竹干黄酮的抑菌性能研究

以大肠杆菌、金黄色葡萄球菌、芽孢杆菌、根霉和毛霉作为供试菌种,通过平板计数法和抑菌圈法研究竹干黄酮的抑菌性能,同时考察了竹干黄酮浓度、pH值、热处理对竹干黄酮抑菌性能的影响。结果表明,竹干黄酮对细菌及霉菌均具有一定的抑制作用,并且对细菌的抑制作用强于霉菌;在酸性条件下,竹干黄酮的抑菌效果更好;竹干黄酮的热稳定性良好,100℃的热处理对其抑菌性能没有明显影响。     

4-酰基吡唑啉酮过渡金属配合物的合成、表征及生物活性研究

合成了4种4-酰基吡唑啉酮过渡金属配合物,通过元素分析、红外光谱、差热-热重分析、紫外光谱等对其结构进行了表征,同时对2种细菌和6种真菌进行了生物活性测试。结果表明,在不同浓度梯度下,配合物对细菌均有一定的抑制作用,大部分配合物对真菌有好的抑制作用,特别是对米曲霉菌和白地霉菌的抑制效果最好。     

茶多酚及其氧化产物清除不同体系产生的活性氧自由基的分光光度法研究

用分光光度法测定了茶多酚及其氧化产物对不同体系产生的活性氧自由基O2· - 和·OH的清除作用。结果表明 :对由光照核黄素体系产生的O2· - ,在试验质量浓度范围 ( 8 3～ 1 67ug mL)内茶多酚及其氧化产物的最大清除率分别为 96 6%和 92 1 %。对由 2 脱氧 D 核糖体系产生的·OH ,在实验质量浓度范围 ( 5～ 80 0ug mL)内茶多酚及其氧化产物的最大清除率分别为83 4%和 88 5%。茶多酚氧化产物 ,SOD粗酶液 ,茶多酚对邻苯三酚自氧化产生的O2· - 均表现出较强的抑制作用 ,抑制率分别为 66 5% ,47 6% ,45 3%。茶多酚及其氧化产物与SOD有显著的协同增效作用 ,但氧化产物的效果强于茶多酚。     

油溶性茶多酚的制备及其抗氧化性能的研究

茶多酚经酰化成为油溶性茶多酚应用于猪油、大豆油中作抗氧化剂 ,活性氧法 (ＡＯＭ )证明其抗氧性能分别为ＢＨＡ(叔丁基 - 4 -羟基茴香醚 )和ＢＨＴ( 2 ,6-二叔基对甲酚 )的 1 5～ 2 0倍 ,也优于粉剂茶多酚 ,制备方法 :豆油脂肪酸 ( 16～ 18个碳 ) 10 0ｇ、醋酐37ｇ ,110℃反应 ,副产物醋酸减压蒸出得豆油脂肪 97ｇ。茶多酚用 170ｇ醋酸乙酯溶解 ,通干燥ＨＣｌ少量在78℃时将 97ｇ豆油脂肪酸滴入 ,保温 8ｈ ,冷却、过滤 ,减压蒸去醋酸乙酯后即为油溶性茶多酚。油溶性茶多酚的制备及其抗氧化性能的研究@高汨$中南大学冶金科学与工程系冶化…     

酸解家蚕丝的光谱性质及其抑菌试验初步探究

用磷酸水解蚕丝得到丝素肽,对金黄色葡萄球菌和大肠杆菌进行抑菌试验。结果表明,丝素肽的结构是无定形的,不同浓度的丝素肽对这两种细菌均有不同程度的抑制作用,可作为食品与化妆品的防腐剂使用。     

生防细菌J352对不同种类线虫的毒力差异

从黄瓜根际分离获得一株对多种病原真菌有较强抑制作用的细菌，用该细菌不同浓度的发酵液测定了对4种线虫的作用。结果表明，该发酵液呈微碱性，不同浓度发酵液对各种线虫均有较好的防治作用，并且毒力作用具有明显差异，对4种线虫的毒力大小顺序分别为小杆线虫、大豆胞囊线虫、根结线虫和腐烂茎线虫。     

