玉米须提取物对食品腐败菌及致病菌抑制作用的研究

首次以玉米须提取物对七种常见的食品腐败菌及致病菌进行抑菌试验,发现玉米须的乙醇提取物的效果最好,其最低抑菌浓度（ＭＩＣ）为３．０ｇ／１００ｇ。此外,对食品加工条件（如杀菌方式等）及食品介质（如ｐＨ）对玉米须提取物抑菌活性的影响也作了研究。结果表明。玉米须提取物在常规食品杀菌条件（ＵＨＴ）及中酸到酸性环境下抑菌活性稳定,因而可做为潜在的食品防腐剂。     

蕨多糖抗食品腐败菌活性的初步研究

从蕨中提取水溶性粗多糖,利用圆形纸片法对7种常见的食品腐败菌进行了抗菌试验。结果表明：蕨多糖对食品腐败菌有较强的抑制活性,其最低抑菌浓度为5mg／ml。     

芝麻饼粕中活性物质对食品腐败菌的抑菌研究

采用滤纸片法和平板培养法研究芝麻饼粕中活性物质对食品腐败菌的抗菌活性.结果表明:芝麻饼粕中活性物质对食品腐败菌有较好的抑菌作用,随着芝麻饼粕中活性物质浓度的增加,对各供试细菌的抑菌活性相应增加,但不同供试细菌对芝麻饼粕中活性物质抑菌作用敏感性不同.芝麻饼粕提取物最低抑菌浓度MIC(体积浓度)分别为:大肠杆菌是0.08,枯草芽孢杆菌是0.06,金黄色葡萄球菌是1.00.各供试菌在芝麻素和甾醇的质量浓度分别达到20×10-3g/mE和6×10-3g/mL时的抑制作用最为明显.     

平贝总碱体外抗菌活性研究

探讨平贝总碱的体外抑菌活性.采用纸片扩散法和琼脂平板稀释法测定平贝总碱对常见致病菌的体外抗菌活性及最低抑菌浓度(MIC).平贝总碱对金黄色葡萄球菌、大肠杆菌、克雷伯氏肺炎杆菌、铜绿色假单胞杆菌皆有抗菌作用,对克雷伯氏肺炎杆菌的最低抑菌浓度为2.5mg/ml;对金黄色葡萄球菌、大肠杆菌、铜绿色假单胞杆菌的最低抑菌浓度为5mg/mL.     

山茱萸总皂甙的抑菌作用研究

以山茱萸为原料,进行山茱萸总皂甙对几种常见的食品腐败菌和致病菌的抑菌作用进行了研究。试验结果表明,山茱萸总皂甙对细菌尤其是金黄色葡萄球菌的抑制效果明显,对酵母菌和霉菌的抑制效果较差;山茱萸总皂甙对金黄色葡萄球菌的最低抑菌浓度为24.82mg/ml;山茱萸总皂甙的最佳抑菌pH为3且山茱萸总皂甙的热稳定性好,在121℃,处理25min仍保持较好的抑菌活性。     

油茶总皂甙抑菌活性的初步研究

初步研究了油茶总皂甙对几种常见的食品腐败菌和植物病原真菌的抑菌活性,结果表明,油茶总皂甙在高浓度下对啤酒酵母、金黄色葡萄球菌和枯草芽孢杆菌抑菌作用较强,其MIC值分别为12.5、12.5和3.2mg/ml,低浓度只起到一定程度的抑制作用;对三种霉菌桔青霉、黑曲霉、米曲霉抑制作用较弱;油茶总皂甙对六种植物病原真菌抑菌活性强弱表现出较强的选择性,对小麦纹枯病菌和棉花黄萎病菌的抑菌活性较强,EC50分别为:0.081、0.169mg/ml,且抑制活性同浓度呈正相关。     

抗耐甲氧西林金黄色葡萄球菌菌株的筛选、鉴定及其活性物质初步研究

从海南红树林土壤分离筛选抗耐甲氧西林金黄色葡萄球菌（MRSA）菌株,通过形态学观察、生理生化试验及分子生物学进行菌种鉴定。采用不同培养基优选抑菌活性物质生成条件;以有机溶剂萃取抑菌活性物质,采用气相色谱-质谱（GC-MS）分析抑菌物质化学成分,采用微量稀释法测定最低抑菌浓度与最低杀菌浓度。结果表明,筛选得到一株抗MRSA菌株,编号为NEL-002,被鉴定为萎缩芽孢杆菌（Bacillus atrophaeus）。菌株NEL-002采用LB液体培养基得到发酵液经石油醚萃取粗提物抗MRSA菌活性最强,且在40～80 ℃、pH在5～10较稳定,对多种蛋白酶不敏感;最低抑菌质量浓度为62.5 μg/mL,最低杀菌质量浓度为500 μg/mL。GC-MS鉴定出抗菌活性物质为十甲基环戊硅氧烷、十二甲基环六硅氧烷及邻苯二甲酸二丁酯。     

