银系抗菌材料对食品污染菌抑制作用的研究

研究银系抗菌材料对几种常见食品污染菌的抑制作用.结果表明,银系抗菌材料对供试菌种有较为明显的抑制作用.在试验浓度下,对G-菌的抑制作用最强,对G+菌的作用次之,对酵母菌和霉菌的作用相对较弱.作用相同时间,浓度越高、添加量越大,抑菌率就越高.银系抗菌材料有良好的热稳定性,经高温处理后仍然有良好的抑菌效果.     

榕树叶抑菌作用的试验研究

本实验就榕树叶的醇提取液对污染食品的几种常见致病菌和腐败菌进行了抗菌试验研究。结果表明：榕树叶醇提取液对所试细菌、青霉、黑曲霉和面包酵母菌的生长均有不同程度的抑制作用，但对毛霉、黄曲霉、啤酒酵母、假丝酵母抑制作用不明显；在相同时间内、提取液浓度越高，抑制率越高；同一浓度的提取液，作用时间越长，抑菌率也越高；且具有热稳定性强、抑菌浓度低的特点。关于抑菌机理有待进一步研究。     

梅干菜提取物抑菌作用的研究

研究了梅干菜的无水乙醇提取物对三种细菌、一种酵母菌和一种霉菌的抑制作用.结果表明,一定浓度的梅干菜提取物对供试的枯草芽孢杆菌、金黄色葡萄球菌和啤酒酵母都有较好的抑制作用,对上述供试菌的最低抑菌浓度(MIC)分别为0.2、0.1、0.3g/mL.但对大肠杆菌和黑曲霉无抑制作用.     

乌饭树树叶水溶性黄酮的抑菌作用的研究

为了拓展栽培乌饭树树叶的有效利用途径.采用二倍稀释法和管碟法对乌饭树树叶粗黄酮提取物进行体外抑菌试验,研究了乌饭树树叶黄酮的抑菌作用并和山梨酸钾的抑菌作用做了比较,并测定了温度、pH值和糖盐对其抑菌效果的影响.结果显示乌饭树树叶粗黄酮对细菌的抑制作用明显,但对霉菌和酵母的抑菌效果不明显.其提取液的抑菌效果强于山梨酸钾的抑菌效果.乌饭树树叶粗黄酮在偏酸性条件下抑菌效果较好,随温度的升高其抑菌效果先增强后减弱.乌饭树树叶粗黄酮类化合物在抑菌作用上和糖盐有较强的协同作用.在相同的时间内,提取液的浓度越高,抑菌率越高;相同浓度的提取液,作用时间越长,抑菌率也就越高.因此,乌饭树树叶有作为药品和天然食品杀菌防腐剂开发的潜力.     

肉桂精油抑茵活性研究

利用滤纸片液相和气相扩散法进行体外抑菌试验,测定肉桂精油对6种供试菌的抑菌圈直径和最小抑菌浓度,以及加热处理和pH值对精油抑菌效果的影响.结果表明:肉桂精油对各供试茵的抑茵圈直径在19.6～43.5mm,对细菌、霉菌和酵母均有很强的抑制作用,对霉菌的抑菌作用高于酵母菌和细菌;气相也具有较强的抑茵作用;120℃加热处理20min对内桂精油的抑菌效果无明显影响;在pH值偏酸或偏碱时内桂精油的抑菌效果增强.     

溪黄草提取物抑菌效果研究

对溪黄草水提取物和乙醇提取物的抑菌特性进行了研究,分别测定了溪黄草提取物对供试细菌、酵母菌和霉菌的抑菌圈直径及其最低抑菌浓度和杀菌农度,并选择自然条件下变质的牛奶混合微生物菌群进行实际抑菌效果买验。实验结果表明,溪黄草提取物对供试非芽抱细菌具有明显的抑制作用,对供试酵母菌和霉菌也具有一定的抑制效果,且醇提物的抑菌效果要优于水提物。低浓度溪黄草水提物对牛奶混合微生物菌群的抑菌效果要优于高浓度溪黄草水提物     

