2.8 Statistical analysis
Regression analysis of anthocyanin extraction was calculated using SPSS Statistics for Windows version 14.0 (SPSS Inc., Chicago, USA) to establish an equation representing anthocyanin concentration based on amount of Clitoria ternatea petals used during the extraction process.
Study on the effect of pH and anthocyanin concentration was performed using response surface methodology. The experimental design and result analysis was established using the Design-Expert software version 7.1 (Statease Inc., Minneapolis, USA). The applied experimental design was that of Central Composite Design (CCD) as shown in Table 1.