大豆根表拮抗细菌的筛选及其防病作用

从大豆根表分离出20株对植物病原真菌有拮抗作用的细菌,其中4株对供试的6种病原真菌均有抑制作用,对小麦赤霉菌、纹枯菌、黑粉菌、番茄灰霉菌、早疫菌、山芋黑疤病菌的拮抗频率分别为18．8％、18．8％、27．1％、22．9％、29．2％、22．9％。发酵液对小麦赤霉病菌、番茄灰霉菌、早疫病菌孢子萌发均有抑制作用,对上述3种病菌引起的病害田间防效良好。     

提取方法对箬叶总黄酮抑菌效果的影响

通过抑菌圈直径及最低抑菌浓度的测定,分别考察了乙醇浸渍法、热回流法、微波法、超声波法提取的箬叶总黄酮对细菌(金黄色葡萄球菌、大肠杆菌)、真菌(白色念珠菌、酿酒酵母菌、青霉菌)的抑菌效果。结果表明,箬叶总黄酮对细菌的抑制作用大于对真菌的抑制作用;且提取方法对箬叶总黄酮的抑菌能力有影响,不同提取方法提取的箬叶总黄酮抑菌效果为:超声波法热回流法乙醇浸渍法微波法。超声波法比较适合于箬叶总黄酮的提取。     

介绍几种防霉剂

橡胶中天然橡胶含有脂肪酸和蛋白质最易受霉菌侵蚀,极性橡胶比非极性橡胶对霉菌有抑制能力。常用的硬脂酸、石蜡、增望剂—酯类、松香、油膏等易长霉,氧化锌、氧化镁、促进剂M对霉菌略有抑制作用,促进剂TMTD当其达到一定用量时,具有防霉剂的作用,故而在不影响材料性能的前题下,应尽量选择对霉菌有抑制作用的胶种和配合剂,但这样做往往仍达不到防霉的要求,或为了满足材料工艺和性能上的要求,不得不采用易被霉菌侵蚀的胶种和配合剂,这样就需要借助于防霉剂的作用。     

1,8-桉树脑对白色念珠菌生物膜影响分析

以生物膜形式存在的细菌通常对常用的抗微生物剂具有耐药性。因此,对化合物1,8-桉树脑的体外抗菌活性进行了评价,以探索新的药剂。通过对8种细菌和真菌的最低抑菌浓度和最低杀菌浓度测定,结果表明,精油对真菌的抑制作用强于对细菌的抑制作用,尤其是对白色念珠菌的抑制作用,最低抑菌浓度为0.156%。     

分子修饰法制备油溶性茶多酚及其抗氧化性能的研究

采用分子修饰法制备了豆油脂肪酸酐修饰的茶多酚,通过红外光谱对分子修饰的茶多酚进行了结构表征。将修饰后的茶多酚作为油脂的抗氧化剂,添加到豆油中,考察其溶解性及抗氧化性能。结果表明,有机基团修饰的茶多酚具有优良的分散性,可提高豆油的抗氧化性能。在相同浓度时,豆油脂肪酸酐修饰的茶多酚抗氧化活性优于茶多酚和BHT。     

碘量比色法测定迷迭香提取物抗氧化活性的研究

以迷迭香为原料采用有机溶剂萃取法提取其中的抗氧化成分,分别采用碘量比色法与传统碘量滴定法进行过氧化值的测定和讨论,结果表明,碘量比色法测定在添加量为0.14%时,对菜籽油的抗氧化性较好。     

Modification of maillard browning in a microwaved glucose/glycine model system by water-soluble natural antioxidants and foods containing them

