Microwave drying effect on drying characteristic and energy consumption of Ficus carica Linn leaves

Abstract

Ficus carica Linn leaves having significant pharmacological properties such as antioxidant, antifungal, antidiabetic, antibacterial, anti-inflammatory, and anti-pyretic are available just in season. The effective utilization of nutritional values of leaves with enhanced shelf life has gained attention. Drying is usually the preferred technique to eliminate microbial attacks and increase shelf life of seasonal food products. Therefore, in the present study, the effect of microwave drying conditions on effective moisture diffusivity, activation energy, specific energy consumption (SEC), and energy efficiency were investigated at various microwave output power levels and sample amounts. The seven mathematical models were applied to describe the microwave drying kinetics of leaves and Page model was found as the best model. The maximum effective moisture diffusivity and drying rate constant values were determined as 9.84 Â 10 À11 m 2 /s and 1.15 1/min, respectively, at microwave output power level of 900 W and sample amount of 20 g. The activation energy values were estimated using the modified Arrhenius equation associated with effective moisture diffusivity (E a = 11.41 W/g) and drying rate constant (E a = 8.28 W/g). Additionally, the minimum SEC and maximum energy efficiency values (%) were found as 5.60 MJ/kg water and 40.31, respectively, at microwave output power level of 360 W and sample amount of 100 g. The results obtained from the present study seemed potentially useful to explore the applicability of microwave drying on Ficus carica Linn leaves to expand the availability of leaves having numerous nutritional ingredients throughout the whole year and take the advantage of their benefits in various industries. Practical ApplicationsEven if the benefits of Ficus carica L. leaves have been well presented in various studies in the literature, no study was found particularly which investigated the microwave drying kinetics of these leaves. Apart from the mathematical modeling of the drying characteristic and energy aspects of the leaf samples, the present study also targets to expand the usage area of these leaves with high shelf life and enable people to reach the leaves easily throughout the whole year. Hence, this study has potential for the commercial usage of these leaves for their effective utilization in various industries; such as beverage, bakery, cosmetic, and so on. In that way, the valuable nutritional ingredients of these leaves have been turned in favor of human consumption.

Effect of microwave power on drying behavior and essential oil yield of microwave dried Eucalyptus camaldulensis Dehnh. leaves

“…As compared the present result with other plant materials, the higher Ea means lower moisture diffusivity [2]. In the literature, the activation energy values for some microwave dried leafy plant materials were calculated as 8.28, 11.41, 12.28 W/g [48].…”

Effect of microwave‐assisted vacuum drying on the drying kinetics and quality parameters of Moringa oleifera leaves

“…At 500 mmHg, the drying rate was highest at power level of 450 W at 0.8997 g of water/g of dry matter × min and decreased to 0.1202 g of water/g of dry matter × min for the lowest power level of 90 W. This may be due to the increased internal heating rate and greater moisture migration from inside to outside of the product (Özbek & Dadali, 2007; Yilmaz et al, 2021). Similar results were reported in drying of various leafy foods by Mujaffar and Bynoe (2020) in Pimenta racemosa leaves, Samad et al (2021), and Potisate and Phoungchandang (2015) in moringa leaves and Yilmaz et al (2021) in Ficus carica Linn leaves. Another important characteristics of the drying rate curve observed were that the shape of the curve resembles each other at the end of the curve.…”

“…There was an increase in diffusion rate by 31.2% by an increase in power level that ultimately resulted in decreased drying time and drying rate. The rapid absorption of microwave energy at a higher power level creates a greater pressure gradient inside the sample that eventually opens the porous structure and results in greater moisture migration (Bualuang et al, 2019; Yilmaz et al, 2021). Similar results were observed in microwave drying of moringa leaves (Potisate & Phoungchandang, 2015), F. carica Linn leaves (Yilmaz et al, 2021), purple basil leaves (Altay et al, 2019), peppermint leaves (Torki‐Harchegani et al, 2016), and several others.…”

“…The rapid absorption of microwave energy at a higher power level creates a greater pressure gradient inside the sample that eventually opens the porous structure and results in greater moisture migration (Bualuang et al, 2019; Yilmaz et al, 2021). Similar results were observed in microwave drying of moringa leaves (Potisate & Phoungchandang, 2015), F. carica Linn leaves (Yilmaz et al, 2021), purple basil leaves (Altay et al, 2019), peppermint leaves (Torki‐Harchegani et al, 2016), and several others. At a constant microwave power level (450 W) and different vacuum levels, the moisture diffusion coefficient ranged from 4.49 × 10 −10 m 2 /s to 7.65 × 10 −10 m 2 /s.…”

“…Microwave drying is regarded as the fastest drying technique where heat transfer takes place by penetration of microwaves onto the food product and continuously reorients water molecules that results in volumetric heating of food from inside to outside as against hot air heating methods where heat should penetrate from outside to inside of the food product. Moisture migration in microwaves is due to the presence of a vapor pressure gradient that drives off moisture outside the sample rather than heating the entire sample (Yilmaz et al, 2021). This results in shortened heating time, reduced energy consumption, and lowered operating costs (Samad et al, 2021).…”