Utilization of zein-based coatings containing vegetable oils on the physicochemical characteristics of vacuum-packaged lamb meat / Utilização de revestimentos à base de zeínas contendo óleos vegetais sobre as características físico-químicas da carne de cordeiro embalada a vácuo

During the shelf-life of fresh meat, physical, chemical, microbiological, and sensory changes may occur. To avoid such changes, the combination of vacuum-packaging and use of edible coatings make a good strategy. This study aimed to evaluate the physicochemical characteristics of vacuum-packaged lamb meat combined with different zein-based edible coatings containing different vegetable oils (pink pepper, rosemary, olive oil, and the combinations of olive oil + pink pepper or rosemary), stored at 5 ± 1 °C. Parameters including pH, instrumental color, water holding capacity (WHC), shear force, and thiobarbituric acid reactive substances (TBARS) were analyzed every seven days, for 29 days. Significant differences (P<0.05) were observed in coating effects and storage time. The combination of olive oil and pepper oil (OLPP) exhibited higher color stability, while the coatings containing rosemary (RO), rosemary and olive oil (OLRO), and pink pepper oil (PP) exhibited the highest oxidative stability in 29 days. The pH, WHC, and shear force parameters did not appear to have been affected by the coatings. In summary, as appearance is an important purchasing factor, the coating containing olive oil and pink pepper oil is very promising as an alternative for maintaining vacuum-packaged lamb meat quality.(AU)

Durante a vida de prateleira da carne fresca podem ocorrer mudanças físico-químicas, microbiológicas e sensoriais indesejadas. Para evitar tais mudanças a combinação da embalagem tradicional à vácuo com revestimentos comestíveis é uma alternativa. O objetivo deste estudo foi avaliar o efeito do uso de diferentes revestimentos comestíveis à base de zeínas em combinação com diferentes óleos vegetais (óleos de: pimenta rosa, alecrim, azeite e combinação de azeite + óleo de pimenta rosa ou alecrim) nas características fisico-químicas da carne ovina, embalada à vácuo e armazenada à temperatura 5±1 °C. Foram realizadas análises de pH, cor instrumental, capacidade de retenção de água (CRA), força de cisalhamento, substâncias reativas ao ácido tiobarbitúrico (TBARS) a cada sete dias, no período de 29 dias. Foram observadas diferenças significativas (P<0,05) para o efeito de revestimentos e o tempo de armazenamento. A combinação de azeite mais óleo de pimenta (OLPP), apresentou maior estabilidade de cor, enquanto que os revestimentos contendo alecrim (RO), alecrim mais azeite (OLRO) e óleo de pimenta (PP) foram os que apresentaram maior estabilidade oxidativa no período de 29 dias. Os parâmetros pH, CRA e força de cisalhamento não parecem ter sido afetados pelos revestimentos. Tendo em vista que aparência é um importante fator de compra, o revestimento contendo azeite e óleo de pimenta rosa foi o mais promissor para ser utilizado na manutenção da qualidade de carne ovina.(AU)

s size with AFM

Atomic Force Microscopy (AFM) can be used to obtain high-resolution topographical images of bacteria revealing surface details and cell integrity. During scanning however, the interactions between the AFM probe and the membrane results in distortion of the images. Such distortions or artifacts are the result of geometrical effects related to bacterial cell height, specimen curvature and the AFM probe geometry. The most common artifact in imaging is surface broadening, what can lead to errors in bacterial sizing. Several methods of correction have been proposed to compensate for these artifacts and in this study we describe a simple geometric model for the interaction between the tip (a pyramidal shaped AFM probe) and the bacterium (Escherichia coli JM-109 strain) to minimize the enlarging effect. Approaches to bacteria immobilization and examples of AFM images analysis are also described.

s size with AFM

Atomic Force Microscopy (AFM) can be used to obtain high-resolution topographical images of bacteria revealing surface details and cell integrity. During scanning however, the interactions between the AFM probe and the membrane results in distortion of the images. Such distortions or artifacts are the result of geometrical effects related to bacterial cell height, specimen curvature and the AFM probe geometry. The most common artifact in imaging is surface broadening, what can lead to errors in bacterial sizing. Several methods of correction have been proposed to compensate for these artifacts and in this study we describe a simple geometric model for the interaction between the tip (a pyramidal shaped AFM probe) and the bacterium (Escherichia coli JM-109 strain) to minimize the enlarging effect. Approaches to bacteria immobilization and examples of AFM images analysis are also described.