Abstract The aim of this study was to evaluate the antimicrobial effect of the essential oils of cinnamon, cardamom, clove, oregano, and thyme and their synergism on vegetative cells and endospores of Clostridium perfringens type A inoculated in meat sausage (mortadella), as well as the influence of blends on the color, and lipid oxidation through the determination of thiobarbituric acid reactive substances (TBARS index). The anticlostridial action of the oil blends was established. The two added oil blends (Treat. 1: oregano, clove, and thyme; Treat. 2: oregano, clove, and cinnamon) in combination with reduced nitrite content (75 ppm) promoted a lower growth of C. perfringens in mortadella stored at 15 °C for 21 days in comparison to treatments containing only 75 ppm of nitrite. The essential oil blends showed antioxidant action and did not alter food color, thus possessing potential application as a preservative for the meat products industry.

ABSTRACT It is know that many plants live in symbiosis with microorganisms that can be found on their interior, the endophytes. Environment and tissue type are modulating factors of this community, in which most of these microorganisms produce important antimicrobial molecules and they may be powerful biocontrol agents in agriculture. Thus, the aim of this study was to evaluate the community of Endophytic fungi from Eremanthus erythropappus in anthropogenic and natural areas (with human interaction, natural habitat and planned planting) of Minas Gerais State, Brazil, through cultivation-based approach and verify their antimicrobial activity against phytopathogenic fungal and pathogenic bacteria. The endophytic fungi isolated were identified by sequencing of the ITS region and subjected an in vitro antagonism test. The antagonisms that show antibiosis were submitted to tests on split plates to verify the volatile compound production. In the pairing testes, the endophytic fungi of the genera Cryptosporiopsis, Diaporthe, Xylaria, Paraconiothyrium and Camarosporium presented antibiosis against phytopathogenic fungi by releasing compounds in the medium. To our knowledge, this paper is the first report on the isolation of twelve genera fungi in E. erythropappus besides verifying their antagonist capacity, which opens the way for discovery of bioactive substances produced by endophytic fungi that inhibit pathogens.

Resumo Óleos essenciais com propriedades antimicrobianas são amplamente utilizados na indústria de alimentos. Neste estudo, objetivou-se avaliar a influência da mistura de óleos essenciais de alho (Allium sativum) e tomilho (Thymus vulgaris) nas propriedades antimicrobianas e mecânicas de filmes de zeína. Quatro bactérias (Escherichia coli enteropatogênica (EPEC), Listeria monocytogenes, Salmonella Enteritidis e Staphylococcus aureus) relacionadas à contaminação de alimentos foram escolhidas para avaliar as propriedades antimicrobianas. Os resultados mostraram que a mistura de óleos atuou como um plastificante, como confirmado por uma diminuição na temperatura de transição vítrea e pelo Módulo de Young dos filmes. A adição de mistura de óleos também resultou em menor solubilidade e absorção de água. A mistura de óleo 0, 2%, 3% e 5% (v/v) adicionada nos filmes de zeína mostrou atividade inibitória contra todas as bactérias testadas com halos inibitórios entre 6,5 mm até 8,27 mm. Os resultados mostram que o revestimento pode ser aplicado como suporte para aumentar o prazo de validade de produtos alimentares.

Abstract Essential oils with antimicrobial properties are widely used in the food industry. This study aimed to evaluate the influence of a blend of garlic (Allium sativum) and thyme (Thymus vulgaris) essential oils on the antimicrobial and mechanical properties of zein films. Four bacteria (Enteropathogenic Escherichia coli (EPEC), Listeria monocytogenes, Salmonella Enteritidis and Staphylococcus aureus) related to food contamination were chosen to evaluate the antimicrobial properties. The results indicated that the oil blend acted as a plasticizer, decreasing the glass transition temperature and the Young’s Modulus of the films. The addition of the oil blend also resulted in lower solubility and water absorption. The addition of the oil blend (0, 2%, 3% and 5% (v/v)) to the zein films showed inhibitory activity against all the bacteria tested, with inhibitory halos of between 6.5 mm and 8.27 mm. The results showed that the coating could be applied as a support to increase the shelf life of food products.

