Improving on Postharvest Quality of Munag Grape Berries Fumigated by Sulfur Dioxide (SO2)
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Abstract:
In order to investigate the effect of postharvest quality and texture characteristics changes of munag grape after fumigation by SO2, the changes of fruit quality indexes during storage were determined. Texture parameters of munag grape were determined by Texture multifaceted analysis (TPA method) and studied by correlation analysis. The results showed that when the fumigation concentration of SO2 was 3000 μl/L, the residue of SO2 in the fruit was 7.55 mg/kg, which is in line with the developed countries in Europe and America on table grape import and export food standards. The browning degree of grape stem and stalk after SO2 fumigation was 2.60% lower than that without fumigation. SO2 fumigation treatment could inhibit chlorophyll decomposition. Its content in stems decreases from 0.091 mg/g to 0.037 mg/g without SO2 fumigation treatment, while decreases to 0.052 mg/g after SO2 fumigation treatment, showing a significant difference (p<0.05). SO2 fumigation treatment could keep the content of soluble solid and titratable acid stable, maintaining postharvest quality of grapes. When the soluble solid content reached the maximum value, SO2 fumigation treatment was 4.2% higher than untreated. At the end of storage, the titratable acid content of SO2 treated fruits was 11.60% higher than that of untreated fruits. TPA method was used to determine the texture parameters of the fruit after SO2 treatment, and it was found that SO2 treatment could well maintain the texture parameters of the fruit. The fruit firmness decreased slowly and was 4.29 N/cm2 at the end of storage. At the end of storage, the cohesiveness was 0.78, showing a significant difference (p<0.05). Elasticity, gumminess and chewiness decreased by 3.8%, 18.1% and 3.68% respectively compared with that at 0 d. The correlation analysis between texture parameters and quality of fruits after SO2 fumigation showed that the texture parameters of fruits could well evaluate the quality of fruits in post-harvest storage. Through the above experimental results, it was clear that 3000 μL/L of SO2 short time fumigation could maintain the quality of munag grape.