大蒜汁对食品污染菌抑制作用的研究

】本文采用了滤纸片法与平板菌落计数法，初步测定了不同浓度的大蒜汁对食品中的常见污染菌的抑制作用。在此基础上，对食品中主要有害菌也作了抑菌率的初步研究，实验结果证明，大蒜汁对细菌、放线菌、酵母菌有较强的抑制作用，抑菌率也较高，对霉菌也有一定的抑制作用，但在同等浓度的蒜汁下，其抑菌率比其它菌要低。     

石榴皮黄酮在牛奶贮藏中的应用研究

提取石榴皮中抑菌成分——黄酮,采用抑菌圈法研究了石榴皮提取物对几种常见的细菌、酵母菌、霉菌以及乳酸菌的抑菌效应,并将其加入鲜牛奶中,通过测定牛乳中活菌数量随放置时间的变化情况来衡量石榴皮提取物对牛乳中微生物的抑制程度.结果表明石榴皮提取物对细菌、霉菌和酵母菌均有抑制作用,其中对乳酸菌和金黄色葡萄球菌的抑制作用最好,对大肠杆菌和霉菌的抑制作用次之,对酵母菌的抑制作用较弱.将其应用于牛奶贮藏中也取得了良好的抑菌效果.     

蜂胶对食品致病菌抑菌作用研究

抑菌实验表明了蜂胶乙醇提取液对食品致病菌有明显的抑制作用。其最小抑制浓度分别为伤寒沙门氏菌，０．８％，志贺氏菌：０．８％，魏氏梭菌：０．８％，肉毒梭菌０．４％，蜡样芽胞相菌：０．１％，小肠结肠炎耶尔森氏菌，０．４％，金黄色葡萄球菌：０．４％，在相同时间内，浓度越高，抑菌率也就越高，同一浓度，作用时间越长，抑菌率也就越高。     

桉叶精油包埋前后抑菌性能及成分比较研究

以包埋前后的桉叶精油为研究对象,采用平板打孔法和气相扩散法分别测定其对供试菌的抑菌活性和气相最低抑菌浓度(minimum inhibitory concentration,MIC)、气相最低杀菌浓度(minimum bactericidal concentration,MBC),探讨桉叶精油包埋前后抑菌性能差异。并用气相色谱-质谱联用技术对比分析桉叶精油包埋前后的化学成分。结果表明:桉叶精油包埋前后对供试细菌、酵母菌和霉菌均有一定的抑制作用。对酵母菌的抑制作用最强,其次为细菌,对霉菌的抑制效果稍差。桉叶精油包埋前后对供试菌的气相MIC和MBC未有太大差异。桉叶精油包埋前后主要成分大体相同,均以萜烯类和醇类化合物为主。包埋后桉叶精油中部分萜烯类化合物的消失或相对含量的减少导致抑菌性能稍有下降,但气相MIC不变,仅对酿酒酵母和桔青霉的气相MBC稍有上升。     

Antimicrobial effects of probiotic bacteria against selected species of yeasts and moulds in cheese-based dips

The antimicrobial properties of selected probiotic bacteria against Aspergillus niger , Penicillium roqueforti , Fusarium spp., Candida albicans and Saccharomyces cerevisiae were examined. Well diffusion and spot and streak methods showed strong inhibition effect of probiotic bacteria and their metabolites against moulds and minimal effect against yeasts. Among the moulds species tested, the inhibitory effect was strongest against Fusarium spp., moderate against Penicillium roqueforti and minimal against A. niger . All strains of Lactobacillus rhamnosus and L. paracasei subsp. paracasei showed maximum inhibitory effect. When probiotic bacteria and yeasts and moulds were co-cultured in broth media, strains of L. rhamnosus showed maximum inhibitory effect, whereas L. paracasei subsp. paracasei , L. acidophilus , Bifidobacterium animalis and Propionibacterium showed moderate inhibitory effect against C. albicans . Saccharomyces cerevisiae was minimally controlled by probiotic bacteria. Pre-grown probiotic bacterial culture metabolites controlled yeasts and moulds more effectively than their freeze-dried or frozen forms. Adding metabolites of probiotic bacteria (5% w/w) showed an effective control against A. niger , Fusarium spp. and C. albicans during the shelf life of 10 weeks at 4 °C and no colonies of yeasts and moulds were formed on the surface of the dip.     

