有较好辐射防护的作用。     

熏鸡加工过程中微生物分布分析

研究熏鸡加工过程中大肠菌群数、大肠埃希菌数和常见致病菌的分布情况。通过对生产流程关键控制环节抽样进行大肠菌群计数、大肠埃希菌计数、沙门氏菌检测、金黄色葡萄球菌检测和单核细胞增生李斯特氏菌检测,掌握熏鸡生产过程中的微生物分布。根据实验数据分析和熏鸡生产流程,研究熏鸡加工过程中生产原料环节和熏制环节的关键控制点作用。     

火腿微生物研究进展

数千年来,微生物参与的食品发酵为人类保存食物和风味多元化提供了重要的方法。这些可再生且易于操作的发酵食品为研究微生物群落提供了理想的材料。干腌火腿就是传统发酵食品之一,在微生物作用下其加工过程发生了蛋白质和脂肪的水解和氧化反应,产生的一些化合物形成了火腿的独特风味。文中描述了不同地域火腿微生物类群及其对火腿品质形成的作用,为火腿微生物今后的研究提出了参考。     

家禽肉产品中致病菌风险分析及质量控制

家禽肉产品是国内外主要的消费食品之一,本文中,笔者从生家禽肉产品、熟家禽肉产品及干家禽肉产品上可能出现致病微生物(沙门氏菌(Salmonella spp.)和嗜热弯曲菌(Campylobacter spp.))的危害及控制、禽肉产品流通及加工过程中禽肉产品的致病微生物的危害及质量控制(单增李斯特菌(Listeria monocytogenes))以及终产品的质量控制等方面进行综述,发现家禽肉产品的贮藏及流通过程中这些致病菌危害存在很大风险,因此,应该加强整个禽肉产品流通流程及加工过程的质量控制。     

烟碱的微生物降解研究进展

烤烟叶面微生物类群有细菌、放线菌、霉菌和酵母菌,它们在烟叶生长、调制、陈化、加工和贮存过程中对烟叶质量产生很大的影响。就烟草生长至加工过程中微生物菌群动态变化及微生物在降解烟叶烟碱上的应用作了概述,分析了微生物降烟碱的应用前景。     

高浓度臭氧水在水产品加工过程中的应用

根据臭氧的氧化性强和不稳定易分解的特点,将高浓度氧水直接用于水产品加工过程中的杀菌、消毒,以控制微生物的污染,同时解决了传统的用饮氯酸钠水作消毒剂所产生的氯残留污染问题,为今后的水产品加工中全方位使用臭氧作用消毒剂提供了依据。     

茶叶加工中的外源酶研究进展

从应用于茶叶加工中的外源酶种类,来源,作用机理及其在红茶,绿茶,黑茶,茶饮料,速溶茶的加工和检测上的应用等方面综述了近半个世纪以来茶叶加工中的外源酶研究成果与进展,并对外源酶在茶叶加工中的应用提出了思考与展望。     

Preliminary Studies on Flavour Volatiles in Qimen Black Tea

Three kinds of flavor enriched black tea in the world are produced from Qimen in China, Darjeeling in India and Uva in Sri Lanka. The results of analysis from the Qimen black tea showed that there are more than twenty flavour volatiles. The essential aromatic compounds are geraniol, 2,6-di-butul-l,4-benzoquinone, 2,6-di-t-butyl-4-methyl phenol, benzenemethanol, benzenethanol, linalool and linalool oxides. In Qimen black tea the aroma acquired is produced during the processing aside from the original compounds of fresh leaves.     

Extraction behavior of caffeine and EGCG from green and black tea

A dipping method was developed to extract the catechins (EGCG) and alkaloids (caffeine) from green tea (Korea) and black tea (Sri Lanka). The effects of the solvent composition (water vs. ethanol), extraction time, temperatures, and solvent pH on the amount of catechins (EGCG) and alkaloids (caffeine) extracted from green and black tea were investigated. Reversedphase high-performance liquid chromatography (RP-HPLC) was used to analyze the catechins (EGCG) and alkaloids (caffeine) extracted. The content of EGCG and caffeine in green tea extracts was in the range of 2.04∼0.30 and 10.22∼0.85 mg/g, respectively. The amount of EGCG and caffeine in black tea extracts was in the range of 0.32∼0.24 and 5.26∼1.01 mg/g, respectively. The amount of caffeine extracted from green and black tea was greater than the amount of EGCG. Pure water is the best solvent for extracting EGCG and caffeine from green tea. The amount of caffeine extracted from green and black tea increased as the temperature, extraction time, and hydrogen ion concentration of the solvent increased. Although the amount of EGCG extracted from green tea increased as the temperature increased, the amount of EGCG extracted from black tea was not affected by temperature. The extraction of EGCG from both green and black tea was not affected by the hydrogen ion concentration of the solvent.     

Tea crude extracts effectively inactivate severe acute respiratory syndrome coronavirus 2

It is well known that black and green tea extracts, particularly polyphenols, have antimicrobial activity against various pathogenic microbes including viruses. However, there is limited data on the antiviral activity against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which emerged rapidly in China in late 2019 and which has been responsible for coronavirus disease 2019 (COVID-19) pandemic globally. In this study, 20 compounds and three extracts were obtained from black and green tea and found that three tea extracts showed significant antiviral activity against SARS-CoV-2, whereby the viral titre decreased about 5 logs TCID₅₀ per ml by 1·375 mg ml⁻¹ black tea extract and two-fold diluted tea bag infusion obtained from black tea when incubated at 25°C for 10 s. However, when concentrations of black and green tea extracts were equally adjusted to 344 µg ml⁻¹, green tea extracts showed more antiviral activity against SARS-CoV-2. This simple and highly respected beverage may be a cheap and widely acceptable means to reduce SARS-CoV-2 viral burden in the mouth and upper gastrointestinal and respiratory tracts in developed as well as developing countries.     

