Hot Air Drying Characteristics and Thermodynamic Properties of Different Varieties of High Oleic Peanuts

To explore the moisture variation law of high oleic peanuts during hot air drying, hot air drying characteristics of various high oleic peanuts under different hot air temperatures (35, 40, 45, 50 ℃) and hot air velocities (0.5, 0.8, 1.1 m/s) were studied in this paper, and their drying processes were analyzed by Weibull distribution function. The results showed that the drying process of high oleic peanuts mainly reduced the rate of drying. Increasing hot air temperature and hot air velocity led to a higher effective moisture diffusion coefficient for high oleic peanuts. In turn, accelerates drying rate and shortens drying time. Among all the peanuts, 'Shengyou 3' peanut had the fastest water diffusion rate and lowest activation energy, and the Weibull distribution function provided the most suitable fit for 'Shengyou 3'. The scale parameter α decreased as hot air temperature and hot air velocity increase. Hot air temperature had a highly significant effect on α (P<0.01), while hot air velocity had a significant effect on α (P<0.05). The drying conditions had no significant effect on the shape parameter β. The increase in temperature promoted the decrease of enthalpy and entropy values, as well as the increase of Gibbs free energy, indicating that the drying process needed to absorb energy from the drying medium to proceed. The Weibull distribution function can be used to describe the hot air drying process of high oleic peanuts, providing a technical basis for the industrialization of high oleic peanut drying and laying a theoretical foundation.