Retardation of Listeria Monocytogenes Growth in Mozzarella Cheese Using Antimicrobial Sachets Containing Rosemary Oil and Thyme Oil

An antimicrobial sachet containing microcellular foam starch (MFS) with embedded rosemary oil and thyme oil was developed to reduce bacterial growth in shredded mozzarella cheese. The efficacy of the volatiles of oils at various concentrations in reducing Listeria monocytogenes as well as the release of the oils from the MFS have been also determined in this study. The cheese, inoculated with a cocktail of 5 strains of L. monocytogenes (approximately 3 log CFU/g), was packaged in a Nylon/EVOH/PE bag. A paper sachet containing MFS embedded with rosemary oil and thyme oil, separately or together, was inserted into the bag. Rosemary and thyme oil volatiles released from the sachet restricted the growth of L. monocytogenes, resulting in a 2.5 log CFU/g reduction on day 9 at 10 °C. The volatile oils also showed inhibitory effects on the growth of lactic acid bacteria (LAB) and total aerobic bacteria (TAB). After 15 d at 10 °C, the numbers of LAB and TAB in the samples containing the sachet with both oils experienced a 1.2 and 1.4 log CFU/g reduction, respectively, compared to untreated samples. Nonetheless, the sachet treatment produced a distinct odor, unfavorably received by the panelists. The results suggest the potential for application of the sachet system for the reduction of growth of L. monocytogenes, LAB, and TAB in food products.     

Nanoencapsulation Approach to Improve Antimicrobial and Antioxidant Activity of Thyme Essential Oil in Beef Burgers During Refrigerated Storage

In this study, thyme essential oil (TEO) loaded chitosan nanoparticles (CS-NP-TEO) are prepared by a two-step process including oil/water emulsion and ionic gelation. Five batches of burgers were prepared by following formulation: control (without any TEO), F-0.05-TEO (0.05 % of free TEO), F-0.1-TEO (0.1 % of free TEO), E-0.05-TEO (0.05 % of encapsulated TEO), E-0.1-TEO (0.1 % of encapsulated TEO), and AA-0.05 (0.05 % of ascorbic acid). All samples treated with TEO significantly reduced the population of investigated microbial counts (P?<?0.05) compared to the control during 8 days of storage. At the end of storage, E-0.05-TEO and E-0.1-TEO, presented, respectively, 2.2 and 3 log cycles reduction of Enterobacteriaceae, along with 3.1 and 3.7 log cycles reduction of Staphylococcus aureus. Oxymyoglobin content and redness values reduced with the increase of storage time for all samples. However, AA-0.05 and E-0.1-TEO samples were more efficient at inhibiting discoloration in comparison with E-0.05-TEO and burgers treated with free TEO after 6th day of storage. A significant improvement (P?<?0.05) in the reduction of thiobarbituric acid reactive substances (TBARS) amount was found for all TEO treated burgers in comparison to control samples after 8 days chilled storage. According to the results of sensory analyses, F-0.1-TEO and AA-0.05 samples at 4 days and F-0.05-TEO sample at 8 days of storage were rejected by assessors and considered as an unacceptable case. On the basis of our results, the encapsulation of TEO in chitosan nanoparticles may be a promising technology for the control of undesirable microbial, chemical, and sensorial changes in meat products.     

蕹菜精油对葵花籽油氧化稳定性的影响

蕹菜具有抗菌抗炎的作用,而蕹菜精油的研究尚少.该研究通过水蒸气蒸馏法提取蕹菜精油,并使用气相色谱-质谱联用技术(GC-MS)研究其精油组成成分,得到主要成分有长叶薄荷酮(48.16％)、薄荷酮(23.41％)与柠檬烯(12.18％).将蕹菜精油与合成抗氧化剂分别加入到葵花籽油中进行为期30 d的储藏试验,每隔6d取样并...     