异硫氰酸苄酯及其类似物抑菌活性的初步探究

本文对异硫氰酸苄酯及其类似物(异氰酸苄酯、异硫氰酸苯酯、异硫氰酸苯乙酯、异硫氰酸乙酯)对大肠杆菌及金黄色葡萄球菌的抑菌活性进行初步探究。通过对抑菌圈、最低抑菌浓度、最低杀菌浓度、生长曲线、能量代谢及构效关系研究,初步探究了异硫氰酸苄酯及其类似物的抑菌基团及抑菌机理。结果表明:5种物质对两种受试菌种均具有抑菌作用,尤其对金黄色葡萄球菌最为敏感;其抑菌活性是由异硫氰酸基团、亚甲基以及苯环三者共同作用的结果,并且异硫氰酸基团对其抑菌活性的决定性作用最大、亚甲基次之、苯环最弱。结构不同物质对细菌的代谢活性及相关酶活性的影响也不同。其中,异硫氰酸基团对能量代谢影响最大,氧原子被硫原子取代后进一步增强了这种作用,苯环的存在对能量代谢的影响产生反向作用。但对能量代谢影响最为明显的抑菌物质,其抑菌活性并不是最强的,这说明可能还存在其他抑菌机理。     

荠菜多糖的超声波提取工艺及其抑菌活性的研究

采用超声波技术提取荠菜多糖,以正交实验设计优化提取工艺条件。结果表明:荠菜多糖的最优提取工艺条件为:超声波功率400W、超声波处理时间35min、料液比1∶20、浸提温度70℃,荠菜粗多糖的提取率高达8.26%。为进一步研究荠菜多糖对几种常见肠道致病菌的抑制效果,进行了体外抑菌实验并测定了最小抑菌浓度(MIC)。结果表明,荠菜多糖对大肠杆菌、枯草杆菌、金黄色葡萄球菌、沙门氏菌都有一定的抑制效果,且随着荠菜多糖浓度的增加其抑菌效果逐渐增强。最小抑菌浓度分别为大肠杆菌8.0mg/mL,枯草杆菌6.0mg/mL,金黄色葡萄球菌10.0mg/mL,沙门氏菌10.0mg/mL。     

纳豆菌的抑菌效果及在豆浆保鲜中应用研究

研究一株纳豆菌的抑菌效果并初步探讨其在豆浆保鲜中的应用。结果表明,纳豆菌具有广谱抗菌作用,对细菌、酵母菌和霉菌均有一定的抑菌作用。纳豆菌抗菌粗提液的抑菌效果接近或优于一些常用食品防腐剂,在豆浆保鲜试验中有显著的抑菌效果,保温24 h的处理样品中活菌数比对照少3个数量级。     

纳豆菌的分离鉴定及其抗菌活性

本研究从日本纳豆分离获得抗菌活性高的纳豆菌，对其进行了菌种鉴定；考察了其对常见的食品污染菌（细菌、酵母菌和霉菌）的拮抗作用，并与常见的食品防腐剂的抗菌作用进行了比较，而且，考察了纳豆菌抗菌作用的遗传稳定性。     

Antimicrobial effect of various combinations of plant extracts

The combined extracts of corni fructus, cinnamon and Chinese chive were used to evaluate its antimicrobial activity on common foodborne micro-organisms, including bacteria, yeasts and moulds. The combined extract (8:1:1, v/v/v) showed an entire antimicrobial spectrum and outstanding inhibitory effect. The combined extract was very stable under heat treatment. The inhibitory effect of the combined extract was greater with more acidic pH values but lowered with increased pH values. With addition of metal ions, the antimicrobial activity of the combined extract was slightly affected. With addition of food additives, its antimicrobial activity was slightly enhanced, except for citric acid. When the combined extract used in food products, the expected antimicrobial effect in dumplings, guava juice and green and black tea was observed. Conclusively, in addition to be used as seasoning, the combined extract is suitable for incorporating in various food products where a naturally antimicrobial additive is desired.     

