Antimicrobial Properties of Teas and Their Extracts in vitro

Tea has recently received the attention of pharmaceutical and scientific communities due to the plethora of natural therapeutic compounds. As a result, numerous researches have been published in a bid to validate their biological activity. Moreover, major attention has been drawn to antimicrobial activities of tea. Being rich in phenolic compounds, tea has the preventive potential for colon, esophageal, and lung cancers, as well as urinary infections and dental caries, among others. The venture of this review was to illustrate the emerging findings on the antimicrobial properties of different teas and tea extracts, which have been obtained from several in vitro studies investigating the effects of these extracts against different microorganisms. Resistance to antimicrobial agents has become an increasingly important and urgent global problem. The extracts of tea origin as antimicrobial agents with new mechanisms of resistance would serve an alternative way of antimicrobial chemotherapy targeting the inhibition of microbial growth and the spread of antibiotic resistance with potential use in pharmaceutical, cosmetic, and food industries.     

植物乳杆菌的抑菌性能及其影响因素研究进展

植物乳杆菌能够产生多种抑菌物质,具有比较优良的抑菌性能,在食品保鲜、拮抗致病菌、改善人体健康中具有潜在的应用前景,逐渐成为研究的热点。为了更全面地了解植物乳杆菌的抑菌性能,并探究其影响因素,以期为植物乳杆菌在食品保鲜和天然物质开发的深入应用提供参考,该文主要对植物乳杆菌抑菌活性、抑菌机制以及抑菌性能的影响因素有关研究进展进行综述分析。由综合分析可知,植物乳杆菌具有广谱抑菌性能,多种因素可影响其抑菌能力,且在多个领域都具有优良的应用潜力。     

Anthocyanins,Antioxidative, and Antimicrobial Properties of American Cranberry (Vaccinium macrocarpon Ait.) and their Press Cakes

ABSTRACT: Amounts of total phenolics, anthocyanins, and ascorbic acid in 4 American cranberry varieties harvested at 4 stages of maturity were measured. The larger amount of phenolic compounds was found in berries of “Black Veil” cultivar (504 mg/100 g) at II stage of maturity. Significantly larger amounts of anthocyanins were determined in the overripe berries of the cultivars “Ben Lear” and “Black Veil.” The amount of ascorbic acid in berries increased during ripening from I to III stage, and slightly decreased in the overripe berries. The biggest quantities of ascorbic acid were found in the ripe berries of “Ben Lear” cultivar (15.8 mg/100 g). The distribution of anthocyanins pigments was determined by HPLC‐UV/MS in mature berries. The composition of individual anthocyanins in berries was quite similar in all the studied cranberry cultivars. While skins of cranberries are rich in anthocyanins and other phenolic compounds, the extracts of the by‐products of cranberries juice—berry cakes, were analyzed and obtained results were compared with the properties of extracts made from whole berries. The anthocyanins and total phenolics content, radical scavenging activity, antimicrobial activity of the whole berries, and their press cakes extracts were measured. All investigated extracts from berries and their press cakes showed good radical scavenging activity and revealed antimicrobial properties. It was found that Bacillus cereus (ATCC 10876) and Micrococcus luteus (ATCC 9341) were the most sensitive among 10 tested Gram‐negative and Gram‐positive bacteria.     

