Development of a sanitizing fabric wipe for use on food contact surfaces

ABSTRACT:  A sanitizer was incorporated into disposable sanitary wipes that were used to eliminate microorganisms on plastic and metal surfaces. These surfaces were inoculated with strains of Bacillus subtilis OSU 494, Enterococcus faecalis OSU 48, Escherichia coli ATCC 29181, Listeria innocua ATCC 33090, Pseudomonas aeruginosa OSU 167, Salmonella enteritidis OSU 799, Staphylococcus epidermidis OSU 838), Candida albicans ATCC 10231, and Aspergillus fumigatus ATCC 10894. These inoculated surfaces were cleaned with the wipes for 5, 10, and 30 s, then organisms surviving on the cleaned surfaces and in the wipes were enumerated. Applying the sanitizing wipe to the plastic and metal surfaces reduced the viability of bacteria (> log 4 for 5 s), yeast cells (> log 5 for 10 s), and fungal spores (< log 4 for all times). The use of large pore sized or thick wipes showed better sanitizing result when compared with the use of the small pore sized and slim wipe. There were no significant differences ( P > 0.05) between surviving numbers on the surface of the plastic compared with that of the metal.     

Use of encapsulated natural compounds as antimicrobial additives in food packaging: A brief review

BackgroundSynthetic chemical preservatives in food can be harmful to human health. These problems have increasingly attracted concern and interest from researchers, which has led to the study and application of non-toxic essential oils with preservative ability in food products and food packaging. A great challenge in this sense is their facile degradation during processing of the food and manufacturing processes during food packing.Scope and approachEncapsulation is an interesting technique to improve the physical-chemical and microbiological stability of these essential oils, as well as to achieve controlled release. This review provides a detailed overview of encapsulation in the food industry, focusing on the application of procedures to encapsulate antimicrobial essential oils.Key findings and conclusionsThis review focuses on recent studies related to nanotechnology and the nano and microencapsulation of essential oils. This study provides valuable insight that may be useful for identifying trends in the commercialization of nanotechnological products or for identifying new research areas. The results published to date confirm that the encapsulation promotes the protection of active compounds, enabling industrial applications of active packaging.     

Antimicrobial activity of different copper alloy surfaces against copper resistant and sensitive Salmonella enterica

Copper has shown antibacterial effects against foodborne pathogens. The objective of this study was to evaluate the antibacterial activity of copper surfaces on copper resistant and sensitive strains of Salmonella enterica. Six different copper alloy coupons (60–99.9% copper) were tested along with stainless steel as the control. The coupons were surface inoculated with either S. Enteritidis or one of the 3 copper resistant strains, S. Typhimurium S9, S19 and S20; stored under various incubation conditions at room temperature; and sampled at various times up to 2 h. The results showed that under dry incubation conditions, Salmonella only survived 10–15 min on high copper content alloys. Salmonella on low copper content alloys showed 3–4 log reductions. Under moist incubation conditions, no survivors were detected after 30 min–2 h on high copper content alloys, while the cell counts decreased 2–4 logs on low copper content coupons. Although the copper resistant strains survived better than S. Enteritidis, they were either completely inactivated or survival was decreased. Copper coupons showed better antimicrobial efficacy in the absence of organic compounds. These results clearly show the antibacterial effects of copper and its potential as an alternative to stainless steel for selected food contact surfaces.     

Evaluation of antioxidant activity of olive leaf extract obtained by ultrasound-assisted extraction and their antimicrobial activity against bacterial pathogens from food

The aim of the present study was to evaluate and compare the phenolic content and antioxidant and antimicrobial properties of olive leaf extracts obtained by ultrasound-assisted extraction (UAE) and conventional extraction (CSE). UAE of olive leaf extracts yielded a higher total phenolic content (TPC) and total flavonoid content (TFC) of 14.31% and 19.50%, respectively. Higher antioxidant activities were found from the extracts prepared with UAE (for 18.5%, 12.5%, 10.9% and 17.6% higher determined by DPPH, ABTS, FRAP and CUPRAC methods, respectively). Good antibacterial inhibitory activity (as MIC and MBC) was observed against both Y. enterocolitica and S. aureus (1.40 ± 0.40 mg mL⁻¹ and 4.00 ± 1.60 mg mL⁻¹, respectively) with the extract prepared with UAE. In conclusion, olive leaf extracts prepared with UAE exhibited higher antioxidant and antimicrobial activities against common food-borne pathogens than CSE extracts and thus could be beneficial in ensuring food quality and food safety.     

