青刺尖茶抑菌作用的初步研究

目的:研究青刺尖茶的水提物和醇提物的抑菌作用。方法:采用滤纸片扩散法和试管二倍稀释法对金黄色葡萄球菌和大肠杆菌进行体外抑菌实验,测定抑菌圈直径、最小抑菌浓度(MIC)和最小杀菌浓度(MBC),比较研究水提物和醇提物对大肠杆菌和金黄色葡萄球菌的抑菌效果,并初步研究pH、温度对青刺尖茶提取物抑菌作用的影响。结果:青刺尖茶水提液对两种菌都有不同程度的抑制作用,对大肠杆菌的抑制作用明显大于对金黄色葡萄球菌,醇提液对大肠杆菌有显著抑制作用。青刺尖茶水提液的抑菌最适pH5~6,对热稳定。结论:青刺尖茶水提液对大肠杆菌具有很强的抑菌效力,水提液的抑菌作用明显优于醇提液。     

湄潭白茶多糖提取工艺优化及其抑菌活性研究

本文以湄潭白茶为对象,研究其多糖的提取工艺条件及体外抑菌活性。考察提取温度、提取时间、料液比3个因素对多糖得率的影响,并通过正交试验确定其最佳提取参数:提取温度90 ℃、提取时间4 h、料液比1:20 g/mL,在此条件下湄潭白茶多糖得率为1.163%±0.011%。体外抑菌活性试验结果表明:湄潭白茶多糖对金黄色葡萄球菌、大肠杆菌、铜绿假单胞菌和白色念珠菌均具有抑制作用,其中对金黄色葡萄球菌的抑制活性最强,其最低抑菌浓度MIC为3.125 mg/mL。研究成果将为湄潭白茶多糖的进一步研究及新产品开发提供理论指导。     

葡萄籽和苹果原花青素对变形链球菌和金黄色葡萄球菌的抑制作用

研究苹果原花青素和葡萄籽原花青素对变形链球菌(Streptococcus mutans)和金黄色葡萄球菌(Staphylococcus aureus)的抑制作用,采用试管液体稀释法和琼脂稀释法抑菌实验测定其最低抑菌质量浓度(MIC)和质量最低杀菌质量浓度(MBC),并通过测定培养基pH值的变化,研究葡萄籽原花青素对变形链球菌产酸能力的影响。结果表明：苹果原花青素、葡萄籽原花青素对变形链球菌和金黄色葡萄球菌生长都有抑制作用;苹果原花青素对变形链球菌的MIC和MBC分别为1.25、4.00mg/mL,葡萄籽原花青素对变形链球菌的MIC和MBC分别为1.75、2.00mg/mL;苹果原花青素对金黄色葡萄球菌的MIC和MBC分别为4.00、9.00mg/mL,葡萄籽原花青素对金黄色葡萄球菌的MIC和MBC分别为2.00、6.50mg/mL。葡萄籽原花青素质量浓度大于1.00mg/mL对变形链球菌的产酸能力有显著抑制效果。     

丁香油与月桂酸对金黄色葡萄球菌的协同抑制作用

该研究探讨了丁香油、百里香油、薄荷油等三种植物精油以及中链脂肪酸月桂酸对金黄色葡萄球菌的抑制作用,筛选出具有协同抑制作用的组合丁香油与月桂酸,测定协同组合对金黄色葡萄球菌生长、细胞膜通透性的影响,并将该组合制成抑菌保鲜液,应用于生鲜米粉保鲜。结果表明,丁香油、薄荷油、百里香油及月桂酸对金黄色葡萄球菌的最小抑菌浓度分别为2.00μg/mL、4.00μg/mL、7.50μg/mL以及9.00μg/mL,丁香油和月桂酸联合使用,在浓度为1/4 MIC丁香油+1/4 MIC月桂酸时具有协同抑菌效果,此时分级抑菌浓度系数为0.50。丁香油与月桂酸协同处理使金黄色葡萄球菌细胞膜损伤,增加通透性。抑菌保鲜液对生鲜米粉中的菌落总数、金黄色葡萄球菌均有抑制作用,对维持生鲜米粉品质具有积极影响。72 h贮藏期间,处理组初始菌落总数比对照组至少低1.50 lg CFU/g;金黄色葡萄球菌降低1.65 lg CFU/g;酸度值比对照组至少低0.8°T;感官评价得分均高于对照组。结果表明,丁香油与月桂酸协同组合制成抑菌保鲜液有可能成为生鲜米粉的可替代复合保鲜液。     