Resumo Pseudomonas aeruginosa é um patógeno oportunista capaz de formar biofilmes de grande relevância para a microbiologia médica e para a indústria de alimentos. Os constituintes do óleo essencial (OE) têm sido pesquisados como novas alternativas para o controle do biofilme. Neste estudo, o cinamaldeído mostrou-se eficaz como OE contra células planctônicas de cepas de P. aeruginosa (p < 0,05) e foi então utilizado para a preparação de soluções sanitizantes que, por sua vez, foram testadas contra biofilmes de P. aeruginosa formados em superfície de aço inoxidável. Cinamaldeído mostrou atividade antibacteriana contra células sésseis de P. aeruginosa (p < 0,05). Para a estirpe ATCC 9027, foi obtida uma eliminação de células bacterianas viáveis em 100% (5,87 log-redução), após tratamento com a solução 6xMIC (0,06% Concentração Inibitória Mínima). As soluções sanitizantes de cinamaldeído podem ser novas alternativas para o controle dessas comunidades sésseis microbianas na indústria alimentícia.

Abstract Pseudomonas aeruginosa is an opportunistic pathogen capable of forming biofilms of great relevance to medical microbiology and the food industry. Essential oil (EOs) constituents have been researched as new strategies for the control of biofilms. In the present study cinnamaldehyde was shown to be an effective EO against the planktonic cells of P. aeruginosa strains (p < 0.05). Thus it was used to prepare sanitizing solutions, which were tested against P. aeruginosa biofilms formed on stainless steel surfaces. Cinnamaldehyde showed antibacterial activity against sessile P. aeruginosa cells (p < 0.05). A 100% (5.87 log-reduction) elimination of viable bacterial cells was obtained after treatment with a 6xMIC (0.06% Minimal Inhibitory Concentration) solution for the strain ATCC 9027. Sanitizing cinnamaldehyde solutions can be used as new alternatives to control such microbial sessile communities in food industries.

RESUMO: Os biofilmes são responsáveis pela maior parte da interferência causada pelos micro-organismos no processamento de alimentos. O objetivo deste estudo foi avaliar a atividade anti-biofilme do óleo essencial de canela (Cinnamomum zeylanicum) e do composto majoritário eugenol. As concentrações utilizadas de óleo essencial foram de 0,0% (controle), 0,12%; 0,48%; 0,96% e 1,92%; a concentração de eugenol foi de 0,76%. As concentrações foram determinadas a partir de outros estudos publicados. Determinou-se o número de células viáveis e quantificou-se a biomassa bacteriana. O tratamento anti-biofilme foi eficaz na prevenção e formação de biofilmes. A concentração de 1,92% foi satisfatória, com redução de 5,91log CFUcm-2 de células viáveis em biofilme de Escherichia coli e redução de 5,17log CFU cm-2 de Staphylococcus aureus. A biomassa de ambas bactérias foi reduzida significativamente (P<0,05), entretanto, o tratamento sanitizante não foi eficaz na redução da biomassa. Diante dos resultados, o óleo essencial de canela e eugenol podem ser alternativas promissoras no controle de biofilmes.

ABSTRACT: Biofilms are responsible for most of the interference caused by microorganisms in food processing. The aim of this study was to evaluate the cinnamon (Cinnamomum zeylanicum) essential oil and eugenol sanitizer and anti-biofilm activity against biofilms. Concentrations used of essential oil were 0.0% (control) 0.12%; 0.48%; 0.96% and 1.92%; the amount of eugenol was 0.76%. Concentrations were determined from other published studies. Number of viable cells and quantification the bacterial biomass were determined. Anti-biofilm treatment was effective in preventing the formation of biofilms. The 1.92% concentration was the most satisfactorily with Escherichia coli reduction of 5.91log CFUcm-2 and Staphylococcus aureus reduction of 5.17log CFUcm-2 (P<0.05) biomass of the two bacteria. Sanitizing treatment was not effective in reducing biomass. Seen this, the cinnamon and eugenol essential oil may be promising alternatives for controlling biofilms.

