Edible coatings inhibit the postharvest berry abscission of table grapes caused by sulfur dioxide during storage

Table grape (Vitis vinifera L.) is one of the most popular berries in the world but easy to decay due to gray mold infiltration during storage. Sulfur dioxide (SO2) treatment is by far the most efficient way of for controlling gray mold development and long-term preserving table grape fruit. However, SO2 treatment causes severe abscission of berry from fruit cluster. In this study, two edible coatings (1.5% chitosan and 1.0% poly-epsilon- lysine) were selected to prevent the berry from SO2-induced abscission in 'Kyoho' table grapes (Vitis vinifera L. x V. Labrusca) during room temperature (20 degrees C) storage. Results indicated that both 1.5% chitosan and 1.0% poly-epsilon-lysine treatments remarkably inhibited the SO2-induced abscission in 'Kyoho' fruits, and the abscission rates of both coating treated-groups were significantly lower even than the blank control (without SO2 treatment) after 6 d of storage. Meanwhile, both edible coating treatments significantly decreased fruit weight loss and inhibited the increase of the cell-wall-degrading enzyme activities. Overall, these two edible coating treatments maintained other fruit qualities such as, total soluble solids (TSS), titratable acids (TA), and content of vitamin C. Thus, the edible coating 1.5% chitosan or 1.0% poly-epsilon- lysine provide potential effective ways to control SO2-induced fruit abscission and quality deterioration in table grape, and they may be of great commercial value during postharvest handling of table grape.