四种天然植物源物质抑菌作用研究

研究了4种常见的天然植物源材料(大蒜、大葱、生姜、洋葱)榨汁液对金黄色葡萄球菌和大肠杆菌的抑菌作用。采用牛津杯法测定4种榨汁液在不同浓度、不同p H、热处理、复配处理等因素下的抑菌能力,并与化学防腐剂进行对比。结果表明,4种植物榨汁液对这2种细菌均有不同程度的抑制作用,且表现出对金黄色葡萄球菌的抑制作用强,对大肠杆菌的抑菌作用相对较弱。4种榨汁液中大蒜汁抑菌能力最强,最小抑菌浓度为6.25%,大葱汁对金黄色葡萄球菌最小抑菌浓度为12.5%,对大肠杆菌最小抑菌浓度为25%,生姜汁与洋葱汁的最小抑菌浓度为50%,不同p H、热处理等因素处理对抑菌效果有一定影响,榨汁液复配后提高了对指示菌的抑菌作用。与化学防腐剂相比,植物源榨汁液的抑菌效果强于或等同于化学防腐剂抑菌效果。     

金黄色葡萄球菌拮抗菌株的筛选及鉴定

从甘肃中部干旱生境土壤中分离筛选到一株对食源性致病菌金黄色葡萄球菌具有抑制作用的拮抗菌,对其发酵液抑菌最低浓度稀释梯度及抑菌谱进行了测定,并通过形态学、生理生化及16S rDNA分子生物学方法鉴定了其种属.结果表明,该金黄色葡萄球菌拮抗菌株还对大肠杆菌、植物酸杆菌和表皮葡萄球菌具有抑制作用,其发酵液对金黄色葡萄球菌抑菌最低浓度稀释梯度为10-6,经鉴定,该拮抗菌为产碱杆菌属菌株Alcaligenes sp..     

枯草芽孢杆菌CCTCC M207209对食源性病原菌的抑制作用

采用杯碟法、对峙培养法和平板对扣法分别检测了枯草芽孢杆菌CCTCC M207209的活菌菌碟、无菌体发酵液、多糖提取液、蛋白质粗提液及其挥发性气体产物对金黄色葡萄球菌、肠球菌、化脓链球菌、大肠杆菌、沙门氏菌等食源性病原菌的抑制作用。结果表明,枯草芽孢杆菌CCTCC M207209的活菌菌碟和发酵液对所有参试病原菌均有显著抑制作用;蛋白质粗提液对除化脓链球菌以外的所有病原菌有显著抑制作用;挥发性气体产物对所有病原菌均无抑制作用;所有抑菌活性物质对金黄色葡萄球菌的抑制作用最强,初步确定其为蛋白类物质。     

植物乳杆菌、戊糖片球菌对产肠毒素金黄色葡萄球菌生长的影响

研究食盐含量、pH值、温度对产肠毒素金黄色葡萄球菌的生长的影响,并主要研究植物乳杆菌和戊糖片球菌对产肠毒素和不产肠毒素金黄色葡萄球菌生长的影响以及之间的差别.结果表明:植物乳杆菌和戊糖片球菌均能抑制金黄色葡萄球菌的生长,植物乳杆菌的抑菌活性显著高于戊糖片球菌(P＜0.05),植物乳干菌和戊糖片球菌对不产肠毒素金黄色葡萄球菌的抑菌效果显著高于产肠毒素金黄色葡萄球菌(P＜0.05).     

