Correlation analysis is a statistical analysis technique mainly for exploring the linear relation between two variables. A good correlation (R2 = 0.9817) between PP and hardness of BSS can be observed in Fig. 3(b), which indicated the close relationship between hardness change and PP change in BSS during blanching. This also confirmed that the hardness decrease in BSS is mainly caused by the nonenzymatic depolymerisation of PP during heating process.