这项工作得到了热带 AgriSciences 学院内部赠款机构的支持 (项目编号: 20175013) 和 CIGA 20182023 两项赠款, 来自捷克生命科学大学。

1. 肉类制剂
<ol><li>从当地的屠杀中获得一小块牛肉 (从股二头肌中的新鲜牛肉), 转移到实验室。 注: 建议在常温下 (20-25 °c) 运输牛肉的腰部, 在密封袋内不超过20分钟。</li>
	<li>为了对牛肉肌肉的外层进行消毒, 在层流安全柜中, 用500毫升的挤压瓶喷洒 70% (v/v) 乙醇, 以洗涤肌肉。应用0.025 克乙醇每1厘米的肌肉表面2 。</li>
	<li>用小刀除去肉灌装的外表面, 以避免在肌肉内部残留乙醇。去掉大约3毫米的肌肉内部, 以保持肌肉的表面均匀。</li>
	<li>将肌肉包装在塑料密封袋中, 并将其转移到冰箱。</li>
	<li>储存的肌肉在-18 °c 1 天。然后, 解冻4摄氏度的冰冻肌肉6小时。 注: 对于解冻, 建议将肌肉从冰箱移动到冰箱。</li>
	<li>在层流安全柜中, 用切肉机将每块肌肉切成0.5 厘米厚的切片。然后, 用小刀把它切成小 5 x 2.5 厘米2矩形样品。</li>
	<li>将长方形的肉类样品包装在塑料袋中, 并将其存放在-18 摄氏度的冷藏库中供以后使用。</li>
</ol>2. 在层流安全柜中编制标准化的接种和接种程序
<ol><li>准备标准化的接种 (1.5 x 108 CFU/毫升) 的大肠杆菌ATCC 25922, 以接种肉类样品。<ol>
<li>为准备库存接种, 首先将冻干细菌培养 (由供应商交付) 转化为15毫升灭菌管, 预填充10毫升消毒的米勒韩丁汤 (BMHB)。在37摄氏度培养24小时的悬浮液。<ol>
<li>准备细菌库存解决方案如下: 采取大约 0.1-0.2 毫升的细菌悬浮和稀释成一个20毫升瓶封闭与橡胶塞子与铝帽预填充与15毫升的灭菌 BMHB。在37摄氏度培养24小时的悬浮液。</li>
			<li>存放在冰箱内的4°c 为标准化接种的准备。</li>
		</ol>
</li>
		<li>从库存解决方案 (见步骤 2.1.1) 的大肠杆菌采取大约 0.1-0.2 毫升的细菌悬浮和稀释在15毫升塑料灭菌管预填充10毫升消毒的韩丁汤 (BMHB)。在37摄氏度的24小时内孵化试管。</li>
		<li>为编制标准化的接种 (1.5 x 108 CFU/毫升), 添加少量此悬浮在15毫升灭菌管预填充与10毫升的灭菌 BMHB。</li>
		<li>彻底涡旋混合物, 并测量光学密度 (OD) 在600毫微米由密度计32。</li>
		<li>重复步骤 2.1.3 2.1.4, 直到表示为麦克法兰值的 OD 比清洁 BMHB 的值增加0.5。</li>
	</ol>
</li>
	<li>为接种做法, 安置长方形肉样品在二个不同的铝箔 (20 cm x 30 cm), 一个为控制样品和第二为被接种的肉样品。<ol>
<li>在第二个铝箔, 接种原始的长方形肉样品与800µL 细菌悬浮的选定的菌株 (这对应于 1.2 x 108 CFU 每肉样品) 通过均匀地分布接种在表面。<ol>
<li>吸管400µL 在样品的一边和轻轻地传播使用无菌的细胞摊铺机在表面上。让他们干10分钟. 在样品的另一侧对其余的悬浮液重复相同的过程。</li>
		</ol>
</li>
	</ol>
</li>
</ol>3. 干燥和特奥应用
<ol><li>将含有矩形肉类样品的铝箔从层流安全柜转移到烘干机: 用铝箔盖住, 然后将样品放在烘干机内。</li>
	<li>在标准的实验室烘干机中进行干燥。 注: 首先, 预热烤箱到摄氏55摄氏度。此过程可以持续20分钟。<ol>
<li>干燥控制样品6小时在55°c, 与干燥空气相对湿度值从 30-45% 不等。 注: 干燥空气相对湿度值根据液体从肉类中蒸发的速率而变化。</li>
	</ol>
</li>
	<li>计算所应用的特奥体积, 并将必要的油浓度表示为每烘干机容积 (mL/升空气) 的特奥量。例如, 1.5 毫升的特奥在53升 (干燥机容积) 的剂量导致浓度为0.028 毫升/升空气。要确定特奥的 MIC 为大肠杆菌, 使用剂量1.5 毫升 (0.028 毫升/升空气), 1 毫升 (0.019 毫升/升空气) 和0.75 毫升 (0.014 毫升/升空气)。</li>
