investigation the effect of grapeguard on quality and controlling fungal contamination of grape in cold storage

in order to study the effect of grapeguard on quality, quantity and control of storage diseases of grape in cold storage a completely randomized design with 3 replicate was conducted on two cultivators of kolahdari and kajanguri in khorasan agricultural research center. the fruits after harvesting were transferred to the sheltered place. before keeping in cold storage, the temperature of fruits was reduced to 6oc during 6-24 hours precooling. the attributes including fungal contamination, berry decay, peduncle length, cluster length, cluster width, berry width, berry length, berry weight, cluster weight, soluble solids, titrable acidity and ph were measured immediately after harvest. grapeguard sheets including 4, 7 and 10% sodium metabisulfite solutions were laid in two layers in bottom and middle of box. all the samples including control and the other treatments kept in 0oc and 90-95% relative humidity for 3 months, and all the tests were done again. sulfur concentration, vitamin c and organoleptic characteristics were measured at the end of third month. the results revealed that fungal contamination and decay of grapes decreased by application of grapeguard sheets. these sheets caused to change tss, decrease titrable acidity and prevent to increase ph during storage time. by increasing metabisulfite sodium solution, the amount of vitamin c increased. results of quality and quantity tests showed that application of grapeguard including 10 percent metabisulfite caused keeping quantity and quality characteristics in grape, but amount of sulfite dioxide was in standard limits and keeping quality of kolahdary is better than kajanguri, and 7% metabisulfite is in second order.