Inhibition of pyrazine formation by natural antioxidants and the foods containing them was measured in a microwaved glucose/glycine model system. Inhibition of lipid oxidation by the same materials was assayed in both bulk and emulsion systems. Pyrazines were determined by solid-phase micro extraction followed by GC. Lipid oxidation volatiles were assayed by polyamide fluorescence produced by either a bulk oil display or a hematin- or 2,2′-azobis-(2-amidino=propane) dihydrochloride-accelerated lecithin or fish oil emulsion. It was shown that (i) the inhibition of pyrazine formation depends on high concentrations of water-soluble antioxidants; (ii) such antioxidants occur naturally in some foods and are usually polyphenols; (iii) during pyrazine inhibition, oxidized polyphenols show enhanced nonfluorescing browning similar to enzymic browning products; (iv) monophenols, which structurally cannot form quinone polymers on oxidation, inhibit pyrazines with less browning; (v) during the final pyrazine-forming phase of the Maillard reaction, polyphenolics and reducing agents such as glutathione and ascorbic acid are partially consumed with some nutritional loss; (vi) fruit powders of grape seed, grape skin, and red wine are highly pyrazine-inhibitory, steeped blueberry strongly so, but plum purees are moderately pro-pyrazine, and freeze-dried vegetables strongly pro-pyrazine; and (vii) black and green tea infusions are highly inhibitory, whereas spices have mixed effects.     

高效液相色谱法测定茶叶中多酚

研究了用高效液相色谱法测定茶叶样品中的6种茶多酚。6种茶多酚用70%甲醇-水溶液提取,以Agilent ZORBAX SB-C18液相色谱柱(4.6 mm×250 mm,5μm)色谱柱为固定相,0.5%醋酸水溶液和甲醇梯度洗脱为流动相,茶叶中主要的茶多酚均达到基线分离;用紫外二极管矩阵检测器检测,得出各组分在其最大吸收波长下的色谱图,根据该色谱图的峰面积定量,并用紫外光谱图对茶叶中主要多酚进行辅助定性。标准回收率为92.5%~102%;RSD为1.2%~1.5%。     

Antioxidant Efficacy of a New Synergistic,Multicomponent Formulation for Fish Oil Omega-3 Concentrates

Today, tocopherols serve as the industrial standard antioxidant protection for fish oil omega-3 concentrates. Synergistic interactions between tocopherols, ascorbyl palmitate and natural polyphenols extracted from plant sources have been demonstrated in model systems. The main goal for this work was to develop a mix of such antioxidants with improved efficacy in the context of preserving industrial marine oil concentrates. The antioxidant formulation comprises tocopherols, ascorbyl palmitate, rosemary extract and green tea catechins. Part of the scope was to develop a method for dissolving green tea catechins in oil. The key element of the method is to introduce green tea on a lipid insoluble carrier when dissolving the extract in the oil, and thereafter remove the carrier by filtration. The antioxidant mix was tested against tocopherol in omega-3 concentrates of minimum 300 mg/g eicosapentaenoic acid (EPA) plus 200 mg/g docosahexaenoic acid (DHA) in the form of triacylglycerides and ethyl esters. The mix was superior compared to tocopherols in suppressing both primary- and secondary oxidation. Weight increase measurements of oil in contact with air correlated well with standard oxidation tests within individual samples and the method was considered simple and useful for monitoring oxidation in omega-3 concentrates.     

Polyphenols and Sunburn

Polyphenols are antioxidant molecules found in many foods such as green tea, chocolate, grape seeds, and wine. Polyphenols have antioxidant, anti-inflammatory, and antineoplastic properties. Growing evidence suggests that polyphenols may be used for the prevention of sunburns as polyphenols decrease the damaging effects of ultraviolet A (UVA) and ultraviolet B (UVB) radiation on the skin. This review was conducted to examine the evidence for use of topically and orally ingested polyphenols in prevention of sunburns. The PubMed database was searched for studies that examined polyphenols and its effects on sunburns. Of the 27 studies found, 15 met the inclusion criteria. Seven studies were conducted on human subjects and eight on animals (mice and rats). Eleven studies evaluated the effects of topical polyphenols, two studies examined ingested polyphenols, and two studies examined both topical and ingested polyphenols. Polyphenol sources included the following plant origins: green tea, white tea, cocoa, Romanian propolis (RP), Calluna vulgaris (Cv), grape seeds, honeybush, and Lepidium meyenii (maca). Eight studies examined green tea. Overall, based on the studies, there is evidence that polyphenols in both oral and topical form may provide protection from UV damage and sunburn, and thus are beneficial to skin health. However, current studies are limited and further research is necessary to evaluate the efficacy, mechanism of action, and potential side effects of various forms and concentrations of polyphenols.     

