Effect of moisture contents on drying rate at varying regulated temperatures and fan speeds of some leafy vegetables

Abstract

This research investigates the effects of drying on some selected vegetables, which are Telfaria occidentalis, Amaranthu scruentus, Talinum triangulare, and Crussocephalum biafrae. These vegetables were collected fresh, sliced into smaller sizes of 0.5 cm, and dried in a convective dryer at varying temperatures of 60.0 ℃, 70.0 ℃ and 80.0 ℃ respectively, for a regulated fan speed of 1.50 ms⁻¹, 3.00 ms⁻¹ and 6.00 ms⁻¹, and for a drying period of 6 h. It was discovered that the drying rate for fresh samples was 4.560 gmin⁻¹ for Talinum triangulare, 4.390 gmin⁻¹ for Amaranthu scruentus, 4.580 gmin⁻¹ for Talinum triangulare, and 4.640 gmin⁻¹ for Crussocephalum biafrae at different controlled fan speeds and regulated temperatures when the mass of the vegetable samples at each drying time was compared to the mass of the final samples dried for 6 h. The samples are considered completely dried when the drying time reaches a certain point, as indicated by the drying rate and moisture contents tending to zero. According to drying kinetics, the rate of moisture loss was extremely high during the first two hours of drying and then steadily decreased during the remaining drying duration. The rate at which moisture was removed from the vegetable samples after the drying process at varying regulated temperatures was noted to be in this trend: 80.0 ℃ > 70.0 ℃ > 60.0 ℃ and 6.0 ms⁻¹ > 3.0 ms⁻¹ > 1.5 ms⁻¹ for regulated fan speed. It can be stated here that the moisture contents have significant effects on the drying rate of the samples of vegetables investigated because the drying rate decreases as the regulated temperatures increase and the moisture contents decrease. The present investigation is useful in the agricultural engineering and food engineering industries.