Real-time in-line detection in subcritical water extraction of betacyanins and phenolic compounds from beet (Beta vulgaris L.)
摘要
This study employed a Central Composite Rotational Design (CCRD), temperature and pH, to optimize the extraction of beet compounds (betacyanins and phenolic compounds) using subcritical water extraction (SWE). An innovative approach of this study was to incorporate an in-line detector to monitor the extraction process in real-time, providing instant data on the compounds being extracted and optimizing the process. The work complies with the principles of green chemistry, using clean technology with a sustainable solvent. The results indicate that the extraction of biocompounds in the treatments with lower temperatures (33.43 °C and 50.00 °C) occurred quickly after 25 min. Extractions with higher temperatures (130.00 °C and 146.56 °C) showed greater efficiency in obtaining betacyanins (extract with red-violet color) and phenolic compounds accumulated under 146.56 °C and pH 5.50. The treatment with a temperature of 130.00 °C and pH 7.00 showed a higher oxidizing response at 45.19 µmol TEAC g−1. The highest concentration of phenolic compounds (20.49 mg GAE g−1) was obtained in the treatment with a temperature of 130.00 °C and pH 4.0. The highest concentrations of glucose and fructose were obtained at 130.00 °C and pH 7.00 with 1.76 mg g−1 and 1.11 mg g−1, respectively. The optimal conditions were observed at the temperature of 146.56 °C, in-line detection wavelength at 535 nm, and pH 7.62, recovering 13.02 mg g−1 of betacyanin, i.e., recovery of approximately 80% in up to 20 min of extraction. This arouses interest for future industrial applications in the development of new products.
Graphical Abstract