The Effects of Ultrasound Wave on the Extraction of Proanthocyanidins from Red Sorghum Grain Using Green Solvent and a Kinetics Model of the Extraction

Abstract

Ultrasound-Assisted Extraction (UAE) was applied to enhance the bioactive compound extraction from the intact red sorghum grains using water as a green solvent that is relatively more available, safe, and less contaminant to the product application. The UAE performance of the ultrasonic probe with 60, 70, and 80% amplitude were compared to evaluate the effect of ultrasound amplitude. A mechanistic model was applied for quantitative evaluation of the UAE performance and prediction of the concentration of total phenolic (TP) and proanthocyanidin (PC) in the extract during the extraction. This research evaluated the effect of amplitude on the extraction rate, the parameters in the model, and the predicted TP and PC concentration from the mechanistic model approach. The wave enhanced the extraction by its propagation, cavitation bubble, and pericarp destruction. The mass transfer coefficient was stretched between 1.271×10–2 - 1.345×10–2 cm–1/minutes for TP and 5.979×10–3 - 8.262×10–3 cm–1/minutes for PC, while the distribution coefficient was 2.222×10–2 -2.248×10–2 grain/cm–3 solvent for TP and 6.739×10–2 - 7.946×10–2 grain/cm–3 solvent for PC. The highest performance resulted from 80% amplitude. The model worked precisely to predict the concentration of TP and PC of UAE, illustrating the amplitude’s effect in enhancing the UAE from its parameter values.