Heat transfer analysis of convective and microwave drying of dragon fruit

Abstract

The purpose of this study was to develop a predictive three‐dimensional analytical model for predicting the temperature profile during microwave and convective drying of dragon fruit. A combined electromagnetic (Maxwell's equation) and heat transfer model was used for modeling of microwave drying. This heat transfer modeling is applicable to describe the thermal dissipation during the microwave and convective drying of agricultural produces. In this process, the dragon fruit cube of 15 mm was dried at a microwave power of 200, 400, and 600 W during the microwave drying process and hot air temperature of 60°C during the convective drying process. During microwave drying, the core or center temperature was maximum compared with the temperature at the surface of the dragon fruit cube. The predicted temperature at the center of the dragon fruit cube exposed to the microwave power of 200, 400, and 600 W for 60 s of drying time was 34.67, 44.34, and 54.02°C, respectively. In convective drying, the temperature at the edges was higher than the temperature at the center point of the dragon fruit cube. During convective drying, the fruit sample attained the maximum temperature of 60°C after being exposed to hot air for 8 min. The RMSE and χ2 values between experimental and model projected values were less than 0.988 and 0.029 in microwave drying and less than 0.891 and 0.018 in convective drying, indicating that the model projected values were in good agreement with the experimental values. Practical Applications The importance of thermal processes in deciding the safety and quality of food products is emergent. This model can predict food product temperature distribution during the hot air drying and microwave drying of Dragon fruit cubes. The economy of the drying process is often influenced by the nature and operation of these processes and hence modeling of the drying process is a crucial factor for the industry. These results can be used to quantify heat and moisture distribution, as well as to monitor the drying process of fruits and vegetables, saving energy and time.

Ultrasound assisted osmotic dehydration of dragon fruit slices: Modeling and optimization using integrated artificial neural networks and genetic algorithms

“…Fruit peel was separated with a knife, and the flesh was cut into slices of mm thickness. The average moisture content of the Dragon fruits slice was found to be on wet basis, determined by the hot air oven drying method at 105°C for 24 h (Bhagya Raj & Dash, 2021).…”

Rheological characteristics of reconstituted freeze‐dried dragon fruit pulp powder: Effect of concentration and temperature

“…The fruits were cleaned under running tap water to remove any foreign materials, and the peel of the fruit was separated from the pulp of the fruit was cut into slices of mm thickness. The fruit moisture content was estimated by drying the sample in a hot air oven at 105°C until a constant weight was attained, and the initial moisture content was found to be wet basis (Bhagya Raj & Dash, 2021). The slices were pretreated with 1.35% citric acid concentration (Bhagya Raj & Dash, 2020a) and dried in a freeze drier (Lyolab Freeze Lab, Lyophilization Systems Inc., USA) for 24 hrs, and the moisture content after drying was approximately 9.86 ± 1.62% (wet basis).…”

“…The ability to predict the experimental data by the used rheological model was authenticated by the valuation of various statistical parameters such as coefficient of determination (), root mean square error (RMSE), and chi‐square () values estimated using Equations (9)–(11) (Bhagya Raj & Dash, 2021). where is the predicted value from the model, is the observed value or experimental values, is the average response value, and n is the number of experiments.…”

Influence of convective and microwave drying on Algerian blood orange slices: Drying kinetics and characteristics, modeling, and drying energetics

“…Several studies reported the application of microwaves in the drying of fruits such as lemon slices (Darvishi et al, 2014), Sorbus fruit (Lüle & Koyuncu, 2015), crispy bananas (Monteiro et al, 2015), blueberries (Zielinska & Markowski, 2016), lemon slices (Kesbi et al, 2016), nectarine slices (Miraei Ashtiani, Sturm, & Nasirahmadi, 2017) pomelo (Yildiz & İzli, 2019), apple slices (Dai et al, 2019), and dragon fruit (Bhagya Raj & Dash, 2021).…”

“…Several studies reported the application of microwaves in the drying of fruits such as lemon slices (Darvishi et al, 2014), Sorbus fruit (Lüle & Koyuncu, 2015), crispy bananas (Monteiro et al, 2015), blueberries (Zielinska & Markowski, 2016), lemon slices (Kesbi et al, 2016), nectarine slices (Miraei Ashtiani, Sturm, & Nasirahmadi, 2017) pomelo (Yildiz & _ Izli, 2019), apple slices (Dai et al, 2019), and dragon fruit (Bhagya Raj & Dash, 2021). Alibas and Yilmaz (2022), investigated microwave and convective drying by providing results on the thermal properties of orange slices, the effect of drying on some phytochemical parameters (color parameters L, a, b, C, α , and ΔE, browning index, whitening index, and ascorbic acid), and modeling using 21 thin-layer drying equations.…”