Development and Characterization of Edible Films from Cranberry Pomace Extracts

The feasibility of using cranberry pomace extract as a new film‐forming material was studied. Cranberry pomaces were extracted using hot water. Low methoxyl pectin (LMP) or high methoxyl pectin (HMP) at a concentration of 0.50% or 0.75% (w/w) and 0.25% (w/w) sorbitol or glycerol was incorporated into film‐forming solutions (FFSs) for improving film functionality. Proximate compositions of cranberry pomace and its extract were determined. The pH and total soluble solid content (SSC) of FFSs, physical and mechanical properties, water vapor permeability, and microstructure of dried films were analyzed. About 1.4% (w/w) of solids was obtained from cranberry pomace water extracts, of which about 93% was carbohydrate. Dried films had bright red color and strong cranberry flavor. Films plasticized with sorbitol were denser in matrix structure and had higher color intensity than those of glycerol plasticized films. In general, LMP and sorbitol incorporated films had higher tensile strength and lower elongation at break and lower water vapor permeability than other films. The higher (0.75%) pectin concentration resulted in increased tensile strength, but decreased elongation at break. Scanning electron microscopy images revealed that sorbitol added films had more regular and compact cross‐section structure than those of glycerol added films. This study demonstrated that it is feasible to create natural colorful and fruit flavor edible films from fruit pomace water extracts. Depending on specific applications of the films, targeted film functionality can be achieved by incorporating proper pectin type and concentration and plasticizer into pomace extracts.     

丁酸钠微胶囊的制备工艺优化、表征及抑菌特性分析

为提高丁酸钠的包埋率和抑菌特性,通过复凝聚法制备海藻酸钠/壳聚糖包埋丁酸钠的微胶囊,运用响应面法优化关键工艺参数,并探究其外观形态、结构特性和抑菌性能。结果表明：丁酸钠微胶囊的最优制备配方参数为海藻酸钠3.0%（m/m）,壳聚糖1.75%（m/m）,丁酸钠2.5%（m/m）,氯化钙3.0%（m/m）,包埋时间3 h,包埋率为95.12%,且回归模型具有极显著差异（P<0.000 1）,失拟项不具备显著差异（P=0.35）,模型拟合度较好（R2=0.98）;扫描电镜发现丁酸钠微胶囊外观呈带凸起的纺锤形;傅里叶变换红外光谱分析发现丁酸钠特征峰全部削弱甚至消失表明海藻酸钠和壳聚糖形成微胶囊。丁酸钠微胶囊对金黄色葡萄球菌和大肠杆菌抑菌率分别比丁酸钠升高28.82%和25.25%,且丁酸钠微胶囊（质量浓度：2.0 g/L）对两种致病菌干预24 h后,其总抑菌率均高于99%。说明此优化工艺制备的丁酸钠微胶囊包埋率高、颗粒紧实牢固,具有较好的抑菌性能,能够为丁酸类绿色抗生素替代品的开发提供理论支撑。     

Antimicrobial Properties of Ethylene Vinyl Alcohol/Epsilon-Polylysine Films and Their Application in Surimi Preservation

Polymer films based on ethylene vinyl copolymers (EVOH) containing a 29 % (EVOH 29) and a 44 % molar percentage of ethylene (EVOH 44), and incorporating ε-polylysine (EPL) at 0 %, 1 %, 5 % and 10 % were successfully made by casting. The optical properties and the amount of EPL released from the films to phosphate buffer at pH 7.5 were evaluated, films showing great transparency and those of EVOH 29 copolymer releasing a greater amount of EPL. The antimicrobial properties of the resulting films were tested in vitro against different foodborne microorganisms and in vivo in surimi sticks. With regard to the antimicrobial capacity tested in vitro in liquid medium at 37 °C and 4 °C against Listeria monocytogenes and Escherichia coli over a period of 72 h, films showed a considerable growth inhibitory effect against both pathogens, more notably against L. monocytogenes, and being EVOH 29 more effective than EVOH 44 films. At 37 °C, total growth inhibition was observed for EVOH 29 films incorporating 10 % EPL against both microorganisms whereas the copolymer EVOH 44 did show total inhibition against L. monocytogenes and the growth of E. coli was reduced by 6.64 log units. At 4 °C, no film was able to inhibit completely bacterial growth. Scanning electron microscopy micrographs showed corrugated cell surfaces with blisters and bubbles, and collapse of the cells appearing shorter and more compact after treatment with EPL. Finally, the films were successfully used to increase the shelf life of surimi sticks. The results show the films developed have a great potential for active food packaging applications.     

