EIGHT UNDEREXPLOITED BROAD BEANS FROM CHINA: (II) EFFECTS OF STEAMING METHODS ON THEIR QUALITY AND MICROSTRUCTURE*

ABSTRACT The effects of different steaming methods (traditional steaming, autoclave steaming and microwave steaming) on the quality and microstructural properties of eight typical and luxuriant broad bean varieties in China were investigated. The color of broad bean seeds was not fresh after all steaming treatments and steaming–cooling treatments. All samples had very low splitting ratios, and no splitting for SYTJQ (no. 4), CXDL1 (no. 5), TX1 (no. 6) and QH10 (no.8) after soaking and traditional steaming. Broad bean seeds after autoclave steaming presented the best tenderness, followed by the traditionally steamed broad beans. As in steamed beans, denaturation of protein during heating made the cell wall rigid and tightly enveloped starch granules. After cooling, the cotyledon cells of all samples presented semblable appearance but with dense gauffers or grooves in the surface of cell wall. Intracellular gelatinization of starch occurred through sequential configurational changes in starch granules during steaming, but no extracellular gelatinization. PRACTICAL APPLICATIONS The broad bean is one of the most important legumes in China. Oriental cooking has always made great use of steaming as a main cooking method, both for health reasons and the sparsity of ovens. Steaming brings about a number of changes in physicochemical and structural characteristics of broad beans. However, very little information is available in the literature regarding the steaming method rather than other cooking methods. Therefore, based on our previous research, the purpose of the present study was to investigate the effects of different steaming methods (traditional steaming at atmospheric pressure, autoclave steaming and microwave steaming) on the quality and microstructure properties of eight typical and luxuriant broad bean varieties in China. Meanwhile, we can discover some excellent broad bean varieties for steamed foods. This study may serve as the foundation for selecting steaming methods to improve the quality of convenient foods made from the broad bean.