Antimicrobial Treatments to Preserve Packaged Ready-to-Eat Table Grapes
Cristina Costa1, Annalisa Lucera1, Amalia Conte1,2 and Matteo A. Del Nobile1,2*
1Department of Food Science, Agricultural Faculty, University of Foggia, Via Napoli 25, IT-25-71121 Foggia, Italy
2Food Quality and Health Research Centre (BIOAGROMED), University of Foggia, Via Napoli 25, IT-52-71121 Foggia, Italy
Article history:
Received February 20, 2012
Accepted July 13, 2012
Key words:
antimicrobial compounds, ready-to-eat table grapes, packaging, shelf life
Summary:
Ready-to-eat table grapes are a product with severe shelf life problems. Mass loss, colour changes, accelerated softening and mould proliferation can greatly influence quality decay of berries. Hence, the effects of different dipping treatments on the quality of packaged ready-to-eat table grapes have been successfully assessed. Various antimicrobial compounds (trans-2-hexenal, potassium sorbate, eugenol, cinnamon bark oil and ethanol) were used at different concentrations for dipping grape berries prior to packaging. All the samples were packaged in biaxially oriented polypropylene and stored at (4±1) °C. During the storage period, headspace gas composition, spoilage microorganisms, appearance of visible moulds and sensory quality were monitored. The composition of the headspace gas was typical of a non-climacteric fruit, thus demonstrating that the antimicrobial compounds did not affect product respiration rate. For the entire storage period, the bacterial counts did not grow significantly. On the contrary, mould proliferation on the product surface affected sensory properties until provoking product unacceptability. Relevant differences were found between the dipped and undipped samples. In particular, 50 % ethanol or 20 % ethanol combined with potassium sorbate (3 %) seemed to be very effective in preventing mould proliferation, thus promoting an increase in shelf life by about 100 %.
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