植物精油对金针菇保鲜效果的研究

为开发天然绿色的食用菌专用型保鲜剂,对4种植物精油抑制黑曲霉(Aspergillus niger)、产黄青霉(Penicillium chrysogenum)、绿色木霉(Trichoderma viride)和木霉(Trichoderma sp.)等病原真菌的效果进行分析,并以金针菇为材料进行初步保鲜效果评价。研究结果显示,薰衣草精油对黑曲霉的抑制率最高,为17.86%,柠檬醛对产黄青霉及木霉的抑制率最高,分别为16.69%和34.41%,而茴香油则对绿色木霉的抑制率最高,达17.39%。经柠檬醛处理的金针菇在保鲜过程中,失重率、褐变度被显著抑制,还原糖含量增加,CAT活性降低的趋势被减缓。这些指标均显示柠檬醛具有较好的保鲜效果,是开发天然绿色保鲜剂的良好材料。     

柠檬醛熏蒸对互隔交链孢生长及其产毒的抑制作用

互隔交链孢是一种重要的能产生交链孢酚（AOH）等真菌毒素的植物病原菌。精油是重要的抑制病原菌侵染的挥发性植物提取物,其活性组分包括柠檬醛等。本研究表明柠檬醛可高效地抑制互隔交链孢的生长和AOH毒素的产生。柠檬醛熏蒸能够引起互隔交链孢菌丝断裂影响其延伸,而对其分生孢子结构的影响不明显。柠檬醛能够引起互隔交链孢活性氧生成的紊乱,这可能是导致AOH显著下降的原因之一。由于柠檬醛能高效抑制互隔交链孢生长和产毒,因此其可作为传统熏蒸剂的潜在替代品,以防控互隔交链孢引起的病害以及毒素污染。柠檬醛抑制互隔交链孢生长产毒的研究为其开发与应用奠定了良好的基础。     

生物保鲜剂对鼠伤寒沙门氏菌等5株病原菌的抑菌效果

利用河北省科学院微生物研究所研制的生物酶保鲜剂对鼠伤寒沙门氏菌等５株病原菌进行抑菌试验,结果表明,生物保鲜剂对３株沙门氏菌,２菌弧菌科病原菌作了敏感,当生物保鲜浓度为０．５－５％时,大多数抑菌圈直径在１５－２４．５毫米,可与０．０１％氟哌酸的抑菌效果相比。     

纯氧对采后杨梅果实腐烂的抑制与抗病相关酶的诱导

为研究高氧对抑制果实腐烂的作用及其与抗病相关酶活性诱导的关系,将杨梅果实采后在5℃用纯氧或空气(对照)处理12 d.结果表明,纯氧处理可显著抑制果实腐烂发生,贮藏12 d后对照果实的腐烂指数达到54%,而处理果实仅为17%.纯氧处理在贮藏前期可诱导杨梅果实几丁质酶和β-1,3-葡聚糖酶活性的升高,并在第6天时达到高峰.另外,纯氧处理增加了苯丙氨酸解氨酶和过氧化物酶的活性及总酚含量,并在整个贮藏期间一直高于对照水平.这些结果表明,高氧抑制杨梅果实腐烂的作用与诱导与抗病相关的酶的活性升高密切相关,抗病性诱导是高氧抑制杨梅果实腐烂的重要原因.     

几种化学保鲜剂对红豆果汁的保鲜效果研究

目的:用不同浓度的化学保鲜剂处理红豆果汁,观察和记录果汁的光泽度、挂壁和总糖含量的变化。方法:从污染的果汁中分离酵母菌,通过平板涂布试验,根据药敏片抑菌圈的大小来检测不同保鲜剂的抑菌效果。结果:供试的4种保鲜剂的保鲜能力由强至弱依次为苯丙烯醛(1.0g/kg)、苯甲酸钠(0.6g/kg)、山梨酸钾(0.6g/kg)和双乙酸钠(0.3g/kg)。结论:为红豆果汁的保鲜和利用提供了科学依据。     

蜂胶在食品保鲜中的应用及机理

蜂胶是一种由蜜蜂分泌加工的具有多种生物活性成分的树脂状物质。它不仅具有抑菌、抑病毒、抗氧化的特性,而且有良好的成膜性,可以抑制有害微生物对食物的侵害及在食品表面形成保护膜,发挥保鲜剂的作用。本文综述了国内外应用蜂胶进行食品保鲜的研究现状,介绍了蜂胶作为食品保鲜剂的作用机理,同时展望了蜂胶在食品保鲜上应用的方向和前景。     

