荸荠叶茎提取物抑菌作用的研究

从荸荠叶茎中可以提取出具有对细菌、酵母菌和霉菌较强的抑菌物质。它对细菌的抑菌能力比对酵母菌和霉菌强。这种抑菌物质比苯甲酸钠的抑菌能力高。它的热稳定性较好，经121℃高温处理15min后，仍具有较强的抑菌能力。     

荸荠叶茎提取物抑菌作用的研究

从荸荠叶茎中可以提取出具有对细菌、酵母菌和霉菌较强的抑菌物质。它对细菌的抑菌能力比对酵母菌和霉菌强。这种抑菌物质比苯甲酸钠的抑菌能力高。它的热稳定性较好 ,经 12 1℃高温处理 15min后 ,仍具有较强的抑菌能力     

硬头黄竹醋液抑菌和杀菌性能的研究

以硬头黄竹醋液为原料,研究了不同稀释比的硬头黄竹醋液对细菌类、酵母菌类和霉菌类中有代表性菌株的抑菌和杀菌性能。试验表明,硬头黄竹醋液及稀释比为1：1时对三类菌的抑菌率和杀菌率均为100％,稀释比为1：2时对大肠杆菌、热带假丝酵母菌、绿色木霉菌及桔青霉菌的抑菌率为100％,对金黄色葡萄球菌、枯草芽孢杆菌、小椭圆酵母菌、酵母菌、黑曲霉菌有抑制作用,其抑菌率分别为90．0％、95．0％、75．76％、91．18％、82．05％;对大肠杆菌、金黄色葡萄球菌、枯草芽孢杆菌杀灭能力分别为100％、90％、90％,对小椭圆酵母菌、热带假丝酵母菌、酵母菌杀灭能力分别为98.3％、100％、99．98％;对黑曲霉菌、绿色木霉菌和桔青霉菌杀灭能力分别为91.3％、99．98％、97．98％。当稀释比为1：3时对大肠杆菌、绿色木霉菌、桔青霉菌还具有较强的抑制力,分别为95．50％、95．50％、100％,对其他菌株也仍具抑制作用;结果表明,硬头黄竹醋液对细菌和真菌均有较强的抑菌和杀菌作用,它是一种具有广谱抑菌和杀菌性能的天然抗菌剂。     

丁香和肉桂精油气相抑菌活性研究

采用超临界CO2萃取法提取丁香和肉桂精油,并通过滤纸片法、固相扩散法、气相扩散法等体外抗菌试验,比较了丁香、肉桂精油及混合精油和常用化学防腐剂山梨酸钾对11株食品中常见污染菌的抑菌作用。结果表明:丁香、肉桂精油及混合精油对供试细菌、霉菌和酵母菌均有较强的抑制作用,抑菌效果显著优于山梨酸钾;对霉菌的抑菌作用显著高于酵母菌和细菌,且气态抑制作用比固相抑菌作用强;混合精油对细菌的抑菌作用有拮抗作用,在气相中的拮抗作用更强;对酵母菌的抑菌作用没有影响;对黄曲霉和黑曲霉有相加作用;对桔青霉有协同作用。     

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.     

尼泊金丁酯对常见食品污染菌抑制作用的研究

用分光光度法和滤纸圆片法研究了尼泊金丁酯对四种细菌、四种酵母菌和两种霉菌的抑制作用。结果表明,尼泊金丁酯对食品中常见污染菌有明显的抑制作用,其中对酵母、霉菌的抑制作用较强,而对细菌尤其是芽抱杆菌抑制作用较弱．其抑菌的M1C为0．01％,该防腐剂热稳定性较好,121℃30min处理仍具有良好的抑菌效果。     

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.     