银离子的释放及敷料的抗菌性能

为了确定不同的含银医用敷料在银的释放量和释放速度上的区别,分析了几种含银医用敷料释放银离子的性能。介绍了测试抗菌性能的3种方法,并总结了含银医用敷料的抗菌性能及临床疗效。结果显示,不同的伤口对银离子的释放量有不同的要求。烧伤病人的伤口特别容易受感染,因此在烧伤伤口上使用的含银医用敷料的银离子释放量高,在伤口上可以维持较高浓度的银。在高吸湿性的医用敷料中,细菌和伤口渗出液一起被吸进敷料,从敷料上释放出少量的银离子即可达到抗菌的目的。     

Investigation of some factors affecting the antibacterial activity of rosemary extracts in food models by a food microdilution method

The activity of rosemary phenolic extracts against Listeria monocytogenes and Escherichia coli was evaluated in 50% food models of meat, vegetable and dairy products in relation to some factors that can affect MIC (minimal inhibitory concentration) values (inoculum level, proportion of food, temperature) using a new food microdilution method. It was shown that the interactions of meat and milk components with plant extracts reduced the antibacterial effectiveness of rosemary extracts. MIC values for L. monocytogenes were lower than for E. coli in all tested conditions. A lower inoculation level caused a decrease in MIC values for E. coli but an increase in MIC values for L. monocytogenes in control media. In food models, MIC values were higher or equal to MIC values in control media regardless of bacterial type. We showed that the food microdilution method represents a simple, rapid, reproducible and inexpensive method for testing the antimicrobial efficiency of plant extracts in food systems.     

Preparation and characterization of agar/silver nanoparticles composite films with antimicrobial activity

Composite films with silver nanoparticles (AgNPs), obtained by reduction of AgNO₃ using an environmentally friendly method (combined reduction of AgNO₃ by trisodium citrate solution and heating), and agar as a polymer matrix and a capping agent were prepared by solvent casting method. The surface color of the resulting agar/AgNPs films exhibited the characteristic plasmonic effect of the silver nanoparticles, and the characteristic properties of the composite films were greatly influenced by changing the concentration of AgNPs added. Significant increase in water vapor barrier properties and surface hydrophobicity were observed with increase in the concentration of AgNPs without reduction in the mechanical strength. In addition, the agar/AgNPs films loaded with more than 1 wt% of silver nanoparticles exhibited strong antimicrobial activity against both Gram-positive (Listeria monocytogenes) and Gram-negative (Escherichia coli O157:H7) bacterial pathogens.     

Chitosan: antimicrobial activity, interactions with food components and applicability as a coating on fruit and vegetables