	<li>在烘干之前, 为应用特奥蒸气 (以麝香作为主要化合物 79%), 浸泡一张滤纸 (12 cm x 20 cm) 与1.5 毫升药量的特奥并且安置入烘干机在风扇前面。</li>
	<li>使用与对照样品相同的程序 (步骤3.1 和 3.2) 将特奥特处理的肉类样品烘干。 注: 干燥过程结束后, 样品被除去, 在烤箱上打开3小时, 在80摄氏度, 并设置空气阀指示100% 排气口, 以清洁的基本油残渣从烤箱。</li>
</ol>4. 微生物分析
<ol><li>在肉接种与细菌之前, 检查肉样品为任何掺假。粘液的出现和发现任何强烈和刺鼻的气味都表明了肉类的腐烂。如果纹理感觉黏糊糊的, 细菌可能已经开始在肉的表面繁殖。</li>
	<li>为了评估接种效率, 对原接种的样品进行试验, 检测是否存在大肠杆菌ATCC 25922, 并将其与未接种的对照样品进行比较。为此目的:<ol>
<li>清洗每个肉类样本 (2 个控制样本和2种接种样本)。用缓冲的蛋白胨水 (8.5 克氯化钠) 将每个肉类样品挂在消毒瓶中. 1 克的蛋白胨, 5 片磷酸盐缓冲盐水, 1 克的吐温80在1升水) 的比率为 1:10 (瓦特/v), pH 值范围从 7-7.3。在室温下用 140 rpm 的摇床摇动10分钟。 注: 在接种程序后立即冲洗。</li>
		<li>用经调整的 6 x 6 滴板程序, 对钢板计数琼脂 (PCA) 和麦康凯琼脂 (MCA) 中的陈、Nace 和欧文33进行总结, 评估细菌数量。 注: 6 x 6 滴法采用发酵液微稀释法, 用多通道吸管制备研究样品的10倍系列稀释, 比常规方法33更节省劳动密集型和更经济性34。</li>
		<li>用 6 x 6 稀释法培养10倍的系列样品, 用于评价大肠杆菌。 注: 特别为 6 x 6 下落方法, 为耕种使用六5µL 下落, 从六选择的稀释被调查的样品与多通道吸管。在适当干燥的培养皿上, 滴入琼脂迅速吸收, 这种方法的种植非常方便和易于管理的34。</li>
		<li>孵育培养皿在37°c 为24小时。在培养期后, 根据第5节所述, 评估培养皿 (CFU g-1 ) 中的大肠杆菌的菌落数量。</li>
	</ol>
</li>
	<li>干燥后, 取两个接种后的干样品, 并将其与两个干燥的非接种对照样品分别进行比较, 以进行可行的大肠杆菌。要确定此四samples 的存在或不存在大肠杆菌, 请按照以下步骤对每个肉类样品进行预浓缩过程:<ol>
<li>将每个肉类样品挂在带有缓冲的蛋白胨水的消毒瓶中 (请参阅步骤 4.2.1), 并在室温下使用 140 rpm 10 分钟的振动筛进行摇动. 然后在6小时内孵化每瓶37摄氏度以进行预富集。</li>
		<li>对于细菌的评价和培养, 按照步骤 4.2.2 4.2.4 中所述的相同步骤进行。</li>
	</ol>
</li>
</ol>5. 审查结果
<ol><li>孵化完成后, 从孵化器中取出培养皿, 并按如下方式检查结果:<ol>
<li>为了评估菌落总数, 在 MCA 上检查温有氧细菌在 PCA (白点) 和典型的大肠杆菌菌落 (红到深粉色) 上存在的板块。如果病原体缺失, 两 agars 均无生长。</li>
		<li>计算菌落数并确定大肠杆菌(CFU/g-1干肉) 的数量。 注意: 在连续的两个稀释 (图 1) 中, 计算30个或更少的菌落数 (N)。CFU/g-1的干肉的编号N确定如下35 <img alt="Equation" src="/files/ftp_upload/57054/57054eq1.jpg"> 在其中, C是计数的所有水滴的菌落总数, v是每滴使用的样本稀释量 (这里, 0.05 毫升), n1 是第一稀释时使用的水滴数, n2 是滴数用于第二次稀释, d表示从其中捕获第一个计数的稀释。</li>
	</ol>
</li>
	<li>要分析微生物数据, 请将菌落数转换为日志 CFU g-1 , 并将其与治疗的主要效果36的方差分析 (方差计算) 进行比较。<ol>
<li>对多个平均比较36执行 Tukey 诚实显著差异测试 (Tukey HSD), 并确定治疗之间的显著差异。</li>
	</ol>
</li>
</ol>

