Aplicação de espectroscopia de infravermelhos na determinação da vida útil de hambúrgueres de carne Maronesa: influência de óleos essenciais e temperatura de armazenamento
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2015
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Os óleos essenciais (OE) podem ser utilizados como conservantes de alimentos para melhorar a segurança alimentar, reduzindo o desenvolvimento da microbiota e aumentando o tempo de vida útil da carne de bovino.
O objectivo deste estudo foi avaliar o efeito de OE de plantas e frutas de ocorrência natural no norte de Portugal sobre a deterioração de carne picada de carne Maronesa armazenados em 2 e 8 ° C, sob diferentes condições de embalagem, bem como avaliar o grau de deterioração através da aplicação de espetrocopia de infravermelho.
A utilização da técnica de espectroscopia de infravermelho com Transformada de Fourier (FTIR), combinada com quimiometria, permite estimar os valores de pH, TBARs e contagens de microorganismos e, ainda, discriminar as amostras que foram tratadas com os diferentes OE e diferenciar o seu grau de frescura.
Para produzir OE as folhas de louro (Laurus nobilis L.) e de murta (Myrtus Communis L.) foram colhidas no jardim botânico da UTAD e a casca da laranja (Citrus sinensis L.) no mercado local. As folhas e cascas secas foram submetidas ao método de hidrodestilação utilizando um aparelho do tipo Clevenger.
A carne de bovina fresca (M. semitendinosus e M. semimembranosus) de raça DOP-Maronesa (machos; n = 3) foram obtidos a partir do mercado local e transportados para o laboratório após 72h do seu abate. Depois da carne ser cortada e picada, obtiveram-se amostras de 40 g que foram embalados individualmente em duplicado em duas condições diferentes: aerobiose (Aero) e vácuo (Vac), com e sem um OE. As amostras foram armazenadas a 2 a 8 °C e analisadas imediatamente em 0,1,2,3,5,7,10,14,21,28 e 35 dias para microbiológica, cor (L * a * b *), pH, oxidação lipídica e análise sensorial. O painel treinado para análise sensorial avaliou cada amostra 60 minutos após o fim do armazenamento. Os microrganismos analisados foram mesófilos e psicrotróficos totais, Enterobacteriaceae, Pseudomonas spp, BAL e Fungos. O OE com melhor efeito foi o OE de murta em todas as análises elaboradas. Também se obtiveram resultados positivos quando as amostras são embaladas em vácuo e armazenadas à temperatura de 2ºC.
Essential oils (EO) can be used as food preservatives to improve food hygiene, reducing the development of the microbiota and increasing the shelf life of beef. The aim of this study was to evaluate the effect of EO of naturally occurring plants and fruit from the north of Portugal on the spoilage of Maronesa minced beef stored at 2 and 8°C under different packaging conditions as well as evaluate the spoilage level by the application of infrared spectroscopy. The use of infrared spectroscopy in Fourier transform (FTIR) combined with the use of chemometrics enables the quantitative prediction of the pH value, TBARs and microorganism counts and to discriminate the samples that were treated with different essential oils and differentiate their degree of freshness. To produce EO, bay leaves (Laurus nobilis L.), myrtle (Myrtus communis L.) were obtained from the botanical garden of UTAD and orange peel (Citrus sinensis L.) from the local market. The leaves and peels were subjected to hydrodistillation using a Clevenger type apparatus. Fresh beef (semitendinosus and semimembranosus) of DOP-Maronesa breed (males; n=3) were obtained from local market and transported to the laboratory. After cut and minced, 20 g samples were individually packed in duplicate in two different conditions: air (Aero) and vacuum (Vac) with and without one EO. Samples were stored at 2 and 8°C and analyzed immediately at 0,1,2,3,5,7,10,14,21,28 and 35 days for microbiological, colour (L*a*b*), pH, lipid oxidation and sensory analysis. A panel of assessors evaluated each sample after 60 min at each storage end time for color and spoiled odor. The microorganisms analyzed were total mesophilic and total psychrotrophic, Enterobacteriaceae, Pseudomonas spp, BAL and Fungi.
Essential oils (EO) can be used as food preservatives to improve food hygiene, reducing the development of the microbiota and increasing the shelf life of beef. The aim of this study was to evaluate the effect of EO of naturally occurring plants and fruit from the north of Portugal on the spoilage of Maronesa minced beef stored at 2 and 8°C under different packaging conditions as well as evaluate the spoilage level by the application of infrared spectroscopy. The use of infrared spectroscopy in Fourier transform (FTIR) combined with the use of chemometrics enables the quantitative prediction of the pH value, TBARs and microorganism counts and to discriminate the samples that were treated with different essential oils and differentiate their degree of freshness. To produce EO, bay leaves (Laurus nobilis L.), myrtle (Myrtus communis L.) were obtained from the botanical garden of UTAD and orange peel (Citrus sinensis L.) from the local market. The leaves and peels were subjected to hydrodistillation using a Clevenger type apparatus. Fresh beef (semitendinosus and semimembranosus) of DOP-Maronesa breed (males; n=3) were obtained from local market and transported to the laboratory. After cut and minced, 20 g samples were individually packed in duplicate in two different conditions: air (Aero) and vacuum (Vac) with and without one EO. Samples were stored at 2 and 8°C and analyzed immediately at 0,1,2,3,5,7,10,14,21,28 and 35 days for microbiological, colour (L*a*b*), pH, lipid oxidation and sensory analysis. A panel of assessors evaluated each sample after 60 min at each storage end time for color and spoiled odor. The microorganisms analyzed were total mesophilic and total psychrotrophic, Enterobacteriaceae, Pseudomonas spp, BAL and Fungi.
Descrição
Dissertação de Mestrado em Segurança Alimentar
Palavras-chave
Segurança alimentar , Óleo essencial , Carne picada , Espectroscopia de infravermelhos