Abstract Bochothrix thermosphacta is an optional aerobic psychrotrophic related to the meat deterioration and consequently loss of a refrigerated cargo contaminated. Predictive microbiology can be used as a quality assurance tool, since it allows the prediction of microbial response based in pass observations. This work aimed model the growth of B. thermosphacta under variation of pH and temperature. For this purpose, the experimental growth data were fitted to the primary models of Baranyi and Roberts and the modified Gompertz model and the data for the maximum rate of growth (μmax) were adjusted to Ratkowsky extended secondary model. The results showed us that the influence of temperature on growth parameters was more evident than pH. Since, by fixing the temperature the change of pH little altered the μmax. However, as the temperature rises the elevation at the μmax is considerable, for example the comparison of predicted values for μmax, when the temperature exceeds 4 °C to 12 °C, it is clear that these rates are more than double. Finally, it is emphasized that all tested models feature good fit to the experimental data, which makes them validated for prediction growth of B. thermosphacta in the same conditions tested experimentally.

Abstract Meat is one of the most perishable foods owing to its nutrient availability, high water activity, and pH around 5.6. These properties are highly conducive for microbial growth. Fresh meat, when exposed to oxygen, is subjected to the action of aerobic psychrotrophic, proteolytic, and lipolytic spoilage microorganisms, such as Pseudomonas spp. The spoilage results in the appearance of slime and off-flavor in food. In order to predict the growth of Pseudomonas fluorescens in fresh meat at different pH values, stored under refrigeration, and temperature abuse, microbial mathematical modeling was applied. The primary Baranyi and Roberts and the modified Gompertz models were fitted to the experimental data to obtain the growth parameters. The Ratkowsky extended model was used to determine the effect of pH and temperature on the growth parameter µmax. The program DMFit 3.0 was used for model adjustment and fitting. The experimental data showed good fit for both the models tested, and the primary and secondary models based on the Baranyi and Roberts models showed better validation. Thus, these models can be applied to predict the growth of P. fluorescens under the conditions tested.

Resumo Objetivou-se o desenvolvimento e caracterização tecnológica e microbiológica de presunto cru desossado contendo lactulose como prebiótico. Os presuntos foram elaborados utilizando-se a transglutaminase como agente ligante e glucona-delta-lactona como acidulante, sendo avaliadas uma formulação controle e outra com adição de 2% de lactulose (LAC). Ambos os produtos obtidos atenderam aos padrões físico-químicos e microbiológicos determinados na legislação brasileira para presuntos crus. A perda de massa na etapa de secagem foi maior (P < 0,05) nos produtos adicionados de lactulose do que no controle. Não foram encontradas diferenças significativas (P > 0,05) entre os tratamentos para os parâmetros avaliados durante o processamento, com os valores de umidade, atividade de água (aw) e nitrito residual reduzindo-se (P < 0,05) e os valores de acidez, bactérias ácido-lática e índice de TBARS aumentando (P < 0,05) com a maturação. Os produtos elaborados apresentaram pH (5,55 ± 0,37) e aw (0,90 ± 0,01) condizentes com produtos curados dessecados, não havendo (P > 0,05) diferenças entre os tratamentos para a composição centesimal e a cor final dos produtos. O teor de lactulose no produto LAC foi de 1,44% ± 0,37%, o que indica a viabilidade da utilização desse prebiótico na elaboração de presuntos crus desossados com vistas à alegação de produto com propriedade funcional.

