Essential oils of herbs and spices in dry-cured meat products: chemical characterization, antimicrobial properties, effect on foodborne pathogens and sensory acceptability in chouriço
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2015-09-21
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Os óleos essências (OEs) tem sido utilizados na industria alimentar como aromatizantes.
As suas características antimicrobianas sobre microrganismos patogénicos alimentares
e/ou deteriorativos tem aumentado o seu interesse como conservantes naturais. As
novas tendências dos consumidores representam um desafio para a indústria alimentar,
sendo estas as responsáveis pelo desenvolvimento de novas estratégias para satisfazer os
seus requisitos sem comprometer a segurança e qualidade dos produtos.
No âmbito dos produtos cárneos, a sua segurança é garantida por uma baixa atividade
agua e baixo pH, os quais actuam como barreiras que dificultam o desenvolvimento de
microrganismos patogénicos e/ou deteriorativos. No entanto, a ocorrência de surtos de
toxinfeções alimentares associados ao consumo de produtos cárneos curados na Europa
e nos Estados Unidos tem colocado em dúvida a sua segurança. Devido à grande
variedade de temperos utilizados na elaboração de produtos cárneos, o objectivo deste
estudo consiste na determinação do efeito antimicrobiano de OEs de especiarias
utilizadas no fabrico deste tipo de produtos contra microrganismos patogénicos e/ou
deteriorativos.
Os OEs de pimenta negra, limão, laranja, salsa, estragão, canela, noz-moscada,
rosmaninho, loureiro, cominho, alho e tomilho foram caracterizados por cromatografia
gasosa – espectrometria de massas. As suas propriedades antimicrobianas foram
determinadas in vitro tanto de forma individual como em combinação. Foi ainda
estudada a influencia da composição do alimento (gordura e proteína), pH, aW e
aditivos (nitratos, fosfatos e acidificantes) sobre as suas propriedades antimicrobianas.
Por último, foi objecto de estudo o efeito antimicrobiano dos OEs em chouriço
inoculado com Salmonella spp., L. monocytogenes e S. aureus.
Os resultados in vitro demonstraram que o efeito antimicrobiano é variável em função
da composição do OE, sendo de maior a menor na seguinte ordem: tomilho e canela,
rosmaninho e cominho, alho, loureiro, pimenta negra, limão, salsa e noz-moscada.
A combinação dos OEs resultou num efeito antimicrobiano sinérgico, obtendo uma
diminuição da concentração mínima inibitória individual. A concentração mínima inibitória do OE de tomilho é semelhante, tanto na utilização individual como em
combinação com outros OEs. A presença do OE de canela em combinação com os OEs
de cominho ou salsa também diminui a concentração mínima inibitória destes últimos.
Os resultados da combinação de OEs mostraram, de uma forma geral, um efeito
sinérgico com uma diminuição da CMI, sendo de especial interesse na utilização no
fabrico de produtos cárneos sem potencial compromisso das suas características
sensoriais.
Relativamente à composição do meio de cultura, a gordura exerce um efeito negativo no
efeito antimicrobiano dos OEs associado à sua diluição na fase lipídica enquanro a
concentração de proteína não influencia o seu efeito antimicrobiano. O pH, aW, nitrito
de sódio ou lactato de sódio não parecem influenciar o efeito antimicrobiano dos OEs.
No entanto, observou-se uma possível interacção entre os fosfatos e os OEs devido ao
progressivo aumento das contagens bacterianas. Os resultados do estudo in vitro da
influência das características do meio de cultura sobre o efeito antimicrobiano é
fundamenta para determinar o comportamento dos OEs contra microrganismos
patogénicos previamente à sua aplicação em alimentos.
A utilização de OEs no fabrico de chouriço pode ser considerada como uma estratégia
natural para incrementar a sua segurança contra Salmonella spp., L. monocytogenes e S. aureus. Embora foram demonstradas as propriedades antimicrobianas dos OEs, a sua
utilização como substancias antimicrobianas devem ser avaliadas em alimentos. De
forma geral, a sua adição na elaboração do chouriço mostrou uma inibição dos
microrganismos patogénicos embora esta inibição varia em função do tipo de OE,
concentração e fase de cura. Entre os OEs estudados, o rosmaninho, o tomilho e o
oregano apresentaram as maiores inibições. De acordo com as contagens de Salmonella
spp e L . monocytogenes, o período de cura pode ser reduzido a 15 dias na presença de
OEs.
