engleski

Shelf life of pre-cooled and packaged raspberry in different atmospheres

Conventional refrigeration method and vacuum pre-cooling were applied on raspberries before packaging. Raspberries were packed into polyamide/polyethylene (PA/PE) pouches. Two different atmosphere were selected: a) Air and b) MAP using gas composition of 20%CO2/5%O2/75%N2. All samples were stored at three different temperatures (1oC, 5oC and 10oC). As a control raspberries in an open polypropylene (PP) tray were used. During seven days storage raspberries were analysed for its textural and sensorial characteristics. Each pouch was also checked for its gas composition (oxygen and carbon dioxide) while gas (O2, CO2) permeability of packaging material was analysed before packaging and after seven days storage. During raspberries storage in PA/PE bags O2 and CO2 were continuously changed in most of the samples and in all cases the behaviour followed the same tendency during the period analysed. During the first 24 hours the CO2 content for vacuum and conventionally pre-cooled samples, stored at 1oC in the air atmosphere, were 7% and 7, 4% respectively. For the vacuum pre- cooled samples at 5oC and 10oC the O2 content decreased from 21% to 14.1% and 14% respectively. Raspberries packed into barrier (O2<4 cm3/m2·day·bar at 8oC) PA/PE pouches showed no traces of mould since the level of carbon dioxide was above the toxicity limit. Steady-state of oxygen is reached after 4 days of storage of conventionally pre-cooled raspberries stored in the air at 1oC and 10oC, and after 5 days storage of vacuum pre-cooled rapsberry in MAP at 10oC. Although MAP had a positive effect on firmness of vacuum-cooled raspberies they got lower sensorial scores compared to air packaged samples. The best sensorial scores were obtained for the conventionally pre-cooled samples packaged in the air and stored at 1oC.

modified atmosphere packaging ; pre-cooled ; raspberry ; shelf-life

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