茶多酚对金黄色葡萄球菌生物膜产生的影响

研究茶多酚在不同条件下对金黄色葡萄球菌生物膜产生的影响。首先测定茶多酚对金黄色葡萄球菌的最小抑菌浓度(MIC);再测定茶多酚对金黄色葡萄球菌生物膜产生的抑制作用;又测定不同NaCl浓度、不同pH、不同加入时间、不同培养温度,茶多酚对金黄色葡萄球菌生物膜产生的影响。结果表明,茶多酚对金黄色葡萄球菌的MIC为8 mg/mL;当茶多酚浓度分别为0.5,1和2MIC时,其对生物膜产生具有明显的抑制作用;20 mg/mL和30 mg/mL NaCl以及酸性条件可增强茶多酚的抑制效果;越早加入茶多酚,其对生物膜抑制效果越好;28℃与37℃培养,茶多酚对金黄色葡萄球菌生物膜的抑制作用基本无影响。     

湄潭白茶多糖对金黄色葡萄球菌的抑菌活性及其稳定性

目的:研究湄潭白茶多糖对金黄色葡萄球菌的体外抑菌活性及其稳定性.方法:采用牛津杯法和微量肉汤稀释法测定湄潭白茶多糖对金黄色葡萄球菌的抑菌活性及最小抑菌浓度(Minimum inhibitory concentration,MIC),并进一步探讨温度、pH、紫外线照射和金属离子对其抑菌活性稳定性的影响.结果:湄潭白茶多糖...     

Anti-obesity and anti-diabetic effects of ethanol extract of Artemisia princeps in C57BL/6 mice fed a high-fat diet

Artemisia princeps is commonly used as a food ingredient and in traditional Asian medicine. In this study, we examined the effects of long-term administration of an ethanol extract of A. princeps (APE) on body weight, white adipose tissue, blood glucose, insulin, plasma and hepatic lipids, and adipocytokines in C57BL/6 mice fed a high-fat diet. Daily feeding of a 1% APE diet for 14 weeks normalized elevated body weight, white adipose tissue, and plasma glucose and insulin levels, and delayed impaired glucose tolerance in mice a fed high-fat diet. These events were not observed in mice fed a control diet containing 1% APE. Liver triglyceride and cholesterol levels were similar in mice fed a 1% APE-diet and those fed a control diet. In the high-fat diet groups, APE inhibited hepatic fatty acid synthase (FAS) and suppressed the elevation of plasma leptin, but had no effect on adiponectin levels. These findings suggest that the regulation of leptin secretion by APE may inhibit FAS activity with subsequent suppression of triglyceride accumulation in the liver and adipose tissues. Inhibition of lipid accumulation can, in turn, lead to improvements in impaired glucose tolerance.     

纳豆溶栓效应的研究

探讨了纳豆产品的溶栓效应。采用冻干纳豆粉灌胃,在复制的大鼠血栓模型上,通过动态观察血压的变化,比较血栓的大小以及检测纤溶酶原激活物质抑制剂(PAI)、组织型纤溶酶原激活物(tPA)活性等指标,观察冻干纳豆粉对血栓的作用及其机理。将SD大鼠随机分5组(N=40),实验组用不同浓度的冻干纳豆灌胃,同等剂量的蚓激酶设为阳性对照,用Powerlab/4s描记股动脉血压,采用酶联免疫吸附法测定血浆中PAI-I及tPA活性。冻干纳豆组与正常对照组、单纯血栓组相比,复制血栓前血压无显著性差异(P>0.05),血栓复制40min后,冻干纳豆组、阳性对照组与单纯血栓组血压相比有显著性差异(P<0.001);冻干纳豆处理的动物与单纯血栓组动物比较,其血栓的湿重、干重显著性降低(P<0.001);冻干纳豆组、阳性对照组血浆中tPA活性升高,PAI/tPA比值与对照相比显著降低(P<0.001)。冻干纳豆对动脉血栓的形成有抑制作用。     

Inhibitory effects of Hibiscus sabdariffa L extract on low‐density lipoprotein oxidation and anti‐hyperlipidemia in fructose‐fed and cholesterol‐fed rats

