Pigmented Heirloom Beans: Nutritional and Cooking Quality Characteristics

Abstract

Dry beans are considered an important source of macro‐ and micronutrients and an economical source of protein and fiber. Although many varieties exist, production is limited to a relatively small set of commodity varieties, whereas little is known about heirloom varieties. To facilitate their adoption into everyday use, this study aimed to characterize the chemical composition, antioxidant capacity, pasting properties, texture, and in vitro starch digestibility of four heirloom varieties (Hutterite Soup, Jacob's Cattle, Koronis Purple, and Tiger's Eye) that are characterized by unique pigmentation. Pinto bean was used as the control. The content in protein, total fiber, and soluble fiber was generally higher in heirlooms compared with Pinto, with Koronis Purple showing the best nutritional characteristics. Moreover, all the heirlooms except Hutterite Soup showed higher in vitro antioxidant capacity than the control. Starch in heirloom varieties was characterized by lower pasting temperature and higher viscosity during heating and cooling, resulting in a paste with greater retrogradation tendency than Pinto. Heirloom in vitro starch digestibility was lower and resistant starch content higher than the control. With regard to cooking quality, Hutterite Soup and Jacob's Cattle showed lower firmness than Koronis Purple and Tiger's Eye, whose texture was similar to Pinto.