真空低温蒸煮技术对鲟鱼鱼堡冷藏品质的影响

研究了经真空低温蒸煮技术处理的鲟鱼鱼堡在冷藏过程中品质的变化,比较不同真空低温蒸煮技术的加热温度对鲟鱼鱼堡品质的影响。结果表明,与未处理组相比,真空低温蒸煮技术处理显著提高鲟鱼鱼堡的凝胶性,并且达到菌落总数限值的时间推迟10 d以上。而汁液流失率和脂肪氧化水平都会显著增加(P0.05)。随着真空低温蒸煮技术加热温度的升高,菌落总数减少,汁液流失率增大,丙二醛和凝胶性的含量呈先增加后降低的趋势。60℃处理组在第0天的凝胶性比80℃处理组高70 g·mm,汁液流失率减少3%。通过主成分分析确定最佳加热温度为60℃。采用傅里叶红外光谱、低场核磁共振及电子鼻技术对鲟鱼鱼堡蛋白质结构、水分含量和组成以及挥发性风味成分进行了研究。     

植物精油及其活性成分的抗菌机理

芳香植物精油普遍具有良好的抗菌能力,是潜在的天然抗菌剂.本文概述山苍子、肉桂、丁香、辣木、百里香、鼠尾草、孜然、八角茴香、牛至、花椒、大蒜等24种精油的主要化学成分、抗菌作用对象和抗菌机理,并对香芹酚、肉桂醛、百里香酚、丁香酚、柠檬醛、柠檬烯等6种精油单体成分对不同微生物的抗菌作用进行分析.     

十二种中药挥发油及其滤液体外抗菌活性研究

本文采用水蒸气蒸馏法提取丁香、肉桂、八角茴香、大蒜、薄荷、肉豆蔻、香茅、藿香、艾叶、干姜、鱼腥草和荆芥等12种中药的挥发油，以金黄色葡萄球菌、大肠杆菌、枯草芽孢杆菌、酵母、黄曲霉和绿色木霉等6种菌作为供试菌，通过体外抗菌试验探讨中药挥发油及其滤液的体外抗菌作用，结果表明12种中药挥发油对6种菌均有一定的抗菌作用，其中尤以大蒜、肉桂、藿香和丁香抗菌作用明显。     

植物精油对食品中常见有害微生物的抑菌活性研究

通过测定抑菌圈、气相熏蒸法等体外抑菌试验研究了罗勒精油、茶树油、百里香精油、丁香精油、小茴香精油、依兰油、甘牛至精油、肉桂精油、桉叶油、芫荽籽精油、香茅油、鼠尾草油、甘松精油十三种植物精油对六种食品常见有害微生物抗菌作用。结果表明:十三种植物精油均对细菌、霉菌和酵母具有一定的抑杀能力。百里香精油和肉桂精油抗菌活性最强,均表现程度不等的抗菌活性。六种供试菌种对百里香精油、肉桂精油极敏感,抑菌圈直径均大于20 mm;当两种精油空间体积浓度达到300μL/L时,两种精油对多数供试菌表现出强抑菌效果。肉桂精油与百里香精油复配后对供试菌没有表现出强的协同增效效果,部分出现相加作用和无关作用。复配精油中肉桂精油占80%时,对供试菌效果最好。     

The Analysis of the Behaviour of Listeria Monocytogenes in Fresh Cheeses with Various Spices During Storage

The aim of this work was to evaluate the growth possibilities of Listeria monocytogens in the artificially contaminated fresh cheese during storage. Three variants of acid homogenized commercial fresh cheeses: mixed herbs, red pepper and garlic-pepper were studied. The lowest value of the specific growth rate of L. monocytogenes in the fresh cheeses was reported for red pepper variant. The highest value of this parameter was determined for the fresh cheese with pepper-garlic. The use of spices in the production of fresh unripened cheeses influence the viability and growth of bacteria L. monocytogenes during storage at the temperature range 3-15^oC.     