冠突散囊菌发酵液的抗菌作用

采用滤纸片法研究茯砖茶浸提液、PDA原液和冠突散囊菌PDA发酵液对细菌、酵母菌、霉菌和放线菌的抑制作用及酸碱度、温度和紫外光照射对冠突散囊菌PDA发酵液抑菌作用的影响。结果表明：茯砖茶浸提液和冠突散囊菌发酵液对细菌有较强的抑制作用,而对酵母菌和霉菌抑制作用不明显。通过对冠突散囊菌PDA发酵液抑菌物质稳定性的初步研究,结果表明,发酵液中的抑菌物质对温度(40～120℃)、紫外光(照射10h之内)和酸碱(pH2～10)稳定。     

蜜环菌抑菌作用的初步研究

采用滤纸片法、液体培养法和活菌计数法,研究了蜜环菌菌索提取液对常见微生物的抑制作用。通过测定MIC值,蜜环菌的抑菌能力依次为:大肠杆菌>金黄色葡萄球菌>枯草芽孢杆菌>啤酒酵母菌。15%的蜜环菌浸提液可抑制细菌生长,高于20%的蜜环菌浸提液可对霉菌和酵母菌产生抑制作用。     

石榴皮黄酮在牛奶贮藏中的应用初探

提取石榴皮中抑菌成分-黄酮,采用抑菌圈法研究了石榴皮黄酮对几种常见的细菌、酵母菌、霉菌以及乳酸菌的抑菌效应,并研究其对牛乳中微生物的抑制作用.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,取得了良好的抑菌效果.     

Aspergillus flavus growth in the presence of chemical preservatives and naturally occurring antimicrobial compounds

The combined effects of water activity ([a(w)] 0.99 or 0.95), pH (4.5 or 3.5) and antimicrobial agent (potassium sorbate, sodium benzoate, sodium bisulfite, carvacrol, citral, eugenol, thymol, or vanillin) concentration (0, 100, 200 up to 1800 ppm) on the growth of Aspergillus flavus were evaluated in potato dextrose agar (PDA). Mold spore germination time and radial growth rates (RGR) were significantly (p<0.05) affected by the variables. For equal antimicrobial concentration, reduction in pH or a(w) had important effects, lowering RGR and delaying germination time. Depending on a(w) and pH, increase in antimicrobial concentration slightly reduced RGR until a critical concentration where RGR was drastically reduced or mold growth was inhibited. Germination time increased as antimicrobial agent concentration increased and when a(w) and pH decreased. Important antimicrobial differences were observed, being, in general, the natural antimicrobials less pH-dependent than chemical preservatives. A. flavus exhibited higher sensitivity to thymol, eugenol, carvacrol, potassium sorbate, sodium bisulfite, and sodium benzoate (at pH 3.5) than to vanillin or citral.     

高效络合银液态抗菌剂用于水刺非织造布后整理

介绍一种新型银系抗菌剂在水刺非织造布后整理中的应用.采用络合纳米银抗菌剂对水刺非织造布进行抗菌整理,赋予其高效抗菌功能,使之广泛应用于医疗、卫生等领域.由于常用的纳米银抗菌粉体不溶于水,而纺织材料的后整理一般都是以水为介质,因此须采用液态抗菌剂.本试验着重研究高效络合银液态抗菌剂在常用纤维水刺非织造布上的抗菌整理及效果...     

Antimicrobial activity of lactoferrin against foodborne pathogenic bacteria incorporated into edible chitosan film

The objectives of this research were to develop and characterize edible chitosan film containing lactoferrin as a natural antimicrobial agent, and to investigate the combination effects of lactoferrin with lysozyme in chitosan film against the growth of Escherichia coli O157:H7 and Listeria monocytogenes. Chitosan films containing lactoferrin, lysozyme, or nisin were fabricated, and the antimicrobial concentrations were 0.5, 1, or 2 mg in a circular disc of chitosan film. Three concentrations of lactoferrin or EDTA (0.28, 0.56, or 1.12 mg per disc) were also incorporated into the chitosan film containing lysozyme to investigate the combination effects of lactoferrin. The water barrier properties of the chitosan films containing lactoferrin were characterized. The antimicrobial activities against E. coli O157:H7 and L. monocytogenes were determined using the agar diffusion assay and cell count assay. The chitosan films containing lactoferrin less than 1 mg per disc did not alter the water vapor permeability of the chitosan film. Although the film containing lysozyme exhibited significant antimicrobial activity, the incorporation of lactoferrin alone into chitosan film did not exhibit significant antimicrobial activity against both E. coli O157:H7 and L. monocytogenes. However, the combination of lactoferrin with lysozyme-containing chitosan film significantly decreased the growth of E. coli O157:H7, exhibiting a comparable effect to that of the combination of EDTA with lysozyme (P < 0.05). Furthermore, the combination of lactoferrin with lysozyme in chitosan film exhibited greater reduction in the growth of L. monocytogenes than did the combination EDTA with lysozyme, resulting in an approximate 3-log reduction.     

