Effective diffusivities and energy consumption of daylily in microwave drying

Abstract

Drying kinetics of fresh daylily flower buds (Hemerocallis Citrine Baroni cv. Mengzihua) in a microwave oven at 60, 120, 180 and 240 W, respectively, were investigated. The results indicated that, drying rate increased at the initial time (a warm-up period) and then decreased at the end time (a falling rate period) after reaching a plateau (a constant rate period). A third-order polynomial model could well describe the relationships between effective diffusivity and moisture content, and the model's coefficients correlated linearly with microwave power level. A logistic model could well present the relationships between activation energy and moisture content. The curves of energy consumption vs. microwave power level indicated that in the initial phase of drying, the energy utilisation efficiency was almost the same at different microwave output power levels; however, at the end phase of drying, drying at lower microwave levels was worse in energy utilisation.

Artificial Neural Network Modeling of Drying Kinetics and Color Changes of Ginkgo Biloba Seeds during Microwave Drying Process

“…As the drying processed, when the material moisture content was lower than about 0.42 (g water/g solid min), a constant rate period was followed by a falling rate period which was controlled by the internal liquid diffusion. The loss of moisture content of samples caused a decrease in the absorption of microwave power and led to a descending in the drying rate [32,33]. These results were in agreement with the study of microwave drying of okra [34], coriander leaves [35], onion slices [20], and daylily flower buds [33], which indicated that a long constant rate period and falling rate period were observed after a short heating period.…”

The effect of osmosis pretreatment on hot‐air drying and microwave drying characteristics of chili (Capsicum annuum L.) flesh

“…The E a of samples directly dried by AD or MD increased as the moisture content decreased (Fig. 4), similar results were obtained by Ding et al (2012). The reason was that as the free water decreased, the bond water began to evaporate, which needed more energy.…”

“…), similar results were obtained by Ding et al . (). The reason was that as the free water decreased, the bond water began to evaporate, which needed more energy.…”

“…The E a was calculated with an Arrhenius‐type equation expressed as follows (Ding et al ., ): …”

Effect of high hydrostatic pressure on the quality of four edible flowers: Viola × wittrockiana, Centaurea cyanus, Borago officinalis and Camellia japonica

“…Until this moment, the unique technologies used by the industry are cold storage (Landi et al, 2015), hot air convective drying, freeze-drying and other drying methods (Oberoi et al, 2007;Ding et al, 2012;Zheng et al, 2015). However, all these methods have drawbacks: cold storage is a short-term food preservation method, hot air convective drying may cause undesirable biochemical and nutritional changes in the processed product that may affect its overall quality, and freeze-drying has high productive costs.…”