10种植物精油对圣女果中三种致病菌抑制效果的研究

通过研究植物精油对圣女果致病菌的抑制效果,筛选出对圣女果有良好贮藏保鲜效果的植物精油。使用不同浓度的10种植物精油,采用体外熏蒸法和直接接触法,筛选出对圣女果中三种致病菌具有较强抑制效果的精油,并研究其最低抑菌浓度(MIC)和最低杀菌浓度(MBC)。结果显示植物精油对三种致病菌的体外熏蒸法优于直接接触法;肉桂精油、山苍子精油、丁香精油、牛至精油对白地霉菌的最低抑菌浓度分别为0.05×104、0.1×104、0.5×104、0.5×104μL/L,最低杀菌浓度分别为0.05×104、0.1×104、0.5×104、1.0×104μL/L;肉桂精油、丁香精油、牛至精油对赤霉菌的最低抑菌浓度分别为0.05×104、0.2×104、0.2×104μL/L,最低杀菌浓度分别为0.05×104、0.2×104、0.5×104μL/L;肉桂精油、丁香精油、牛至精油、山苍子精油对毛霉菌的最低抑菌浓度分别为0.1×104、0.5×104、1.0×104、1.0×104μL/L,最低杀菌浓度分别为0.1×104、0.5×104、1.0×104、1.0×104μL/L。肉桂精油、山苍子精油、丁香精油、牛至精油对白地霉菌均有较好抑制作用;肉桂精油、丁香精油、牛至精油对赤霉菌具有良好的抑菌及杀菌作用;肉桂精油、丁香精油对毛霉菌有较好抑制作用,牛至精油对毛霉菌有一定的抑菌作用,但杀菌效果不明显,山苍子精油对毛霉菌的抑菌杀菌效果最差。     

不同植物精油对大米青霉和黑曲霉的抑菌效果

为探明部分植物精油对大米的防霉效果,选取提自蓝桉叶、薄荷、山苍子、孜然、丁香、肉桂、花椒、香茅以及迷迭香的9种精油为研究对象,以大米青霉和黑曲霉为目标菌,通过测定抑菌圈直径、最小抑菌浓度、最低生长下降浓度和联合抑菌效果,以确定单一精油的抑菌效果、复配精油的协同抑菌效果及其最佳配比。结果表明,在所选9种精油中,肉桂和丁香精油对大米青霉和黑曲霉的抑菌效果最好,山苍子和蓝桉叶精油次之。在两两复配精油中,当肉桂精油与山苍子精油的比例为3:1(v/v)时,对大米青霉和黑曲霉的抑制效果最佳,其最小抑菌浓度为0.1 μL/mL,比单一精油的浓度下降了20~180倍。研究表明按适当比例复配的肉桂与山苍子复合精油是具良好应用前景的大米防霉保鲜剂。     

丁香精油的抗菌活性及其在豆制品中的应用

丁香精油是一种天然植物精油,它具有良好的抑菌、杀菌性能。因其安全绿色、无毒副作用的优势,使它在天然食品添加剂的开发中拥有较好的应用前景。本试验通过测定丁香精油对金黄色葡萄球菌和大肠杆菌的最小抑菌浓度(MIC)和最小杀菌浓度(MBC)评价了丁香精油的杀菌性能。并且研究了丁香精油在嫩豆腐、老豆腐、内酯豆腐以及盐卤豆腐中的杀菌特性,从而评价了丁香精油在豆制品中的应用效果。从试验结果可知,丁香精油对金黄色葡萄球菌、大肠杆菌两种试验菌株的MIC均为0.025%,MBC均为0.05%。结果表明,丁香精油对两种试验菌株都显示了较好的抑菌和杀菌效果。在豆制品中的应用试验中,丁香精油作用24 h后,四种豆制品中细菌致死率均达到了99.9999%以上,表明丁香精油在四种豆制品中显示了较好的保鲜效果。     

复合精油对黄曲霉联合抑菌作用研究

采用联合抑菌评价方法,通过测定植物精油抑菌圈直径、最低抑菌浓度(Minimum Inhibition Concentration,MIC)、最低生长下降浓度(Reduction Concentration,RC)、联合抑菌指数(Fractional Inhibitory Concentration,FIC),对植物精油单独及联合使用后的抑菌效果进行评价,筛选最佳抑制黄曲霉活性作用的复合精油种类及配比。结果表明:大蒜、肉桂、丁香、薄荷精油单独或复合使用均有较强抑制黄曲霉活性的作用。大蒜与肉桂精油联合抑菌评价为相加作用。当大蒜精油与肉桂精油复合体积比为1∶3时,复合精油具有最佳抑制黄曲霉活性的效果。因此,复合精油作为有效防霉保鲜成分具有良好的研发与应用前景。     

