Quality changes during storage of sous vide cooked green beans (Phaseolus vulgaris)

The acceptability and quality of sous vide cooked green beans (Phaseolus vulgaris) were investigated during chilled storage. A suitable heating procedure was established whereby 2.0-kg packages were heat processed at 90 degrees C for 25 min, corresponding to an average pasteurization value, PV70,10, Of 14 min. During storage for up to 25 days at 3 degrees C drip loss, pH, colour (Minolta L*a*b*), texture (Instron) and microbiological stability were examined and sensory characteristics evaluated by a trained sensory panel. No marked changes in texture, drip loss, pH or microbiological counts were observed but a change of colour from green to olive green was observed by both objective and sensory analyses. This detrimental change in colour, which had begun during the first week, was the limiting factor for shelf-life during storage. Subsequent reheating, however, resulted in further colour changes which partially obscured the initial differences observed during the storage period. Storage for mon than 1 week resulted in undesirable quality changes in the odour and flavour of the green beans. Therefore, a maximum shelf-lift of 8 days at 3 degrees C was recommended. Inoculation trials showed that psychrotrophic Bacillus cereus were able to germinate and grow to levels of 10(7) g(-1) in the packages at abuse temperatures (7 degrees C and 17 degrees C), whereafter numbers declined.