Bio-functional Compounds in Pigmented Rice: Recent Updates on Extractions, Delivery Mode, and Application in Food Systems

Abstract

Pigmented rice including red, black, purple, green, and brown has nutraceutical properties since it contains several bioactive compounds, significantly more than those of normal white rice, but consumption is less due to a lack of awareness. This review examines the potential of pigmented rice varieties as sources of anthocyanins and highlights bioactive such as essential oils, sterols, γ-oryzanols, tannins, tocopherols, and amino acids with a focus on the recent techniques available for effective extraction, recovery, application in the food system, and its health benefits. Given their inherent labile nature, encapsulation in the form of micro, nano, and liposomal offers protection from the extreme conditions employed in the different processing and formulation treatments of foods. A plethora of information is available on the use of solvent extraction and other novel extraction approaches for bioactive, such as enzyme-assisted, microwave-assisted, supercritical fluid–based, radiofrequency-assisted, ultrasound-assisted extractions, and integrated thermal-thermal, thermal-non-thermal, non-thermal-non-thermal approaches; however, their application to pigmented rice is limited. Moreover, encapsulation technologies like spray drying, spray chilling, freeze-drying, and the use of liposomes have also been widely recommended. However, there is considerable disparity between claims made for extraction and encapsulation of such products on a practical industrial scale because of viability on extremely small laboratory scales. A key recommendation is to focus their attention on scaling up laboratory processes.