Devido a que impacto sensorial dos OEs tem sido descrito como um dos seus
inconvenientes, foi estudado o impacto de vários OEs em três concentrações (0.005%,
0.05% e 0.5%) em chouriço. Foi avaliado o impacte geral, a adequação à intensidade
assim como as tendências de consumo e compra. Os resultados mostraram que os
chouriços com a menor concentração de OEs apresentaram uma maior aceitabilidade.
Verificou-se que o aumento da concentração do OE tem um impacto negativo na
aceitabilidade do produto. Entre os OEs estudados, chouriços elaborados com OEs de
alho e orégano a 0.005% foram os mais valorados pelos consumidores.
Os resultados do presente estudo podem ajudar à indústria alimentar a seleccionar os OEs mais adequados no fabrico dos produtos cárneos garantindo a segurança alimentar
sem compromiso das suas características naturais, saudáveis e prontos para consumo de acordo com as tendências dos consumidores
In food industry, essential oils (EOs) have been traditionally used as flavouring agents although their antimicrobial properties against foodborne and spoilage microorganisms increase their utilization as natural preservatives. Nowadays, consumers demand minimally processed product without addition of chemical additives, easily prepared, and ready-to-eat. These consumers´ trends represent a challenge for food industry that need develop new strategies to comply the consumers´ requirements without compromising the safety and quality of foodstuffs. Dry-cured meat products are considered safe products mainly by the low water activity and pH that acts as hurdles that delay the growth of foodborne and spoilage pathogens. The occurrence of foodborne outbreaks in both Europe and United States have put the spotlight onto the safety of meat products. Because manufacture of meat products admits a large variety of seasonings, the objective of the current study consists on the chemical characterization and antimicrobial determination of EOs of herbs and spices commonly used on manufacture of dry-cured meat products against foodborne a spoilage bacteria. Antimicrobial effect of combination of EOs were assessed by checkerboard while the influence of culture media composition (fat and protein content) pH, aW and food additives (sodium nitrite, phosphates and sodium lactate) on the antimicrobial properties of EOs was studied. At last, to shed light onto the scarce information about utilization of EOs in meat products, the antimicrobial effect against foodborne pathogens and sensory assessment were determined. Results showed that in vitro antimicrobial activity of EOs was variable. According to the potency of inhibitory action, the EOs can be ordered, from the highest to the lowest, as follows: thyme and cinnamon, rosemary and cumin, garlic, bay, black pepper, lemon, parsley and nutmeg. The EOs of orange, basil and tarragon were considered as noninhibitory. Combination of selected EOs displayed a synergic effect against foodborne pathogens and also an important decrease of their individual minimal inhibitory concentration (MIC). Essential oils of thyme and cinnamon presented the largest antibacterial activity against foodborne pathogens. Moreover, the utilization of cinnamon EOs also improved the reduction of the individual MIC of EOs of cumin and parsley. Thus, combinations of selected EOs inhibit foodborne pathogens, improving their performance to be used in the manufacture of meat products avoiding their potential organoleptical rejection. The influence of food composition on the antimicrobial effect of EOs showed that fat has a negative effect probably due to its dilution on the lipid phase. The level of protein does not influence the inhibitory effect of EOs although slightly reduction was observed in the lowest protein level tested. The pH and aW not appear influence the antimicrobial effect of EOs. With regards of food additives, the addition of nitrite and sodium lactate did not influence the inhibitory effect of EOs. However, the current study revealed that a possible interaction of food phosphates with EOs leading to its progressive inactivation. The in vitro study of the influence of food characteristic on the antimicrobial effect of EOs are an important step to address the behaviour of EOs against specific foodborne pathogens previously its application in foodstuff. Utilization of EOs in manufacture of chouriço resulted in a natural strategy to improve its safety against Salmonella spp, L. monocytogenes and S. aureus. Although, EOs possess antibacterial properties in vitro, their utilization as food antimicrobial agents must be assessed in the food product. The antibacterial effect varies according to the EOs, concentration and drying period. Among them, EOs of rosemary, oregano and thyme presented the highest inhibition properties. Regarding Salmonella spp. and L. monocytogenes counts, drying period could be shortened to 15 days in the presence of EOs, being interesting for meat industry to increase the yield production Because the sensorial impact of EOs in foodstuff has been described as a constrain, the current work studies the sensory impact of several EOs at three levels (0.005%, 0.05% and 0.5%) in dry-cured chouriço by overall acceptability, just-about-right scale, consumption trend and potential purchase. Results showed that chouriço made with the lowest EO concentration, presented the best performance. Moreover, the increase of the EO concentration showed a negative impact on the acceptance of the meat products. Among the EOs tested, essential oils of garlic and oregano, used in the manufacture of chouriço at 0.005%, were the most appreciated by consumers. Thus, the results of the current study may help the food industry to select the more appropriate EOs to guarantee the food safety of meat products maintaining the compromise of manufacture of natural, healthy and ready-to-eat meat products according to the consumers´ demands.