植物复合精油对5种稻谷霉变优势菌株抑菌作用研究

为了研究天然植物精油(百里香、丁香、肉桂)对霉变稻谷的抑菌效果,以5种稻谷霉变优势菌株为受试菌,以霉菌抑菌圈直径大小和最低抑菌浓度（MIC）为指标,通过混料设计方法建立复合精油抑菌模型,结合方差分析得到抑菌效果最佳的植物精油配比。研究结果表明,单一精油抑菌活性对亮白曲霉（A. candidus）,杂色曲霉（A. versicolor）和聚多曲霉（A. sydowii）为肉桂精油>丁香精油>百里香精油;对稻黑孢霉（N. oryzae）为肉桂精油=丁香精油>百里精香油;对布罗克青霉菌（P. brocae）为丁香精油=百里香精油<肉桂精油。当肉桂精油:丁香精油:百里香精油的体积比为55.2%︰26.9%︰17.9%时,3种植物精油对5种菌株抑制效果最佳,复合抑制值大于90.9%。     

植物精油对杏干优势微生物的抑制效果研究

以新疆小白杏为实验材料,研究新疆小白杏杏干在储藏期间微生物含量变化,通过分离、纯化从杏干上得到3株优势霉菌,形态观察初步鉴定为根霉菌、链格孢菌和青霉菌。选取9种植物精油对杏干上的混合菌进行抑菌实验,根据抑菌率筛选出3种抑菌活性较强的精油,并通过测定抑菌圈直径和最低抑菌浓度(MIC)进一步研究这3种精油对杏干上优势霉菌的抑菌活性。结果表明,9种植物精油对杏干上微生物均有一定的抑制作用,其中肉桂精油、月桂精油和茴香精油具有较强的抑菌性,且异味较小,对3种优势霉菌也有显著的抑制作用,抑菌活性显著优于卡那霉素,抑菌效果依次为:肉桂精油月桂精油茴香精油,肉桂精油可以作为天然保鲜剂用于杏干制品,达到抑菌和延长货架期的目的。     

植物精油的熏蒸抗菌活性及其机理研究

本文采用平板熏蒸法测定六种植物精油在气相状态下对四种常见细菌的最低抑菌浓度(Minimum Inhibitory Concentration,MIC)和最小杀菌浓度(Minimum Bactericidal Concentration,MBC),对效果好的精油进行复配研究并将其应用于小米椒保鲜,通过透射电镜和电导率来阐述肉桂精油熏蒸对大肠杆菌的抗菌机制。结果表明,六种精油中抑菌效果显著的是香茅精油、肉桂精油和罗勒精油,在精油浓度为0.125μL/mL时可以抑制所有的供试菌,而杀菌效果较好的是香茅精油和肉桂精油,除铜绿假单胞菌外,在精油浓度为0.125μL/mL时可杀死其余供试菌。将香茅精油、肉桂精油和罗勒精油进行复配,当三者比例为4:1:8时联合熏蒸抗菌效果最好,复配精油对大肠杆菌和沙门氏菌表现出协同增效作用,而对金黄色葡萄球菌则表现为拮抗作用。GC-MS结果表明,香茅精油的熏蒸抗菌能力主要来自香茅醛、香叶醇和香茅醇;肉桂精油主要来自于肉桂醛;罗勒精油则主要来自于草蒿脑、芳樟醇。当复合精油空间浓度为0.125μL/mL时,对小米椒具有较好的防腐保鲜效果。透镜结果显示经肉桂精油熏蒸后的大...     