Use of Electrospinning to Develop Antimicrobial Biodegradable Multilayer Systems: Encapsulation of Cinnamaldehyde and Their Physicochemical Characterization

In this work, three active bio-based multilayer structures, using a polyhydroxybutyrate-co-valerate film with a valerate content of 8 % (PHBV8) as support, were developed. To this end, a zein interlayer with or without cinnamaldehyde (CNMA) was directly electrospun onto one side of the PHBV8 film and the following systems were developed: (1) without an outer layer; (2) using a PHBV8 film as outer layer; and (3) using an alginate-based film as outer layer. These multilayer structures were characterized in terms of water vapour and oxygen permeabilities, transparency, intermolecular arrangement and thermal properties. The antimicrobial activity of the active bio-based multilayer systems and the release of CNMA in a food simulant were also evaluated. Results showed that the presence of different outer layers reduced the transport properties and transparency of the multilayer films. The active bio-based multilayer systems showed antibacterial activity against Listeria monocytogenes being the multilayer structure prepared with CNMA and PHBV outer layers (PHBV + zein/CNMA + PHBV) the one that showed the greater antibacterial activity. The release of CNMA depended on the multilayer structures, where both Fick’s and Case II transport—polymer relaxation explained the release of CNMA from the multilayer systems.Overall, the deposition of electrospun CNMA-loaded zein fibres on a PHBV8 layer is a promising methodology for the development of active bio-based multilayer systems, with a great potential for food packaging applications.     

酸型防腐剂分子解离度对其抗菌活性影响的研究

本文对常见的酸型防腐剂苯甲酸、山梨酸、丙酸、对翔基苯甲酸、富马酸、肉桂酸及其盐类和相应的酯类、严等衍生物的抗菌活性进行了比较，并分别进行了量子化学特性参数的科教片，分析和比较。结果表明，酸型防腐剂的解离度极大地影响了其抗菌效果，随解离度的减少，抗菌５活性增高，酸型抗菌剂在非游离态、衍生物酯化态和醛基态三种非解离态情况下，其抗菌活性相应地高于其带电离子态。量子化学计算结果揭，酸型防腐剂呈非解离态时的     

半乳糖基甘油月桂酸单酯的抑菌活性和稳定性

研究半乳糖基甘油月桂酸单酯对食品中几种常见腐败菌的抑菌作用及其稳定性。方法：采用倍比稀释法测定半乳糖基甘油月桂酸单酯对5 种细菌和3 种真菌的最小抑菌浓度（minimum inhibitory concentration,MIC）。同时以大肠杆菌和蜡样芽孢杆菌为指示菌,研究pH值、温度、紫外线照射及NaCl质量分数对半乳糖基甘油月桂酸单酯抑菌稳定性的影响。结果：半乳糖基甘油月桂酸单酯对大肠杆菌、蜡样芽孢杆菌等5 种细菌具有较好的抑菌活性,而对黄曲霉、黑曲霉和酿酒酵母等真菌的抑制效果不明显或无抑制效果。半乳糖基甘油月桂酸单酯对荧光假单胞菌的MIC为0.078 mg/mL,对大肠杆菌、枯草芽孢杆菌、蜡样芽孢杆菌和金黄色葡萄球菌的MIC均为0.156 mg/mL。半乳糖基甘油月桂酸单酯在pH 5～8范围内具有较好的抑菌活性,经温度和紫外线照射处理后,抑菌活性有微弱下降,随着NaCl质量分数的增加,其抑菌活性显著下降。     

Quantitative Methods for Anthocyanins. 4. Determination of Individual Anthocyanins in Cranberry and Cranberry Products

SUMMARY– A new method was developed to determine the quantities of the four major anthocyanins in cranberry and cranberry products. The pigments were streaked on Whatman No. 1 paper and separated by multiple ascending chromatography with 1-butanol-benzene-formic acid-water (100:19: 10:25). The individual bands were measured by transmission densitometry at 525 nm. The ratio of individual pigments was calculated from the densitometric peak areas. The linearity of densitometric response for anthocyanins was established. The amount of each individual anthocyanin present was calculated from the total anthocyanin content and the ratio of individual anthocyanins. The reproducibility of the methods was 6% for the two arabinosides and 4 to 5% for the two galactosides expressed as the coefficient of variability.     

