Effects of Sulfur Dioxide SO₂ on the Texture and Wax Injury of Peel in Grape Berries

In order to explore changes of grape's fruit texture and wax structure on texture of grape after fumigation by sulfur dioxide(SO₂),the effect of red globe grape fruit's texture was treated with different concentrations of SO₂(0,100,500 μL/L). Texture parameters were detected by texture profile analysis(TPA). The fruit texture parameters were analyzed with methods of correlation analysis and principal component analysis(PCA). The results showed that,with prolongation of storage time,SO₂ could delay decrease of fruit hardness,gumminess and chewiness,the elasticity and cohesion could be maintained at a high level. The following parameters have good positive correlations:hardness,springiness and chewiness of fruit;pulp cohesiveness,gumminess,springiness and chewiness;pulp springiness and pulp gumminess and chewiness;and among fruit hardness,chewiness,cohesiveness,springiness and gumminess. The scanning electron microscope(SEM)observation showed that 100 μL/L SO₂ treatment could inhibit the change of waxy structure of grape peel. By PCA analysis,two principal components were extracted from 5 TPA texture indexes,and cumulative variance contribution rate was 96.81%. The two principal components could be used to distinguish the control,100 and 500 μL/L SO₂.In conclusion,100 μL/L SO₂ treatments could better maintain the texture of red globe grape and reduce the damage of the wax in the pericarp.