Summary The objective was to develop and characterize technologically and microbiologically a boneless dry-cured ham containing lactulose as a prebiotic. The dry-cured hams were processed using transglutaminase as the binder and glucono-delta-lactone as the acidifying agent, evaluating one control formulation and another with the addition of 2% lactulose (LAC). Both products obtained complied with the physical, chemical and microbiological standards set by the Brazilian legislation for dry-cured hams. The mass losses during the drying stage were higher (P < 0.05) for the products containing added lactulose than for the control. No significant differences were found (P > 0.05) between treatments for the evaluated parameters during processing, with the moisture content, water activity (aw) and residual nitrite reducing ( P< 0.05), and the acidity, lactic acid bacteria and TBARS values increasing (P < 0.05) during the ripening stage. The finished products showed pH (5.55 ± 0.37) and aw (0.90 ± 0.01) values consistent with dried cured products, with no differences (P > 0.05) between treatments for the proximate composition and colour of the products. The lactulose content of the LAC product was 1.44 ± 0.37%, indicating the feasibility of using this prebiotic in the preparation of boneless dry-cured hams in order to obtain products with a functional property claim.

Lactococcus lactis e Saccharomyces cerevisiae foram avaliados em co-cultura durante fermentação para a produção de cachaça. L. lactis UFLA CA 312 e S. cerevisiae UFLA CA 11 foram utilizados com populações de aproximadamente 105 CFU mL-1 e 108 UFC mL-1, respectivamente. O meio contendo caldo de cana de açúcar, adicionado de 1% de extrato de levedura (SCM) foi eficiente para o crescimento de L. lactis UFLA CA 312 e S. cerevisiae UFLA CA 11 (letra 'b' no teste de Tukey). Nas fermentações conduzidas em frascos e dornas o crescimento da levedura não foi influenciado negativamente pela bactéria lática. Entretanto, após 19h de fermentação, a população bacteriana apresentou pequeno decréscimo. Considerando os parâmetros alcoóis superiores e aldeídos, a cachaça produzida pela cultura pura de S. cerevisiae foi semelhante à cachaça produzida pela cultura mista. A cachaça produzida pela cultura mista apresentou elevados valores de acidez volátil (letra 'b' no teste Scott-Knott), sendo caracterizada por este parâmetro na análise de componente principal. Uma elevada porcentagem de aceitação (81,10%) para o atributo aroma foi observada para as amostras de cachaça produzidas com a cultura mista.

Lactococcus lactis and Saccharomyces cerevisiae in co-culture were evaluated during sugar cane fermentantion for cachaça production. The inocula containing L. lactis UFLA CA 312 and S. cerevisiae UFLA CA 11 were used in the population of approximately 105 CFU mL-1 and 108 CFU mL-1, respectively. The sugar cane medium plus 1% of yeast extract (SCM) was efficient for growth of L. lactis UFLA CA 312 and S. cerevisiae UFLA CA 11 (letter 'b'-Tukey test). In flasks and vats fermentation the growth of UFLA CA 11 was not negatively influenced by L. lactis UFLA CA 312. However, after 19 hours of fermentation, bacterial population showed a slight decrease. Considering parameters higher alcohols and aldehydes, cachaça produced by pure culture of S. cerevisiae was similar to cachaça produced by mixed culture. Cachaça produced by mixed culture showed high values of volatile acidity (letter 'b'-Tukey test) being characterized by this parameters in the principal component analysis. High percentage of acceptance (81.10%) for the attribute aroma was observed in samples from cachaça produced by mixed culture.