Fungi associated with black tea and tea quality in the Sultanate of Oman

Forty-eight samples of four popular commercial brands of black tea ( Camellia sinensis L.) were purchased from the local markets in Muscat area, Sultanate of Oman. Tea leaves were surveyed for mycoflora. Five fungal species were isolated with A. niger as the most dominant in all the brands having percentage contamination ranging between 0.66% and 30.34%. Other fungi isolated were Aspergillus flavus, Penicillium spp. and Pacelomyces spp. but having average percentages of 0.6%, 0.84% and 0.21% respectively. Significant differences were found among the batches contaminated by A. niger. None of the 25 A. flavus strains screened for aflatoxins were found aflatoxigenic. The total ash, water-soluble ash, and mineral concentration of the samples were within the British standards and were not affected by fungal contamination. The results showed that black tea is contaminated by fungi that might constitute health hazards for humans. The post harvest contamination of tea could be eliminated or reduced if processing is conducted under more hygienic conditions. This revised version was published online in June 2006 with corrections to the Cover Date.     

优质红碎茶资源的鉴定与筛选

我国生产的红碎茶在国际市场竞争力一直不强,缺乏适制红碎茶品种是原因之一.近年来,对原生起源中心云南茶区为主的120份茶树资源进行系统的发掘和鉴定,探明了我国适制红碎茶资源的基本情况,筛选出一批优异资源.加速这些资源的利用,将促进我国红碎茶品种的改良和红碎茶品质的提高.     

基于多酚类物质的红茶滋味特征分类与判别

为探讨以多酚类为指标对茶叶滋味类型进行鉴别的可靠性,以中国13种红茶为材料,进行感官审评和化学成分分析。感官审评结果为:13种红茶在滋味上可分为甜醇温润、清甜鲜爽、甜醇浓烈和小种4个类型。化学分析结果为:以茶多酚、茶三素和7种儿茶素的相对含量进行主成分分析、聚类分析和判别分析,主成分、聚类分析的结果与茶叶感官审评分类结果基本一致,相似度77%;以感官审评分类结果为依据进行判别,判别准确率达92.3%。因此,根据多酚类含量可区分和判别红茶的滋味类型。本试验可为茶叶滋味分类和鉴别提供依据和应用参考。     

夏秋季遮光对山东黄金芽茶树生理生化特性的影响

选用遮光率分别为55%、70%、85%的黑色、蓝色遮阳网,观测遮光后茶园小气候、茶树叶色、叶绿素荧光参数、茶树生长状况及茶叶生化成分,分析不同遮光处理对山东黄金芽生理生化特性的影响,明确适宜夏秋季的遮光方式.结果表明: 与对照相比,遮光直接降低光照强度,茶园空气温度、叶面温度明显降低,空气湿度则增高;遮光程度越大,黄金芽叶色返绿越明显,叶绿素含量增幅越大;55%遮光处理能保持品种叶色黄化特性,且生化品质较好;而70%遮光率处理茶苗生长势较好,不受光胁迫;与蓝色遮阳网相比,黑色遮光处理能更好地促进茶树生长,保持叶色黄化和提高茶叶品质.黄金芽茶树品种苗期管理宜选择黑色70%遮光率处理(日光合有效辐射为1.2～3.5万lx),以促进茶树生长;成龄后则以黑色55%遮光处理(日光合有效辐射为1.8～5.5万lx)为优,既能保证黄金芽叶色黄化又能提高茶叶生化品质,从而充分发挥其品种特色,实现优质高产目标.     

Effect of green tea and black tea on the metabolisms of mineral elements in old rats

A 2-mo experiment with the white Sprague-Dawley (SD) rats was conducted to investigate the effect of the water extracts of black tea (BTWE) and green tea (GTWE) and the black tea leaves (BTF) and the green tea leaves (GTF) on the metabolism of mineral elements. One hundred eight 12-mo-old white SD rats were randomly divided into 13 groups; 6 of these drank the BTWE or GTWE in which the water extracts concentrations of black tea or green tea were, respectively, 0.6%, 1.2%, and 2.4%, and 6 of these had black tea leaves (BTF) and green tea leaves (GTF) added in which the contents of BTF or GTF were, respectively, 0.5%, 1.0%, and 2.0%, one of these was control. The teas and their water extracts could promote the absorption of manganese and copper. In GTF, BTF, GTWE, and BTWE, the apparent absorption rates of manganese were significantly increased. The manganese contents in the tibia were also elevated, and the differences between GTWE and GTF were significant. The apparent absorption rates of copper and the copper contents in the tibia were increased, but not significantly. The teas and their water extracts inhibited the absorption of calcium (p > 0.05) and iron (p < 0.05). The cerebrum calcium contents were significantly decreased, but the contents of calcium and iron in tibia were not significantly changed. Compared with the control, although the apparent absorption rates of aluminum in all experimental groups were not observed to be different, the aluminum contents in the tibia (p > 0.05) and cerebrum (p < 0.05) were increased. GTF and GTWE decreased the apparent absorption rates of zinc, but BTF and BTWE increased them; the zinc contents in tibia were a little improved, whereas its contents in the cerebrum were gradually decreased with the increase of tea leaves dose and tea concentration.     

茶叶抗病毒作用研究的新进展

绿茶的儿茶素、黑茶的茶黄素以及茶叶特有的L-茶氨酸是重要的药用化学成分。近年,国内外科学家在茶叶抗流感病毒、艾滋病毒、丙型和乙型肝炎病毒等研究方面取得重要突破。本文综述了茶叶抗病毒作用的基础研究及临床应用的新进展。