Submitted to: Postharvest Biology and Technology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/23/2004
Publication Date: 12/3/2004
Citation: Stevens, C., Khan, V.A., Wilson, C.L., Lu, J.Y., Chalutz, E., Droby, S. 2004. The effect of fruit orientation of postharvest commodities following low dose ultraviolet light-c treatment on host induced resistance to decay. Postharvest Biology and Technology. Crop Protection 24: 756-759. Interpretive Summary: Over twenty-five percent of our harvested fruits and vegetables is lost to decay. We have depended heavily on synthetic fungicides to control these losses. Health and environmental concerns have been raised about the use of synthetic fungicides on food and a need has developed for safer alternatives. In cooperative research between the USDA ARS Appalachian Fruit Research Station and Tuskegee University, it has been discovered that low dose UV-C light will 'turn on' resistance to postharvest decay in a wide variety of commodities, eliminating the need to use synthetic fungicides. The original research utilizing this technology required that the fruit or vegetable being treated with low-dose UV-C be irradiated on all four sides. The research described in this paper demonstrates that irradiating the commodity at one point at the stem end is just as effective as treating all four sides of the fruit or vegetable. This new discovery will make the treatment of harvested fruits and vegetables on a processing line with low-dose UV-C light more practical and will reduce the potential of damaging the commodity.
Technical Abstract: The possibility of inducing resistance to bitter rot (Colletotrichum gloeosporioides), brown rot (Monilinia fructicola), and green rot (Penicillium digitatum) in apples, peaches, and tangerines respectively by treating them with UV-C at the stem end in a stationary position without rotation was investigated. This approach was compared with the conventional procedure where the commodities are rotated four times, thereby exposing the entire surface area to the UV-C light treatment. Results of this study revealed that when the stem ends of apples, peaches, and tangerines were exposed in a stationary position surface to the UV-C light treatment, induced host resistance to postharvest decay was equal to or slightly better than when the fruits were rotated four different times. In addition, when the fruits were not rotated, thus exposing only one side to the UV-C light and when rotated two different times, the disease incident appeared to increase, compared to those commodities where only the stem ends were treated or those rotated four different times. The possible practical application of UV-C light to the stem ends of fruits for controlling postharvest decay for an on-line UV-C apparatus is discussed.