苹果籽油中甾醇物质的提取工艺及抑菌活性研究

本实验采用薄层层析法对苹果籽油中的植物甾醇进行纯化,采用K-B纸片法研究甾醇纯化物的菌制活性及pH值、温度等对抑菌性的影响,并且测定其最低抑菌浓度(MIC)。结果表明,分离纯化植物甾醇的最佳薄层层析条件为：展开剂为乙醚-石油醚(3:7,V/V),显色剂为三氯化铁溶液。抑菌实验结果表明,甾醇对金黄色葡萄球菌及枯草芽孢杆菌具有很好的抑制作用,最低抑菌浓度分别为18μg/ml和30μg/ml,对大肠杆菌及蜡样芽孢杆菌有抑制作用,对黑曲霉没有抑制作用。在pH5～6 条件下其抑菌效果最佳;一定温度内热处理不影响苹果籽油中甾醇的抑菌活性。苹果籽油中植物甾醇有广谱和常温的抑菌活性。     

辣椒碱的抑菌活性研究

辣椒碱是辣椒中的主要活性物质，在食品和医药方面有重要应用价值。本文以辣椒碱晶体（含量96％）为原料，采用平板空穴扩散法进行辣椒碱的抑菌活性研究。结果证明辣椒碱对供试细菌有较强抑制活性，但对霉菌的抑制作用弱。同时，辣椒碱的抑菌作用受其浓度的影响，浓度在0．0125mg／ml以下无抑菌活性。提爪辣椒碱可作为食品的辣味剂和抗菌剂。     

二氢杨梅素抗菌活性研究

使用滤纸片法和试管二倍稀释法测定二氢杨梅素对几种常见食品微生物的抗菌效果.结果表明:二氢杨梅素对细菌有很强的抑制活性,对真菌抑制效果不明显;对供试菌种的最低抑菌浓度(MIC)不超过1.76 g/L;对大肠杆菌和金黄色葡萄球菌的最低杀菌浓度(MBC)分别是1.76 g/L和0.88 g/L,对链球菌和枯草芽孢杆菌的最低杀菌浓度高于3.52 g/L;抑菌活性在pH3～4的酸性环境中最强;二氢杨梅素在一定温度处理后仍具有良好的抑菌效果.     

Antimicrobial activity of whey protein isolate edible films with essential oils against food spoilers and foodborne pathogens

The use of antimicrobial edible film is proposed as a means of improving food safety and extending the shelf-life of food systems by controlling the release of antimicrobials on food surfaces. In this work we first selected and studied 8 different essential oils (EOs) from plants, namely, oregano, clove, tea tree, coriander, mastic thyme, laurel, rosemary, and sage as natural antimicrobials against 2 gram-positive bacteria (Listeria innocua and Staphylococcus aureus) and 2 gram-negative bacteria (Salmonella enteritidis and Pseudomona fragi) by using the agar disk diffusion method. EOs from oregano, clove, and tea tree produced the largest surfaces of inhibition against the growth of the 4 bacterial strains tested. Second and following the assessment of compatibility, stable antimicrobial edible films based on whey protein isolate (WPI) with increasing concentrations (0.5% to 9%) of the 8 EOs were developed and tested for antimicrobial activity against the same gram-positive and gram-negative bacteria. WPI-edible films incorporating oregano or clove EO were found to have the most intense inhibitory effect of microbial growth. The bacterial strain gram-negative P. fragi presented the less susceptibility to the effect of those films. Moreover, only the edible films based on these 2 EOs were active against all 4 studied microorganisms. On the other hand, the edible films incorporating tea tree, coriander, mastic thyme, laurel, rosemary, or sage EOs even at high concentrations (7% to 9%) did not cause any antimicrobial effect against the pathogens S. aureus or S. enteritidis. PRACTICAL APPLICATION: Potential applications of this technology can introduce direct benefits to the food industry by improving safety and microbial product quality. The results of this research have direct application in the food industry with potential applications in various foodstuffs, including meat and poultry products where the control of spoilage bacteria such as P. fragi throughout their chilled storage or the improvement of food safety by controlling pathogens such as S. enteritidis are topics of particular interest for the industry.     

