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     

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.     

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.     

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…     

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。     

Nutritional Composition and Antimicrobial Properties of Three Nigerian Condiments

Three Nigerian condiments were analyzed. Dried Irvingia gabonensis seeds and freshly fermented Parkia biglobosa and Prosopis africana were analyzed for their proximate composition, mineral contents and antimicrobial properties. The condiments were found to be very rich in protein (21.35 – 26.13%) with high energy values (351.13–595.05 kcal/ kg). The moisture content of P. biglobosa and P. africana were very high (20.30 – 27.01%) compared to that of Irvingia gabonensis (3.75%) which, however, had a higher fat content (55.09%). I. gabonensis also had higher content of macro elements while P. africana was superior in micro elements. The extracts had higher anti-fungi activities but lower antibacterial activities. The activity index increased with the polarity of solvent of extraction, methanolic extract being the most potent with the highest inhibition activities between 22 ± 1 and 27 ± 1 for fermented P. biglobossa.     

钻石的特殊性质及其应用

钻石以其在自然界里最高的硬度和无与伦比的光学效果．在首饰行业得到了广泛应用。然而它还有更多的特殊性质并有着特殊的用途。     

酵母菌的生存因子及其特性

麦角甾醇是酵母的“生存因子”之一,它能够延长处于衰减阶段的酵母生存时间,增强酵母菌株对酒精的抵抗能力,使酵母进一步发酵,降低葡萄酒中的残糖,但酵母细胞内麦角甾醇的富积与其生存条件、发酵环境、选择与保存条件之间有密切的关系,因而,酵母的“生存因子”对葡萄酒的酿造具有重要意义。     

不对称富马酸酯的量子化学特征与抗菌活性关系的初步研究

合成了几种不对称富马酸酯 ,并对其抗菌活性与量子化学参数间的关系进行了初步研究。结果表明 :α、β不饱和羰基结构是不对称富马酸酯类分子的抗菌活性中心 ,其抑菌力与最高占有轨道能量EHOMO及前沿轨道能差呈显著相关 ,而与最低空轨道能量ELUMO无显著相关关系。抗菌半衰期与最低空轨道能量以及前沿轨道能差呈显著相关 ,与最高占有轨道能量之间的关系不显著。     

对位芳纶浆粕结构及性能的表征

对4种造纸用芳纶浆粕的结构与性能进行了研究,探讨了造纸用芳纶浆粕的表征方法.用光学显微镜及SEM观察纤维形态.用kajaani FS-200测定纤维的粗度、平均长度及长度分布;用打浆度、保水值表征浆粕的滤水性;用BET法测定浆柏的比表面积;比较了4种造纸用芳纶浆粕的抄造性能及芳纶纸的物理强度.结果表明,芳纶浆粕纤维的表面细纤维化程度、打浆度、保水值、比表面积的变化呈现一致的规律性.纤维粗度、长度变化规律性不明显,这种评价方法可以有效地表征浆粕的性能,在抄造芳纶特种纸时,要综合考虑浆柏纤维的长度、粗度以及比表面积等相关因素.     

抗菌性能的检测方法及其在皮革行业中的应用

概述了国内外用于抗菌产品抗菌抑菌性能测试的常用方法。首先将这些方法按照一定标准进行分类,并采用分类对比的方法评述了每种方法的优缺点及其在皮革行业中应用的可行性,在此基础上提出了对皮革抗菌抑菌性能的测试方法建议,即溶出性抗菌产品采用琼脂平皿扩散法和晕圈法,不溶出性抗菌产品采用振荡法和奎因法。最后,考虑到安全性等问题,提出了抗菌并不是消毒,在选择测试方法时,还应与人体健康密切联系。     

Processing of Potato Protein Concentrates and Their Properties

Protein recoveries from potato juice by ultrafiltration, polyelectrolyte-coagulation and cryoconcentration were compared. The best yield was obtained by ultrafiltration. Depending on the method of potato juice concentration, differences were observed in: foaming and emulsifying properties, wettability, swelling, and buffer capacity of preparations. The dried preparations contained a high level of proteolytic enzymes inhibitors and glucoalkaloids. Thermal inactivation of preparations before drying led to 43–48% destruction of protease inhibitors and 81–89% glycoalkaloids. At the same time it was observed that thermal treatment led to distinct changes in the amino acid composition of the proteins and had an adverse effect on the properties of the dried preparations.     

磷脂及其衍生物的功能特性探讨

大豆磷脂具有多种功能特性，而磷脂的衍生物，特别是溶血磷脂具有更活泼的生物活性。磷脂及其衍生物能够促进胎儿和婴儿的大脑发育、调节人体免疫功能、抗肿瘤、防止脂肪肝和肝炎的发生等．以磷脂为主要组分的脂质体在不同的场合下被用作免疫增强剂或免疫抑制剂．磷脂及其衍生物具有抗菌作用，在食品保鲜和医疗上有广泛的应用前景，其表面活性剂性质有助于药物的渗透，应用于化妆品中能调节皮肤、舒展皱纹。     

Isolation and Characterization of Bacteria Resistant to the Antimicrobial Activity of Garlic

Twenty-six bacteria were isolated from garlic (Allium sativum) and characterized. They all were identified as Leuconostoc mesenteroides subsp. mesenteroides. All the isolates were resistant to antimicrobial activity of garlic and grew or survived in TSB with 10% garlic extract while other bacteria and yeasts from our laboratory collection were killed when 1–2% garlic extract was in the culture media. Garlic isolates were also more tolerant than common laboratory strains to the toxic effect of methyl methanethiosulfonate, a thiol inhibitor similar to allicin. This is the first report of the isolation of naturally occurring bacteria resistant to antimicrobial activity of garlic.