O controle do crescimento microbiano tanto na indústria de alimentos quanto em ambientes hospitalares é de extrema importância. Entretanto, observa-se aumento da resistência dos microrganismos aos desinfetantes mais empregados, observando-se a necessidade de estudos com novos antimicrobianos. Assim, o objetivo desse trabalho foi avaliar a atividade antimicrobiana e a curva de morte termoquímica de soluções desinfetantes de óleos essenciais sobre Escherichia coli, Staphylococcus aureus e Salmonella Enteritidis. Foram utilizados os óleos essenciais de Thymus vulgaris (tomilho), Elettaria cardamomum (cardamomo), Eugenia caryophyllus (cravo botão) e Foeniculum vulgare dulce (funcho doce). As concentrações mínimas inibitórias foram determinadas utilizando-se a técnica de diluição em placas. As concentrações testadas foram de (%): 0,00; 0,25; 0,5; 1,0; 2,0; 2,5; 3,0; 3,5; 4,0; 4,5; e 5,0. Escherichia coli foi a única bactéria sensível a todos os óleos em concentrações abaixo de 5%. Cravo da índia não inibiu o crescimento de S. aureus nas concentrações testadas. Somente o óleo essencial de tomilho inibiu o crescimento de Salmonella Enteritidis. Observando-se as curvas de morte termoquímica de S. aureus, nota-se que a solução desinfetante contendo óleo essencial de tomilho foi a mais eficiente, tanto a 25 quanto a 40°C, sendo necessário apenas 10min. de contato para não serem mais detectadas células viáveis. A solução desinfetante contendo 0,25% de óleo essencial de tomilho, tanto a 25 quanto a 40°C, eliminou as células de S. Enteritidis após10min. de contato. Já pra E. coli , os melhores resultados foram obtidos com as soluções desinfetantes contendo óleos essenciais de funcho doce e cravo da índia a 25 e 40°C e tomilho a 40°C. Todos os tratamentos, exceto aqueles contendo óleo essencial de cardamomo, reduziram o número de células viáveis das bactérias testadas em pelo menos 5 ciclos log, sendo considerados adequados para utilização como desinfetantes

The control of microbial growth in the food industry and in hospital environments is extremely important. However there is increasing resistance of microorganisms to disinfectants normally applied, which leads to the need for new antimicrobial studies. The aim of this study was to evaluate the antimicrobial activity and thermochemical death curve of disinfectant solutions from essential oils on Escherichia coli, Staphylococcus aureus and Salmonella Enteritidis. The essential oils of Thymus vulgaris (thyme), Elettaria cardamomum (cardamom), Eugenia caryophyllus (clove bud) and Foeniculum vulgare dulce (sweet fennel) were used. The minimum inhibitory concentrations were determined using dilution technique in Petridish. The concentrations tested were (%): 0.00 , 0.25, 0.5, 1.0 , 2.0, 2.5 , 3.0, 3.5, 4.0 , 4.5, and 5.0. Escherichia coli were the only bacteria sensitive to all oils at concentrations below 5%. Cloves did not inhibit the growth of S. aureus at the concentrations tested. Only the thyme essential oil inhibited the growth of Salmonella Enteritidis. Observing the thermochemical death curves of S. aureus one can see that the disinfectant solution containing thyme essential oil was the most effective, both at 25 and 40°C, requiring only 10min contact to no longer detecte viable cells. The disinfectant solution containing 0.25% thyme essential oil, both at 25 and 40°C removed S. Enteritidis cells after 10min. contact. For E. coli the best results were obtained with disinfectant solutions containing fennel and sweet clove essential oils at 25 and 40°C and thyme at 40°C. All treatments, except that containing cardamom essential oil, reduce the number of viable bacteria cells tested in at least 5log cycles, being considered suitable for use as disinfectants

This study was developed in order to evaluate two alternatives for the control of Listeria monocytogenes in raw bovine meat pieces, both based on the use of Thymus vulgaris and Rosmarinus officinalis essential oils (EOs). The antilisterial activity of different concentrations of the EOs was tested in vitro using agar dilution and disk volatilization techniques. In addition, L. monocytogenes was inoculated in meat pieces, which were submerged in edible gelatin coatings containing 2% (v/v) EOs or submitted to the vapor of EOs (0.74 μL.cm-3). L. monocytogenes was quantified after one, 48 and 96 hours of storage (7 °C). In the in vitro tests, the EO of T. vulgaris presented higher activity. The two options used (edible gelatin coating and vapor activity), in spite of exercising effects with differentiated behaviors, presented antibacterial activity against L. monocytogenes inoculated in raw bovine meat (p < 0.05). Greatest antibacterial activity were obtained in the experiment that used edible coatings containing EOs, at 48 hours of storage reductions in bacterial counts between 1.09 and 1.25 Log CFU.g-1 were obtained. In the vapor effect experiment, the EO of T. vulgaris caused the highest reduction in the population of bacteria inoculated in raw bovine meat (p < 0.05), 0.40 Log CFU.g-1 at 96 hours of storage. This study supplied important information regarding new and promising natural alternatives, based on the concept of active packaging, for the control of L. monocytogenes in the meat industry.