Hibiscus sabdariffa L extract (HSE) is an aqueous extract of Hibiscus sabdariffa L flowers that is used as a local soft drink and medical herb in Taiwan. Oxidation of low‐density lipoprotein (LDL) has been shown to increase the incidence of atherosclerosis. In this study, we determined the antioxidative activity of HSE on LDL oxidation by examining relative electrophoretic mobilities (REM) and thiobarbituric acid‐reactive substances (TBARS). The data revealed an inhibitory effect of HSE on Cu²⁺‐mediated REM and TBARS. HSE exhibited a remarkable ability to reduce cholesterol degradation and ApoB fragmentation. Overall, HSE showed a high potency to inhibit the production of oxidized LDL induced by copper and, specifically, to reduce serum triglycerides in high‐fructose diet (HFD) fed rats and serum cholesterol in high‐cholesterol diet (HCD) fed animals. The levels of LDL and the ratio of LDL‐cholesterol (LDL‐C) to HDL‐cholesterol (HDL‐C) were reduced by HSE in both hyperlipidaemia models. Based on these findings, we suggest that HSE may be used to inhibit LDL oxidation and to prevent various types of hyperlipidaemia in HFD‐ or HCD‐fed rats. Copyright © 2004 Society of Chemical Industry     

Nutrient digestion and lactation performance of dairy cows fed combinations of prilled fat and canola oil.

Four combinations of prilled fat and canola oil were fed to 10 lactating Holstein cows in a replicated 5 x 5 Latin square to determine whether mixing plant oil with a rumen inert fat had additive effects on digestive and lactation responses. Five diets of concentrate and corn silage (1:1, DM basis) contained either no added fat (control) or 5% fat comprising 100, 67, 33, or 0% prilled fat and the remainder canola oil. The fat supplement containing 100% prilled fat appeared to be rumen-inert because it caused no changes in ruminal VFA concentration, acetate to propionate ratio, or total tract fiber digestion. Prilled fat increased milk production, FCM, and milk fat percentage but decreased milk protein percentage, including casein content. Increasing canola oil in the fat supplement caused linear declines in ruminal VFA, acetate to propionate ratio, and milk production. Milk production efficiency (weight FCM/weight DMI) exceeded the control diet when fat supplements contained 100 or 67% prilled fat but dropped below control for 33 and 0% prilled fat. This study demonstrates additive effects of combining canola oil with hydrogenated, prilled fat on ruminal fermentation but nonadditive effects on milk production efficiency and milk composition. At low levels of supplementation, plant oils, such as the canola oil used in this study, can inhibit ruminal fermentation but still maintain milk production efficiency.     

Effects of dietary components including garlic on concentrations of skatole and indole in subcutaneous fat of female pigs

The results reported here showed that threshold concentrations of skatole and indole in rice-bran oil for Singaporean consumers were 0.028 μg/g and 0.051 μg/g, respectively, and that skatole and indole levels in subcutaneous fat of pigs can be affected by diet. In Experiment A, 31 female pigs were fed with diets based on plant products only (P) or plant plus animal by-products (AP), with added levels of garlic essential oil from zero to 2.15 g/kg feed. Concentrations of skatole and indole increased with increasing garlic concentration (P < 0.001). In Experiment B, P and AP diets were fed to 47 female pigs with different dietary lipid sources (fish oil, tallow, and a mix of linseed oil and soya oil). Skatole and indole concentrations were higher in backfat of pigs fed with the AP diet (P < 0.05), but were unaffected by the type of lipid.     

