Natural blue colourant preparations from blue pea flower and spirulina: A comparison stability study

Abstract

The effect of different pH and thermal treatments on the stability of blue pea flower colourant preparations was investigated and compared with those from spirulina. The total anthocyanin content, total phenolic content, antioxidant activity [free radical scavenging activities and ferric reducing antioxidant power] and total colour change (∆E) were determined at 6 days intervals for pH treatment (pH 3, 4, 5, and 6 for 30 days at 4 and 26 °C) and after thermal treatment (60, 80, and 100 °C for 10 and 30 min). The blue pea flower colourant preparations demonstrated high storage stability at pH 3 and 4 at 4 °C storage for 30 days and higher thermal stability than spirulina at all heat treatments. At refrigerated storage, the antioxidant activity of the blue pea flower colourant preparations at all pH conditions was higher than that of spirulina. Using liquid chromatography-mass spectrometry analysis, delphinidin-3-(trans-p-coumaroyl)-glucoside was the predominant anthocyanin in blue pea flower colourant preparations. The ∆E of the blue pea flower colourant preparation was lower than that of spirulina colourant preparation at refrigerated storage and all thermal treatments. Therefore, blue pea flower colourant preparations are suitable for food applications requiring thermal processing between 60 and 100 °C and refrigerated storage.

Keywords

• Antioxidant activity
• Anthocyanin
• Clitoria ternatea
• Delphinidin
• Natural colour
• Phycocyanin