This study demonstrates the possibility of using sanitizing detergents based on natural products for the elimination and/or reduction of Aeromonas hydrophila biofilm formed on stainless steel surfaces. The goal of this work was to determine the reduction effect of sanitizing detergents containing essential oils of Thymus vulgaris (thyme) and Cymbopogon citratus (lemongrass) on biofilm formed by A. hydrophila on AISI 304 stainless steel coupons, using UHT skimmed milk as substratum. There was adhesion and biofilm formation by A. hydrophila at 28 ºC, presenting 7.60 log cfu.cm-2 after the fourth day of cultivation. There was no significant difference between the lemongrass treatment and that of the thyme oil (p < 0.05). However, both treatments significantly reduced the biofilm, differing significantly from the NaOH control (p > 0.05). The treatment with lemongrass solution reduced the biofilm by 4.51 log cfu cm-2 at 25 ºC. The thyme detergent also reduced the number of cfu cm-2 by 3.84 log cycles at 25 ºC. The use of the lemongrass and thyme solutions efficiently reduced the A. hydrophila biofilm.

This research evaluated the antimicrobial effect of the clove (Syzygium aromaticum) and lemongrass (Cymbopogon citratus (DC.) Stapf.) essential oils (EOs) against Listeria monocytogenes ATCC 19117 growth added to bovine ground meat stored under refrigeration (5 ± 2 °C) for three days. The EOs, extracted by hydrodistillation and analyzed by gas chromatography-mass spectrometry (GC-MS), were tested in vitro using an agar well diffusion methodology for determination of Minimum Inhibitory Concentration (MIC). The MIC concentrations for both essential oils on culture tested of L. monocytogenes were 1.56%. The EOs concentrations applied in contaminated ground beef were 1.56, 3.125 and 6.25% (w/v) based on MIC levels and possible activity reductions by food constituents. The bacteria populations were significantly reduced (p < 0.05) after one day of storage in ground meat samples treated with clove and lemongrass EOs at concentrations of 1.56%. There were no significant counts of L. monocytogenes in samples at the other concentrations of the two oils applied after the second day of storage. The sensory acceptability evaluation of the bovine ground meat samples treated with EOs showed that the addition at concentrations higher than 1.56% promote undesirable alterations of taste, odor and characteristic color. The application of EOs at low concentrations in food products can be used in combination with other preservation methods, such as refrigeration, to control pathogens and spoilage bacteria during shelf-life; which goes according to current market trends, where consumers are requesting natural products.

O trabalho foi realizado com o objetivo de avaliar a qualidade de pequis inteiros e fatiados submetidos ao congelamento por ar forçado durante 12 meses de armazenamento. Os frutos foram selecionados, lavados, sanitizados, descascados, branqueados, resfriados, fatiados e mantidos inteiros, acondicionados em saco de polietileno de baixa densidade, congelados em túnel de congelamento com ar forçado por 6 horas (-18°C) e armazenados em congelador doméstico a -18°C (±2°C), por 12 meses. A cada três meses, foram realizadas as seguintes análises: pH, acidez titulável, sólidos solúveis, firmeza, valores L*, a*, b*, h° e C*, carotenoides totais, β-caroteno, vitamina C, índice de peróxidos, coliformes a 35°C e a 45°C e pesquisa de Salmonella sp. O congelamento do pequi inteiro é mais efetivo em preservar os teores de sólidos solúveis e vitamina C e os valores L* e b* quando comparado com o do pequi fatiado. O tempo de armazenamento de 12 meses determina redução nos valores a*, b*, C* e de firmeza e nos teores de sólidos solúveis, carotenoides totais, β-caroteno e vitamina C em pequi congelado, independentemente do corte usado. O pequi congelado não sofre o processo de rancificação oxidativa nem alterações no pH, nos teores de acidez titulável e na tonalidade de cor (h°). Pequis congelados, na forma inteira e fatiada, são considerados seguros microbiologicamente durante 12 meses de armazenamento, não oferecendo riscos à saúde dos consumidores, desde que obedecidas à cadeia de frio e às boas práticas de fabricação.

