Modelling and Kinetic Study of Novel and Sustainable Microwave-Assisted Dehydration of Sugarcane Juice

Abstract

Sugarcane juice is a perishable food with a good nutritional profile. Thus, there is a need to increase its shelf life by reducing water content which facilitates storage and transportation. In this study, process conditions were optimized to concentrate the sugarcane juice at various microwave powers (30, 50, 80, 100 W). A central composite design was applied to optimize the process conditions (power and time). The overall evaporation time depends on microwave powers; increase in power reduced the processing time. The results showed that at 100 W sugarcane juice was concentrated to 75° brix for 15 min which reduced the energy consumption to 1.3 times compared to other powers. Moreover, microwave processing better retained the sensory properties of concentrate and preserved its antioxidant activity. Thus, 100 W was most energy efficient in concentrating sugarcane juice. In general, microwave processing reduced the processing time and cost making it a sustainable approach to concentrate juices.

Effects of microwave heating on quality attributes of pineapple juice

“…However, the kinetic constant at 80W (0.0002 s −1 or 0.012 min −1 ) was also about four times lower than the result (0.047 min −1 ) reported by previous researchers who used similar microwave power (80 W) to concentrate sugarcane juice (Alvi et al, 2019). The difference could be due to the variance of chemical composition, especially high sugar content in sugarcane juice (>15 o Brix) compared to only 7.4 o Brix in pineapple juice.…”

“…Higher mass per power would have lower diffusivity because of higher resistance in molecular diffusion in juice medium. The diffusivity of pineapple juice (0.92–7.3 × 10 –8 m 2 /s) was found to be higher than the value for sugarcane juice (3.36 × 10 –15 m 2 /s) in microwave heating (Alvi et al., 2019). This could be due to lower sugar content in pineapple juice which was only 7.4 o Brix in this study.…”

“…The surface plots show to have parabolic increment in relation with the variable of mass evaporation rate. The mass evaporation rate is the net rate of moisture evaporation from the surface of pineapple juice and the mass transfer of internal moisture to the surface of pineapple juice (Alvi et al., 2019). The sugar content in pineapple juice was linearly increased with the mass evaporation rate.…”

“…The mechanism of water evaporation from pineapple juice was assumed to follow the Fick's second law of diffusion under the unsteady state condition through infinite slab geometry (Alvi et al., 2019). Based on the assumptions of uniform initial moisture distribution, isothermal environment, as well as negligible external resistance and shrinkage, the concentration of pineapple juice can be described by Equation 5.…”

Microwave assisted drying and extraction technique; kinetic modelling, energy consumption and influence on antioxidant compounds of fenugreek leaves

“…reduced drying time and cost. Thus, microwave method of drying is energy efficient and easy to use compared to other drying methods (Alvi et al, 2019;Gamboa-Santos & Campañone, 2019;Khan et al, 2016;Lv et al, 2019). However, loss of water-soluble bioactive compounds is still a major problem in microwave-based dehydration systems.…”