Reduction of Listeria monocytogenes in Raw Catfish Fillets by Essential Oils and Phenolic Constituent Carvacrol

The antimicrobial activity of various essential oils and carvacrol was determined on fresh raw catfish fillets against a 4-strain Listeria monocytogenes mixture representing serotypes 1/2b, 3b, 4b, and 4c that were predominantly isolated from catfish processing environments. Thyme oil, oregano oil and carvacrol exhibited concentration and time dependent responses in broth against L. monocytogenes; for example 0.5% concentrations resulted in 4 log CFU/mL reduction within 30 min whereas 0.1% concentrations required more than 24 h for the same level of reduction. Lemon, orange, and tangerine oils, at 0.5% showed listeriostatic effect in which 4 log CFU/mL of the initial L. monocytogenes load was unchanged at 4 °C in 10 d whereas 1% concentrations were listericidal in a time dependent manner. Apart from carvacrol, efficacy of tested essential oils in reducing L. monocytogenes and total microbial load from catfish fillet was very limited. Dipping treatment of catfish fillets in 2% carvacrol solution for 30 min at 4 °C reduced L. monocytogenes to an undetectable level from their initial load of 5 log CFU/g and reduced total microbial load from catfish fillets by approximately 5 log CFU/g. In sensory analysis trained panelist preferred control samples over 2% carvacrol treated samples implying potential limitation in applicability of carvacrol for fillet treatments.     

Chemical Composition and Antidiabetic Activity of Essential Oils Obtained from Two Spices (Syzygium aromaticum and Cuminum cyminum)

The current aim was to evaluate antidiabetic potential of Syzygium aromaticum and Cuminum cyminum essential oils and their emulsions by alpha amylase inhibition assay. Antidiabetic activity of C. cyminum and S. aromaticum was examined in dose dependent mode (1 to 100 µg/mL). The maximum antidiabetic activity for S. aromaticum and C. cyminum essential oils was noted at the highest dose (100 µg/mL). Five emulsions (essential oil + surfactant [tween 80] + co-surfactant [ethanol] + water) of different concentrations for S. aromaticum (A1 to A5) and C. cyminum (B1 to B5) essential oils were formulated. Among different emulsions, A5 of S. aromaticum and B5 of C. cyminum essential oil exhibited a maximum antidiabetic activity with 95.30 and 83.09% inhibition of α-amylase, respectively. Moreover, the analysis of essential oils showed that eugenol (18.7%) and α-pinene (18.8%) were the major components of S. aromaticum and C. cyminum essential oils, respectively.     

Determination of the Most Bioactive Phenolic Compounds from Rosemary Against Listeria Monocytogenes: Influence of Concentration, pH, and NaCl

ABSTRACT: The anti-Listeria monocytogenes effects of 8 phenolic compounds, carnosol, carnosic acid, 12-methoxy carnosic, ferulic and caffeic acid, rosmarinic acid, luteolin and luteolin-7-glucoside were evaluated with a Plackett and Burman design in mixtures mimicking the phenolic composition of rosemary extract without essential oils. At 30°C carnosic acid was the most efficient compound during 24 h, whereas luteolin became more active after 72 h. The antibacterial effect of pure carnosic acid was modeled under a range of different pH and NaCl concentration, using a Doehlert design. Under moderately acidified conditions, carnosic acid displayed a bactericidal effect at low concentration (5.5 μg/ml). Its activity was not greatly influenced by NaCl.     

Characterization of Microencapsulated Rosemary Essential Oil and Its Antimicrobial Effect on Fresh Dough

This study aimed to characterize rosemary essential oil particles obtained by spray-drying and to evaluate their antimicrobial activity. Measurements of mycelial growth of Penicillium and Aspergillus fungi, isolated from fresh dough, were made applying oil concentrations of 1.0, 5.0, 10.0, 20.0, and 50.0 μL/mL. Fungi and yeast counts in the fresh dough submitted to the control (no oil), pure oil, and microencapsulated oil treatments were also conducted. The microcapsules showed 50 % oil retention after drying, and the major oil components identified were 1,8-cineole (29.0 %), camphor (26.6 %), and α-pinene (10.6 %). The analysis of the particles revealed surfaces without fissures, with a mean particle size of 12.2 μm and presenting an amorphous structure. The growth inhibiting effect of Penicillium sp. fungus, compared to the control, was verified at concentrations of 1.0, 5.0, and 10.0 μL/mL rosemary essential oil, which did not differ among them. For Aspergillus sp., the application of 10.0 μL/mL oil provided greater inhibition compared to 1.0 and 5.0 μL/mL. Complete inhibition occurred with the application of 50.0 μL/mL for both fungal genera tested. At 8 days of dough storage at 25 °C, a decrease of at least 0.7 and 1.5 log cycles of fungal growth was observed in the dough with pure oil and that with microencapsulated oil, respectively, relative to the control. The microencapsulation process retained the antimicrobial property of rosemary essential oil and provided further extension of this activity over time when applied to fresh dough.     

