14B-8

H. Y. CHUNG, Bio, Dept., Food and Nutritional Sciences Programme, and Food Sci. Lab., The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, Hong Kong, China and K. Ng.

Phaseolus angularis, also known as red bean, is used as a major ingredient in preparing deserts and soups in southern China. It has a reddish outer seed coat and a smaller size than a soybean. Recently, more researches have focused in the nutritional values of this underutilized bean. But the flavor quality, which may have a larger impact on the acceptability of this bean, has received much less attention. The objectives of this research were to determine the volatile components of the red bean, and to compare their composition with those of the soybean and its isolate in the literature. Red beans were ground and screened before extraction in a steam distillation and solvent extraction (SDE) apparatus with dichloromethane as solvent. Extracts were analyzed by a gas chromatography/ mass spectrometry (GC/MS). Positively identified compounds were verified with authentic standards. One hundred forty-three compounds were found in the samples including 37 tentatively identified ones. These compounds included 11 aldehydes, 17 alkanes, 5 aromatics, 8 esters, 11 nitrogen-containing compounds, 11 naphthalenes, 16 furans, 34 alcohols, 23 ketones and 5 sulfur-containing compounds. Twenty-eight of them were previously found in soybean. Among them, alcohols (8) and ketones (5) were the largest groups. The rest of the groups mostly contained one or two compounds. Ten out of 17 compounds responsible for the off-flavor in soybean isolate were also found in red bean. Based on these findings, red bean might not be highly acceptance to consumers who did not have previous exposure to it unless methods to minimize the impact of off-flavor components could be found.