Comparison of hot water and acetone extraction methods on anthocyanin content and color characteristics of butterfly pea flower extracts.

Research Poster
Danielle Voss
M. Monica Giusti
Department of Food Science and Technology

Naturally derived pigments are increasing in popularity as food manufacturers look to replace their synthetic counterparts to address consumer demands. The food industry is challenged by sourcing viable blue pigments as there are limited natural sources. One promising source is butterfly pea flower (Clitoria ternatea, BPF)-an anthocyanin-rich natural flower originating from Asia historically used for food color and tea. The extraction procedure for naturally derived colorants is efficiently done with the use of organic solvent; however, extra processing steps are required for subsequent removal to ensure safety for consumption. The purpose of this study was to compare the efficiency of dried BPF pigment extraction with water to that with organic solvents. Hot water (90°C) extraction was used as a safe, environmentally friendly process that mimicked tea brewing; acetone extraction was used for comparison as a standard laboratory method. The extracts were evaluated for total anthocyanin content, pH, absorbance spectra, and CIE*L*c*h color characteristics. 
The hot water extraction method resulted in 3.3 times more total anthocyanin content than the acetone extraction method. The solution obtained after organic solvent extraction had a final pH of 4.6, and it expressed a purple/blue color. At this pH anthocyanins are typically pale or colorless. In contrast, the solution obtained after water extraction had a final pH of 6.7 and expressed a blue/green color. These results showed that hot water was an effective extraction method for pigments from dried BPF, yielding more pigment than the organic solvent under the conditions of this study.