Effect of Sulphur Dioxide Fumigation on Postharvest Longan Fruit (cv. shixia) and Its Residues
The fresh longan fruit (cv. shixia). fumigated with sulphur dioxide at various levelswere stored at a low temperature, and SO2 residues in longan fruits observed during storage.The results indicated that after an appropriate SO2 fumigation, the appearance of fruits wasbleached and their storage and shelf life were prolonged because SO2 reduced their mildewand rot rates, affected ethylene production rate to some extent and strongly inhibited respiration rate. During storage the sulphur residues in fruits declined and dropped to 10 μg／g FWwithin 1-2 weeks in pulp. At a given SO2 rate, the main factors affecting sulphur residuechange included fumigation time and the ability of fruits absorbing and detoxifying SO2. Thestorage effects and sulphur residue changes showed that it was suitable for longan fruits tobe fumigated for 20 minutes with a high eoncentration (about 2.0 %-2.5 %) of SO2 and thenstored at a low temperature of 4 ℃.