Antibacterial activity of plants used in cooking for aroma and taste

Thirty-three plants used in cooking for aroma and taste were examined for antibacterial activity against pathogens causing foodborne infections. Vibrio parahaemolyticus and Staphylococcus aureus were sensitive to many kinds of plant extracts, whereas Listeria monocytogenes, Escherichia coli O157:H7, and Salmonella Enteritidis populations decreased in only six, one, and three plant extracts, respectively. The polyphenol content in the plants was significantly different between the antibacterial plants and nonantibacterial plants, indicating that the polyphenols were related to the antibacterial action of these plants. Antibacterial activity of various concentrations of leaf extracts from Japanese persimmon, white cedar, and grape were investigated. Japanese persimmon and white cedar leaf extracts at low concentrations affected L. monocytogenes and V. parahaemolyticus rapidly. With grape leaf extract at low concentrations, the population of L. monocytogenes decreased similarly to Japanese persimmon and white cedar leaves. This study demonstrates that many plants used in cooking for aroma and taste contain polyphenols and exhibit antibacterial activity against foodborne pathogens.     

荷叶中抑菌成分的提取及其抑菌活性的研究

以乙醇溶液对荷叶进行抽提试验,得到了荷叶提取物;用荷叶提取物对几种常见的食品微生物进行抑菌活性测定,结果表明,荷叶的抑菌作用显著,且对大多数供试菌的MIC（最低抑菌浓度）值小于或等于8％。［实验结果同时表明了荷叶提取物在中、弱碱性条件下抑菌活性最强,并能耐受高温短时及超高温瞬时的热处理。     

In vitro Inhibition of Food Spoilage and Foodborne Pathogenic Bacteria by Essential Oil and Leaf Extracts of Magnolia liliflora Desr.

ABSTRACT:  The aim of this study was to examine the chemical composition of the essential oil isolated from the floral parts of Magnolia liliflora Desr. by hydrodistillation, and to test the efficacy of essential oil and various leaf extracts against a diverse range of microorganisms comprising food spoilage and foodborne pathogenic bacteria. The chemical composition of essential oil was analyzed by GC-MS. It was determined that 52 compounds, which represented 78.07% of total oil, were present in the oil. The oil contained mainly levoxine (15.59%), methylcyclopropane (24.26%), 2-β-pinene (5.3%), caryophyllene oxide (4.01%), and β-caryophyllene (1.7%). The oil (1000 ppm/disc) and leaf extracts (1500 ppm/disc) exhibited promising antibacterial effects against the tested pathogens as a diameter of zones of inhibition (9 to 18 and 7 to 12 mm) and MIC values (125 to 1000 and 500 to 3000 μg/mL), respectively. Also, the oil had a potent detrimental effect on the viable count of the tested bacteria. The results obtained in this study support the role of essential oil and the leaf extracts derived from M. liliflora as a remarkable approach to inhibit the growth of food spoilage and foodborne pathogens.     

Microalgal and cyanobacterial cell extracts for use as natural antibacterial additives against food pathogens

Intra‐ and extracellular extracts of thirteen cyanobacteria and twelve microalgae were screened for their activity against a few of the most relevant food‐borne pathogens – viz. Salmonella sp., Pseudomonas aeruginosa, Escherichia coli and Staphylococcus aureus. Strain M2‐1 of Scenedesmus obliquus was the microalga that exhibited the highest antibacterial activity, except against Salmonella sp. Although cyanobacteria possessed in general wider antibacterial spectra than microalgae, the former have also been associated with toxin production – and may thus be less useful in food formulation. Nostoc sp. was particularly effective against E. coli and P. aeruginosa, whereas Gloeothece sp. stood out because of its capacity to inhibit all food pathogens tested. Typically, the intracellular extracts were more powerful than their extracellular counterparts; and those with antibacterial features were found to possess high contents of long chain fatty acids – some of which are well‐known for their antibacterial activities.     

Use of encapsulated bacteriophages to enhance farm to fork food safety

Bacteriophages have been successfully applied to control the growth of pathogens in foods and to reduce the colonization and shedding of pathogens by food animals. They are set to play a dominant role in food safety in the future. However, many food-processing operations and the microenvironments in food animals' guts inactivate phages and reduce their infectivity. Encapsulation technologies have been used successfully to protect phages against extreme environments, and have been shown to preserve their activity and enable their release in targeted environments. A number of encapsulation technologies have shown potential for use with bacteriophages. This review discusses the current state of knowledge about the use of encapsulation technologies with bacteriophages to control pathogens in foods and food animals.     