Chitosan has recently gained more interest due to its applications in food and pharmaceutics. Among others, the antimicrobial activity of chitosan has been pointed out as one of its most interesting properties of chitosan.The aim of this study was threefold: (1) the quantification of the antimicrobial effect of chitosan with a deacetylation degree of 94% and a molecular weight of 43 kDa on different psychrotrophic spoilage organisms and food pathogens. (2) The determination of the influence of different food components (starch, whey protein, NaCl and oil) on the antimicrobial effect of chitosan and (3) the investigation of the effects of chitosan coatings on controlling decay of minimally processed fruits and vegetables (strawberry and lettuce). For the first aim several bacteria and yeast were exposed to chitosan concentrations varying from 40 to 750 mg/l. Generally, Gram-negative bacteria seemed to be very sensitive for the applied chitosan (MIC0.006% (w/v)) while the sensitivity of Gram-positive bacteria was highly variable and that of yeast was intermediary (0.01% (w/v)). To achieve the second aim, the media, with one of these components added, were inoculated with Candida lambica (±2 log cfu/ml) and were incubated at 7°C until the yeast reached the stationary phase. Starch, whey proteins and NaCl had a negative effect on the antimicrobial activity. Oil conversely had no influence. For the third aim, the chitosan coating was formed by dipping the products in a chitosan–lactic acid/Na-lactate solution from which the pH was adjusted to the pH of the products. These products were equilibrium modified atmosphere (EMA)-packaged, stored at 7°C and during storage sensorially and microbiologically evaluated. A chitosan coating on strawberries was applicable while on mixed lettuce the chitosan coating was not applicable due to the development of a bitter taste. The microbiological load on the chitosan-dipped samples was lower for both products. The antimicrobial effect of chitosan on lettuce disappeared after 4 days of storage, while it maintained on the strawberries during 12 days.     

Temperature-sensitive polyurethane (TSPU) film incorporated with carvacrol and cinnamyl aldehyde: antimicrobial activity,sustained release kinetics and potential use as food packaging for Cantonese-style moon cake

Temperature-sensitive polyurethane (TSPU) films incorporated with carvacrol and cinnamyl aldehyde were prepared for the potential use of food packaging. The antimicrobial properties and sustained release kinetics of carvacrol and cinnamyl aldehyde in TSPU film were investigated. Results indicated that cinnamyl aldehyde and carvacrol had favourable antimicrobial properties at relatively low addition ratio. The diffusion and release of carvacrol were linearly related to temperature and its addition ratio. The release rates of carvacrol from TSPU film increased from 0.6% to 2.2% with the increase of addition ratio and temperature. The first-order kinetic equation could be used to describe its diffusion and sustained release process. TSPU films could significantly prolong the shelf life of Cantonese-style moon cakes by effectively inhibiting microbial growth and decreasing lipid oxidation comparing with commonly used polyethylene food packaging. Results obtained in the present work can provide technical guide of sustained release food packaging films with antimicrobial properties.     

金属离子对漆酶活性的影响

以2，2-连氮-双(3-乙基苯并噻唑-6-磺酸)(ABTS)为底物，在pH4、5的条件下，用分光光度法考察了5种金属离子(Fe^2 、Ca^2 、Mg^2 、Mn^2 、Cu^2 )对漆酶催化活性的影响。实验发现Fe^2 对漆酶的催化活性显示出抑制作用，并进一步探讨了其抑制特征、抑制位点和作用方式。结果表明，Fe^2 对漆酶催化活性抑制属竞争性抑制过程，抑制作用是通过还原ABTS来实现的。     

Characterisation and potential migration of silver nanoparticles from commercially available polymeric food contact materials

The potential for consumer exposure to nano-components in food contact materials (FCMs) is dependent on the migration of nanomaterials into food. Therefore, characterising the physico-chemical properties and potential for migration of constituents is an important step in assessing the safety of FCMs. A number of commercially available food storage products, purchased domestically within the United States and internationally, that claim to contain nanosilver were evaluated. The products were made of polyethylene, polypropylene and polyphenylene ether sulfone and all contained silver (0.001–36 mg kg^–1 of polymer). Silver migration was measured under various conditions, including using 3% acetic acid and water as food simulants. Low concentrations (sub-ppb levels) of silver were detected in the migration studies generally following a trend characterised by a surface desorption phenomenon, where the majority of the silver migration occurred in the first of three consecutive exposures. Silver nanoparticles were not detected in food simulants, suggesting that the silver migration may be due solely to ionic silver released into solution from oxidation of the silver nanoparticle surface. The absence of detectable silver nanoparticles was consistent with expectations from a physico-chemical view point. For the products tested, current USFDA guidance for evaluating migration from FCMs was applicable.     

