Ultrasound-assisted extraction from defatted oat (Avena sativa L.) bran to simultaneously enhance phenolic compounds and beta-glucan contents: Compositional and kinetic studies

In this research, the influence of ultrasonic application and temperature on extraction yields of free, esterified, bound phenolics, and beta-glucan from defatted oat bran was investigated. Ultrasonic-assisted extraction (UAE) and conventional extraction (CE) were performed at different temperature. Extracts kinetics were monitored by determining the total phenolic content (TPC), antioxidant capacity (ORAC), and total avenanthramides of free phenolic compounds by mathematical model. HPLC-DAD was used to identify and quantify the main phenolic compounds. The results suggested that phenolic extraction yields of UAE was faster and higher than that of CE for free phenolics, with fitting to mathematically model (MRPD < 6%) well, whereas the bound fractions decreased. Besides, the TPC, ORAC and total avenanthramides of free phenolics were significantly improved by increasing the temperature in both UAE and CE, whereas the bound were significantly decreased. beta-Glucan yields pretreated in UAE were approximately 37% higher than that in CE. (C) 2017 Elsevier Ltd. All rights reserved.