Effects of small-diameter silver nanoparticles on microbial load in cow milk

Controlling bacterial growth in fluid milk is of economic interest, and supplemental methods to stop or reduce bacterial growth before and during the cooling chain may be valuable. Silver is effective in controlling growth of single-celled organisms, but has no effect on tissue cells. Smaller diameter (6-8 nm) silver nanoparticles were produced, with purity over 99.99% (no chemical reaction used in the process), by using a terminated gas condensation principle. The first trial investigated effects of time, temperature, and accelerating voltages on total aerobic bacteria count in control milk and milk treated with silver nanoparticles. Metal braids were coated with silver nanoparticles using 3 accelerating voltages, 0, 100, and 200V, the results of which indicated that the braids coated using 100V (AgNP100) were optimal. The AgNP100 particles were effective at all treatment temperatures and durations except for 10h, which indicated that the treated milk could be used after 10h for other dairy products such as yogurt, which require microbial activity. The second experiment investigated the effects of silver nanoparticles on counts of yeasts and molds, coliform bacteria, Escherichia coli, and Staphylococcus aureus in cow milk by treating milk with AgNP100 braids at 22 °C for 1h. Inductively coupled plasma mass spectrometry analyses indicated that the maximum amount of silver found in the AgNP100-treated milk was 6.1μg/L, which is below the safety limits. Counts in milk samples containing the nanoparticle-coated braids were lower for all yeasts and molds and bacteria investigated compared with the control milk samples, which were kept under the same conditions but without the braids. The differences were significant for coliforms, Escherichia coli, and Staphylococcus aureus but not for yeasts and molds, although ranking of the counts (AgNP100 < initial load < control) were the same for all microorganisms. Small-diameter, silver nanoparticle-coated braids can stop or reduce bacterial growth in fluid milk. Silver nanoparticles inhibited microbial growth and may be useful in complementing the cooling chain and the thermal processes. These results warrant more research on the sensory properties and long-term safety of the use of silver nanoparticles in dairy products.     

Nisin延长低脂再制干酪保质期的应用

Nisin已广泛应用于食品保质期的研究中,本试验研究在贮存过程中,Nisin对低脂再制干酪细菌、肠杆菌、霉菌和酵母菌的抑菌效果及pH的变化。在低脂再制干酪样品中,空白样品贮藏到5个月时,样品变质不可食用,添加0.2%、0.3%Nisin的样品到6个月时,细菌总数、肠杆菌、酪霉菌和酵母菌合格,而添加0.2%Nisin、0.3%Nisin抑菌效果差异不显著,因此添加0.2%Nisin为宜。随着贮藏期时间的增加,pH显著增加。     

An inorganic biocide using a novel presentation of silver

A silver-based preservative system has been developed which overcomes difficulties often associated with metals, namely solubility, dispersion and toxicity. It comprises a silver chloride titanium dioxide composite which allows the controlled release of silver ions. Microbiological data has shown the composite to be active at concentrations less than 25 ppm against a wide range of micro-organisms, including Gram-negative non-fermentative bacteria, yeasts and moulds. The composite has satisfactory preservative activity against bacteria and fungi at application concentrations of between 50 ppm and 500 ppm, depending on the formulation. At high concentrations (>300 ppm) there may be some grey discoloration of the product, but the composite remains effective. To overcome this problem, a system of enhancing antimicrobial activity was devised, based on a sulphosuccinate salt dispersing agent. This allows lower concentrations of composite to be used whilst maintaining equivalent antimicrobial activity.     

乌饭树树叶不同提取物抑菌作用的初步研究

采用二倍稀释法和管碟法对乌饭树树叶提取物进行体外抑菌试验,研究了乌饭树树叶不同提取物的抑菌作用以及提取物的最小抑菌浓度。结果发现,乌饭树树叶提取物对细菌的抑制作用明显,但对霉菌和酵母的抑菌效果不明显。除乌饭树树叶粗多糖对枯草杆菌的抑菌效果不明显外,乌饭树树叶提取物对大肠杆菌、金黄色葡萄球菌和枯草芽孢杆菌等有害细菌抑制效果较好。此外,热处理会降低乌饭树树叶水提物和醇提物的抑菌效果,而会改善乌饭树树叶粗多糖的抑菌效果。