Improvement of the antimicrobial activity of edible mushroom extracts by inhibition of oxidative enzymes

The antimicrobial properties of water and methanol extracts from edible mushroom species were evaluated against Escherichia coli, Staphylococcus aureus and Candida albicans . Only water extracts from Lentinus edodes, Boletus edulis and Pleurotus ostreatus showed antimicrobial activity against all tested microorganisms. Their methanol extracts showed antimicrobial activity too but to a lower extent than the water extracts. Moreover, methanol extracts from Cantharellus cibarius and Lactarius deliciosus, showed also a slight activity against S. aureus. However, the antimicrobial properties of the mushroom water extracts might have been always underestimated considering that when oxidative enzymes inhibitors were added before the experimental assay, the water extracts from C. cibarius, L. deliciosus, Agaricus bisporus and Amanita cesarea showed important antimicrobial activity and the water extracts of B. edulis and P. ostreatus increased their activity. These enzymes might degrade potential antimicrobial compounds during the extraction procedure or interfere with their activity.     

添加麝香草酚和丁香油的马铃薯淀粉基抗菌膜的制备及性能研究

以马铃薯淀粉、普鲁兰多糖、明胶为成膜物质,甘油为增塑剂,氯化钙为交联剂,采用流延法制备马铃薯淀粉基复合膜,研究了抗菌剂麝香草酚和丁香油对复合膜性能的影响。结果表明:麝香草酚和丁香油能够显著影响复合膜的机械性能,增加复合膜的水蒸气透过率和水溶性,降低复合膜的透光率。添加抗菌剂的复合膜对大肠杆菌和金黄色葡萄球菌均有较强的抑制作用,随着抗菌剂含量的增加,复合膜的抗菌作用逐渐增强,且添加两种抗菌剂的复合膜对金黄色葡萄球菌的抑制作用均强于对大肠杆菌的抑制作用。     

Controlled release of sorbic acid from bacterial cellulose based mono and multilayer antimicrobial films

Biodegradable bacterial cellulose (BC) based films, incorporating sorbic acid (SA) as antimicrobial agent, have been obtained. Monolayer films, prepared using powdered BC (BCP) and poly(vinyl) alcohol (PVA), were coated with BC membrane to obtain multilayer films. Tests indicated that both SA and BCP concentration influenced sensitivity to water, release rate and antimicrobial ability of mono and multilayer films. Swelling degree, water vapour permeability and water solubility increased with SA content, but decreased with BCP addition. However in case of multilayer films, water solubility was negligible. Colour measurements indicated no degradation of SA during film preparation. The release of SA was faster when BCP concentration was higher but significantly slower, as a consequence of formed crystals dissolution, when antimicrobial concentration was increased. Furthermore, compared to the results for the monolayer films, an important decrease of SA release rate through the multilayer films was determined. The antimicrobial effect was tested against Escherichia coli K12-MG1655. The results obtained indicated that the new biocomposite films could be promising antimicrobial food packaging materials.     