药食两用保健水果冷饭团果实的保鲜研究

该研究以冷饭团果实为材料,用甘油、淀粉、明胶、琼脂、焦亚硫酸钠按不同比例配制成3种保鲜剂处理冷饭团果实,放在平均温度11℃、平均湿度85%的冰箱保鲜层保鲜;用壳聚糖配制成4种不同质量分数浓度的保鲜剂处理冷饭团果实,放在平均温度11℃、平均湿度85%的冰箱保鲜层保鲜;用真空和臭氧装置保鲜处理,放在平均温度15℃、平均湿度40%的屋中,共4种保鲜方法对冷饭团果实进行保鲜处理.通过测定冷饭团果实的失重率、可溶性固形物的含量以及抗坏血酸(Vc)含量的变化来判断各种保鲜的效果,探索出最好的保鲜方法.结果表明:4种保鲜方法均能明显降低冷饭团果实的失重率,延缓可溶性固形物和Vc含量的降低速率;两类保鲜剂中,以甘油3 g、淀粉4 g、明胶1.5 g、琼脂1 g、焦亚硫酸钠1.5 g混合,用蒸馏水配制成500 mL保鲜剂的保鲜效果最好;真空和臭氧对冷饭团果实的保鲜中,真空的保鲜效果比臭氧好.     

白姜花根茎提取物抑菌效果及在冷鲜肉上的保鲜应用

为开发天然复合防腐剂,实现白姜花根茎(姜根)有效利用,本研究采用滤纸片法对姜根提取物的抗菌能力进行了测定,针对感官评价、液汁流失、菌落总数和肉样p H值这四方面研究了姜根提取物和复配保鲜剂的保鲜效果。结果表明:姜根提取液对金黄色葡萄球菌、大肠杆菌、黑曲霉、青霉均有抑菌作用;浓度为70%姜根提取物对冷鲜肉的保鲜效果最佳;而姜蒜复配保鲜剂(体积比为1:1)保鲜效果略优于浓度为70%姜根提取物保鲜剂,研究结果将为天然防腐剂的开发利用提供理论依据。     

孜然种子提取物枯茗醛和枯茗酸抑菌作用研究

以番茄早疫病菌、棉花黄萎病菌、小麦纹枯病菌、烟草赤星病菌、小麦全蚀病菌、油菜菌核病菌、辣椒疫霉病菌、水稻纹枯病菌、小麦白粉病菌和番茄灰霉病菌等为供试菌种,采用离体与活体相结合的方法系统地测定了枯茗醛和枯茗酸的抑菌活性。离体抑菌活性测定结果表明,枯茗醛和枯茗酸对多种病原菌具有一定的抑制效果,其中对油菜菌核病菌菌丝生长的抑制效果高于其它供试病原菌,有效中浓(EC50)分别为2.1和7.3 mg/L;枯茗醛和枯茗酸对小麦白粉病的防治实验结果表明,供试浓度为1000 mg/L时,两种药剂的保护防效均高于50%;相同处理浓度下,枯茗酸对油菜菌核病的保护防效与速克灵处理相当,达到57.52%。     

用于樱桃番茄保鲜的纳米银复合膜材料研究与应用

纳米银（silver nanoparticles, AgNPs）及其他纳米颗粒因具有抑菌和阻隔特性,在果蔬保鲜中的应用越来越受到重视。为了开发高效的果蔬绿色保鲜涂膜,利用菊花提取物绿色合成了纳米银,并研究了其对交链孢霉菌的抑制性能。制备了AgNPs和壳聚糖（chitosan,CTS）的AgNPs-CTS复合涂膜,并考察了其对樱桃番茄保鲜的影响。结果发现,所合成AgNPs呈球形,尺寸小且分散良好,对交链孢霉菌具有良好的抑菌活性。樱桃番茄的保鲜试验表明,AgNPs-CTS涂膜的保鲜性能优于CTS组和空白组,贮藏15 d后AgNPs-CTS涂膜对保持樱桃番茄中较高的可溶性固形物、滴定酸和Vc含量具有积极作用,并能显著降低樱桃番茄的腐烂率和失重率。综上表明,该AgNPs合成方法可减少有毒化学试剂的使用,绿色环保,抑菌性能良好,其与壳聚糖复合成膜可应用于樱桃番茄的采后保鲜。研究结果可为绿色环保纳米银复合保鲜涂膜的开发及应用提供科学参考。     

