Pulsed microwave radiation for extraction of betalains from red beetroot: Engineering and technological aspects

Betalains are water-soluble plant-derived red pigments with high red color intensity besides functional proper-ties. Extraction is a critical step in isolating these bioactive compounds from natural sources. In this study, microwave treatments with different powers, duty cycles, and process times were applied to extract betalains, from red beet. Results revealed that increments in power, extraction time, and duty cycle led to a steep tem-perature increase in all samples. However, the severity of temperature rise declined at higher power, time, and duty cycle. The minimum non-uniform heating was obtained at power 450 W, duty cycle 0.17, and process time 0.5 min. The minimum energy consumption was observed at the lowest power, time, and duty cycle. The highest betacyanin content (about 175-200 mg/L) was shown at higher microwave powers. Increment in all extraction parameters, namely process time, power, and duty cycle, improved the total phenolic content. Maximum anti-oxidant capacity, 73 %, was obtained at 1.5 % citric acid, 0.17 duty cycle, 230 W microwave power, and 4 min extraction time. Overall, microwave with pulsed radiation is a powerful and advanced technique for efficiently extracting betalains from red beetroot for usage in the food industries.