Effect of Cooking Conditions on the Nutritional Composition of Some Cooked Dry Beans

Abstract

Dry beans are cooked before consumption. The heat from cooking helps to modify the structure and chemical composition of some nutritional compounds, particularly the protein complexes and bound phenolic compounds, which enables them to be digested easily. Some chemical compositions may be modified, and nutritional value may be changed. Two dry beans (black and red kidney) were selected to be cooked under two different cooking conditions (conventional steam and saturated steam under pressure) for this study. Therefore, the main objective of this presentation was to determine the effect of cooking conditions on the nutritional properties of these two cooked dry beans. For preliminary purposes, both types of dry beans were subjected to an 8-hour soaking period prior to cooking. The conventional steaming time for black beans was 35 minutes and 45 minutes for red kidney beans at 100°C under normal atmospheric pressure, whereas the pressure steaming time was 10 minutes for black beans and 20 minutes for red kidney beans at 10psi above atmospheric pressure. The nutritional value of soaked beans was also determined. Before the determination of nutritional value, both types of beans were ensured that they were equally cooked by textural analysis (hardness measured by a puncture test). The average puncture force of each cooked bean was around 360-380gf, which was considered soft and palatable. For nutritional value, the results of crude protein, crude fat, and crude ash content in cooked beans obtained from the two different cooking methods proved no significant difference. This occurred in both types of beans. However, cooking caused some changes in crude fiber content of dried beans. Especially in red kidney beans, the saturated steam under pressure cooking method led to a significant reduction in their crude fiber content. Hence, the difference in nutritional values which is affected by cooking conditions in these two types of bean (comparing with soaked beans) is essential to prove which cooking method provides utmost benefits in terms of overall nutritional values provided by cooked beans.