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Food Agric. 97 (1), 82-87 (2017).</li><li>Garc&#237;a-D&#237;ez, J., Alheiro, J., Falco, V., Fraqueza, M. J., Patarata, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chemical+characterization+and+antimicrobial+properties+of+herbs+and+spices+essential+oils+against+pathogens+and+spoilage+bacteria+associated+to+dry-cured+meat+products.">Chemical characterization and antimicrobial properties of herbs and spices essential oils against pathogens and spoilage bacteria associated to dry-cured meat products.</a> J. Essent. Oil Res. 29 (2), 117-125 (2017).</li><li>Cavanagh, H. M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Antifungal+Activity+of+the+Volatile+Phase+of+Essential+Oils:+A+Brief+Review.">Antifungal Activity of the Volatile Phase of Essential Oils: A Brief Review.</a> Nat. Prod. Commun. 2 (12), 1297-1302 (2007).</li><li>Tajkarimi, M. M., Ibrahim, S. A., Cliver, D. O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Antimicrobial+herb+and+spice+compounds+in+food.">Antimicrobial herb and spice compounds in food.</a> Food Control. 21 (9), 1199-1218 (2010).</li><li>Nedorostova, L., Kloucek, P., Kokoska, L., Stolcova, M., Pulkrabek, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Antimicrobial+properties+of+selected+essential+oils+in+vapour+phase+against+foodborne+bacteria.">Antimicrobial properties of selected essential oils in vapour phase against foodborne bacteria.</a> Food Control. 20 (2), 157-160 (2009).</li><li>Burt, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Essential+oils:+Their+antibacterial+properties+and+potential+applications+in+foods+-+A+review.">Essential oils: Their antibacterial properties and potential applications in foods - A review.</a> Int. J. Food Microbiol. 94 (3), 223-253 (2004).</li><li>Ramanathan, L., Das, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Studies+on+the+control+of+lipid+oxidation+in+ground+fish+by+some+polyphenolic+natural+products.">Studies on the control of lipid oxidation in ground fish by some polyphenolic natural products.</a> J. Agric. Food Chem. 40 (1), 17-21 (1992).</li><li>Yamazaki, K., Yamamoto, T., Kawai, Y., Inoue, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Enhancement+of+antilisterial+activity+of+essential+oil+constituents+by+nisin+and+diglycerol+fatty+acid+ester.">Enhancement of antilisterial activity of essential oil constituents by nisin and diglycerol fatty acid ester.</a> Food Microbiol. 21 (3), 283-289 (2004).</li><li>Garc&#237;a-D&#237;ez, J., Alheiro, J., Falco, V., Fraqueza, M. J., Patarata, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synergistic+activity+of+essential+oils+from+herbs+and+spices+used+on+meat+products+against+food+borne+pathogens.">Synergistic activity of essential oils from herbs and spices used on meat products against food borne pathogens.</a> Nat. Prod. Commun. 12 (2), 281-286 (2017).</li><li>Hussein Hamdy Roby, M., Atef Sarhan, M., Abdel-Hamed Selim, K., Ibrahim Khalel, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evaluation+of+antioxidant+activity,+total+phenols+and+phenolic+compounds+in+thyme+(Thymus+vulgaris+L.),+sage+(Salvia+officinalis+L.),+and+marjoram+(Origanum+majorana+L.)+extracts.">Evaluation of antioxidant activity, total phenols and phenolic compounds in thyme (Thymus vulgaris L.), sage (Salvia officinalis L.), and marjoram (Origanum majorana L.) extracts.</a> Ind. Crops Prod. 43, 827-831 (2013).</li><li>Gouveia, A. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Antimicrobial+Effect+of+Essential+Oils+Against+Listeria+monocytogenes+in+Sous+vide+Cook-Chill+Beef+during+Storage.">The Antimicrobial Effect of Essential Oils Against Listeria monocytogenes in Sous vide Cook-Chill Beef during Storage.</a> J. Food Process. Preserv. 41 (4), (2017).</li><li>Chen, C., Nace, G., Irwin, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+6+x+6+drop+plate+method+for+simultaneous+colony+counting+and+MPN+enumeration+of+Campylobacter+jejuni,+Listeria+monocytogenes,+and+Escherichia+coli.">A 6 x 6 drop plate method for simultaneous colony counting and MPN enumeration of Campylobacter jejuni, Listeria monocytogenes, and Escherichia coli.</a> J. Microbiol. Methods. 55 (2), 475-479 (2003).</li><li>Herigstad, B., Hamilton, M., Heersink, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=How+to+optimize+the+drop+plate+method+for+enumerating+bacteria.">How to optimize the drop plate method for enumerating bacteria.</a> J. Microbiol. Methods. 44 (2), 121-129 (2001).</li><li>. Practical food microbiology Available from: <a target="_blank" href="https://drive.google.com/file/d/0BzyVOLllJ0B1YmlEemZ5M1RZekU/view?ts=590d8019">https://drive.google.com/file/d/0BzyVOLllJ0B1YmlEemZ5M1RZekU/view?ts=590d8019</a> (2003)</li><li>Smith-Palmer, A., Stewart, J., Fyfe, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Antimicrobial+properties+of+plant+essential+oils+and+essences+against+five+important+food-borne+pathogens.">Antimicrobial properties of plant essential oils and essences against five important food-borne pathogens.</a> Lett. Appl. Microbiol. 26 (2), 118-122 (1998).</li><li>Burt, S. a., Reinders, R. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Antibacterial+activity+of+selected+plant+essential+oils+against+Escherichia+coli+O157:H7.">Antibacterial activity of selected plant essential oils against Escherichia coli O157:H7.</a> Lett. Appl. Microbiol. 36 (3), 162-167 (2003).</li></ol>