铁观音绿茶茶多酚提取工艺研究

将有机溶剂提取法这一技术应用于提取绿茶的有效成分---茶多酚.采用正交实验法优化茶多酚的最佳提取条件,选择浸提温度、浸提次数、浸取时间和有机溶剂的浓度作为考察因素,以茶多酚的提取率为评价指标,通过单因素试验的考察,每个因素选取4个水平.得出最佳的提取工艺为:温度65℃,洗提次数3次,有机溶剂提取时间35 min,有机溶剂浓度55%.在这种条件下从绿茶中提取的茶多酚的收率为最高.并采用红外波谱法对提取出的产品进行定性分析,检测得出绿茶提取物的主要成分为茶多酚.     

High‐temperature pre‐conditioning of rapeseed: A polyphenol‐enriched oil and the effect of refining

In this work, a pretreatment process for rapeseeds, which involves the use of high‐temperature steam, is presented. This method, besides accomplishing the beneficial effects of the conventional industrial thermal treatment, leads to an enrichment of some important minor compounds (polyphenols and phosphatides) in the resulting oil. Rapeseeds were pretreated at different operative conditions. Then, the seeds were pressed and the press‐cake was solvent extracted. The obtained oils were then refined by both chemical and physical refining techniques, and the influence of each refining step on the content of minor compounds was evaluated. The results show that the amounts of polyphenols and phospholipids present in the oil coming from pretreated seeds increase and that their concentrations depend on the conditioning time. The polyphenols present in the oil correspond mostly to 2,6‐dimethoxy‐4‐vinylphenol (vinylsyringol). The content of polyphenols was only slightly reduced during degumming. Neutralization resulted in a complete removal of these minor compounds. For the physical refining process, the type and amount of bleaching clay used had a significant influence on the content of polyphenols. After deodorization, oil samples with a considerable amount of polyphenols were obtained. These samples show a higher oxidative stability than chemically refined oils.     

食品乳化剂柠檬酸甘油单,二酸酯的合成

采用以乙酸为溶剂,柠檬酸和单甘酯进行酯化反应合成了质量指标均符合ＦＡＯ／ＷＨＯ标准的柠檬酸甘油单,二酸酯,确定了合成的最佳工艺条件,并以此为原料配制了两种在常温下呈液态的复合型搞氧剂。试验结果表明,其抗氧化效果超过了国外同类产品,在油脂及含油食品中具有广泛应用价值。     

Antioxidant activity of tea extracts in lipids and correlation with polyphenol content

The present study examined the antioxidative activity of water and ethanol extracts of green and black tea leaves against the oxidation of heated sunflower oil and lard. Oxidation was conducted at 110 °C in the Rancimat test. Total polyphenols and catechin contents in tea extracts were measured. The research showed that the total polyphenol content in green and black tea leaves was 205.2 and 148.7 mg/g, respectively. In tea leaves extracts, it ranged between 245.9 mg/g and 837.7 mg/g and depended on the extraction solvent and the kind of tea used (p <0.001). The highest polyphenol content was observed in samples extracted with 95% ethanol, lower contents were found with the use of water. Results showed that the highest antioxidant activity, measured as an induction period, with 1000 ppm green tea ethanol extract, was comparable to á‐tocopherol activity in sunflower oil. In lard, the longest induction period was measured with 500 and 1000 ppm of green tea ethanol extract. Other tea extract concentrations were significantly less active. Statistical analysis of the tea extract antioxidant activity in lipids in the Rancimat test showed an essential influence of the catechin contents. Further statistical analysis also showed an influence of (?)‐epicatechin gallate (ECG), (?)‐epicatechin (EC), and (+)‐catechin (C) contents in the tea extracts on the antioxidant activity in lipids. It was stated that the antioxidant activity was higher in tea extracts containing high levels of ECG, EC, and C.