The effect of ultrasound on some properties of pulse hulls

The aim of this study was to understand the effects of different ultrasound conditions on dietary fiber, phytic acid, total phenolics content, water and oil binding capacity, antioxidant capacity and phenolic acid composition of hull from green and red lentils (Lens culinaris), faba bean (Vicia faba), and pea (Pisum sativum). The highest and the lowest total dietary fiber content was observed in red lentil and faba bean hulls, respectively. Insoluble dietary fiber contents of the untreated pulse hulls were above 66% regardless of the pulse type. Phytic acid content of the pulse hulls ranged between 1.37 and 1.66 mg/g and was not affected from either the pulse type or ultrasound treatment. High and significant correlations were found between total phenolics content and Trolox equivalent antioxidant capacity both of which showed higher values for lentil hulls. Bound (hydrolyzable) extracts contained higher amounts of phenolic acids compared to free form extracts. Protocathechuic, p-coumaric and ferulic acids either in free or bound (hydrolyzable) form were present in hull from all the pulses. Ultrasound treated samples showed significantly lower total phenolic content and TEAC values compared to control for lentil hulls, while no consistent trend was observed for phenolic acids with regard to the ultrasound conditions.