作者没有什么可透露的。

先前的研究表明, 导致食源性疾病的微生物在干燥过程中生存了10。因此, 必须在干燥前应用防腐剂, 以保证食品安全。在这项研究中, 我们专注于使用特奥。其原因有两个方面: 第一, 消费者对使用天然产品作为替代添加剂以提高食品质量的需求很高16;其次, 前一项研究表明, 在肉类干燥过程中使用 OEO 的结果为22。因此, 在肉类干燥过程中应用 OEO...

干燥作为传统的保存食物的方法已经被使用了从远古时代。如今, 对干燥的兴趣越来越浓厚, 作为一种有效的食品保鲜方法1,2,3。它是用来制造各种特殊加工的肉类。其中最知名的是干。
干法是肉类保鲜的最古老的方法之一, 其基础是固化和干燥, 以降低水分活动, 从而延长其保质期4。如今, 干腌肉仍然很受欢迎, 食品的安全性、风味和质地是必不可少的。干制剂可用于几乎任何类型的肉类, 包括牛肉, 猪肉, 家禽, 或游戏5, 它需要切肉在瘦肉条和干燥。通常, 浸泡在固化溶液中的肉或吸烟与干燥一起使用, 以使干它的特色风味6。
尽管干燥的巨大兴趣, 以真正保存食物, 食源性暴发的风险由大肠杆菌从干燥肉是关键的, 需要控制。有一些研究报告食源性胃肠炎暴发, 特别是与大肠杆菌O157:H7, 归因于不充分的热处理在家庭干燥。即使在商业准备的生涩的7、8、9中也发生类似情况。莱文et al。10建议, 食源性微生物可以在干燥条件 (约60°c) 的情况下生存。大肠杆菌O157:H7 二十世纪九十年代中旬的食源性疾病暴发归因于地面干肉制品6,11。有趣的是, 在以前的所有病例中, 主要的风险是由被确认为可行但非可培养 (VBNC) 的细菌病原体引起的。在诸如温度变化或饥饿等各种压力下,大肠杆菌单元可以进入一个称为 VBNC 状态1213的特定状态。VBNC 细胞可以通过暴露在适当的条件下恢复到可培养细胞, 然后由于食源性污染而对人类健康构成威胁 14, 15.这意味着, 如果肉类是在干燥后立即消耗的产品, 它是安全的。但是, 如果储存不足, 如湿度增加, 病原体和微生物生长的复发风险很高。
除了干燥和腌料的方法, 消费者有很高的需求, 使用天然产品作为替代添加剂, 以改善食品质量16,17。对肉类天然食品添加剂的应用特别感兴趣, 而不是传统的合成防腐剂18,19,20,21。尽管在干燥肉类时使用精油缺乏足够的实验证据, 但该领域早期的研究已经显示出积极的结果22,23。
自中世纪以来, 人们已经认识到必需的油脂化合物 (EOCs) 的抗菌剂, 杀虫, 和寄生虫特征24,25,26。今天, EOCs 是最重要的一组生物活性天然化合物的一部分。在不同的 EOCs 中, 麝香是其中一个最知名的。它由85% 以上的特奥23组成。这种苯酚能防止微生物和化学物质在食物中变质。此外, 它的抗菌性能可能会改善与其他天然防腐剂2,27,28,29,30。现在, 百里香 (胸腺), 一种属于唇形家族的药草, 已被公认为调味剂, 也是一种非常有效的肉类防腐剂 31.由加西亚-Díez et进行的一项研究。30在肉类产品上发现, 与其他精油相比, 特奥对食源性致病菌的抑制作用更大。因此, 在干燥过程中施用精油, 有机会增加干肉的价值, 减少食源性疾病的风险。
在本协议中, 我们提出了一种新的方法来应用特奥在肉类干燥, 特别是使用它在蒸气形式直接在干燥室。为了评估, 我们使用麦克风来确定治疗样本中的致病菌与原生细菌的缺失。初步结果表明, 该方法是一种高效的合成防腐剂替代品, 大大减少了干肉中的微生物负荷。

<table>
	<tbody>
		<tr>
			<td>Meat cutter</td>
			<td>Kalorik</td>
			<td>KP 3530</td>
			<td>from Miami Gardens, FL, USA</td>
		</tr>
		<tr>
			<td>Laminar safety cabinet</td>
			<td>Faster s.r.l</td>
			<td></td>
			<td>from Italy</td>
		</tr>
		<tr>
			<td>Squeeze bottle of 500 mL</td>
			<td>Merci</td>
			<td>632 524 325 025</td>
			<td>from CZ</td>
		</tr>
		<tr>
			<td>Standard laboratory drier UFE 400</td>
			<td>Memmert</td>
			<td>DE 66812464</td>
			<td>from Germany</td>
		</tr>
		<tr>
			<td>Incubator</td>
			<td>BT 120</td>
			<td>N/A</td>
			<td>from CZ</td>
		</tr>
		<tr>
			<td>Refrigerator and Freezer</td>
			<td>Bosch</td>
			<td>KGN34VW20G</td>
			<td>from DE</td>
		</tr>
		<tr>
			<td>Densitometer</td>
			<td>Biosan</td>
			<td>220 000 050 122</td>
			<td>Latvia; supplier Merci, CZ</td>
		</tr>
		<tr>
			<td>Escherichia coli ATCC 25922</td>
			<td>Oxoid</td>
			<td>CL7050</td>
			<td>from CZ</td>
		</tr>
		<tr>
			<td>Vortex</td>
			<td>Chromservis</td>
			<td>22008013</td>
			<td>from CZ</td>
		</tr>
		<tr>
			<td>Sterilized plastic tubes 15 mL</td>
			<td>Gama</td>
			<td>331 000 020 115</td>
			<td>from CZ, supplier Merci</td>
		</tr>
		<tr>
			<td>20 mL injection vial</td>
			<td>Healthy vial</td>
			<td>hvft169</td>
			<td>from China</td>
		</tr>
		<tr>
			<td>20 mm sterile butyl rubber stopper</td>
			<td>Merci</td>
			<td>22008013</td>
			<td>from CZ</td>
		</tr>
		<tr>
			<td>20 mm aluminum cap</td>
			<td>Healthy vial</td>
			<td>N/A</td>
			<td>from China</td>
		</tr>
		<tr>
			<td>Thyme essential oil</td>
			<td>Sigma Aldrich</td>
			<td>W306509</td>
			<td>from St Louis, MO, USA</td>
		</tr>
		<tr>
			<td>Mueller Hinton Broth</td>
			<td>Oxoid</td>
			<td>CM0337</td>
			<td>from CZ</td>
		</tr>
		<tr>
			<td>NaCl</td>
			<td>Penta</td>
			<td>16610-31000</td>
			<td>from CZ</td>
		</tr>
		<tr>
			<td>Peptone</td>
			<td>Oxoid</td>
			<td>LP0034</td>
			<td>from CZ</td>
		</tr>
		<tr>
			<td>Phosphate-buffered saline</td>
			<td>Sigma Aldrich</td>
			<td>P4417</td>
			<td>from CZ</td>
		</tr>
		<tr>
			<td>Polysorbate 80 (Tween 80)</td>
			<td>Roth</td>
			<td>T 13502</td>
			<td>from DE, supplier P-lab</td>
		</tr>
		<tr>
			<td>Shaker SHO-1D</td>
			<td>Verkon</td>
			<td>DH.WSR04020</td>
			<td>from CZ,&#160; 10 - 300 rpm. 350 x 350 mm with a platform for flasks</td>
		</tr>
		<tr>
			<td>Ethanol 70%</td>
			<td>Bioferm</td>
			<td>N/A</td>
			<td>from CZ</td>
		</tr>
		<tr>
			<td>MacConkey Agar</td>
			<td>Oxoid</td>
			<td>CM007</td>
			<td>from CZ</td>
		</tr>
		<tr>
			<td>Plate Count Agar</td>
			<td>Oxoid</td>
			<td>CM0325</td>
			<td>from CZ</td>
		</tr>
		<tr>
			<td>Filter paper</td>
			<td>Merci</td>
			<td>480 622 080 040</td>
			<td>from CZ</td>
		</tr>
		<tr>
			<td>Erlenmeyer flasks 250 mL</td>
			<td>Simax</td>
			<td>610 002 122 636</td>
			<td>from CZ; supplier Merci CZ</td>
		</tr>
		<tr>
			<td>Multichannel pipette</td>
			<td>Socorex</td>
			<td>S852820</td>
			<td>from Switzerland; supplier P lab, CZ</td>
		</tr>
		<tr>
			<td>Microtiter plate</td>
			<td>Gamma</td>
			<td>V400916</td>
			<td>CZ</td>
		</tr>
		<tr>
			<td>Microlitre pipette 100-1000 &#956;L</td>
			<td>Eppendorf</td>
			<td>333 120 000 062</td>
			<td>from Germany; supplier Merci, CZ</td>
		</tr>
	</tbody>
</table>

