Inhibitory activity of sulfur dioxide preservative on Botrytis cinerea of Muscat Hamburg table grapes

To find the proper low density of SO₂, which could preserve the table grapes effectively, influences of SO₂ on pathogenic bacteria on Muscat Hamburg grape berries was analyzed. Vitro experimental system was carried out in this study as well. The results showed that the total microbial population on the surface of Muscat Hamburg grape berries decreased significantly in SO₂-fumigated environment, while the main pathogenic bacteria, Botrytis cinerea, was completely inhibited. Sodium metabisulfite could effectively inhibit spore germination, development and growth of Botrytis cinerea. The inhibitory activity increased as the concentrations increased and the duration prolonged. Low temperature could enhance the inhibitory effects of sodium metabisulfite on the germination of spore and the mycelial growth of Botrytis cinerea. Sodium metabisulfite showed strong bacteriostatic effect at 300 and 600 mg/L under pH ≤ 4.00. Besides, the bacteriostatic effect under pH=3.00 was higher than that under pH=4.00. No visible mycelium could be observed after Botrytis cinerea spores were incubated with 300 mg/L sodium metabisulfite for 1 h followed by 45 d microbial culture at 4℃. The results indicated that the application of a certain density of SO₂ preservatives has beneficial antimicrobial effects on Botrytis cinerea. Low density of sodium metabisulfite together with low pH treatment could make preferable effect on the storage of table grapes.