Quantifying water distribution between starch and protein in beans and chickpeas during cooking

The cooking of pulses causes gelatinization−melting of starch and denaturation of proteins. These thermal transitions were studied in beans and chickpeas using differential scanning calorimetry (20−160 °C, water contents ranging from 0.2 to 4.0 kg kg−1 dry basis). In the thermogram, the shape and temperature of the transition peaks depended on the water content in starch and protein. The thermogram was analyzed to quantify water distribution between starch and protein, assuming the coexistence of two water populations. After modeling the peaks as Gaussian functions, the distribution of water during heating was modeled as a Weibull distribution with water dependent parameters. Most water was available in protein, and was reallocated from protein to starch during heating. The fraction of water attributed to starch increased from less than 10 % of total water to 35−45 % at the end of cooking. Competition between starch and protein for available water delayed all thermal transitions.