This research was carried out aiming to evaluate the quality of pequi fruit (whole and sliced) after forced-air freezing storage during 12 months. The fruits were submitted to treatments as follows: selecting, washing, sanitizing, peeling, blanching, cooling, and slicing or not. After that, the fruits were storage using low density polyethylene bags and submitted to forced-air freezing (-18°C) for 6 hours and stored in freezer at the same temperature (±2°C) for 12 months. Each three months were measured: pH, titratable acidity, soluble solids, firmness, color (L*, a*, b*, h° and C* values), total carotenoids, β-carotene, vitamin C, peroxide value, coliforms at 35°C and 45°C and Salmonella sp. Frozen whole pequi fruits is more effective in preserving the soluble solids and vitamin C contents and L* and b* values as compared to the sliced pequi fruits. The freezing-storage time reduce a*, b* and C* values, firmness values, soluble solids, total carotenoids, β-carotene and vitamin C contents of the pequi fruit, whole or sliced. Pequi fruit frozen is not affected by rancidity oxidative process, and also does not alter the pH, titratable acidity, and color (h°). Pequi fruit frozen and stored during 12 months are considered microbiologically safe, not offering health risks to consumers, since that the good practices of manufacture are realized and the freezing and stored process are performed correctly.

Diversos óleos essenciais de plantas condimentares e medicinais possuem atividade antimicrobiana comprovada, sendo de grande interesse para a indústria de alimentos. Dessa forma, as Concentrações Mínimas Inibitórias (CMI) desses óleos para diversas bactérias devem ser determinadas. As CMI variam de acordo com o óleo utilizado, dos compostos majoritários e da fisiologia da bactéria em estudo. Na presente pesquisa, os óleos essenciais das plantas Thymus vulgaris (tomilho), Cymbopogon citratus (capim-limão) e Laurus nobilis (louro) foram quantificados quimicamente e determinou-se a CMI sobre as bactérias Staphylococcus aureus ATCC 25923, Escherichia. coli ATCC 25922, Listeria monocytogenes ATCC 19117, Salmonella entérica Enteritidis S64 e Pseudomonas aeruginosa ATCC 27853. O óleo essencial de C. citratus demonstrou atividade bacteriana em todas as concentrações testadas e sobre todas as bactérias, sendo seus constituintes majoritários o geranial e neral. O constituinte majoritário de T. vulgaris foi 1,8 cineol e do óleo de L. nobilis, que apresentou menor atividade antibacteriana, foi o linalool, seguido pelo 1,8 cineol. As bactérias Gram-negativas demostraram maior resistência perante o uso dos óleos essenciais testados neste estudo, E. coli foi a menos sensível, sendo inibida apenas pelos óleos de C. citratus e L. nobilis.

Several essential oils of condiment and medicinal plants possess proven antimicrobial activity and are of important interest for the food industry. Therefore, the Minimum Inhibitory Concentrations (MIC) of those oils should be determined for various bacteria. MIC varies according to the oil used, the major compounds, and the physiology of the bacterium under study. In the present study, the essential oils of the plants Thymus vulgaris (time), Cymbopogon citratus (lemongrass) and Laurus nobilis (bay) were chemically quantified, and the MIC was determined on the bacteria Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922, Listeria monocytogenes ATCC 19117, Salmonella enterica Enteritidis S64, and Pseudomonas aeruginosa ATCC 27853. The essential oil of C. citratus demonstrated bacterial activity at all concentrations tested and against all of the bacteria tested. The majority of essential oil compounds were geranial and neral. The major constituent of T. vulgaris was 1.8-cineol and of L. nobilis was linalool, which presented lower antibacterial activity, followed by 1.8-cineol. The Gram-negative bacteria demonstrated higher resistance to the use of the essential oils tested in this study. E. coli was the least sensitive and was inhibited only by the oils of C. citratus and L. nobilis.