Enhancing Safety and Aroma Appealing of Fresh-Cut Fruits and Vegetables Using the Antimicrobial and Aromatic Power of Essential Oils

ABSTRACT:  Microbial and aroma attributes are within the most decisive factors limiting safety and sensory appealing of fresh-cut fruits and vegetables. Alternatively, several plant essential oils (EOs) are constituted of several volatile active compounds and most of them present antimicrobial potential and had different aroma profile. Considering these premises, this hypothesis article states that safety and aroma appealing of fresh-cut produce could be improved with EO treatment. EOs could prevent fresh-cut fruit decay; however, their volatile constituents could be sorbed by the produce, and according to the aroma notes of the antimicrobial oil, sensorial appealing of odor, and flavor of the treated produce might be affected positively or negatively. Specifically, garlic oil is a natural antimicrobial constituted by sulfur compounds, which are responsible for its odor and antimicrobial properties. Besides, fresh-cut tomato is a highly perishable product that needs antimicrobial agents to preserve its quality and safety for a longer period of time. From the sensorial point of view, aroma combination of garlic and tomato is a common seasoning practice in Europe and America and well accepted by consumers. Once the right combination of flavors between the EOs and the fresh-cut produce has been selected, safety and quality of the treated fruit could be improved by adding antimicrobial protection and extra aroma. Therefore, other combinations between EOs and fresh-cut produce are discussed. This approximation could reinforce the trends of natural food preservation, accomplishing the demands of the increasing sector of consumers demanding tasty and convenient fresh-cut produce, containing only natural ingredients.     

Antimicrobial Activity of Thyme (Tymus vulgaris) and Oregano (Origanum vulgare) Essential Oils against Some Food-borne Microorganisms

The aim of this study was to investigate antibacterial effects of oregano and thyme essential oils (EOs) on some food-borne bacteria. GC-MS analysis of EOs was performed in order to determine their composition and phenols were predominant constituents. The investigation of the antibacterial effects of EOs was performed on Salmonella Enteritidis, Salmonella Thyphimurium, Staphylococcus aureus, methicillin resistant Staphylococcus aureus, Escherichia coli and Bacillus cereus, and MICs were determined by broth microdilution method. EOs exhibited antibacterial activity against all tested microorganisms.     

Antifungal Effect of Allium tuberosum,Cinnamomum cassia,and Pogostemon cablin Essential Oils and Their Components Against Population of Aspergillus Species

Antifungal activity of Allium tuberosum (AT), Cinnamomum cassia (CC), and Pogostemon cablin (Patchouli, P) essential oils against Aspergillus flavus strains 3.2758 and 3.4408 and Aspergillus oryzae was tested at 2 water activity levels (a_w: 0.95 and 0.98). Main components of tested essential oils were: allyl trisulfide 40.05% (AT), cinnamaldehyde 87.23% (CC), and patchouli alcohol 44.52% (P). The minimal inhibitory concentration of the plant essential oils against A. flavus strains 3.2758 and 3.4408 and A. oryzae was 250 ppm (A. tuberosum and C. cassia), whereas Patchouli essential oil inhibited fungi at concentration > 1500 ppm. The essential oils exhibited suppression effect on colony growth at all concentrations (100, 175, and 250 ppm for A. tuberosum; 25, 50, and 75 for C. cassia; 100, 250, and 500 for P. cablin essential oil). Results of the study represent a solution for possible application of essential oil of C. cassia in different food systems due to its strong inhibitory effect against tested Aspergillus species. In real food system (table grapes), C. cassia essential oil exhibited stronger antifungal activity compared to cinnamaldehyde.