Abstract
The aim of the study was to compare the quality of table grapes (cv. Italia) held on the vine compared to grapes stored in cold rooms with or without modified-atmosphere packaging (MAP). The grapes were harvested from 12 plants in 2 vineyards in the same area, differing for the age of the plant. Four- and a fourteen-year-old vines were cultivated with the “Apulia tendone” system. After the first harvest, grapes were divided into small clusters and used for storage treatments in air and in MAP. Samples of 400 g were packaged in polypropylene (PP) trays sealed with a polypropylene/polyamide (PP/PA) film with 20% CO2 in air. MAP and control samples were then stored in the same cold room at 0 °C. Initially and after 8, 21, and 28 days, grapes stored in air and MAP were compared to fresh harvested grapes, stored on the plants. Quality attributes included color, texture, maturity index, phenols, antioxidant activity, sugars, organic acids, sensory parameters, and volatile compounds. The results obtained demonstrated that grapes held on the plant and in MAP showed better quality in terms of appearance scores compared to grapes stored in air. In particular, the application of high CO2 contributed to reduce the deterioration rate of the clusters, minimizing weight loss, and delaying degradation processes, and this particularly for grapes from the 14-year-old vine, where grapes held on the plant degraded faster than grapes in the younger vines. Most volatile compounds did not change their concentration with the storage treatment, except for ethyl acetate and ethanol, which increased in MAP at the end of storage, and to some compound responsible for green odor. In conclusion, keeping the grapes on the plant can be considered a good agronomic practice to preserve the quality, whereas MAP can be applied to better maintain postharvest quality of the product throughout storage and distribution.
Highlights
Table grapes are one of the most consumed fruits in the world, and a valuable source of phytonutrients [1,2].It is a non-climacteric fruit, and for this reason, unlike many other fruit crops, the ripening process does not continue off the vine
The results obtained demonstrated that grapes held on the plant and in modified-atmosphere packaging (MAP) showed better quality in terms of appearance scores compared to grapes stored in air
Most volatile compounds did not change their concentration with the storage treatment, except for ethyl acetate and ethanol, which increased in MAP at the end of storage, and to some compound responsible for green odor
Summary
Table grapes are one of the most consumed fruits in the world, and a valuable source of phytonutrients [1,2].It is a non-climacteric fruit, and for this reason, unlike many other fruit crops, the ripening process does not continue off the vine. Table grapes are one of the most consumed fruits in the world, and a valuable source of phytonutrients [1,2]. A common practice used in southern Italy is to appositely cover canopies with plastic film (i.e., low-density polyethylene) during August to delay the harvest times of table grapes from October to the late November or early December [4]. This “late” forcing, to the “early” one, aimed to anticipate the shoot sprouting, is executed to delay the harvest as much as possible, [5] while protecting fruit form autumnal rains. Some authors [5,6] reported the benefits of this agronomic technique to meet the demand for high-quality table grapes during Christmas time, resulting in a higher profitability for the producers
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