Submitted to: Postharvest Biology and Technology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/28/2014
Publication Date: 6/1/2014
Citation: Feliziani, E., Romanazzi, G., Smilanick, J.L. 2014. Application of low concentrations of ozone during the cold storage of table grapes. Postharvest Biology and Technology. 93:38-48. Interpretive Summary: A large portion of table grapes rot after harvest unless measures are taken to control the fungi that cause the grapes to rot. Ozone is a disinfectant gas that we evaluated for the control of rot on harvested grapes and from this work we identified the best practices to use ozone for this purpose. Ozone provides an option to increase the storage life of grapes for conventional and "organic" growers, so as to increase the availability of this fresh fruit to consumers, without the use of synthetic pesticides.
Technical Abstract: The control of postharvest decay of table grapes, caused by Botrytis cinerea and other pathogens, by ozone was evaluated in chambers and commercial storage facilities. Ozone at 0.100 µL/L or higher inhibited the spread of gray mold among stored grapes. Ozone diffusion into many types of commercial packaging was measured. Boxes made of uncoated paper corrugate inhibited diffusion more than those composed of coated paper corrugate, hard plastic, or expanded polystyrene. Internal packaging of hard plastic clamshell containers inhibited diffusion less than low density polyethylene cluster bags. Atmospheres of 0.100 µL/L ozone in the day and 0.300 µL/L at night reduced the natural incidence of gray mold by approximately 70% after 5 to 8 weeks of storage. Its effectiveness to control postharvest decay was compared to sulfur dioxide fumigation. After 68 days at 1°C the incidence of gray mold among grapes stored in air, ozone, or with weekly sulfur dioxide fumigation was 38.8, 2.1, and 0.1%, respectively. However, decay by other fungi, such as Alternaria spp. and Pencillium spp., was controlled by sulfur dioxide, but not ozone. In most tests, rachis appearance was moderately harmed by ozone. The combination of ozone use in storage following a single initial sulfur dioxide fumigation, or its use in between biweekly sulfur dioxide fumigations, controlled both gray mold and other pathogens and matched the commercial practice of initial and weekly sulfur dioxide weekly fumigation. The use of both gases in this way reduced sulfur dioxide use greatly. The difference of flavor of grapes treated with ozone was not detectable compared to those stored in air, and was preferred over those treated with sulfur dioxide.