the effect of the application of thyme essential oil on microbial load during meat drying

肉类是一种高蛋白的膳食, 用于配制干, 一种流行的食品零食, 在那里保存和安全是重要的。为了保证食品安全和延长肉类和肉类产品的保质期, 使用合成或天然防腐剂来控制和消除食源性细菌。越来越多的人对天然食品添加剂在肉类中的应用增加了兴趣。微生物, 如大肠杆菌, 污染肉类和肉类产品, 造成食源性疾病. 因此, 有必要改进肉类的保护过程。然而, 在肉类干燥时使用精油还没有深入研究。在这方面, 有机会增加干肉的价值, 并通过在干燥过程中应用精油降低食源性疾病的风险。在本议定书中, 我们提出了一种新的方法来应用百里香精油 (特奥) 在肉类干燥, 特别是在蒸气形式直接在干燥室。为了评估, 我们使用最小的抑制浓度 (MIC) 来检测样本中有害细菌的数量与原样品相比。初步结果表明, 该方法是一种可行的、可替代的合成防腐剂, 大大减少了干肉中的微生物负荷。

我们首先开发了这种方法, 通过使用牛至精油 (OEO), 以提高食品安全和提高干肉的价值。一般而言, 上述实验表明, 在干燥过程中,大肠杆菌进入 VBNC 状态作为一种生存策略。这是由事实证明, 在干燥完成后没有可培养细菌 22.因此, 6 小时的预浓缩过程是必要的, 以允许计数的应变。在较短的时期内, 生长细胞的数量仍然非常低。结果是在预富集过程后, ...

Watch this Scientific Journal Video about The Effect of the Application of Thyme Essential Oil on Microbial Load During Meat Drying at JoVE.com

The Effect of the Application of Thyme Essential Oil on Microbial Load During Meat Drying

百里香精油应用于肉类干燥过程中微生物负荷的影响

微生物如大肠杆菌污染肉类产品会引起食源性疾病. 精油在肉类干燥过程中的应用尚未深入研究。在此, 我们提出了一种新的方法, 将百里香精油应用于肉类干燥过程中, 以减少干肉中的微生物负荷。

Meat is a high protein meal that is used in the preparation of jerky, a popular food snack, where preservation and safety are important. To assure food ...

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9.2K 次观看.  Czech University of Life Sciences Prague. 微生物如大肠杆菌污染肉类产品会引起食源性疾病. 精油在肉类干燥过程中的应用尚未深入研究。在此, 我们提出了一种新的方法, 将百里香精油应用于肉类干燥过程中, 以减少干肉中的微生物负荷。

视频: The Effect of the Application of Thyme Essential Oil on Microbial Load During Meat Drying

Determination of Microbial Extracellular Enzyme Activity in Waters, Soils, and Sediments using High Throughput Microplate Assays

Much of the nutrient cycling and carbon processing in natural environments occurs through the activity of extracellular enzymes released by microorganisms. Thus, measurement of the activity of these extracellular enzymes can give insights into the rates of ecosystem level processes, such as organic matter decomposition or nitrogen and phosphorus mineralization. Assays of extracellular enzyme activity in environmental samples typically involve exposing the samples to artificial colorimetric or fluorometric substrates and tracking the rate of substrate hydrolysis. Here we describe microplate based methods for these procedures that allow the analysis of large numbers of samples within a short time frame. Samples are allowed to react with artificial substrates within 96-well microplates or deep well microplate blocks, and enzyme activity is subsequently determined by absorption or fluorescence of the resulting end product using a typical microplate reader or fluorometer. Such high throughput procedures not only facilitate comparisons between spatially separate sites or ecosystems, but also substantially reduce the cost of such assays by reducing overall reagent volumes needed per sample.

