Dehydration of infrared ginger slices: heat and mass transfer coefficient and modeling

Abstract

Dehydration of plant products extends its shelf life and reduces its mass and volume, which increases transport and storage efficiency and adds value to food. However, it is an intensive process in energy and time, making necessary the search for more efficient technologies, Thus, this study aimed to investigate the infrared ginger dehydration process by approaching the constant period of dehydration to the theory of mass and heat transfer process to the wet bulb thermometer and the decreasing period of dehydration to liquid diffusion theory. We submitted 5.0 mm thickness and 2.0 cm diameter slices to a dryer with infrared radiation at 50, 60, 70, 80, 90 and 100 °C until constant mass. Heat and mass transfer coefficients, and effective diffusion coefficient increased linearly with temperature increasing, resulting in values ranging from 69.40 to 92.23 W m-2 °C-1, 0.062 to 0.089 m s-1 and 3.81 x 10-9 to 1.13 x 10-8 m2 s-1. Variation of heat and mass transfer coefficients was described by a linear model and the variation of effective diffusion coefficient with the temperature was described with the Arrhenius relation, whose activation energy was 22.07 kJ mol-1. The modified Henderson and Pabis model was able to satisfactorily describe the period of decreasing drying rate.

Drying process of Lentinula edodes: Influence of temperature on β-glucan content and adjustment of mathematical models

“…Therefore, it is possible to hypothesize that the performance observed in this study is typical of mushroom drying. It is also similar to the behavior of other fruits and vegetables (Onwude et al, 2016;Corrêa et al, 2019). The moisture content plays an important role in the product quality and composition.…”

Dehydration of pequi slices (Caryocar brasiliense Camb.) by infrared: Modeling and effective diffusion coefficient

“…During the drying process, the reduction of the moisture content present in the composition of agricultural products occurs due to heat and mass transfers (Younis et al, 2018). According to Corrêa et al (2019), water has the characteristic of moving within a product subjected to drying by different mechanisms. In agricultural products, usually hygroscopic porous, the possible mechanisms of moisture movement are liquid diffusion, capillary diffusion, surface diffusion, steam diffusion, thermal diffusion, and hydrodynamic flow (Martinazzo, Corrêa, Resende, & Melo, 2007).…”

“…According to Younis et al (2018), the most appropriate approach to describe the kinetics of the drying process is through mathematical modeling. Among the types of models, the empirical ones are based on variables external to the product, such as the temperature and relative humidity of the drying air (Oliveira, Resende, Smaniotto, Campos, & Chaves, 2012); and although they are not based on theories, they are generally simpler and easier to apply (Brooker, Bakker-Arkema, & Hall, 1992;Corrêa et al, 2019).…”

“…Several research have been carried out in recent years focusing on mathematical modeling of infrared drying of different agricultural products, such as apple (Santos, Corrêa, Baptestini, Botelho, & Magalhães, 2011), carrot (Botelho et al, 2011), tomato (Corrêa et al, 2012), pineapple (Baptestini et al, 2016), banana (Baptestini et al, 2017), ginger (Corrêa et al, 2019), and among others. Some works in the literature use the forced convection technique for drying the pequi pulp, aiming to obtain raw material for oil production.…”

“…A dryer with an infrared radiation source (Model IV 2500, Gehaka, São Paulo, Brazil) was used for drying pequi slices under temperatures of 55, 65, 75, 85, and 95 C. This temperature range was chosen based on infrared drying studies found in the literature, such as the dehydration of ginger slices (Corrêa et al, 2019), carrot slices (Botelho et al, 2011), and apple slices (Santos et al, 2011). The infrared dryer contains a precision scale of 0.001 g and an automatic data acquisition system, capable of inferring a variation in the mass of the product every minute.…”