Salmonellosis in finishing pigs in Spain: prevalence, antimicrobial agent susceptibilities, and risk factor analysis

A herd-based survey of Salmonella in pigs was carried in a major pig producing region of Spain. Mesenteric lymph nodes were collected from the carcasses of 25 pigs from each of 80 herds at time of slaughter. Salmonella spp. were isolated from 31% of animals and 94% of herds. Within-herd prevalence ranged from 4 to 88%, with the prevalence in most herds being greater than 10%. A large diversity of Salmonella serotypes was found, with Typhimurium, 4,[5],12:i:-, and Rissen being the most prevalent. Two or more serotypes coexisted in 73% of the herds. Salmonella Typhimurium was present in 68% of the herds. Most (82%) of the Salmonella isolates belonged to serogroups targeted by enzyme-linked immunosorbent assay tests for pig salmonellosis. Resistance to at least one antimicrobial agent was detected in 73% of the strains, and one or more resistant strains were recovered from pigs in 93% of the herds. Antimicrobial agent resistance (AR) was more frequent among the most prevalent than it was among the rarer serotypes. Twenty-five multi-AR patterns were found. Resistance to three or more families of antimicrobial agents was found in 75% of AR strains. The finding that many of the herds yielded isolates of several multi-AR patterns indicates that Salmonella infections were acquired from multiple sources. High prevalence of Salmonella in herds was associated with lack of rodent control programs, herds from farms with only finishing pigs, herds managed by more than one full-time worker, herds for which the source of drinking water was not a city supply, and relatively long fattening times.     

Antimicrobial activity of plant extracts against Salmonella Typhimurium, Escherichia coli O157:H7, and Listeria monocytogenes on fresh lettuce

Plant extracts have been found to be effective in reducing microorganisms. This study evaluated antimicrobial activity of 12 plant extracts against Salmonella Typhimurium, Escherichia coli O157:H7, and Listeria monocytogenes by using a disk diffusion assay, and Syzygium aromaticum (clove) showed the highest inhibitory effect. To investigate the efficacy of clove extract that inactivates pathogens on lettuce, inoculated lettuce with S. Typhimurium, E. coli O157:H7, and L. monocytogenes was treated with diluted clove extracts or distilled water for 0, 1, 3, 5, and 10 min. Clove extract treatment significantly reduced populations of the 3 tested pathogens from the surface of lettuce. Practical Application: This result indicated that clove extract is a useful antimicrobial agent to reduce the microbial level of foodborne pathogens on fresh lettuce. It also might be a natural antimicrobial for reducing or replacing chemical sanitizers in food preservation.     

新疆榅桲中黄酮的提取及抗菌活性测定

本实验分别用水和70% 乙醇从榅桲中提取其活性成分黄酮,测试其抑菌作用。结果表明,榅桲提取物对微生物有不同程度的抑制作用。5 种受试菌中,铜绿假单胞菌对样品的抗菌活性较为敏感,榅桲的醇提液比水提液具有更明显的抑菌效果。这将为榅桲开发为新型抗菌药物提供一定的理论依据。     

Physical and mechanical properties of chitosan films as affected by drying methods and addition of antimicrobial agent

Incorporation of an antimicrobial agent into a biopolymer matrix not only affects the antimicrobial property, but also the physical, mechanical and barrier properties of the resulted films. In addition to the effect of antimicrobial agent different drying methods that are used to prepare the films should also be considered. The aim of this study was to investigate the combined effects of drying methods, namely, hot air drying and low-pressure superheated steam drying (LPSSD), and addition of a natural antimicrobial agent, namely, galangal extract, at concentrations of 0%, 0.6%, 0.9%, 1.2% and 1.5% (w/w film forming solution) on selected physical properties (thickness, moisture content, color and opacity), mechanical properties (tensile strength and percent elongation), barrier properties (water vapor and oxygen permeabilities), degree of crystallinity and degree of swelling of antimicrobial films prepared from chitosan. X-ray diffraction (XRD) analysis, Fourier-transform infrared (FTIR) spectroscopy as well as dynamic mechanical analysis (DMA) were also performed and their results used to explain the observed combined effects. The combined effects were noted to have a statistically insignificant influence on the moisture content, thickness and water vapor permeability of the films. On the other hand, the combined effects had a statistically significant influence on the color, degree of crystallinity, degree of swelling, tensile strength, percent elongation and oxygen permeability of the films. Only the galangal extract concentration had a statistically significant influence on the film opacity. The DMA patterns and FTIR spectra confirmed the formation of crosslinkage interactions between the galangal extract and chitosan matrix.