Comprehensive assessment of antioxidant activity of essential oils

Essential oils have been studied for their unique ability to act as antioxidants. Antioxidant activities of 423 essential oils of 48 different botanical families were evaluated for their antioxidant activities as free radical scavenging agents using the 1,1-diphenyl-2-picrylhydrazyl method. Seventy-three oils showed 50% or more inhibition at a concentration of 1.25 mg/mL. The 73 most active oil samples were further evaluated for their scavenging activities using series of dilutions to estimate their EC(50) . The EC(50) of the 73 most active oils ranged from 4 to 2000 μg/mL. Oils having an EC(50) of less than 300 μg/mL (20 selected samples) were subjected to β-carotene bleaching antioxidant activity test and more detailed analysis including thin layer chromatography, gas chromatography/mass spectrometry, high performance liquid chromatography and bioautography. Essential oils of the botanical families Lamiaceae and Myrtaceae were the most effective antioxidants. Thymol and carvacrol were the major constituents in most of the essential oils of the family Lamiaceae and eugenol was the major terpene in all of the essential oils of the family Myrtaceae. Practical Applications: Supplementation of food with spices containing essential oils may counteract and retard the process of oxidative damage, lipid oxidation and elevate antioxidant activity of the final product.     

辛香料精油在食品保藏中的应用研究进展

文章综述了近年来国内外对于辛香料精油在抑菌方面的研究,以及在果蔬采后保藏及肉品保藏方面的应用性研究进展。辛香料精油对多种食源性致病细菌和真菌均具有很好的抑菌效果,是一种高效、安全的食品防腐剂来源。     

香辛料抗氧化活性的研究现状

香辛料有很多功能，而抗氧化活性是其重要功能之一。本文论述了30种香辛料的抗氧化活性和一些香辛料对高含DHA鱼油的抗氧化抑制效果，并介绍了从一些香辛料中分离出的具有高活性的抗氧化性物质。     

Antimicrobial activity of the essential oils of Turkish plant spices

The antimicrobial activity of the essential oils of nine plant spices (savory, laurel, oregano, basil, cumin, seafennel, myrtle, pickling herb, and mint) were tested at three concentrations (1, 10, and 15%) and tested on various microorganisms (Salmonella typhimurium, Bacillus cereus, Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Yersinia enterocolitica, Saccharomyces cerevisiae, Candida rugosa, Rhizopus oryzae and Aspergillus niger). The results showed that the essential oils tested varied in their antimicrobial activity. Individual or combinations of plant essential oils may provide an efficacious mixture for the inactivation of pathogenic and spoilage microorganisms, and to achieve adequate shelf-life of foods.     

植物精油的提取、成分分析以及抗氧化活性研究

植物精油近年来得到越来越多的关注,人们对于精油的功效寄予厚望,对多种植物精油进行了研究,包括唇形科、菊科、桃金娘科以及姜科等植物的精油。不同植物精油在成分和含量上存在较大差异,因此在生物活性方面也存在一定差异。文章主要对近几年来关于植物精油的提取、成分分析以及抗氧化活性的研究进行总结与概述,为精油的开发利用奠定研究基础。      

Antibacterial efficiency of Finnish spice essential oils against pathogenic and spoilage bacteria

The antibacterial properties of 13 essential oils, derived from spices grown in Finland, were examined with an agar diffusion method against 12 bacterial strains. The organisms tested included both spoilage and pathogenic bacteria. The gram-positive bacteria appeared to be more sensitive than the gram-negative organisms, Clostridium botulinum and Clostridium perfringens being the most sensitive. Oregano, savory, and thyme showed the broadest antibacterial activity by distinctly inhibiting the growth of all the organisms tested. By gas chromatography-mass spectrometry analysis, differences were noted in the composition of oregano and thyme oils in comparison to previous reports.     

狮头柑挥发油化学成分分析

采用水蒸气蒸馏提取挥发油,用Gas Chromatography/Mass Spectrometry(GC-MS)对狮头柑挥发油化学成分进行了定性定量分析。狮头柑的出油率很高,达到3.78%。检出42种成分,其主要成分为柠檬精油(75.5%)。     

Antimicrobial activity of essential oils from plants against selected pathogenic and saprophytic microorganisms.