Microplate based procedures are described for the colorimetric or fluorometric analysis of extracellular enzyme activity. These procedures allow for the rapid assay of such activity in large numbers of environmental samples within a manageable time frame.

在使用高通量微孔板测定水，土壤，沉积物和微生物测定胞外酶活性的

Much of the nutrient cycling and carbon  processing in natural environments occurs through the activity of extracellular  enzymes released by ...

科研

环境科学

Methods for Facilitating Microbial Growth on Pulp Mill Waste Streams and Characterization of the Biodegradation Potential of Cultured Microbes

The kraft process is applied to wood chips for separation of lignin from the polysaccharides within lignocellulose for pulp that will produce a high quality paper. Black liquor is a pulping waste generated by the kraft process that has potential for downstream bioconversion. However, the recalcitrant nature of the lignocellulose resources, its chemical derivatives that constitute the majority of available organic carbon within black liquor, and its basic pH present challenges to microbial biodegradation of this waste material. Methods for the collection and modification of black liquor for microbial growth are aimed at utilization of this pulp waste to convert the lignin, organic acids, and polysaccharide degradation byproducts into valuable chemicals. The lignocellulose extraction techniques presented provide a reproducible method for preparation of lignocellulose growth substrates for understanding metabolic capacities of cultured microorganisms. Use of gas chromatography-mass spectrometry enables the identification and quantification of the fermentation products resulting from the growth of microorganisms on pulping waste. These methods when used together can facilitate the determination of the metabolic activity of microorganisms with potential to produce fermentation products that would provide greater value to the pulping system and reduce effluent waste, thereby increasing potential paper milling profits and offering additional uses for black liquor.

Industrial wastes can be collected and modified to analyze microbial growth. Lignocellulose extraction techniques provide components to analyze specific biodegradation ability. Gas chromatography-mass spectrometry identifies fermentation products of microorganisms grown on pulping waste. These methods determine the metabolic capacity of microorganisms to degrade pulping waste.

方法对纸浆厂污水流和培养微生物的生物降解能力的表征促进微生物生长

The kraft process is applied to wood chips for separation of lignin from the polysaccharides within lignocellulose for pulp that will produce a high ...

Application of Two-spotted Spider Mite Tetranychus urticae for Plant-pest Interaction Studies

The two-spotted spider mite, Tetranychus urticae, is a ubiquitous polyphagous arthropod herbivore that feeds on a remarkably broad array of species, with more than 150 of economic value. It is a major pest of greenhouse crops, especially in Solanaceae and Cucurbitaceae (e.g., tomatoes, eggplants, peppers, cucumbers, zucchini) and greenhouse ornamentals (e.g., roses, chrysanthemum, carnations), annual field crops (such as maize, cotton, soybean, and sugar beet), and in perennial cultures (alfalfa, strawberries, grapes, citruses, and plums)1,2. In addition to the extreme polyphagy that makes it an important agricultural pest, T. urticae has a tendency to develop resistance to a wide array of insecticides and acaricides that are used for its control3-7.
T. urticae is an excellent experimental organism, as it has a rapid life cycle (7 days at 27 &#176;C) and can be easily maintained at high density in the laboratory. Methods to assay gene expression (including in situ hybridization and antibody staining) and to inactivate expression of spider mite endogenous genes using RNA interference have been developed8-10. Recently, the whole genome sequence of T. urticae has been reported, creating an opportunity to develop this pest herbivore as a model organism with equivalent genomic resources that already exist in some of its host plants (Arabidopsis thaliana and the&#160;tomato Solanum lycopersicum)11. Together, these&#160;model organisms could provide insights into molecular bases of plant-pest interactions.
Here, an efficient method for quick and easy collection of a large number of adult female mites, their application on an experimental plant host, and the assessment of the plant damage due to spider mite feeding are described. The presented protocol enables fast and efficient collection of hundreds of individuals at any developmental stage (eggs, larvae, nymphs, adult males, and females) that can be used for subsequent experimental application.

Application of Two-spotted Spider Mite Tetranychus urticae for Plant-pest Interaction Studies

Protocols for efficient preparation of homogenous samples of spider mites, infestation of experimental plants, and assessment of plant damage, as required for studies of plant-pest interaction were developed.

二斑叶螨的应用<em&gt;二斑叶螨</em&gt;植物病虫害的相互作用研究

The two-spotted spider mite, Tetranychus urticae, is a ubiquitous polyphagous arthropod herbivore that feeds on a remarkably broad array of species, with ...

A New Application of the Electrical Penetration Graph (EPG) for Acquiring and Measuring Electrical Signals in Phloem Sieve Elements

Electrophysiological properties of cells are often studied in vitro, after dissociating them from their native environments. However, the study of electrical transmission between distant cells in an organism requires in vivo, artifact-free recordings of cells embedded within their native environment. The transmission of electrical signals from wounded to unwounded areas in a plant has since long piqued the interest of botanists. The phloem, the living part of the plant vasculature that is spread throughout the plant, has been postulated as a major tissue in electrical transmission in plants. The lack of suitable electrophysiological methods poses many challenges for the study of the electrical properties of the phloem cells in vivo. Here we present a novel approach for intracellular electrophysiology of sieve elements (SEs) that uses living aphids, or other phloem-feeding hemipteran insects, integrated in the electrical penetration graph (EPG) circuit. The versatility, robustness, and accuracy of this method made it possible to record and study in detail the wound-induced electrical signals in SEs of central veins of the model plant Arabidopsis thaliana1. Here we show that EPG-electrodes can be easily implemented for intracellular electrophysiological recordings of SEs in marginal veins, as well as to study the capacity of SEs to respond with electrical signals to several external stimuli. The EPG approach applied to intracellular electrophysiology of SEs can be implemented to a wide variety of plant species, in a large number of plant/insect combinations, and for many research aims.

