Solar and Convective Drying: Modeling, Color, Texture, Total Phenolic Content, and Antioxidant Activity of Peach (Prunus persica (L.) Batsch) Slices

Peach is a fruit highly appreciated by consumers; however, it is highly perishable, so drying is an alternative to preserve its physical and chemical properties. In this study, the effect of drying in natural and forced convection at three different temperatures (40 degrees C, 45 degrees C and 50 degrees C) and solar drying with two air velocities (1 m/s and 3 m/s) on the color, texture, total phenol content and antioxidant capacity of peach (Prunus persica (L.) Batsch), were evaluated. The experimental data of the drying kinetics were adjusted to five different mathematical models (Page, Logarithmic, Two-term exponential, Wang and Singh, and Verma et al.). The model that best represented the experimental data in natural convection was the Wang and Singh model (r(2) > 0.998; RMSE < 0.016; chi(2) < 2.85 x 10(-4)); in forced convection (45 degrees C and 50 degrees C), it was the Verma et al. model (r(2) > 0.997; RMSE < 0.025; chi(2) < 8.12 x 10(-4)); and finally, for solar drying, it was the Logarithmic model at 3 m/s (r(2) = 0.999; RMSE < 0.012; chi(2) < 1.12 x 10(-4)) and Wang and Sing model (1 m/s) (r(2) = 0.998; RMSE = 1.31 x 10(-4); chi(2) = 1.92 x 10(-4)). The highest color difference was in samples dried by the natural convection method. The highest values of hardness were obtained by the solar drying method. The value of chlorogenic acid increased with the temperature of natural convection, while the concentration of neochlorogenic acid increased with the temperature at forced convection. For solar drying, the values of chlorogenic acid were greater at 3 m/s; in contrast, the neochlorogenic acid was greater at 1 m/s.