COMPARATIVE STUDIES ON FREE RADICAL SCAVENGING CAPACITIES AND TOTAL PHENOLIC CONTENTS OF WHOLE AND DEHULLED ADLAY (COIX LACRYMA-JOBI VAR. MA-YUEN) AS AFFECTED BY THERMAL PROCESSING METHODS BAOJUN XU 1 and XUE CHEN Food Science and Technology Program, Beijing Normal University–Hong Kong Baptist University United International College, Zhuhai, Guangdong Province 519085, China 1 Corresponding author. TEL: +86-756-3620636; FAX: +86-756-3620882; EMAIL: baojunxu@uic.edu.hk (1) Thermal processing remarkably affected phenolic contents of adlay. (2) Thermal processing significantly changed the antioxidant capacities of adlay. (3) Dehulled adlay lost lot of phenolics and antioxidants. (4) Roasting significantly increase phenolics and antioxidant capacities of adlay. (5) Processed adlay contained substantial amounts of antioxidants. Accepted for Publication January 23, 2012 doi:10.1111/j.1745-4549.2012.00683.x ABSTRACT Substantial researches have been performed to support the beneficial effects of adlay; however, there were limited studies on the effects of processing methods on these claimed benefits. This study investigated the effects of roasting, boiling, and steam- ing on the total phenolic contents (TPCs) and radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging properties of both whole and dehulled adlay.Whole adlay dem- onstrated higher TPC and better DPPH radical scavenging activities than dehulled adlay.Different processing methods significantly changed the content and activity of antioxidants of both whole and dehulled adlay. All processed adlay samples exhib- ited significant (P < 0.05) differences in TPC and antioxidant activities as compared with the respective raw adlay sample. The thermal processed adlay samples still con- tained substantial amounts of antioxidants. Roasting is considered to be the best processing methods, which increased TPC and radical DPPH scavenging activities of both whole and dehulled adlay. PRACTICAL APPLICATIONS This research would have practical applications in providing value-added food products or nutraceuticals derived from hull and dehulled adlay.Presented informa- tion will guide home-cooking practice as well as food industry to retain more health benefit components through selecting optimum cooking methods. The results indi- cate that thermal processing remarkably affected phenolic contents of adlay and sig- nificantly changed the antioxidant capacities of adlay. In addition, dehulled adlay lost lot of phenolics and antioxidants, roasting significantly increase phenolics and antioxidant capacities of adlay. Therefore, to increase bioavailability of active com- ponents from adlay and gain more health promoting effects, the roasting method may be a good processing method. INTRODUCTION Adlay (Job’s tears, Chinese pearl barley), seed of Coix lacryma-jobi var. ma-yuen (family Poaceae), is one of the most widely used medicinal food materials that are regarded as both a common herbal medicine and a nourishing food in traditional Chinese medicine (TCM). According to TCM, adlay with or without shell, preheated or not, are different in characteristics as herbal medicines. Generally, whole adlay, which retains the hulls, is commonly used as an herbal medi- cine, while the dehulled seeds are generally treated as food. With its hard seed hull removed, the white kernel inside can be cooked and eaten like rice or barley in soups and cereals, or ground to make flour. Adlay is an important source of protein, fiber and minerals. It also contains some very unique chemical components. The grain has always been an important component in Chinese herbal medicine, specifically in diet therapy. Currently, the Journal of Food Processing and Preservation ISSN 1745-4549 630 Journal of Food Processing and Preservation 37 (2013) 630–636 © 2012 Wiley Periodicals, Inc.