鲜切西兰花贮藏期病原菌分离鉴定及植物精油对其抑制效果

以‘冬至绿’西兰花为试材,分离、纯化并鉴定鲜切西兰花贮藏期病原菌,筛选出抑制病原菌效果较好的植物精油。通过分离、纯化及致病性实验得到病原真菌菌株AB01,以病原菌内源转录间隔区序列进行进化树分析,鉴定该病原菌为链格孢菌（Alternaria alternata）。选用肉桂、茴香、牛至、丁香、百里香和香茅6 种精油对AB01进行抑菌性实验,通过体外抑菌和活体抑菌筛选出最优的精油种类及含量。结果发现,肉桂精油对AB01的抑菌效果最好,其最低抑菌浓度和最低杀菌浓度分别为0.05 μL/mL和0.15 μL/mL,其次是茴香和牛至精油。0.15 μL/mL肉桂精油用于鲜切西兰花可有效降低花球黄花率和切面褐变率。     

肉桂精油抑菌性及其在酱卤牛肉保鲜中的应用

以肉制品中常见的5种食品腐败菌和致病菌为研究对象,重点研究与酱卤肉加工过程相关的不同pH、温度、Na Cl浓度等对肉桂精油抑菌效果的影响,并进行气态防腐试验和酱卤牛肉保鲜实验。结果表明:肉桂精油具有广谱抑菌作用,对受试的5种菌均表现出良好的抑菌作用,其中以枯草芽孢杆菌对肉桂精油最为敏感。肉桂精油与pH存在协同抑菌的作用。在酸性环境中肉桂精油的抑菌性能强烈。肉桂精油与一定浓度范围的Na Cl有协同抑菌效果,且肉桂精油具有良好的热稳定性。气态防腐实验表明:肉桂精油具有良好的挥发性,不与菌体直接接触条件下,在密闭培养皿中对受试菌同样表现出良好的抑菌活性。经肉桂精油浸泡过的酱卤牛肉中微生物的生长受到明显的抑制。     

“贵长”猕猴桃致病菌的鉴定与天然抑菌剂筛选

对“贵长”猕猴桃在贮藏过程中几种致病菌进行了分离纯化,并研究了肉桂、丁香、薄荷、花椒等天然精油的抑菌效果。通过致病菌的鉴定,确定了致病菌的种类;通过抑菌试验,研究了不同精油的抑菌效果。鉴定结果表明：“贵长”猕猴桃中分离出四种不同的致病真菌,分别为黑曲霉菌（Aspergillusniger）、葡萄座腔菌（Botryosphaeriadothidea）、可可毛色二胞（Lasiodiplodia pseudotheobromae）、黄曲霉菌（Aspergillus flavus）,四种真菌对“贵长”猕猴桃均具有很强的致病性。抑菌试验表明：肉桂、丁香、薄荷3种精油在0.25%的体积分数下具有良好的抑菌效果,对四种致病菌抑制率达到78.00%以上,而复合精油具有更低的抑菌浓度和更广的抑菌范围。由体积分数0.12%的肉桂和薄荷配制的复合精油在对4种致病菌抑菌率分别达到了100.00%、99.43%、98.35%、95.01%,其中薄荷精油能够显著增强复合精油的抑菌效果。通过天然精油的复配能有效抑制“贵长”猕猴桃贮藏过程中几种常见致病菌的生长,实现对有害微生物的防控。     

薄荷属植物精油和多酚类的抑菌性及抗氧化性研究

研究了椒样薄荷(Mentha piperita L.)与苏格兰留兰香(Mentha cardiaca G.)精油的抑菌活性,测定了精油的最小抑菌浓度(MIC)和最小杀菌浓度(MBC).同时对两种薄荷叶片以及精油提取后残渣的多酚含量和抗氧化性进行研究,以期为椒样薄荷与苏格兰留兰香的多角度开发利用提供理论依据.结果表明:2种薄荷精油对于大肠杆菌、金黄色葡萄球菌、鼠伤寒沙门氏菌和李斯特菌均有抑制作用,而对于肠炎沙门氏菌及黑曲霉没有抑制作用,椒样薄荷精油的抑菌效果比苏格兰留兰香精油强.另外,椒样薄荷多酚含量在提取精油后显著性减少,而苏格兰留兰香未显著性降低.两种薄荷精油提取后残渣具有较强的DPPH自由基清除能力,而FRAP抗氧化能力却显著性降低.     

