Development of natural colouring powder from butterfly pea flowers (Clitorea ternatea)

Abstract

Butterfly pea (Clitoria ternatea) is a multi-purpose forage legume with deep blue flowers. Natural colouring powder is worth developing since the use of food colorant from natural sources is much in demand worldwide. This study was done to develop natural colouring powder from Butterfly pea flowers, differentiate the effect of drying towards the natural colouring powder and determine the anthocyanin concentration. Analysis on colour profile, moisture, ash and anthocyanin were done. Freeze dried sample gave better value for colour profile, moisture, ash and anthocyanin content. The moisture content for freeze dried sample was 9.00 ± 0.10 compared to oven dried sample 11.96 ± 1.58 while ash content for freeze dried sample was 4.87 ± 0.29 and 2.08 ± 0.91 for oven dried sample. They were not significantly different for both analyses. Colour profile analyses exhibited that freeze dried and oven dried sample were significantly different for 'L', 'a' and 'b' attributes. The values for freeze dried sample were 28.97 ± 0.30, 2.44 ± 0.02 and -1.56 ± 0.04 respectively. Oven dried sample showed the values at 34.75 ± 0.20, 2.86 ± 0.05 and -0.13 ± 0.09 for 'L', 'a' and 'b' attributes. The highest anthocyanin concentration for freeze dried sample was 504.92 mg per 1 gram sample and the lowest anthocyanin content was 243.85 ± 41.12 mg per 1 gram sample. For oven dried sample, the highest anthocyanin content was 504.92 mg per I gram sample and the lowest value was 280.14 ± 62.58 mg per I gram sample. Fresh petal contained the highest anthocyanin content with 326.44 mg per 1 gram sample and the lowest value with 65.53 ± 3.66 mg per 1 gram sample. All samples were significantly different. Extraction should be done up to the second hour only since the anthocyanin concentration in the freeze dried sample maintained till the second hour. This study showed that Butterfly pea flowers are suitable to be developed as natural colouring since the anthocyanin content is quite high. The suitable drying method to develop natural colouring powder from Butterfly pea flower could be freeze drying.