Quantification of factors affecting the probability of development of pathogenic bacteria,in particularClostridium botulinum,in foods

Summary The success of a preservation method with respect toClostridium botulinum can be measured by its effect on the probability that a single spore would result in growth and formation of toxin. In canned, low-acid foods, the minimum heat-process is designed to reduce the probability of survival of a single, heat-resistant spore ofC. botulinum by a factor of 10¹². In some foods, safety depends on the combination of inactivation and inhibition ofC. botulinum. The degree of protection (Pr) can be expressed asPr=Ds+In, whereDs is the decimal destruction of spores ofC. botulinum andIn is the decimal inhibition. A similar approach can be used in the case of other bacteria.Pr=log 1/P, whereP=the probability that an individual spore or bacterium will survive and result in growth.P can be estimated as the number of spores or bacteria that survive and initiate growth in a culture medium or food divided by the number of viable spores or bacteria inoculated into the medium or food. The effects of combinations of preservative factors can be measured by their effect onP at a stated temperature for a stated time. In experiments to determine the effects of preservative factors on an anaerobic bacterium such asC. botulinum it is essential that oxygen should be eliminated, unless it is controlled as an inhibitory factor. Thus experiments in culture media should be done under strictly anaerobic conditions at a known, low redox potential. The results of experiments to determine the effects of preservative factors onP after a series of incubation times can be modeled by methods similar to those used to model the effect of preservative factors on rate of growth and on lag period. Experiments to determine the effect of preservative factors on the probability of growth from a single spore or bacterium ofC. botulinum are discussed. A few reports of similar experiments with other bacteria have been published and are described. This approach has the advantage that it takes account of the inoculum level of bacteria.Mention of brand of firm names does not constitute an endorsement by the US Department of Agriculture over others of a similar nature not mentioned.     

Change in cyanobacterial biovolume due to preservation by Lugol's Iodine

Cyanobacterial biovolume is used as a guide to the public health risk from these organisms for users of potable and recreational waters. Most routine surveillance programs preserve phytoplankton samples before analysis. We tested the effect of Lugol's Iodine, a common preservative, on the cell biovolume of four common freshwater cyanobacteria, Microcystis aeruginosa, Anabaena circinalis, Cylindrospermopsis raciborskii and Aphanocapsa incerta. Linear dimensions and cell area were measured with an image analyser. All four species shrank after preservation. The magnitude of shrinkage varied with species and preservation time but was not affected by Lugol's concentration. The maximum shrinkage in each species was a 30–40% reduction compared to the live cell biovolume. These results suggest shrinkage can be a greater source of uncertainty in estimating the biovolume of toxigenic cyanobacteria in aquatic environments than natural variability in the cell dimensions, instrument precision or cell counting. Standardised cyanobacterial biovolume lists based on agreed geometric shapes and formulae would improve the value of this information for public health risk assessment.     

红枣贮藏期果面微生物多样性

以2种成熟度不同的红枣(Zizyphus jujuba Mill.)为试验材料在入库前采用保鲜剂处理,未采用保鲜剂处理的红枣为试验对照,研究红枣不同贮藏时期果面微生物多样性。结果表明:红枣贮藏期果面微生物种群中,细菌是优势类群,占微生物总数80%以上,真菌较少;采摘期红枣果面上就携带微生物,真菌优势菌株属于链格孢(Alternaria),其次为镰刀菌(Fusarium)和木霉(Trichoderma),贮藏期优势菌株属于链格孢(Alternaria)、青霉(Penicillium)、木霉(Trichoderma)和镰刀菌(Fusarium),曲霉(Aspergillus)、毛霉(Mucor)和根霉(Rhizopus)次之。红枣贮藏期果面微生物种群动态失衡是导致贮藏病害发生的主要原因,成熟度较高的红枣果面微生物总数、真菌和细菌的数量明显高于成熟度较低的红枣,使用保鲜剂后有效地降低了红枣贮藏期果面微生物的多样性,贮藏时间越长红枣果面微生物的多样性越明显。     