载银抗菌衬垫对冷鲜肉的保鲜效果研究

将含有不同质量分数MMT-Ag(3%,5%,8%,10%)的衬垫放入托盘包装的底部,以玉米苞叶为隔离层,其上放置新鲜肉末,保鲜膜缠绕密封后于4℃保存。每天测定鲜肉的菌落总数、TVB-N、TBARS、pH值、水分含量、蒸煮损失和感官评分,以考查MMT-Ag含量以及隔离层的使用对衬垫保鲜效果的影响。结果表明:衬垫的保鲜效果随MMT-Ag含量的增加而提高,当其含量为10%时效果最好,冷鲜肉的货架期为6d,比对照组延长了3d。抗菌衬垫的使用有效抑制了鲜肉中微生物的生长,延缓了TVB-N值、TBARS值和pH值的增长,并降低了水分含量和蒸煮损失,改善了感官品质。玉米苞叶隔离层的添加可防止衬垫的黏附,且不会显著缩短鲜肉的货架期。     

食品中Nisin抗菌效果影响因素的研究

研究了木瓜蛋白酶的添加量、Nisin的添加量及 p H对 Nisin抗菌效果的影响。得出了处理后细菌数和各因素间的二次回归方程 :y=30 .44- 1 8.74x1 1 6.52 x- 4.36x3- 1 8.2 x1x2 1 8.1 0 x     

Surface coating of silver nanoparticles on polyethylene for fabrication of antimicrobial milk packaging films

In this study, antimicrobial packaging films were prepared by coating silver (Ag) nanoparticles onto the surface of low density polyethylene (LDPE) films modified by corona air plasma. The possibility of these films for use in the packaging of milk was studied. The influence of input power of the corona discharge treatment on the surface modification and performance of the fabricated Ag/LDPE nanocomposite films was also investigated. The prepared antimicrobial packaging films showed promising antimicrobial efficiency against micro‐organisms that are present in milk and were able to increase the microbial shelf life of the milk. Packages fabricated at corona input powers of 210, 500 and 800 W reached the maximum limit after 5, 8 and 14 days (respectively).     

Assessment of factors influencing antimicrobial activity of carvacrol and cymene against Vibrio cholerae in food

Carvacrol and cymene, phenolic compounds naturally present in the essential oil of oregano and thyme, were examined for their antimicrobial activity against Vibrio cholerae (ATCC 14033, VC1, and VC7) inoculated in carrot juice. Carvacrol exhibited a dose dependent inhibitory effect on the bacteria. Although cymene did not have antimicrobial activity against the bacteria, it enhanced the inhibitory ability of carvacrol. At 25 °C, the lowest concentrations of carvacrol and cymene required for zero detectable viable count varied depending on bacterial strains; 5 and 5 ppm, respectively, for VC7; 5 and 7.5 ppm, respectively, for VC1; and 7.5 and 7.5 ppm, respectively, for ATCC 14033. This study also examined several factors influencing the antimicrobial activity of carvacrol and cymene against V. cholerae ATCC 14033, including temperature, bacterial cell number, and food substrate. Carvacrol and cymene inhibited the bacterium in carrot juice at 25 °C more efficiently than at 15 and 4 °C. The doses of both compounds required for zero detectable viable count increased as the number of the bacterial cells in the carrot juice increased. The fat content and the complexity of foods were shown to decrease the antimicrobial activity of the compounds.     

四种不同接触表面蜡样芽孢杆菌菌膜形成的影响

为了解食源性致病菌蜡样芽孢杆菌在食品加工环境中菌膜形成能力,以玻璃、不锈钢、聚氯乙烯、聚丙烯为接触面,采用超声波平板菌落计数法测定不同环境因素(温度、pH、氯化钠、葡萄糖、苯甲酸钠及山梨酸钾)、不同材料表面蜡样芽孢杆菌(B.cereus)菌膜形成的变化趋势。结果表明:四种材质表面形成B.cereus菌膜能力的大小顺序为:玻璃 > 不锈钢 > 聚氯乙烯 > 聚丙烯。其中,30 ℃,pH7.0时菌膜形成量最大,添加低浓度葡萄糖(4.0%)或氯化钠(0.5%)对B.cereus菌膜形成有显著促进作用(p<0.05),添加0.15%苯甲酸钠、山梨酸钾的菌膜形成量显著高于添加0.10%的菌膜形成量(p<0.05)。本研究为蜡样芽孢杆菌风险评估提供基础数据,为食品工业蜡样芽孢杆菌菌膜的预防和控制奠定基础,为改进蜡样芽孢杆菌的清洗控制措施提供参考。     