纤溶豆豉的制备及其对小鼠溶栓效果的评价

利用动物血栓模型,饲喂纤溶豆豉来研究其在动物体内的溶栓作用。通过小鼠腰背部皮下注射10mg/mL角叉菜胶溶液诱发小鼠尾静脉形成血栓,实验组A饲喂豆豉纤溶豆豉并自由饮用纤溶豆豉提取液,对照组B(模型小鼠)、对照组C(正常小鼠)分别饲喂全价营养鼠粮,并自由饮水。结果表明：各组小鼠生长情况良好;饲喂纤溶豆豉的实验组A小鼠体质量先降低后增高,饲喂5d以后尾部形成的血栓长度逐渐变短,10d时凝血酶原时间、凝血酶时间稍有延长,但差异不显著,15d后凝血酶原时间、凝血酶时间均明显延长(P＜0.05),血浆中纤维蛋白原(FIB)含量相应降低,D-二聚体在饲喂10d后呈阳性;而饲喂全价营养鼠粮的对照组B及注射生理盐水的对照组C,其PT、TT差异均不显著。因此食用纤溶豆豉能激活机体纤溶系统,抑制凝血系统作用,有助于预防和辅助治疗血栓性疾病。     

Crop health and its global impacts on the components of food security

The literature on the importance of plant pathogens sometimes emphasizes their possible role in historical food shortages and even in famines. Aside from such major crises, plant pathogens should also be seen as important reducers of crop performances, with impacts on system sustainability, from the ecological, agronomical, social, and economic standpoints – all contributing ultimately to affecting food security. These views need reconciliation in order to produce a clearer picture of the multidimensional effects of plant disease epidemics. Such a picture is needed for disease management today, but would also be useful for future policies. This article attempts to develop a framework that would enable assessment of the impacts of plant diseases, referred collectively to as crop health, on food security via its components. We have combined three different existing definitions of food security in order to develop a framework consisting of the following six components: (1) Availability. Primary production; (2) Availability. Import - Stockpiles; (3) Access. Physical and supply chain; (4) Access. Economic; (5) Stability of food availability; (6) Utility-Safety-Quality-Nutritive value. In this framework, components of food security are combined with three attributes of production situations: the nature of the considered crop (i.e. food- or non-food), the structure of farms (i.e. subsistence or commercial), and the structure of markets (i.e. weakly organized and local, to strongly organized and globalized). The resulting matrix: [Food security components] × [Attributes of production situations] provides a framework where the impacts of chronic, acute, and emerging plant disease epidemics on food security can be examined. We propose that, given the number of components and interactions at play, a systems modelling approach is required to address the functioning of food systems exposed to plant disease risks. This approach would have application in both the management of the current attrition of crop performances by plant diseases, and also of possible disease-induced shocks. Such an approach would also enable quantifying shifts in disease vulnerability of production situations, and therefore, of food systems, as a result of climate change, globalization, and evolving crop health.     

Composition and aroma compounds of Ragusano cheese: native pasture and total mixed rations

Raw milk from 13 cows fed TMR supplemented with native pasture and from 13 cows fed only TMR on one farm was collected separately 4 times with an interval of 15 d between collections. Two blocks (14 kg each) of cheese were made from each milk. The objective was to determine the influence of consumption of native plants in Sicilian pastures on the aroma compounds present in Ragusano cheese. Milk from cows that consumed native pasture plants produced cheeses with more odor-active compounds. In 4-mo-old cheese made from milk of pasture-fed cows, 27 odor-active compounds were identified, whereas only 13 were detected in cheese made from milk of total mixed ration-fed cows. The pasture cheeses were much more rich in odor-active aldehyde, ester, and terpenoid compounds than cheeses from cows fed only total mixed ration. A total of 8 unique aroma-active compounds (i.e., not reported in other cheeses evaluated by gas chromatography olfactory) were detected in Ragusano cheese made from milk from cows consuming native Sicilian pasture plants. These compounds were 2 aldehydes ([E,E]-2,4-octadienal and dodecanal), 2 esters (geranyl acetate and [E]-methyl jasmonate), 1 sulfur compound (methionol), and 3 terpenoid compounds (1-carvone, L(-) carvone, and citronellol). Geranyl acetate and (E)-methyl jasmonate were particularly interesting because these compounds are released from fresh plants as they are being damaged and are part of a possible plant defense mechanism against damage from insects. Most of the odor-active compounds that were unique in Ragusano cheese from pasture-fed cows appeared to be compounds created by oxidation processes in the plants that may have occurred during foraging and ingestion by the cow. Some odor-active compounds were consistently present in pasture cheeses that were not detected in the total mixed ration cheeses or in the 14 species of pasture plants analyzed. Either these compounds were present in other plants not analyzed, created in the rumen or in cheese after the pasture-plant material had been consumed, or the compounds were lost in the method of sample extraction used for the plant analysis (i.e., steam distillation) versus the solid-phase microextraction method used for the cheeses. This research has demonstrated clearly that some unique odor-active compounds found in pasture plants can be transferred to the cheese.     

