Modeling and Optimization of Quality Properties of Lentils During the Hot Air Drying Process Utilizing the Response Surface Methodology (RSM)

ABSTRACT This study aimed to investigate optimal drying conditions for lentils by utilizing the response surface methodology. Lentil seeds were subjected to drying within a hot air dryer, with three distinct temperature tiers (50°C, 60°C, and 70°C) and three distinct airflow velocities (1, 1.5, and 2 m/s) until the seeds attained a moisture content of approximately 12%. Subsequent to this, a comprehensive assessment of their qualitative traits was conducted. With increasing temperature and air velocity, the drying process exhibited augmented hardness (From 192N at 50°C and 1 m/s to 317N at 70°C and 2 m/s); however, the influence of air velocity on drying time was relatively diminished with increasing temperature (From 380 s at 50°C and 1 m/s to 120 s at 70°C and 2 m/s). Conversely, escalating temperature engendered a reduction in sample luminosity (L), and color variations denoted a shift from the green spectrum (−a) to the red spectrum (+a), accompanied by changes in color parameter b indicative of reduced yellow hues within the sample. Enhanced temperature corresponded with reduced protein and carbohydrate content within the dried samples, while heightened heat transfer rates exhibited the opposite effect (from 25.50% and 42.69% at 50°C and 2 m/s to 13.62% and 40.62% at 70°C and 1 m/s). By leveraging the response surface methodology, the optimal drying conditions for lentil seeds were identified as 50°C temperature and 1.13 m/s air flow velocity, boasting a reliability coefficient of 0.906; so, the response surface methodology emerges as a judicious and precise technique for modeling and optimizing the quality attributes of lentils within the ambit of hot air drying conditions.