Modelling the kinetics of mass transfer and change in colour during deep fat frying of green peas (Pisum sativum L.) at different frying temperatures

Abstract

The investigation was carried out to study the mass transfer and change in colour during deep fat frying green peas (Pisum sativum L.) at different frying temperature ranging from 120 to 180 °C. The results showed that the kinetics of moisture loss (kx) and fat uptake (ky) during deep fat frying followed first order kinetic equation (R2 > 0.96, p < 0.001). The kinetic rate constant for moisture loss was significantly (p < 0.05) increasing from 0.484 to 2.212 min−1 with increase in temperature, where as the oil uptake was increasing from 0.241 to 0.371 min−1 with increasing temperature. The CIE color parameters were significantly (p < 0.05) affected by frying time as well as frying temperature. The change in CIE colour parameters such as lightness (L*), Total colour difference (∆E) and dominant wavelength (λd) were described by first order kinetic equation, where as, other colour parameters such as greenness-redness (a*), yellowness (b*), chroma (c*) and hue angle (h*) were described by zero order kinetic equation. The degradation of chlorophyll content of green peas was described by first order kinetic equation and rate constant varied from 0.0861 to 0.1872 min−1 with increase in frying temperature. The temperature dependency of rate constants was described by Arrhenius equation. The activation energy of mass transfer, change in colour values and degradation of chlorophyll varied from 3.94 to 39.28 KJ/mol. A significant correlation was observed among mass transfer, colour and pigment content parameters during deep fat frying of green peas at different frying conditions.