水溶性的抗菌小麦醇溶蛋白纳米粒子构建及性能研究

本研究围绕小麦醇溶蛋白(gliadin)自组装展开,以NaCas作为稳定剂利用水相反溶剂过程中gliadin与thymol共组装构建水溶性的抗菌gliadin/NaCas胶体粒子。利用纳米粒度仪、扫描电镜等技术手段表征纳米粒子的形貌、尺度,并研究了thymol的释放动力学及纳米粒子的持续抗菌性能。Gliadin/NaCas胶体粒子是纳米尺度的球形颗粒,尺度均一(PDI=0.31)。此类纳米粒子具有良好的水溶性及冻干复溶性,荷载疏水类抗菌剂(thymol)不影响胶体粒子的复溶性能。Gliadin/NaCas胶体粒子具有很强的荷载和控释能力,thymol与gliadin比例介于1:10~3:4时胶体粒子的尺度仅略有增加(从约270 nm增加至约300 nm),thymol的包封率高达96%;经过7 d释放,仅释放约30%的thymol。Gliadin/NaCas纳米粒子在模拟食品体系中具有持续抗菌能力。本研究为功能性抗菌食品配料的研制提供全新的技术解决手段。     

Antimicrobial Properties of Vitamin B2

Riboflavin or B2, isolated from a wide variety of animals and plant products is an important vitamin commonly found in the diets of various cultures. This vitamin has been generally known to impart antimicrobial properties when exposed to ultra-violet A irradiation. In the current work, we investigated the possibility of preventing or reducing pathogenic infections using both ultra-violet A assisted and stand-alone riboflavin solutions on selected strains of bacteria. The antimicrobial properties of riboflavin were determined by the effective inhibition of the growth of pathogens through the disc diffusion method. Zones of inhibition studies indicated that riboflavin on its own was found to be quite effective and was able to inhibit the pathogens when diffused at a concentration of 50.0 µL. Stand-alone riboflavin solution successfully inhibited Staphylococcus aureus, Enterococcus faecalis, Salmonella typhi, and Pseudomonas aeruginosa with an inhibition range of (18.7 ± 0.6) mm; (17.7 ± 0.6) mm; (17.3 ± 0.6) mm, and (15.7 ± 0.6) mm, respectively. Intermediate zones of inhibition were observed for Escherichia coli and Candida albicans with a range of (11.7 ± 0.6) mm and (11.7 ± 0.6) mm, respectively. Klebsiella pneumoniae was the only resistant pathogen at (7.7 ± 0.6) mm for the riboflavin concentration used in this work. These results may indicate the exciting prospects of the applications of riboflavin as a complementary approach toward inactivation of pathogenic infections.     

乳杆菌抑菌和粘附性能的研究

本文以4株乳杆菌为研究对象,标准益生菌L.rhamnosus GG作为对照。研究它们对低酸和高浓度胆盐的耐受性,对抗生素的敏感性,对食源性病原菌的抑制能力以及对Caco-2细胞的粘附性。结果表明,其中Lactobacillus casei 142,L.plantarum 89的耐酸耐胆盐性能较好。四株乳杆菌对Listeria monocytogenes,Escherichia coli,shigella sonnei都有较好的抑制作用,同时它们对本研究中的5种抗生素都具有敏感性。本文采用Caco-2细胞模型,研究乳杆菌对Caco-2细胞的粘附能力,结果发现L.plantarum 89,L.plantarum 27和L.plantarum 13在Caco-2细胞上的粘附能力强(>20 cfu/cell),L.rhamnosus GG的粘附数为8(cfu/cell),而L.casei142则不具有粘附性能。     

