Chemical and microstructural evaluation of “Hard-to-Cook” phenomenon in legumes (Pinto bean and small-type lentil)

M. Pirhayati, N. Soltanizadeh and M. Kadivar. 2011. Chemical and microstructural evaluation of “Hard-to-Cook” phenomenon in legumes (Pinto bean and small-type lentil). International Journal of Food Science & Technology. 46: 1884–1890.

Abstract

Some physicochemical and microstructural characteristic of hard-to-cook (HTC) and east-cook Pinto beans and small-type lentils was compared. The development of HTC was monitored over six months from changes in physicochemical properties. Results indicated that hardness, extent of water absorption and solid loss of HTC legumes was respectively 21-97%, 7-72% and 62-236% higher than that of easy-to-cook (ETC). In addition, darkness of hard-to-cook beans and lentils was significantly higher than that of easy-cook ones. SEM observations indicated deteriorations in cytoplasmic contents of cotyledon cells of hard seeds. Phytic acid and total phenolics contents were respectively decreased 36-61% and 43-61% during storage whereas hardness of seeds was increased 3-6 times. The soaking of hard seeds in sodium solutions resulted in improvement of legume texture.

Keywords: Hard to cook; Lentil; Bean; Phenolic compounds; Texture; Microstructure.