Abstract

Natural pigments, betalains represent a promising and safe alternative to the synthetic colors or dyes. Therefore, the present study was conducted during June to September 2020 at Plant Physiology Laboratory, Department of Crop Botany, Bangladesh Agricultural University, Mymensingh in collaboration with Department of Crop Botany, Khulna Agricultural University, Khulna to extract betalains pigment from red beetroot and to evaluate the proximate composition, the stability of color, phenolic compounds, flavonoids contents along with its antioxidant properties. The beetroot extract was obtained and then demonstrated absorbance peaks at 230 and 538 nm under UV/Vis spectrophotometric analysis. Absorbance peak at 538 indicated the presence of betacyanin, a type of betalains. Degradation of betacyanin color intensity due to pH was monitored with a UV/Vis spectrophotometer at 538 nm and Hunter Lab colorimeter, respectively. Results revealed that at low pH ranging from 3 to 6 was able to preserve the color whilst a significant degradation was noticed at high pH 10. The phenolic compounds and flavonoids in the ethanolic extract of beetroot were 16.88 and 10.80%, respectively, of the mass of the extract and their contents in the aqueous extract were 7.812 and 4.77%, respectively. The reducing powers of the ethanolic and aqueous extracts were also determined. The reducing power was increased by increasing the sample concentration and reached 88.89% for the ethanolic and 80.89% for the aqueous extract. Finally, betacyanins derived from red beetroot showed remarkable antioxidant properties suggesting its potential application in food industries and natural functional pigment.