A New Application of the Electrical Penetration Graph EPG for Acquiring and Measuring Electrical Signals in Phloem Sieve Elements

Electrical Penetration Graph (EPG) is a well-established technique for studying the feeding behavior of stylet-bearing insects. Here we show a new application of EPG as a non-invasive tool for the acquisition of intracellular electrophysiology recordings of sieve elements (SEs), the cells that form the phloem vasculature in plants.

在电气贯穿图（EPG）的韧皮部筛分子获取和测量电信号中的新应用

Electrophysiological properties of cells are often studied in vitro, after dissociating them from their native environments. However, the study of ...

Measurement of H2S in Crude Oil and Crude Oil Headspace Using Multidimensional Gas Chromatography, Deans Switching and Sulfur-selective Detection

A method for the analysis of dissolved hydrogen sulfide in crude oil samples is demonstrated using gas chromatography. In order to effectively eliminate interferences, a two dimensional column configuration is used, with a Deans switch employed to transfer hydrogen sulfide from the first to the second column (heart-cutting). Liquid crude samples are first separated on a dimethylpolysiloxane column, and light gases are heart-cut and further separated on a bonded porous layer open tubular (PLOT) column that is able to separate hydrogen sulfide from other light sulfur species. Hydrogen sulfide is then detected with a sulfur chemiluminescence detector, adding an additional layer of selectivity. Following separation and detection of hydrogen sulfide, the system is backflushed to remove the high-boiling hydrocarbons present in the crude samples and to preserve chromatographic integrity. Dissolved hydrogen sulfide has been quantified in liquid samples from 1.1 to 500 ppm, demonstrating wide applicability to a range of samples. The method has also been successfully applied for the analysis of gas samples from crude oil headspace and process gas bags, with measurement from 0.7 to 9,700 ppm hydrogen sulfide.

Measurement of H2S in Crude Oil and Crude Oil Headspace Using Multidimensional Gas Chromatography, Deans Switching and Sulfur-selective Detection

A multidimensional gas chromatography method for the analysis of dissolved hydrogen sulfide in liquid crude oil samples is presented. A Deans switch is used to heart-cut light sulfur gases for separation on a secondary column and detection on a sulfur chemiluminescence detector.

h的测量<sub&gt; 2</sub&gt; S在原油和原油顶空用多维气相色谱法，院长交换和选择性硫检测

A method for the analysis of dissolved hydrogen sulfide in crude oil samples is demonstrated using gas chromatography. In order to effectively eliminate ...

Evaluating the Effect of Environmental Chemicals on Honey Bee Development from the Individual to Colony Level

The presence of pesticides in the beekeeping environment is one of the most serious problems that impacts the life of a honey bee. Pesticides can be brought back to the beehive after the bees have foraged on flowers that have been sprayed with pesticides. Pesticide contaminated food can be exchanged between workers which then feed larvae and therefore can potentially affect the development of honey bees. Thus, residual pesticides in the environment can become a chronic damaging factor to honey bee populations and gradually lead to colony collapse. In the presented protocol, honey bee feeding methods are described and applied to either an individual honey bee or to a colony. Here, the insect growth regulator (IGR) pyriproxyfen (PPN), which is widely used to control pest insects and is harmful to the development of honey bee larvae and pupae, is used as the pesticide. The presenting procedure can be applied to other potentially harmful chemicals or honeybee pathogens for further studies.

Herein we present a method to feed pesticide contaminated food to both an individual honey bee and a beehive colony. The procedure evaluates the pesticide effect on individual honey bees by in vivo feeding of basic larval diet and also on the natural condition of beehive colony.

从个体到群体度评价环境化学物质对蜜蜂发展的影响

The presence of pesticides in the beekeeping environment is one of the most serious problems that impacts the life of a honey bee. Pesticides can be ...

Measurement of the Rheology of Crude Oil in Equilibrium with CO2 at Reservoir Conditions

A rheometer system to measure the rheology of crude oil in equilibrium with carbon dioxide (CO2) at high temperatures and pressures is described. The system comprises a high-pressure rheometer which is connected to a circulation loop. The rheometer has a rotational flow-through measurement cell with two alternative geometries: coaxial cylinder and double gap. The circulation loop contains a mixer, to bring the crude oil sample into equilibrium with CO2, and a gear pump that transports the mixture from the mixer to the rheometer and recycles it back to the mixer. The CO2 and crude oil are brought to equilibrium by stirring and circulation and the rheology of the saturated mixture is measured by the rheometer. The system is used to measure the rheological properties of Zuata crude oil (and its toluene dilution) in equilibrium with CO2 at elevated pressures up to 220 bar and a temperature of 50 &#176;C. The results show that CO2 addition changes the oil rheology significantly, initially reducing the viscosity as the CO2 pressure is increased and then increasing the viscosity above a threshold pressure. The non-Newtonian response of the crude is also seen to change with the addition of CO2.

Measurement of the Rheology of Crude Oil in Equilibrium with CO2 at Reservoir Conditions

A method for measuring the rheology of crude oil in equilibrium with carbon dioxide at reservoir conditions is presented.

与CO平衡的原油流变学测量<sub&gt; 2</sub&gt;在水库条件

A rheometer system to measure the rheology of crude oil in equilibrium with carbon dioxide (CO2) at high temperatures and pressures is described. The ...