Antimicrobial Properties of Sinigrin and its Hydrolysis Products

Sinigrin, a thioglucoside of Cruciferae plants, may be enzymatically hydrolyzed to yield up to four distinct aglycones when the plants are injured or mechanically disrupted. These aglycones, allyl isothiocyanate (AITC), allyl cyanide (AC), 1-cyano-2,3-epithiopropane (CETP), and allyl thiocyanate (ATC), were tested for their minimum inhibitory concentration (MIC) in broth to 9 species of bacteria and 8 species of yeasts. Sinigrin, AC, and CETP at 1,000 ppm were not inhibitory to any of the bacteria or yeasts tested. The inhibitory activity of ATC was uncertain due to its gradual conversion to AITC. AITC had an MIC of 50 to 1,000 ppm for bacteria and 1 to 4 ppm for nonxerotolerant yeasts, and, against xerotolerant yeasts at 50 ppm, it retarded but did not prevent growth.     

Antioxidant and Antimicrobial Properties of Selected Spice Extracts

Tinctures of eleven plants used as spices (basil, celery, dill, horsetail, lovage, marjoram, milfoil, oregano, parsley, rosemary, and thyme) were tested for their antiradical properties by means of the DPPH (1,1-diphenyl-2-picrylhydrazyl) assay over a two year period. Seven of these plants (basil, lovage, marjoram, milfoil, oregano, rosemary and thyme) were selected to obtain a mixture, which was tested in situ as antioxidant on vegetable and animal fats by an accelerated oxidation test at 110°C. The herbal extract also showed antimicrobial activity against Staphylococcus aureus (ATCC 25923), Streptococcus pyogenes (ATCC 49399), Escherichia coli (ATCC 25922) and Candida albicans (ATCC 24433).     

壳聚糖山梨酸酯的合成、表征及抑菌活性研究

通过2步反应合成了壳聚糖山梨酸酯。第1步,山梨酸在氯化亚砜中回流制备山梨酰氯;第2步,壳聚糖与山梨酰氯在甲烷磺酸的催化下酯化合成了壳聚糖山梨酸酯衍生物。采用红外光谱(FT-IR)和核磁共振氢谱(1H NMR)对衍生物的结构进行了表征。结果表明,壳聚糖的羟基与山梨酰氯发生了取代反应,其氨基仍以游离形式存在。在不同的反应物比例下,制备了取代度(DS)分别为0.44、1.21、1.93的3种衍生物,抑菌实验的结果显示:取代度为1.21的壳聚糖山梨酸酯对大肠杆菌、金黄色葡萄球菌和黑曲霉抑制作用最强,最小抑菌浓度分别为0.125,0.125和0.5 g/L。壳聚糖山梨酸酯的抑菌活性远高于壳聚糖,具备作为防腐剂在食品中应用的基础。     

抗菌肽及其在食物储藏与保鲜中的应用

抗菌肽是抵抗外源病原微生物的天然免疫小分子多肽,存在于多种生物体内,具有广谱抗菌、可抑制多重耐药菌的繁殖、活性稳定、免疫原性低、绿色无公害等优点,在食物储藏与保鲜中显示了巨大的应用潜力.对抗菌肽的功能、制备方法、抗菌机制及其在食品储藏和保鲜中的应用进行了总结分析,以期为发展有针对性的新型食物保鲜剂提供思路.     

具有永久抗菌性能的生物活性纤维

德国专门从事聚酯生产的厂商法兰克福Trevira公司开发出一种具有生物活性的多功能纤维 Trevira Bioactive。这种纤维已被用于服装和床用织物 ,最近在法国巴黎举行的 Expolfil纱线和纤维展览会上已展出了这种纤维。据称 ,这种纤维能杀除所有常见的细菌种类 ,它还被认为可影响微生物的细胞膜。该公司的市场部主任 Ulrich Girrbach认为 ,该纤维的这种抗菌效果是纤维整体中的一部分 ,它与加入添加剂或后处理具有抗菌效果的产品是不同的。这种纤维已经经过由德国 Hohenstein研究院所作的测试。这些测试显示出它的抗菌作用在经过 1 0 0多次洗涤…