KINETIC OF WATER ADSORPTION IN COMMON BEAN: CONSIDERATIONS ON THE SUITABILITY OF PELEG'S MODEL FOR DESCRIBING BEAN HYDRATION

Water uptake of common bean samples belonging to both commercial cultivars and Italian local varieties and representing different market classes was studied. Three hydration groups characterized by slow, intermediate and fast water uptake were identified. Predictive efficacy of Peleg model, commonly used to describe legume soaking, was evaluated by analyzing data relative to samples belonging to the three hydration groups. It was observed that different hydration rate gave rise to significant variation of both Peleg constants within as well as among the groups. Moreover, the Peleg model predicted adequately only the hydration kinetic of common bean samples belonging to the fast hydration group. PRACTICAL APPLICATIONS Common bean is a worldwide crop, but it is underutilized because of long soaking and cooking times needed to achieve required digestibility. Because water absorption by seeds is the first step to prepare dishes based on legumes, there is interest in obtaining mathematical models to describe this process. As diffusional models are complex and cumbersome, empirical equations, such as Peleg's model, are commonly used to fit water absorption data of different food materials. This note shows as Peleg's model, which describes efficaciously the hydration of several legume species, is not able to always fit the water absorption data of common bean. This suggests the necessity for further studies aimed to the establishment of alternative mathematical models that are able to adequately describe water absorption kinetic in common bean.