Efeito da atmosfera modificada sobre a conservação de lombo de atum (Thunnus albacares) embalado / Effect of modified atmosphere packing on tuna-fish (Thunnus albacares) loin conservation

RESUMO

O trabalho objetivou avaliar o efeito da atmosfera modificada em lombo de atum (Thunnus albacares) embalado. As amostrasforam submetidas a cinco tratamentos: embaladas a vácuo e com aproximadamente 1,5 L de: ar (100 por cento), CO2 (100 por cento), 40/60e 80/20 CO2/N2. Durante os 20 dias de armazenamento, tomaram-se amostras determinando o pH, a produção de basesvoláteis totais (BVT), a concentração de histamina e a contagem total de microrganismos heterotróficos aeróbios mesófilos.Os parâmetros de crescimento (fase de latência, tempo de duplicação e contagem na fase estacionária de crescimento) foramdeterminados através da equação modificada de Baranyi. Observaram-se diferenças marcantes entre as amostras mantidasem aerobiose e os demais tratamentos. Pôde-se concluir que a embalagem com 100 por cento de CO2, se destacou das demais, apresentando um bom desempenho na preservação do lombo de atum, estendendo o prazo de vida comercial, sendo eficazpara manutenção dos parâmetros físico-químicos dentro dos limites de aceitabilidade propostos pela legislação vigente.

ABSTRACT

The objective of this study was to evaluate the effect of modified atmosphere packing on tuna-fish (Thunnus albacares). Thesamples were submitted to 5 treatments: vacuum packed and with approximated 1,5 L of: air (100 por cento), CO2 (100 por cento), 40/60 e 80/20 CO2/N2. During the 20 days of storage, samples were collected to determine the pH, total volatile bases (TVB), histamineconcentration and total viable count (TVC). The growth parameters (lag phase, doubling time and the counting during thestationary phase) were determined by Baranyi modified equation. It was observed that the samples kept in aerobiosis showeda quick increase in TVB values, reaching their peak on the 20th day of storage (27.5 mg TVB-N/100 g). The production of TVB inthe other samples stayed, during storage period, around 11 mg de TVB-N/100 g. The samples packed under aerobiosisshowed an increase in their pH as of the 13th storage day, reaching a maximum of 6.43 on the 15th day. The other atmospherespresented similar pH patterns, with little difference from the initial sample. Except for the samples kept in aerobiosis, in whichit was detected approximately 10 mg/100g of histamine on the 15th storage day, all the other samples presented non-detectablelevels of histamine during storage. The TVC in samples packed under aerobiosis, as of the 7th day stood out, this bigger growthwas sustained until the last day of storage, in which, higher TVC was found in vacuum packed samples and 40/60 CO2/N2. The80/20 CO2/N2 and 100 por cento CO2 atmospheres did not reach as high TVC results as the other 3 atmospheres. The 100 percent CO2atmosphere reached the proposed limit just on the last day of storage (7.4 Log de UFC/g). It can be concluded that the 100 percent CO2packing, stood out in relation to the others, showing good performance preserving tuna-fish loin, extending shelf-life, beingeffective in keeping the quality parameters within the limits of acceptance proposed by...