Study of the stability of sliced cooked ham in modified atmosphere. / Estudo da estabilidade de presunto cozido fatiado em atmosfera modificada.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2004

RESUMO

The purpose of this study was to evaluate the efficiency of packaging systems with modified atmosphere to preserve the quality of sliced cooked ham. Thus the quality stability of the product at 4 +/_:t 1°C, packed in a gas barrier package with three kinds of modified atmosphere (100% CO2, 60% CO2/40% N2 and 25% CO2 I 75% N2), was studied. The shelf-life of each condition of atmosphere was analysed. Comparatively, the shelf-life of the same product packed in conventional under vacuum was also evaluated. No expanded polystyrene trays with about 200g of sliced cooked ham were placed in a hot sealed poliolefinic film packages, nominated as primary packages. After that, six primary packages of sliced cooked ham were placed inside a barrier bag called "master pack" (secondary packages), formed of low density polyethylene and copolymer of ethylene vinylindene alcohol. The material permeability rates to oxygen was 1,87 cm3 (CNTP)/m2/atmlday at 23°C and dry. For the conventional product, the trays were wrapped in a thermoform film. The products were periodically evaluated as to their organoleptie quality (appearance and odour), microbiological quality (counts of Enterobacteriaceae, aerobic psychrotrophic microorganisms, lactic acid bacteria and Pseudomonas sp.) and physical and chemical characteristics (colour and pH). The headspace gas composition of the modified atmosphere packages were periodically evaluated. The cooked ham did not present any physical or chemical alteration in any of the packaging systems during the analysed period. The shelf-life for each packaging system was established based on organoleptic alterations that defined as the limitin classification: characteristic collor of the fresh ham and characteristic odour of the fresh ham moderates. The shelf life of the ham in the conventional under vacuum was 15 days. At the end of this period, the counts of Enterobacteriaceae, aerobic psychrotrophie microorganisms, ladie acid bacteria and Pseudomonas sp. were 4,0 log CFU/g, 5,1 log CFU/g, 4,5 log CFU/g and <1 CFU/g, respectively. The product placed in a 25% CO2/75% N2 atmosphere, the shelf-life of the was 22 days and during this period, the counts of Enterobacteriaceae, aerobic psychrotrophie microorganisms, lactic acid bactería and Pseudomonas sp. were <1, 5,1, 4,5 and <1 109 CFU/g, respectively. higher it s effect. However, it was verified a significant shelf-life increase of sliced cooked ham in atmospheres with high concentrations of carbon dioxide in relation to the conventional under vacuum, as fo 11 ows: 29 days (93,3% increase) for products in 100% CO2 and 60% CO21 40% N2 atmosphere. Due to the bacteriostatic action of the carbon dioxide, the development of aerobic psychrotrophics microorganisms was retarded and the growth of Enterobacteriaceae and Pseudomonas sp. was inhibited in the 100% CO2 atmosphere. When the atmosphere was 60% CO2 I 40% N2, the development of both aerobic psychrotrophic microorganisms and Pseudomonas was retarded, and the counts of Pseudomonas sp. was 4,7 log CFU/g, after 50 days of storage and the development of Enterobacteriaceae was inhibited. Based on the obtained results, it was confirmed the positive effect of the packaging in modified atmosphere with carbon dioxide on the shelf-life increase of sliced cooked ham. It has been proved that, the higher the concentration of carbon dioxide in the headspace.

ASSUNTO(S)

vacuo - embalagens vacuum microbiological growth diagnostico microbiologico ham

ACESSO AO ARTIGO

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