Influence of extraction parameters and stability of betacyanins extracted from red amaranth during storage

Natural colorants are important alternatives to synthetic colorants. They are considered harmless and positively affect biological activities owing to their antioxidant potential. The present study deals with the assessment of the extraction processes and the effects of pH (1.0, 3.0, and 5.0), extraction media (water and 50% ethanol) and storage condition (ambient and refrigeration) on betacyanin content, color values, as well as degradation kinetics of total betacyanins in red amaranth. Betacyanin content was more stable at higher than at lower pH. The degradation rate constant (K) was higher and the half-life (t_1/2) was lower at ambient temperature compared to refrigeration temperature. Betacyanin degradation was higher at ambient temperature (30 ± 2 °C) than at refrigeration temperature (4 °C). The pH, storage time, and temperature affected the stability of the color attributes. Therefore, this work suggests that water and lower temperature (4 °C) could be applied to extract more betacyanins from red amaranth and betacyanins might be used as an alternative to synthetic color.