叶下珠药材HPLC指纹图谱的比较研究

采用反相高效液相色谱法,对叶下珠药材不同产地、不同采收期、不同部位指纹图谱进行测定和比较分析,并与中成药叶下珠胶囊的HPLC指纹图谱进行了比较研究。结果显示:(1)建立了叶下珠药材的HPLC特征指纹图谱,标定18个共有峰,利用对照品指认4个峰;11批(来源地不同)叶下珠样品的HPLC图谱相似度(相合系数,均值)在0.89~0.99之间。(2)7批不同采收期的叶下珠药材的HPLC指纹图谱相似度在0.94以上,各共有峰的峰面积大多随生长期而增加,至10月5日达到最高,建议叶下珠药材应于每年的10月上旬进行采收。(3)不同部位叶下珠药材HPLC指纹图谱相似度分析发现,叶、果的相似度较高(0.98~0.99),根、茎的相似度较低(0.86~0.87),说明根、茎中各成分含量较低,建议采收叶下珠药材的地上部分即可。(4)比较叶下珠胶囊和叶下珠药材的指纹图谱,发现二者的化学成分非常相似,但峰面积差异较大,其差异可能是由于加工过程所致。该研究所建立的HPLC指纹图谱分析方法简便、重现性好,可用于叶下珠药材及中成药的鉴定与质量评价。     

贝莱斯芽孢杆菌TMQ-KSL-1分离鉴定及其发酵液对番茄根结线虫的生防作用

镰刀菌(Fusarium spp.)和根结线虫(Meloidogyne spp.)都是植物的重要病原物,这两种病原物在寄主植物中存在着非常复杂的互作关系,可导致严重的植物土传病害。为探寻对番茄根结线虫病害具有高效防治作用的优良菌株,本研究以禾谷镰刀菌(Fusarium graminearum)为靶标病菌,采用平板稀释涂布法从多年种植番茄的设施大棚土壤中分离和筛选到一株抑菌效果较好的生防细菌菌株TMQ-KSL-1,根据形态特征、生理生化特性和16S rRNA基因测序对该菌株进行鉴定;测定不同浓度的发酵液及发酵上清液对根结线虫卵孵化率以及根结线虫二龄幼虫死亡率的影响,通过盆栽实验分析其发酵液对根结线虫病害的防治效果。结果表明,菌株TMQ-KSL-1具有较强的杀线虫活性,其发酵液和发酵上清液处理48 h线虫卵孵化抑制率分别为94.76%和90.72%;处理24 h番茄根结线虫二龄幼虫的校正死亡率分别为100%和97.37%;菌株TMQ-KSL-1发酵液100倍稀释液、200倍稀释液对番茄根结线虫病害防治效果分别为59.54%和12.14%,且100倍液处理防效与阿维菌素500倍液处理防效(6...     

Loquat fruit size is increased through the thinning effect of naphthaleneacetic acid

The thinning effect of naphthaleneaceticacid was examined in loquat trees (Eriobotryajaponica Lindl.). The effect depended on theconcentration applied and on the treatment date. Themost effective treatment found to thin fruit andincrease the average fruit size was the application of20 mg l^–1 of naphthaleneacetic acid 10–15 daysafter anthesis. Treatment reduced the fruit resistanceto puncturing and improved total soluble solidsconcentration and coloration and, consequently,harvest time was markedly advanced.     

Suppression of important pea diseases by bacterial antagonists

The potential for widespreadand severe infection makes ascochyta blight,seedling blight, and root rots major hindrancesto pea production in Alberta, Canada. Over 300bacterial strains were isolated from pea seedand soil samples taken from pea fields. Thesestrains were investigated for their biologicalcontrol potential against four fungal pathogens(Pythium ultimum, Rhizoctoniasolani, Fusarium avenaceum and Ascochyta pisi) of field pea in vitro. Selected bacterial strains were furtherevaluated in vivo. In an initial agarplate bioassay, 30 strains exhibitedantagonistic properties against the fourpathogens, with inhibition zones ranging from 5to 25 mm. Thirteen of these strains, allisolated from soil, inhibited only one or twoof the pathogens, while the remainingseventeen, including nine strains isolated frompea seeds, inhibited either three or all fourpathogens. In a more stringent bioassay, eightof the thirty strains failed to demonstrate theantagonistic features shown in the initialbioassay. Eight strains inhibited only onepathogen, six inhibited two, four inhibitedthree, and four strains inhibited all fourpathogens tested. Two strains ofPseudomonas fluorescens, five strains of Serratia spp. and two strains of Bacillus spp. were further evaluated ingreenhouse experiments. Five of the isolatesreduced the severity of diseases caused byPythium or Ascochyta, two isolatesreduced the severity of Rhizoctonia andone reduced the severity of Fusarium.     

