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Effects of Selected Barley Cultivars and Their Pearling Fractions on Inhibition of Human LDL Oxidation In Vitro Using a Modified Conjugated Dienes Method

¹Agriculture and Agri-Food Canada, Guelph Food Research Centre, 93 Stone Road West, Guelph, ON, Canada, N1G 5C9. ²Corresponding author. Phone: (519) 780-8031. Fax: (519): 829-2600. E-mail address: abdelaale@agr.gc.ca ³University of Alexandria, Faculty of Agriculture, Department of Food Science, and Technology, El-Shatby 21545, Alexandria, Egypt.

Oxidation of LDL cholesterol is an important factor in the development of atherosclerosis and heart disease. In this study, selected Canadian and Egyptian barley cultivars and their pearling fractions were evaluated for antioxidant capacity to inhibit human LDL oxidation in vitro. Measurement of conjugated dienes (CD) at 234 nm was optimized to determine the degree of LDL oxidation. Dilution of oxidized LDL with iso-propanol gave a distinct diene conjugation peak. Significant differences in total phenols content (TPC) were found between the cultivars tested, with the hulless barley having greater TPC and inhibition capacity compared with hulled barleys. The outer layers fraction contained the highest TPC, lowest CD formation, and longest lag time, whereas the inner, or endosperm fraction, had the lowest inhibition effects. The middle pearling and hull fractions possessed intermediate inhibition effects. The inhibitory effect of barley extracts was dependent on phenols concentration following a linear or quadratic pattern. The results suggest that barley whole meals, outer layers, middle pearling, or hull fraction would be a potential LDL antioxidant.