OPTIMISATION OF BIOACTIVE COMPOUNDS EXTRACTION FROM RED BEETS (Beta vulgaris L.)

Red beets are a rich source of antimicrobial and antioxidant compounds such as betalains, a class of red and yellow natural pigments found in plants. This study aimed to optimize the recovery of betalains and total phenolic compounds (TPC) from beetroot. A 2 × 2 factorial design with three central points was utilised to determine the optimal solvent type and pH as independent variables. Therefore, a total of seven experiments were carried out in triplicate: E1 - water with pH 3.0; E2 - ethanol with pH 3.0; E3 - water with pH 7.0; E4 - ethanol with pH 7.0; E5, E6, E7 - 70% ethanol with pH 5.0. The response variables were betalain content (BC) and TPC, which were measured spectrophotometrically. The central point experiments showed the highest recovery of betalains (0.89 mg/100g at 480 nm and 0.83 mg/100g at 535 nm). The central point conditions also showed higher efficiency for TPC recovery, ranging from 50.81 to 59.45 mg GAE/100g. The E4 (9.6 mg GAE/100g) showed a value below the desired value. The extracts showed a range of colour parameters perceptible to the eye, ranging from yellow to red. The E5, E6 and E7 treatments presented higher redness (a*). Therefore, the extracts produced had considerable variations according to the solvent type and pH condition. The best extraction conditions were achieved by using 70% ethanol and pH 5.0 (E5, E6 and E7). These results were a primordial factor in choosing and using extracts as natural additives.