The total colour difference (DE) is a colour change index of BSS before and after the blanching treatment. DE is widely applied as a colorimetric parameter to represent the colour change in food during processing. Many researches regarded DE = 2 as the threshold of visual discrimination (Zhou et al., 2009). The colour changes when DE ranges from 0 to 2 are invisible, but those when DE>2 are evident and visible. According to Table 1, the DE of BSS of all blanching time valued higher than 2, indicating great visible colour difference of BSS before and after blanching treatment. Ndiaye et al. (2009) also reported great colour difference in fruits and vegetables after blanching. However, further research on its influence mechanism is still required.