Nanoencapsulation of essential oils to enhance their antimicrobial activity in foods

This work focuses on the encapsulation of essential oils into nanometric delivery systems for incorporation into fruit juices, in order to enhance their antimicrobial activity while minimizing the impact on the quality attributes of the final product. A terpenes mixture and d-limonene were encapsulated into nanoemulsions based on food-grade ingredients, prepared by high pressure homogenization at 300 MPa.The effect of the delivery systems on the antimicrobial activity of terpenes was investigated by determining the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) for three different classes of microorganisms (Lactobacillus delbrueckii, Saccharomyces cerevisiae, Escherichia coli). The increase of the antimicrobial activity resulted to depend on the formulation and mean diameter of the delivery systems as well as on the microorganisms class. Additionally, GC-MS analysis revealed that high intensity processing for nanoemulsion production may affect the chemical stability of several active compounds.The application of the most efficient antimicrobial nanocapsules was tested in pear and orange juices inoculated with L. delbrueckii. Due to the higher antimicrobial activity of the nanoencapsulated compounds, lower antimicrobial concentrations are required for a bactericidal action under accelerated aging at 32 °C, with a minimal alteration of the organoleptic properties of the juice.     

Antimicrobial activity of essential oils on the native microflora of organic Swiss chard

The antimicrobial activity of several essential oils on the native microflora of Swiss chard was evaluated. The agar diffusion technique (paper disc) was used to establish, in a rapid way, the susceptibility of the native microflora to the different essential oils and to choose those with the greatest antimicrobial activity. An optical method (turbidimetry) and a microdilution method (plate count) were used to determine the minimum bactericidal concentration (MBC) and the minimum inhibitory concentration (MIC). Both methods produced similar results. The essential oils of Eucalyptus globules, Melaleuca alternifolia, Pimpinella anisum and Syzygium aromaticum presented the largest antimicrobial activity. For these oils, the MBC values were in the range of 0.093–1.5 mL/100 mL.     

Chemical composition, antioxidant, and antimicrobial activities of essential oil from pine needle (Cedrus deodara)

The chemical composition of essential oil from pine needles (Cedrus deodara) was determined, and its antioxidant and antimicrobial activities were evaluated. Twenty-three components, representing 95.79% of the oil, were identified by gas chromatography mass spectrometry. The main components include α-terpineol (30.2%), linalool (24.47%), limonene (17.01%), anethole (14.57%), caryophyllene (3.14%), and eugenol (2.14%). Pine needle essential oil showed remarkable antioxidant activity in scavenging free radicals, in lipid peroxidation, and in reducing power assays. Moreover, the essential oil revealed strong antimicrobial activity against typical food-borne microorganisms, with minimum inhibitory concentration and minimum bactericidal concentration values of 0.2 to 1.56 and 0.39 to 6.25 μg/mL, respectively. Transmission electron microscope observation ascertained that the bactericidal mechanism of pine needle essential oil may be the induction of cytoplasmic outflow and plasmolysis. These results suggest that the essential oil from pine needles has potential to be used as a natural antioxidant and antimicrobial agent in food processing. PRACTICAL APPLICATION: The present study provides a theoretical basis for the potential application of essential oil from pine needles (C. deodara) to be used as a natural resource of antioxidant and antimicrobial agents in food industry.     

New compound from the aerial parts of Achillea millefolium

Essential oils extracted by hydrodistillation from the aerial parts of Achillea millefolium was characterized by means of gas chromatography and nuclear magnetic resonance. A new compound, dihydro-a-cyclogeranyl hexanoate, along with 24 known were isolated from the essential oils A.millefolium. The new compound and borneol (known main component) were also subjected to antimicrobial, anti-inflammatory, and antioxidant activities. The new compound was particularly active against Escherichia coli, with the lowest minimum inhibitory concentration and minimum bactericidal/fungicidal concentration value. The new compound exhibited a higher activity in each antioxidant system with a special attention for β-carotene bleaching test, lipid peroxidation inhibition and reducing power. The new compound exhibited a potent nitric oxide scavenging effect and inhibited the expression of inducible nitric oxide synthase. These results indicated that dihydro-a-cyclogeranyl hexanoate might be applicable in natural medicine and healthy food.     