23种中草药的体外抗菌活性筛选研究

为考察中草药抗菌物质基础筛选出活性提取物,该研究通过80%乙醇冷浸和95%乙醇回流提取制备23种中草药的提取物,采用琼脂扩散法测量抑菌圈直径,用微量液体培养基倍比稀释法测定最低抑菌浓度(minimum inhibitory concentration,MIC)和最低杀菌浓度(minimum bactericidal/fungicidal concentration,MBC/MFC),并测定了提取物对临床4种常见病原菌体外抗菌活性。结果表明:紫珠草、千斤拔、黄龙尾等9种中草药对金黄色葡萄球菌有较强的抑菌活性,其MIC/MBC值除个别菌是12.5 mg·mL~(-1)外,其他都在0.09～3.12 mg·mL~(-1)之间;千斤拔、大红袍、过江龙等5种中草药对铜绿假单胞菌有较强抑菌活性,其MIC/MBC值在3.12～12.5 mg·mL~(-1)之间;紫珠草、千里光、石楠等13种中草药对大肠埃希菌有较强的抑菌活性,其MIC/MBC值在0.09～6.25 mg·mL~(-1)之间;八角对白色念珠菌有较强抑菌活性,其MIC/MFC值在0.78～12.5 mg·mL~(-1)之间。23种中草药的抗细菌活性较好,尤其是千斤拔、大红袍、过江龙、八角、黄药子对金黄色葡萄球菌、大肠埃希菌、铜绿假单胞菌都具有较好的抑菌活性,具有广谱抗菌活性;但对真菌抑菌效果不明显,仅有八角对白色念珠菌有抑菌活性。此外,提取溶剂浓度、提取温度和提取时间对中草药的提取率和活性均有影响,冷提稍优于热提。     

Inhibitory activity of probiotics <Emphasis Type="Italic">Streptococcus phocae</Emphasis> PI80 and <Emphasis Type="Italic">Enterococcus faecium</Emphasis> MC13 against Vibriosis in shrimp <Emphasis Type="Italic">Penaeus monodon</Emphasis>

Occurrence of widespread epizootics among larval and cultured shrimp has put on viable preventive approaches such as application of probiotics on a high priority in aquaculture. In the present study, four probiotics bacteria were isolated from marine fish and shrimp intestine based on the antagonistic activity and nonpathogenic to the host. The isolates of probiotics strains Streptococcus phocae PI80, Enterococcus faecium MC13, Lactococcus garvieae LC149, B49 and one commercial probiotics (ECOFORCE) were fed to post larvae of Penaeus monodon obtained from two different hatcheries to analyze the growth and protection against Vibrio harveyi and V. parahaemolyticus. Growth of P. monodon post larvae fed with probiotic strain S. phocae PI80 was significantly (P < 0.001) higher when compared with control and other three strains in both experiments. The treatment of post larvae with B49 reduced the growth as well as Specific growth rate. Among the three probiotic strains S. phocae PI80 and E. faecium MC13 have effectively inhibited the pathogens. In experiment I high survival (92%) were observed in S. phocae PI80 treated post larvae when challenged with Vibrio harveyi followed by E. faecium MC13 (84%), B49 (76%) and ECOFORCE (68%) but PI80 did not protect the post larvae in the same experiment when they were exposed to V. parahaemolyticus. The probiotic isolate of MC13 has protected the post larvae against V. parahaemolyticus when compared to other probiotics and control. Similarly in the second experiment feeding of S. phocae enhanced the survival of larvae when challenged with V. harveyi. The laboratory studies proved that bacterial probionts S. phocae and E. faecium isolated from shrimp and brackishwater fish has potential applications for controlling pathogenic vibriosis in shrimp culture.