Alternative atmosphere treatments for keeping quality of ‘Autumn seedless’ table grapes during long-term cold storage

Abstract

Abstract White seedless table grapes (Vitis vinifera cv. Autumn seedless) were stored under several gas treatments for up to 60 days at 0 °C followed by 7 days in air at 15 °C. To generate a modified atmosphere packaging (MAP) of 15 kPa O2 and 10 kPa CO2, a 35 μm thick microperforated polypropylene (PP) film with and without 0.7 g Na2S2O5 kg−1 was used. A controlled atmosphere (CA) of 5 kPa O2+15 kPa CO2 and continuous exposure to 0.1 μl l−1 O3 enriched air were also tested. As a control, macroperforated PP film was used. After shelf life, control berries showed the highest decrease in lightness and greenness while slight changes for gas-treated berries were found. At any time, no noticeable changes in firmness, SSC, pH, titratable acidity, maturity index, aroma and softness were detected. At the end of the experiment, severe browning of the rachis in control clusters occurred, due to the high weight losses reached (9.65%). Control clusters showed the highest fungal infection (over 9%), mainly caused by Botrytis cinerea. Visual appearance and eating texture of berries under gas treatments were higher after shelf life than in control fruit, with no differences among treatments except for CA-treated grapes. A progressive increase in the total sugar contents in all treatments was found. Glucose and fructose, in almost equal quantity, were the main sugars. Principal organic acids were tartaric and malic, and compared to values at harvest, no differences for any treatment at any sampling time were found. As a main conclusion, the gas treatment could be an alternative to replace the use of SO2 for keeping quality of ‘Autumn seedless’ grapes. MAP with 15 kPa O2+10 kPa CO2 provided the best results and also had a lower cost.