Antioxidant and antimicrobial activity and potential of heather (Erica spp.) extracts in the control of Listeria monocytogenes

In this work, heather and its flowers were studied regarding their antioxidant and antimicrobial activities. Plants were subjected to ultrasound-assisted methanolic extraction followed by fractionation. A phytochemical characterisation of extracts content in total phenols and flavonoids, and their antioxidant activity was performed. The antimicrobial activity was evaluated through the determination of minimum inhibitory concentration and by bioautography. Following, studies on the antilisterial potential were carried out by: time-kill curves, inhibition of biofilm formation and tolerance of Listeria monocytogenes to adverse conditions. The results evidenced the antioxidant activity in both extracts, as well as, the antimicrobial activity against Gram-positive bacteria. Concerning the evaluation of the antilisterial potential, a bacteriostatic behaviour and inhibition of biofilms formation ability were observed. Listeria monocytogenes showed an increased susceptibility to adverse conditions when preincubated with extracts. Thus, heather and its flowers may be a source of new compounds with antilisterial activity potential.     

Preparation,characterization and antimicrobial study of a hydrogel (soft contact lens) material impregnated with silver nanoparticles

PurposeContact lenses that incorporate antimicrobial properties may reduce the risk for microbial-associated adverse events for lens wearers. The aim of this study was to assess the antimicrobial effects of silver nanoparticles (NP) when impregnated in a hydrogel material.MethodsHydrogel disks, used as a proxy for soft contact lenses, were prepared with silver NPs to add an antimicrobial effect to the polymer. Six groups of disks were created, each with a different concentration of silver NPs. The antimicrobial effect of the hydrogels against Pseudomonas aeruginosa (ATCC15442) and Staphylococcus aureus (ATCC6538) was evaluated at 6, 24, 48 and 72 h.ResultsSilver NP concentrations ranged from 20.71 to 98.06 μg/disk. All groups demonstrated excellent antibacterial effects against P. aeruginosa at each time point. After 6 h all disks didn’t exhibit desirable antibacterial activity against S. aureus; whereas except those with 20.71 μg silver NPs showed antibacterial activity at 24 h and only the disks with 57.13 and 98.06 μg silver NPs showed antimicrobial activity at 48 and 72 h.ConclusionsThe development of contact lenses made of a silver NP-impregnated hydrogel material may bring antimicrobial effects sufficient to decrease the risk of microbial-related adverse events for lens wearers.     

Effect of high hydrostatic pressure on antimicrobial activity and quality of Manuka honey

The antimicrobial activity of Manuka honey is of major interest to beekeepers and the honey industry. In this study, the effect of high hydrostatic pressure and thermal treatments on antimicrobial activity and quality parameters (principally, diastase number and hydroxymethylfurfural levels (HMF)) of Manuka honey were investigated. The honey was subjected to different pressures (100-800MPa) at 25°C for a range of holding times (15-120min). The antimicrobial activity was found to increase with applied pressure for a given holding time, while the diastase number and HMF levels remained, more or less, unaffected. The percentage inhibition in microbial growth correlated linearly (R(2)=0.94) with methyglyoxal concentration in the honey after treatment over the entire range of pressure, temperature and holding times studied. Maximum percentage inhibition (78.83%) was achieved when honey was subjected to 800MPa compared to the control (57.93%). Thermal treatments at higher temperatures were found to have a detrimental effect on antimicrobial activity based on percentage inhibition as well as methylglyoxal content. Thus, it can be concluded that the levels of methylglyoxal, and therefore the antimicrobial effect of Manuka honey, can be enhanced by using high pressure processing without adversely affecting honey quality.