EFFECT OF ULTRASOUND PRETREATMENT ON DRYING KINETICS, SPECIFIC ENERGY CONSUMPTION AND QUALITY INDICES OF MICROWAVE-DRIED JUTE LEAVES

Abstract

This study investigates the effect of ultrasound pretreatment on drying kinetics, specific energy consumption and quality indices of microwave-dried jute leaves. Fresh jute leaves were pretreated with ultrasonic cleaner for 30 mins. The effect of the ultrasound pretreated jute leaves (UPJL) and untreated jute leaves (UNJL) on the drying time, rehydration ratio, drying kinetics, specific energy consumption and quality indices (protein, vitamin A, vitamin C, iron and potassium) were determined using standard procedures. Eight drying models (Page, Logarithmic, Henderson and Pabis, Newton (Lewis), Wang and Singh, Parabolic, Midilli, Prakash and Kumar) were used to determine the drying kinetics. UPJL has lower drying time and energy consumption compared to UNJL. However, the UNJL has a higher rehydration ratio than UPJL. The Page model was found to best fit the experimental data compared to other models. The protein content of the dried jute leaves ranged from 12.05% to 12.83%, Vitamin A (2.81 to 2.87 mg/100g), Vitamin C (30.46 to 35.08 mg/100g), iron (5.42 to 6.53 mg/100g) and potassium (213.25 to 215.16 mg/100g), respectively. UNJL gave higher vitamin A, vitamin C and protein while UPJL favours iron and potassium contents. Ultrasound pretreatment enhances jute leaf drying rate and quality, thus showing promising potential.