The beneficial health effects of extracts from many types of plants that are used as seasoning agents in foods and beverages have been claimed for centuries. The purpose of this study was to examine the effectiveness of selected herb and spice essential oils for control of growth and survival of microorganisms. Inhibition of growth was tested by the paper disc agar diffusion method. Antibiotic susceptibility discs were used as control. Minimum lethal concentration (MLC) was determined by the tube dilution method. Essential oils from anise, angelica, basil, carrot, celery, cardamom, coriander, dill weed, fennel, oregano, parsley, and rosemary were evaluated. Inhibition ranged from complete with oregano to no inhibition with carrot oil for each of the test strains that included: Listeria monocytogenes, Staphylococcus aureus, Escherichia coli O:157:H7, Yersinia enterocolitica, Pseudomonas aeruginosa, Lactobacillus plantarum, Aspergillus niger, Geotrichum, and Rhodotorula. Oregano essential oil showed the greatest inhibition (zone, > or = 70 to 80 mm) (MLC, approximately 8 ppm). Coriander and basil were also highly inhibitory (MLC, approximately 25 to 50 ppm) to E. coli O:157:H7 and to the other bacteria and fungi tested. Anise oil was not particularly inhibitory to bacteria (inhibition zone, approximately 25 mm); however, anise oil was highly inhibitory to molds. Because some of the herbal and spice essential oils are highly inhibitory to selected pathogenic and spoilage microorganisms, they may provide alternatives and supplements to conventional antimicrobial additives in foods.     

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.     

Antimicrobial activity of clove and cinnamon essential oils against Listeria monocytogenes in pasteurized milk

The antimicrobial activity of essential oils (EOs) of cinnamon bark, cinnamon leaf, and clove against Listeria monocytogenes Scott A were studied in semiskimmed milk incubated at 7 degrees C for 14 days and at 35 degrees C for 24 h. The MIC was 500 ppm for cinnamon bark EO and 3,000 ppm for the cinnamon leaf and clove EOs. These effective concentrations increased to 1,000 ppm for cinnamon bark EO, 3,500 ppm for clove EO, and 4,000 ppm for cinnamon leaf EO when the semiskimmed milk was incubated at 35 degrees C for 24 h. Partial inhibitory concentrations and partial bactericidal concentrations were obtained for all the assayed EOs. The MBC was 3,000 ppm for the cinnamon bark EO, 10,500 ppm for clove EO, and 11,000 ppm for cinnamon leaf EO. The incubation temperature did not affect the MBC of the EOs but slightly increased the MIC at 35 degrees C. The increased activity at the lower temperature could be attributed to the increased membrane fluidity and to the membrane-perturbing action of EOs. The influence of the fat content of milk on the antimicrobial activity of EOs was tested in whole and skimmed milk. In milk samples with higher fat content, the antimicrobial activity of the EOs was reduced. These results indicate the possibility of using these three EOs in milk beverages as natural antimicrobials, especially because milk beverages flavored with cinnamon and clove are consumed worldwide and have been increasing in popularity in recent years.     

Chemical composition and antioxidant and antimicrobial activity of two Satureja essential oils

Hydro-distilled volatile oils from the aerial parts of Satureja montana L., and Satureja subspicata Bartl. ex Vis., growing wild in Bosnia and Herzegovina, were analyzed by GC/MS. More than one hundred compounds were identified in both plant oils, representing 92.4–98.1% of the total oil. The major constituents of essential oils obtained from the plant material of S. montana, collected from two different localities, were thymol (31.7%), and geraniol (22.3%), respectively. The most abundant compounds in essential oils of S. subspicata, collected at two different stages of development, were thymol (28.6%), and spathulenol (37.6%), respectively. The screening of antimicrobial activity of essential oil samples was individually evaluated against Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Pseudomonas aeruginosa and Bacillus subtilis using a paper disc diffusion method. All tested microorganisms were inhibited by essential oil samples. Antioxidant activity was tested using the DPPH radical-scavenging method. All samples showed activity comparable to thymol, which was used as a positive probe.     

Antivirulence properties and related mechanisms of spice essential oils: A comprehensive review

In recent decades, reduced antimicrobial effectiveness, increased bacterial infection, and newly emerged microbial resistance have become global public issues, leading to an urgent need to find effective strategies to counteract these problems. Strategies targeting bacterial virulence factors rather than bacterial survival have attracted increasing interest, since the modulation of virulence factors may prevent the development of drug resistance in bacteria. Spices are promising natural sources of antivirulence compounds owing to their wide availability, diverse antivirulence phytochemical constituents, and generally favorable safety profiles. Essential oils are the predominant and most important antivirulence components of spices. This review addresses the recent efforts of using spice essential oils to inhibit main bacterial virulence traits, including the quorum sensing system, biofilm formation, motility, and toxin production, with an intensive discussion of related mechanisms. We hope that this review can provide a better understanding of the antivirulence properties of spice essential oils, which have the potential to be used as antibiotic alternatives by targeting bacterial virulence.     

Composition and antioxidant activity of essential oils from Oregano plants grown wild in Greece

In this study, four samples of essential oils obtained from plant species with a wide distribution in Greece and economic importance for the world-wide spice market and also carvacrol and thymol were tested for their possible antioxidant activity. The four plant species wereOriganum vulgare subsp.hirtum, O. onites, Coridothymus capitatus andSatureja thymbra. The essential oils were chemically characterised by gas chromatography-ion trap detection. All the essential oils examined and also carvacrol and thymol were found to have antioxidant activity when tested on TLC plates and by measuring peroxide values of lard stored at 35° C. The results indicate that the antioxidant effect may be related to the presence of carvacrol and thymol in essential oils.     