Antimicrobial efficacies of essential oils/nanoparticles incorporated polylactide films against L. monocytogenes and S. typhimurium on contaminated cheese

Polylactide based films were formulated by incorporating polyethylene glycol, selected nanopowders (zinc oxide, silver-copper), and essential oils (cinnamon, garlic, and clove) by solvent casting method. Films were tested against three foodborne pathogens (one gram-positive and two gram-negative) for their antibacterial activity. The effectiveness of selected cinnamon oil-based film was ascertained by performing a challenge test with cheese as a food model. In vitro antibacterial efficacies of nanopowders and essential oils were also determined by the decimal reduction concentrations and the minimum bactericidal concentrations for those foodborne pathogens. It was observed that nanopowders exhibited considerably poorer decimal reduction concentrations and minimum bactericidal concentration values in comparison to the essential oils. Silver-copper alloy nanopowders exhibited lower decimal reduction concentrations and minimum bactericidal concentrations values than ZnO against tested pathogens whereas essential oils showed distinct antimicrobial effectiveness against all those pathogens with in vitro decimal reduction concentration values of 87–157 and 77–220 µg/mL for cinnamon and clove oils, respectively. Among the various formulations, it was observed that only essential oils (especially cinnamon and clove) incorporated films exhibited a significant antimicrobial activity against the selected microorganisms. These results indicate that the poor antibacterial activity of the nanopowders and the hydrophobicity of polylactide could be responsible for the ineffectiveness of nanopowders in polylactide based films. Furthermore, the challenge test indicated the polylactide/polyethylene glycol/cinnamon oil film was appropriate to inhibit the growth of L. monocytogenes and S. typhimurium on cheese up to 11 days at refrigerated storage.     

水菖蒲内生菌分离与抗菌活性菌株筛选

对水菖蒲内生真菌进行分离,并进行抗菌活性的筛选。采用改良氯化三苯四氮唑显色(TTC)微量稀释法筛选抗菌活性菌株。以18 种常见导致食品腐败的细菌、酵母菌和霉菌为指示菌研究活性菌株的抗菌能力。结果显示,水菖蒲内存在广泛的具有抗菌活性的内生菌,占内生菌总数的40.7%,高活性菌株占内生菌总数的12.39%。其中S9 菌株发酵液具有抗细菌、酵母菌和丝状真菌的广谱抗菌能力,是潜在的食品防腐抗菌资源。     

生姜贮藏期病原菌分离鉴定及精油抑菌效果

分离、纯化及鉴定生姜贮藏期病原菌,筛选出对抑制病原菌效果较好的精油并验证该精油抑菌效果。通过分离、纯化及致病性实验得到了病原菌菌株ljr4及ljw2。以病原菌18S rDNA序列进行进化树分析,结果表明该两种病原菌分别属于镰刀菌属及被孢霉属。根据病原菌种属选择了6 种精油进行抑菌性实验,结果发现肉桂精油及百里香精油在用量为2 000 μL/L时对病原菌生长抑制率均为100%。在药敏实验中发现肉桂精油比百里香精油抑菌活性更强。肉桂精油对ljr4、ljw2这2 种病原菌最低抑菌用量分别为64、32 μL/L,最低杀菌用量分别为125、500 μL/L。与未熏蒸生姜相比,在贮藏30 d后肉桂精油熏蒸处理分别使接种ljr4及ljw2的生姜感病率下降了59.33%和47.33%。肉桂精油作为生姜贮藏前的熏蒸剂有较好的应用前景。     

Three new compounds from the seeds of Trachyspermum copticum

The effect of the application of nano-silicon (SiO₂; 1.5 and 3 mM) on components of essential oils of Trachyspermum copticum was evaluated. Essential oils extracted by hydrodistillation from Iranian T. copticum was characterized by means of gas chromatography-mass spectrometry and Nuclear Magnetic Resonance. Three new compounds, (1) 2, 5-Dihydroxy-4-methoxy-phenanthrene 2-O-b-Dglucopyranoside; (2) 4-Methoxy-2,5,7,9S tetrahydroxy-9,10-dihydrophenanthrene; and (3) trans-Ethyl cinnamate along with 12 known were isolated from the Eos T. copticum. The essential oil was also subjected to antimicrobial and antioxidant activities. The new compounds were particularly active against Bacillus cereus and Candida albicans, with the lowest minimum inhibitory concentration and minimum bactericidal concentration and minimum fungicidal concentration value. Three new compounds exhibited a higher activity in each antioxidant system with a special attention for β-carotene bleaching test, lipid peroxidation inhibition, and reducing power. The Thin-layer chromatography-bioautography screening and fractionation resulted in the separation of the main antioxidant compound which were identified as trans-Ethyl cinnamate (3). These results indicated that three new compounds might be applicable in natural medicine and healthy food.