Optimization and Kinetics of Thermal Air Drying of Guava

In this paper,the hot-air drying kinetics of guava was studied by single factor hot-air drying experiments at different temperature,loading,salt solution and scalding time. The drying time,drying rate,color,rehydration ratio and unit energy consumption were measured and compared. Three factors,hot air temperature,scalding time and salt concentration,were obtained. The comprehensive effect on drying quality and unit energy consumption was analyzed by response surface analysis(RSM),and the optimum parameter combination was determined. On this basis,the mathematical models of Newton model,Page model,Henderson and Pabis model and multinomial were used to fit the model. The dynamic equation of drying was established,and the effective water diffusion coefficient was calculated to study the water diffusion characteristics and the model was validated.he results showed that the optimum processing parameters of guava were as follows: drying temperature 90 ℃,blanching time 1.99 min,salt concentration 1.96%. The results showed that the drying rate was the fastest,the drying time was 120 min,the value of L^* was small,the value of a^* and b^* were the smallest,the rehydration ratio was 5.82,the energy consumption was 118.04 kJ/g.The best mathematical model is polynomial,and the expression was: Y=-0.0003x⁵+0.018x⁴-0.3944x³+3.2166x²-11.364x+99.921,R² was 0.998. The effective water diffusivity of guava was 9.01×10^-9 m²/s. This study provides a theoretical basis for the application of hot-air drying of guava.