Effect of Microwave Drying on the Drying Characteristics, Color, Microstructure, and Thermal Properties of Trabzon Persimmon

Abstract

In this study, changes in the drying kinetics, color change, and the energy consumption for microwave energy were investigated for Trabzon persimmon. In addition to that, the microstructure of the persimmon was also investigated by considering its thermal changes. It is important to be aware of the purpose of the drying process for determining the drying system. Results of this research showed that 460 W for 7 mm slice thickness depending on energy consumption, 600 W for 5 mm slice thickness depending on drying time, and 600 W depending on color changes were found as suitable drying processes depending on drying conditions. The effective diffusion values varied between 2.97 × 10−8 m2 s−1 and 4.63 × 10−6 m2 s−1. The activation energy values for 5 mm, 7 mm and 9 mm slice thickness were estimated as 32.82, 18.64, and 12.80 W g−1, respectively. The drying time and energy consumption decreased, whereas drying rate increased with an increase in the microwave energy. The number of pores increased compared to structure of fresh sample, and the pores got to be larger for 5 mm slice thickness as the power level increased. Results showed that the applied microwave energy had an important effect on the heating of the material and the change in the microstructure.

Influence of the Duration of Microwave Irradiation of Scots Pine (Pinus sylvestris L.) Cones on the Quality of Harvested Seeds

“…For 15-second exposure, the temperature approached 100 • C for whole cones and 80 • C for cone halves. These figures are comparable to those obtained by Çelen [17] during the microwave drying of vegetables (87-155 • C). Sample images of both intact and cut cones, made with a thermal imaging camera, are shown in Figure 7.…”

“…The correlation between increased loss of weight and higher time of exposure to microwaves, which was revealed in all cases, confirms the results obtained by Çelen [17], who carried out a similar study on persimmon drying (through also changing the microwave power).…”

“…However, there are divergent opinions on the influence of EMR on biological materials, as it depends on numerous factors, including the moisture content, structure and composition of the material, as well as the frequency and length of the electromagnetic waves used [9][10][11]. It has been well documented that prolonged microwave irradiation of biological samples can cause structural damage to both tissues and cells [12][13][14][15][16][17][18][19][20][21][22][23]. The available studies have also investigated the effect of intermittent microwave drying on biophysical properties of various plants, such as rice [24], colza [25], or tree seeds and seedlings [26].…”

Analysis of the Anthocyanin Degradation in Blue Honeysuckle Berry under Microwave Assisted Foam-Mat Drying

“…. As can be observed, the drying time was shortened, and the final temperature of the dried product was increased with the increase in microwave intensity [30]. The amount of anthocyanins degradation decreased slowly in the pre-heating drying stage and the early foaming drying stage, as shown in Figure 3.…”

“…Due to the berry puree bubbling during the foaming drying stage, the evaporation was accelerated, and the moisture loss increased remarkably. Meanwhile the temperature fluctuated in the range of 75-85 • C. During the rapid heating stage, the moisture content of the berry puree continued to decrease until the end of drying (M < 15%), and the final temperature was close to 120 • C. As can be observed, the drying time was shortened, and the final temperature of the dried product was increased with the increase in microwave intensity [30]. reagent was a mixture of 1% (w/v) vanillin methanol solution and 8% (w/v) hydrochloric acid methanol solution in a ratio of 1:1.…”