EFFECT OF O₃ AND HIGH CO₂ APPLICATION DURING COLD STORAGE ON QUALITY OF ORGANIC TABLE GRAPE (VITIS VINIFERA L. 'ITALIA')

The mediterranean climate creates perfect conditions for table grape (Vitis vinifera L.), which makes Italy one of the world’s leaders in grape production and export. However, during postharvest handling and shipping, fruit quality decreases mainly because of development of grey mold (Botrytis cinerea). The growing demand for organic fresh products leads to a search for new alternatives to conventional handling methods in order to prolong shelf-life of organic fruits, which are more vulnerable to fungi infestation as use of fungicides is not permitted.
Quality assessment of organic table grapes (‘Italia’) was carried out in order to compare effectiveness of different pre- and postharvest treatments, on shelf-life of table grapes. The evaluation was done through chemical, physical and sensory analysis of grape samples subjected in the field to the treatment with potassium bicarbonate (KHCO₃) and during cold storage with ozone (O₃) alone or in combination with high carbon dioxide (CO₂), in order to control the development and the diffusion of B. cinerea. Organic table grapes, packaged in perforated polypropylene bags, were stored at 0°C and 90-95% RH for 28 days and treated with continuous O₃ (0.8-1.2 µl/L) or combination of CO₂ (30 kPa for 48 h) and O₃ after field treatment of KHCO₃. Samples were analyzed on weekly basis. The experimental conditions including pre-treatment in the field with KHCO₃, packaging with perforated polypropylene bags, low temperature (0°C) and high relative humidity (90-95%) combined with CO₂ (30 kPa for 48 h) and O₃ (0.8-1.2 µl/L), have restricted the development of B. cinerea and preserved good commercial quality for 28 days of storage plus 1 day of shelf-life (12°C). The obtained results conclude that appropriate combination of different treatments can help to increase the time of commercialization of fresh organic grapes.