Lab-Scale Model to Evaluate Odor and Gas Concentrations Emitted by Deep Bedded Pack Manure

A lab-scaled simulated bedded pack model was developed to study air quality and nutrient composition of deep-bedded packs used in cattle mono-slope facilities. This protocol has been used to effectively evaluate many different bedding materials, environmental variables (temperature, humidity), and potential mitigation treatments that can improve air quality in commercial deep-bedded mono-slope facilities. The model is dynamic and allows researchers to easily collect many chemical and physical measurements from the bedded pack. Weekly measurements, collected over the course of six to seven weeks, allows sufficient time to see changes in air quality measurements over time as the bedded pack matures. The data collected from the simulated bedded packs is within the range of concentrations previously measured in commercial deep-bedded mono-slope facilities. Past studies have demonstrated that 8 - 10 experimental units per treatment are sufficient to detect statistical differences among the simulated bedded packs. The bedded packs are easy to maintain, requiring less than 10 minutes of labor per bedded packs per week to add urine, feces, and bedding. Sample collection using the gas sampling system requires 20 - 30 minutes per bedded pack, depending on the measurements that are being collected. The use of lab-scaled bedded packs allows the researcher to control variables such as temperature, humidity, and bedding source that are difficult or impossible to control in a research or commercial facility. While not a perfect simulation of &#34;real-world&#34; conditions, the simulated bedded packs serve as a good model for researchers to use to examine treatment differences among bedded packs. Several lab-scale studies can be conducted to eliminate possible treatments before trying them in a research or commercial-sized facility.

A protocol has been developed to measure gases, odors, and nutrient composition in lab-scaled bedded manure packs, which can be used to study ways to improve air quality in commercial cattle facilities using deep-bedded manure packs.

用实验室尺度模型评价深层包粪排放的恶臭和气体浓度

A lab-scaled simulated bedded pack model was developed to study air quality and nutrient composition of deep-bedded packs used in cattle mono-slope ...

The Plant Infection Test: Spray and Wound-Mediated Inoculation with the Plant Pathogen Magnaporthe Grisea

Plants possess a powerful system to defend themselves against potential threats by pathogenic fungi. For agriculturally important plants, however, current measures to combat such pathogens have proved too conservative and, thus, not sufficiently effective, and they can potentially pose environmental risks. Therefore, it is extremely necessary to identify host-resistance factors to assist in controlling plant diseases naturally through the identification of resistant germplasm, the isolation and characterization of resistance genes, and the molecular breeding of resistant cultivars. In this regard, there is need to establish an accurate, rapid, and large-scale inoculation method to breed and develop plant resistance genes. The rice blast fungal pathogen Magnaporthe grisea causes severe disease symptoms and yield losses. Recently, M. grisea has emerged as a model organism for studying the mechanisms of plant-fungal pathogen interactions. Hence, we report the development of a plant virulence test method that is specific for M. grisea. This method provides for both spray inoculation with a conidial suspension and wounding inoculation with mycelium cubes or droplets of conidial suspension. The key step of the wounding inoculation method for detached rice leaves is to make wounds on plant leaves, which avoids any interference caused by host penetration resistance. This spray/wounding protocol contributes to the rapid, accurate, and large-scale screening of the pathotypes of M. grisea isolates. This integrated and systematic plant infection method will serve as an excellent starting point for gaining a broad perspective of issues in plant pathology.

The Plant Infection Test: Spray and Wound-Mediated Inoculation with the Plant Pathogen Magnaporthe Grisea

Here, we present a protocol to test plant virulence with the plant pathogen Magnaporthe grisea. This report will contribute to the large-scale screening of the pathotypes of fungi isolates and serve as an excellent starting point for understanding the resistant mechanisms of plants during molecular breeding.

植物感染试验: 以植物病原菌为载体的喷雾和伤口介导接种

Plants possess a powerful system to defend themselves against potential threats by pathogenic fungi. For agriculturally important plants, however, current ...

Experimental Study of the Relationship Between Particle Size and Methane Sorption Capacity in Shale

The amount of adsorbed shale gas is a key parameter used in shale gas resource evaluation and target area selection, and it is also an important standard for evaluating the mining value of shale gas. Currently, studies on the correlation between particle size and methane adsorption are controversial. In this study, an isothermal adsorption apparatus, the gravimetric sorption analyzer, is used to test the adsorption capacity of different particle sizes in shale to determine the relationship between the particle size and the adsorption capacity of shale. Thegravimetric method requires fewer parameters and produces better results in terms of accuracy and consistency than methods like the volumetric method. Gravimetric measurements are performed in four steps: a blank measurement, preprocessing, a buoyancy measurement, and adsorption and desorption measurements. Gravimetric measurement is presently considered to be a more scientific and accurate method of measuring the amount of adsorption; however, it is time-consuming and requires a strict measuring technique. A Magnetic Suspension Balance (MSB) is the key to verify the accuracy and consistency of this method. Our results show that adsorption capacity and particle size are correlated, but not a linear correlation, and the adsorptions in particles sieved into 40 - 60 and 60 - 80 meshes tend to be larger. We propose that the maximum adsorption corresponding to the particle size is approximately 250 &#181;m (60 mesh) in the shale gas fracturing.

We use an isothermal adsorption apparatus, the gravimetric sorption analyzer, to test the adsorption capacity of different particle sizes of shale, in order to find out the relationship between particle size and the adsorption capacity of shale.

页岩中粒径与甲烷吸附能力关系的实验研究

The amount of adsorbed shale gas is a key parameter used in shale gas resource evaluation and target area selection, and it is also an important standard ...