Kinetic modelling of polyphenol degradation during common beans soaking and cooking.

Phenolic compounds are phytonutrients with anti-inflammatory attributes that are significant for brain, heart and gut health. Losses of natural phenolic compounds in foods occur due to degradation during processing. The extent of degradation depends on the processing conditions applied. In this study, the degradation of total phenolic compounds during the processing of common beans (Phaseolus vulgaris L.) cultivars was investigated. The effects of soaking time, soaking water temperature and cooking conditions on polyphenol degradation were examined. The total phenolic compounds were determined as gallic acid equivalents. The result shows that increase of hydration time and process water temperature significantly (p < 0.05) increased polyphenol degradation. There was a strong positive Pearson correlation (r > 0. 85) between the rate of water uptake and polyphenol degradation regardless of the water temperature and cultivar. The rate of degradation varied from 0.041 - 0.098 and 0.014-0.069 mg/g per hour for Kabulangeti and Maine cultivar, respectively. The addition sodium chloride (NaCl) and potassium carbonate (K₂CO₃) during cooking to soften the beans significantly increased the degree of degradation. The activation energy for degradation was estimated as 45.4 and 26.3 kJ/mol for Kabulangeti and Maine cultivar, respectively.