Properties and antioxidant activity of fish skin gelatin film incorporated with citrus essential oils

Properties of protein-based film from fish skin gelatin incorporated with different citrus essential oils, including bergamot, kaffir lime, lemon and lime (50% based on protein) in the presence of 20% and 30% glycerol were investigated. Films containing 20% glycerol had higher tensile strength (TS) but lower elongation at break (EAB), compared with those prepared with 30% glycerol, regardless of essential oils incorporated (p < 0.05). Films incorporated with essential oils, especially from lime, at both glycerol levels showed the lower TS but higher EAB than the control films (without incorporated essential oil) (p < 0.05). Water vapour permeability (WVP) of films containing essential oils was lower than that of control films for both glycerol levels (p < 0.05). Films with essential oils had varying ΔE^* (total colour difference), where the highest value was observed in that added with bergamot essential oil (p < 0.05). Higher glycerol content increased EAB and WVP but decreased TS of films. Fourier transforms infrared (FTIR) spectra indicated that films added with essential oils exhibited higher hydrophobicity with higher amplitude at wavenumber of 2874–2926 cm⁻¹ and 1731–1742 cm⁻¹ than control film. Film incorporated with essential oils exhibited slightly lower thermal degradation resistance, compared to the control film. Varying effect of essential oil on thermal degradation temperature and weight loss was noticeable, but all films prepared using 20% glycerol had higher thermal degradation temperature with lower weight loss, compared with those containing 30% glycerol. Films added with all types of essential oils had rough cross-section, compared with control films, irrespective of glycerol levels. However, smooth surface was observed in all film samples. Film incorporated with lemon essential oil showed the highest ABTS radical scavenging activity and ferric reducing antioxidant power (FRAP) (p < 0.05), while the other films had lower activity. Thus, the incorporation of different essential oils and glycerol levels directly affected the properties of gelatin-based film from fish skin.     

Antimicrobial activity in the vapour phase of a combination of cinnamon and clove essential oils

The antimicrobial activity of the vapour generated by a combination of cinnamon and clove essential oils against the growth of four Gram-negative (Escherichia coli, Yersinia enterocolitica, Pseudomonas aeruoginosa and Salmonella choleraesuis) and four Gram-positive bacteria (Staphylococcus aureus, Listeria monocytogenes, Bacillus cereus and Enterococcus faecalis) was assessed by means of the fractional inhibitory concentration index (FIC) of the mixture. The presence of synergism or antagonism effects depended on the reference parameter used to estimate such an index. If the minimal inhibitory concentrations were applied, the vapours of the combination of essential oils exerted an antagonistic effect on the growth of E. coli, while they wielded a synergistic effect for the inhibition of L. monocytogenes, B. cereus and Y. enterocolitica when the concentrations of maximal inhibition were used. This fact revealed a clear concentration-dependent interaction.     

几种常用香辛料精油对冷藏调理鸡肉串的保鲜效果

文中研究了桂皮精油、八角精油、花椒精油、大蒜精油、生姜精油、丁香精油6种精油对冷藏调理鸡肉串的保鲜效果,并通过单因素实验和正交试验筛选出最佳复合香辛料精油保鲜剂。结果表明:6种香辛料精油的保鲜效果差异显著(P0.05),通过抑菌与感官风味的综合评价,其保鲜效果顺序为,桂皮精油八角精油与花椒精油丁香精油与姜油大蒜精油。香辛料精油的最佳复合保鲜剂组合是:0.1%八角精油、0.08%花椒精油、0.04%桂皮精油,该复合保鲜剂能使调理鸡肉串在4℃下保鲜达20 d,25℃下保鲜16~18 h,同时能使鸡肉串产品保持复合香味浓郁、略带麻辣香味,风味协调宜人。     

芹菜籽精油的抑菌与抗氧化作用研究

目的:测定芹菜籽精油(Celery seed essential oil)对几种常见食品污染微生物的抑菌活性以及抗氧化作用。方法:采用琼脂扩散法及肉汤稀释法测定精油的抑菌作用、采用DPPH(对二苯代苦味肼基)法、ABTS(2,2-联氮-二(3-乙基-苯并噻唑-6-磺酸)二铵盐)法、清除超氧离子法和抗亚油酸脂质过氧化法测定芹菜籽精油的清除自由基、抗氧化作用。结果:芹菜籽精油对于多种病原性微生物有良好的抑制作用,尤其对于革兰氏阳性菌,抑制效果尤为明显。并且,芹菜籽精油具有良好的清除自由基、抗氧化的作用,其作用要强于丁基羟基苯甲醚(BHA)和二丁基羟基甲苯(BHT)。