Abstract

Red chicory is a leafy vegetable, currently used for the preparation of ready-to-eat salads, that undergoes heavy losses during cold storage mainly due to microbial soft rot development. In this work, low doses of gaseous ozone (0.1-1 ppm) were applied during 21 days of cold storage (1°C) under passive cooling in order to reduce postharvest losses of this vegetable. Conventional refrigeration in absence of gaseous ozone was used as the reference storage method. In addition, in order to evaluate the antimicrobial effect, a challenge test was performed inoculating sound red chicory heads with a specific spoilage microbiota, accounting approximately 8 log cfu/mL bacteria and 7 log cfu/mL yeasts and moulds, responsible for soft rot development under cold storage. The results showed that soft rot developed from day 8, especially in the inoculated samples, even though the leaf appearance was unchanged. At the end of cold storage, non-inoculated red chicory heads stored under conventional conditions loosed all characteristics related to vegetable fresh appearance; on the contrary, color brightness and tissue turgidity were retained in samples stored under passive cooling. Oxidative discoloration of leaf margins was recorded in red chicory heads stored under 1 ppm ozone. At the day 21 microbial counts of spoiled vegetable, regardless the different cold storage conditions, did not show any significant difference. Conversely, as expected, evident difference in soft rot severity was recorded between inoculated and non-inoculated samples. Passive cooling determined a lower amount of food waste in comparison with conventional refrigeration. Control samples, inoculated or not, showed 100% of losses whereas those under passive cooling produced 40.09 ± 4.24 and 90.69 ± 12.03 % of food waste for inoculated and non-inoculated samples, respectively. A further reduction in the amount of vegetable waste (ranging from 10 to 30%) was registered when passive refrigeration was associated with gaseous ozone treatment at 0.1 ppm. Higher ozone doses caused no significant additional improvements. In conclusions, the combined application of gaseous ozone and passive cooling resulted a valid approach to counteract soft rot development on red chicory heads and to reduce the amount of food waste. However, ozone exposure need to be carefully calibrated to preserve vegetable tissues from oxidative damages caused by this gas.

Autore Pugliese

• Baruzzi Federico , Caputo Leonardo

Tutti gli autori

• L. Pinto ; T. Yaseen ; L. Caputo ; C. Furiani ; C. Carboni ; F. Baruzzi

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Anno di pubblicazione

2017

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