采收期对安溪油柿柿叶化学成分含量的影响

柿叶具有多种对人体健康有益的生物活性物质和营养成分。本文以安溪油柿鲜叶为原料,研究采收期对柿叶化学成分含量的影响。结果表明:安溪油柿柿叶的叶绿素、类胡萝卜素、类黄酮、维生素C、多酚等主要化学成分含量在9月份基本上都达到其最高值。因此,供制作柿叶保健茶的安溪油柿叶的适宜采收期为9月份。     

Molecular Characterization of Lactobacilli Isolated from Piper betle L. var. Pachaikodi and Comparative Analysis of the Antimicrobial Effects of Isolate Lactobacillus plantarum KJB23 and Betel Leaves Extract

Traditionally Piper betle L. leaves have been used in India for fermenting certain foods. In our previous study, while fermenting Uttapam batter along with Piper betle L. var. Pachaikodi leaves led to suppression of gas formation and altered Lactic acid bacteria profile, especially in bacilli isolates compared to those observed in plain Uttapam batter fermentation. Hence, the aim of the present study was to understand the rationale behind these changes through characterization of Lactobacillus isolates from Piper betle L. var. Pachaikodi and also the leaves extracts for antimicrobial activity. Out of 72 isolates obtained from the betel leaves, only 10 isolates were bacilli which were chosen for their molecular characterization and to elucidate their inhibitory effects against major food borne pathogens and gas-forming bacteria and to compare with the effect of betel leaves extract. Random amplified polymorphic DNA (RAPD)-PCR and phenotype analysis was used to differentiate the isolates at strain level, 16S rRNA gene sequence for phylogenetic analysis and species-specific multiplex PCR analysis for sub-species identification. All isolates were identified as Lactobacillus plantarum subsp. plantarum. All Lactobacillus isolates were indigenous to leaf as they were resistant to betel leaves extract and showed maximum activity against some LAB and non-LAB indicator strains except Lactobacillus plantarum MTCC 6160 which was resistant. Among them, KJB23, 36 and 47 were the most effective. Particularly, the isolate KJB23 and ethanolic betal leaf extract showed rivaling inhibitory activity against major food borne pathogens, while dissimilar activity against gas forming bacteria. This study revealed that either Piper betle L. leaf or Lactobacillus strains from the leaves can be valuable for food applications when added to fermented products.     

Antimicrobial activity of epsilon-polylysine against Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes in various food extracts

ABSTRACT:  This study compared the antimicrobial effects of ɛ-polylysine (ɛ-PL) against Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes in 6 food extracts and in broth. The food extracts (10% (w/w) in distilled water) evaluated were fat-free and whole fat milk, beef, bologna, rice, and vegetables (50:50 ratio of broccoli and cauliflower). ɛ-PL was tested at 0.005% and 0.02% (w/v) against E. coli O157:H7 and L. monocytogenes , and 0.02% and 0.04% (w/v) against S. Typhimurium . The substrates were inoculated (5 log CFU/mL) and periodically analyzed for surviving populations during storage at 12 °C for 6 d. In general, all 3 pathogens reached 7 to 9 log CFU/mL within 2 d in control substrates (no ɛ-PL). Immediate bactericidal effects ( P < 0.05) following exposure to ɛ-PL were obtained in the rice (all pathogens) and vegetable ( E. coli O157:H7 and S. Typhimurium ) extracts. During storage, antimicrobial effects of ɛ-PL were more pronounced in the food extracts than in the broth medium. The greatest antimicrobial activity for all 3 pathogens was obtained in the rice and vegetable extracts, where counts were reduced ( P < 0.05) to below the detection limit (0.0 log CFU/mL) by one or both ɛ-PL concentrations tested. In the other food extracts (fat-free milk, whole fat milk, beef, and bologna), both ɛ-PL concentrations tested generally resulted in lower ( P < 0.05) pathogen levels at the end of storage compared to initial counts, with better bactericidal effects exerted by the higher of the 2 ɛ-PL concentrations. Additional research is needed to explore the potential antimicrobial effects of ɛ-PL in real food systems.     

Antibacterial mode of action of seed essential oil of Eleutherococcus senticosus against foodborne pathogens

This study investigated the antibacterial mechanism of action of the seed essential oil of Eleutherococcus senticosus (ESEO) against foodborne pathogenic bacteria. Preliminarily, the ESEO (1000 μg disc^?1) showed potential antibacterial effect as diameter of inhibition zones (12.0 ± 0.2–37.0 ± 2.0 mm) against the tested foodborne pathogens. The MIC and MBC values of ESEO against the tested bacteria were found in the range of 125–500 and 500–1000 μg mL^?1, respectively. At MIC concentration, the ESEO had potential inhibitory effect on the cell viability of the tested pathogens. In addition, SEM analysis showed the inhibitory effect of ESEO as confirmed by considerable morphological alterations on the cell wall of B. cereus ATCC 13061 and E. coli O157:H7 ATCC 43889. Moreover, the ESEO revealed its mode of action against foodborne pathogens on membrane integrity as confirmed by release of extracellular ATP, 260‐nm absorbing materials and leakage of potassium ions. These findings confirm that the ESEO can be used as a potential antibacterial agent in food industry to inhibit the growth of various foodborne pathogens.