Electrohydrodynamic Drying of Carrot Slices

Abstract

Carrots have one of the highest levels of carotene, and they are rich in vitamins, fiber and minerals. However, since fresh carrots wilt rapidly after harvest under inappropriate storage conditions, drying has been used to improve their shelf life and retain nutritional quality. Therefore, to further investigate the potential of this method, carrot slices were dried in an EHD system in order to study the effect of different voltages on drying rate. As measures of quality, carotene content and rehydration ratio were, respectively, compared against the conventional oven drying regime. Carotene, the main component of the dried carrot, and rehydration characteristics of the dried product can both indicate quality by physical and chemical changes during the drying process. Mathematical modeling and simulation of drying curves were also performed, using root mean square error, reduced mean square of the deviation and modeling efficiency as the primary criteria to select the equation that best accounts for the variation in the drying curves of the dried samples. Theoretically, the Page model was best suited for describing the drying rate curve of carrot slices at 10kV to 30kV. Experimentally, the drying rate of carrots was notably greater in the EHD system when compared to control, and quality, as determined by carotene content and rehydration ratio, was also improved when compared to oven drying. Therefore, this work presents a facile and effective strategy for experimentally and theoretically determining the drying properties of carrots, and, as a result, it provides deeper insight into the industrial potential of the EHD drying technique.

Electrohydrodynamic (EHD) drying of the Chinese wolfberry fruits

“…The drying rate increased under the EHD process with increasing electric field ranged from 20 to 32 kV. In addition, the drying rate of Chinese wolfberry fruits exposed to EHD process at four levels of voltages was higher than that of the control in the 17 h and improved by 1.8777, 2.0017, 2.3676 and 2.6608 times, respectively, at 20, 24, 28 and 32 kV, compared to that of the control in the 5 h. These results agree with those studies which reported enhancement in drying rate with increase of applied voltage (Ding et al 2015; Basiry and Esehaghbeygi 2010). The principal mechanism accounted for EHD drying is the production of corona wind by applying a high voltage between two electrodes with substantially different radii of curvature (Dinani et al 2014), the impingement of this wind on wet materials has produced an impact and thus, enhances mass transfer rates of water through increased turbulence (Esehaghbeygi et al 2014).…”

“…The Chinese wolfberry fruits were weighed after removing excess water with the help of absorbent paper. RR was determined using the following equation (Ding et al 2015). where m a is the weight of the dried Chinese wolfberry fruits after rehydration, m b is the weight of dried Chinese wolfberry fruits before rehydration.…”

“…R 2 also gives predictive power of the model relative to the drying behavior of the product, and its highest value is 1. These statistical values can be calculated as follows (Dinani et al 2014; Ding et al 2015):where MR exp, i is the i th experimental moisture, MR pre, i is the i th predicted moisture, N is the number of observations, n is the number of constants in the drying model, and i is the number of terms.…”

“…Bajgai and Hashinaga (2001a) found that ascorbic acid contents in spinach were substantially higher after EHD drying than after oven drying. Ding et al (2015) demonstrated that the application of EHD contributed toward an increase by 11.53 % in the carotene contents of dried carrots, compared to oven drying. Bai et al (2013) found that sea cucumbers dried by EHD displayed much higher protein values, which is more than that of those dried oven.…”

High-Voltage Electric Field-Assisted Thawing of Frozen Tofu: Effect of Process Parameters and Electrode Configuration

“…e thawing experimental equipment is shown schematically in Figure 1 [12,15]. e HVEF thawing equipment consists of three parts: highvoltage power system, thawing system, and control system.…”