Kinetics of color degradation of chestnut kernel during thermal treatment and storage

Thermal treatments are commonly used for disinfesting chestnuts before storage. Color is a first and sensitive quality attribute of chestnuts after thermal treatments and storage. The purpose of this study was to investigate L* and b* values in chestnuts during thermal treatment at 50-70°C for periods varying from 0 to 160 min, and during storage at 3°C for 5 months using a computer vision system (CVS). Results showed that the L* and b* values decreased with increasing temperature, and heating or storage time. The first-order reaction model showed a better fit for the L* and b* values than zero-order reaction model with coefficients of determination (R2) ranging from 0.923 to 0.977 during the thermal treatment and storage. The activation energies of chestnuts were 287.19 and 347.48 kJ/mol during thermal treatments and 89.18 and 78.47 kJ/mol during storage for L* and b* values, respectively, suggesting that the yellowness (b*) was more sensitive to temperature changes than the lightness (L*). According to requirements of L*>50, a potential disinfestation treatment protocol could be developed for chestnuts at 52-62°C.