Performance of lactating dairy cows fed corn as whole plant silage and grain produced from genetically modified corn containing event DAS-59122-7 compared to a nontransgenic, near-isogenic control

The nutritional equivalency of grain plus whole plant silage from genetically modified corn plants containing the DAS-59122-7 (59122) event expressing the Cry34Ab1 and Cry35Ab1 proteins to grain and silage from a near-isogenic corn hybrid without this trait (control) was assessed using lactating dairy cows. Corn plants with event 59122 are resistant to western corn rootworm and tolerant to the herbicide active ingredient glufosinate-ammonium. Effects on feed intake, milk production, and milk composition were determined. The 59122 grain and the control grain were produced in 2005 from isolated plots in Richland, Iowa. Whole plant corn silage for the 59122 and control treatments were grown in isolated plots at the Kansas State University Dairy Center and ensiled in Ag-Bags. Thirty lactating Holstein cows blocked by lactation number, day of lactation, and previous energy-corrected milk production were used in a switchback design. All cows were fed diets that contained 22.7% grain plus 21.3% whole plant silage from either the 59122 or the control hybrid, in addition to 21% wet corn gluten feed, 12.3% protein mix, 8.0% whole cottonseed, and 14.7% alfalfa hay. Each period of the switchback trial included 2 wk for diet adjustment followed by 4 wk for data and sample collection. Milk samples (a.m. and p.m.) collected from 2 consecutive milkings of each collection wk were analyzed for fat, protein, lactose, solids-not-fat, milk urea nitrogen, and somatic cell count. Percentages of milk fat, protein, lactose, and solids-not-fat were not affected by dietary treatment. Yields of milk, 4% fat-corrected milk, energy-corrected milk, solids-corrected milk, and the concentrations and yields of milk fat, milk protein, milk solids, and milk lactose were not significantly different between treatments. Efficiencies of milk, fat-corrected milk, energy-corrected milk, and solids-corrected milk production also were not different when cows were fed crops from 59122 than when they were fed the control hybrid. Milk production efficiency averaged 1.48 and 1.50 kg/kg of dry matter intake for cows fed diets containing the control and 59122 corn, respectively. These data indicate that the nutritional value for milk production was not different between a diet containing grain plus whole plant corn silage produced from a 59122 corn hybrid versus a diet containing grain and corn silage from its near-isogenic control corn hybrid.     

Tools to maintain postharvest fruit and vegetable quality through the inhibition of ethylene action: a review

Ethylene is a plant hormone controlling a wide range of physiological processes in plants. During postharvest storage of fruit and vegetables ethylene can induce negative effects including senescence, over-ripening, accelerated quality loss, increased fruit pathogen susceptibility, and physiological disorders, among others. Apart from the endogenous ethylene production by plant tissues, external sources of ethylene (e.g. engine exhausts, pollutants, plant, and fungi metabolism) occur along the food chain, in packages, storage chambers, during transportation, and in domestic refrigerators. Thus, it is a great goal in postharvest to avoid ethylene action. This review focuses on tools which may be used to inhibit ethylene biosynthesis/action or to remove ethylene surrounding commodities in order to avoid its detrimental effects on fruit and vegetable quality. As inhibitors of ethylene biosynthesis and action, good results have been found with polyamines and 1-methylcyclopropene (1-MCP) in terms of maintenance of fruit and vegetable quality and extension of postharvest shelf-life. As ethylene scavengers, the best results can be achieved by adsorbers combined with catalysts, either chemical or biological (biofilters).