In food industry, essential oils (EOs) have been traditionally used as flavouring agents although their antimicrobial properties against foodborne and spoilage microorganisms increase their utilization as natural preservatives. Nowadays, consumers demand minimally processed product without addition of chemical additives, easily prepared, and ready-to-eat. These consumers´ trends represent a challenge for food industry that need develop new strategies to comply the consumers´ requirements without compromising the safety and quality of foodstuffs. Dry-cured meat products are considered safe products mainly by the low water activity and pH that acts as hurdles that delay the growth of foodborne and spoilage pathogens. The occurrence of foodborne outbreaks in both Europe and United States have put the spotlight onto the safety of meat products. Because manufacture of meat products admits a large variety of seasonings, the objective of the current study consists on the chemical characterization and antimicrobial determination of EOs of herbs and spices commonly used on manufacture of dry-cured meat products against foodborne a spoilage bacteria. Antimicrobial effect of combination of EOs were assessed by checkerboard while the influence of culture media composition (fat and protein content) pH, aW and food additives (sodium nitrite, phosphates and sodium lactate) on the antimicrobial properties of EOs was studied. At last, to shed light onto the scarce information about utilization of EOs in meat products, the antimicrobial effect against foodborne pathogens and sensory assessment were determined. Results showed that in vitro antimicrobial activity of EOs was variable. According to the potency of inhibitory action, the EOs can be ordered, from the highest to the lowest, as follows: thyme and cinnamon, rosemary and cumin, garlic, bay, black pepper, lemon, parsley and nutmeg. The EOs of orange, basil and tarragon were considered as noninhibitory. Combination of selected EOs displayed a synergic effect against foodborne pathogens and also an important decrease of their individual minimal inhibitory concentration (MIC). Essential oils of thyme and cinnamon presented the largest antibacterial activity against foodborne pathogens. Moreover, the utilization of cinnamon EOs also improved the reduction of the individual MIC of EOs of cumin and parsley. Thus, combinations of selected EOs inhibit foodborne pathogens, improving their performance to be used in the manufacture of meat products avoiding their potential organoleptical rejection. The influence of food composition on the antimicrobial effect of EOs showed that fat has a negative effect probably due to its dilution on the lipid phase. The level of protein does not influence the inhibitory effect of EOs although slightly reduction was observed in the lowest protein level tested. The pH and aW not appear influence the antimicrobial effect of EOs. With regards of food additives, the addition of nitrite and sodium lactate did not influence the inhibitory effect of EOs. However, the current study revealed that a possible interaction of food phosphates with EOs leading to its progressive inactivation. The in vitro study of the influence of food characteristic on the antimicrobial effect of EOs are an important step to address the behaviour of EOs against specific foodborne pathogens previously its application in foodstuff. Utilization of EOs in manufacture of chouriço resulted in a natural strategy to improve its safety against Salmonella spp, L. monocytogenes and S. aureus. Although, EOs possess antibacterial properties in vitro, their utilization as food antimicrobial agents must be assessed in the food product. The antibacterial effect varies according to the EOs, concentration and drying period. Among them, EOs of rosemary, oregano and thyme presented the highest inhibition properties. Regarding Salmonella spp. and L. monocytogenes counts, drying period could be shortened to 15 days in the presence of EOs, being interesting for meat industry to increase the yield production Because the sensorial impact of EOs in foodstuff has been described as a constrain, the current work studies the sensory impact of several EOs at three levels (0.005%, 0.05% and 0.5%) in dry-cured chouriço by overall acceptability, just-about-right scale, consumption trend and potential purchase. Results showed that chouriço made with the lowest EO concentration, presented the best performance. Moreover, the increase of the EO concentration showed a negative impact on the acceptance of the meat products. Among the EOs tested, essential oils of garlic and oregano, used in the manufacture of chouriço at 0.005%, were the most appreciated by consumers. Thus, the results of the current study may help the food industry to select the more appropriate EOs to guarantee the food safety of meat products maintaining the compromise of manufacture of natural, healthy and ready-to-eat meat products according to the consumers´ demands.
Descrição
Tese de Doutoramento em Ciências Veterinárias
Palavras-chave
Produto à base de carne , Carne curada , Óleos essenciais , Antimicrobianos , Chouriço