Drying kinetics and effective moisture diffusivity of pomelo albedo under vacuum‐assisted microwave drying and its semi‐product

Author(s):  
Ha Le Nguyen ◽  
Tuan Quoc Le
2011 ◽  
Vol 396-398 ◽  
pp. 1306-1312 ◽  
Author(s):  
Bao Yan Zhang ◽  
Yin Zhe Jin ◽  
Yu Dong Cheng

To study the effect of microwave output power on the drying kinetics of tilapia fillets, the drying experiments were carried out at 150W, 250W, 500W, 700W and 900W, respectively. And ten mathematical models were involved to fit experimental data. It was found that Midilli et al model gave a best fitness for this conditions applied. Besides, effective moisture diffusivity increased progressively from 1.6248×10-9(m2/s) to 10.0735×10-9(m2/s) as the power increased from 150W to 900W. In addition, to obtain more homogeneous samples, temperature distribution of tilapia fillets was analyzed when they were put in different layout forms.


Author(s):  
Magesh Ganesh Pillai ◽  
Iyyasamy Regupathi ◽  
Lima Rose Miranda ◽  
Thanapalan Murugesan

The drying characteristics of plaster of paris (POP) under microwave conditions at different microwave power input, initial moisture content, sample thickness and drying time were studied. Further the experimental data on moisture ratio of POP for different operating conditions were obtained and calculations were made using nine basic drying model equations. The appropriate model with modified constants and coefficients to represent the drying kinetics of POP was found through the analysis of the statistical analysis. The effective moisture diffusivity of the drying process was also computed for different experimental conditions and a relationship between the drying rate constant and the effective moisture diffusivity was obtained. The energy consumption for microwave drying of plaster of paris at different experimental conditions were also computed.


2020 ◽  
Vol 24 (5 Part A) ◽  
pp. 2833-2843
Author(s):  
Montree Montreepila ◽  
Nattapol Poomsa-Ad ◽  
Lamul Wiset

Konjac glucomannan (KGM) can be obtained from tubers (called corms) of various species within the Amorphophallus genus. Among the most popular species for use in food industry is Buk Nuea Sai (Amorphophallus muelleri), a native species in Thailand. Drying process can be helpful in preserving KGM during long storage periods. However, the existing drying systems are often slow and lead to drying delays and subsequently quality reduction of the dried product. Given the economic importance of KGM, new, more efficient drying systems, have to be developed. The present study focuses on the drying kinetics of konjac dices in a fluidized bed, operating at a constant air velocity of 2.5 m/s and air temperatures of 50, 60, and 70?C. Six empirical mathematical models were selected to describe and compare the drying characteristics of konjac dices subjected to these conditions. The model coefficients were determined by non-linear regression analysis. Among the tested models used to describe the drying kinetics of konjac dices, the two-term model was found as the best one. The moisture loss from the dice was described by the Fick?s diffusion equation, and based on the obtained results the effective moisture diffusivity was estimated, getting a value in the range between 9.60526 ? 10?9 m2/s and 1.2006 ? 10?7 m2/s. The relationship between the temperature and the effective moisture diffusivity was described adequately by means of Arrhenius-type equation. An activation energy value between 8.65 kJ/mol and 61.28 kJ/mol was obtained. The findings allow the successful simulation of konjac dice drying in a fluidized bed between 50 and 70?C, 30-60 mm bed height and 6-15 mm dice thickness.


2019 ◽  
Vol 62 (4) ◽  
pp. 919-928 ◽  
Author(s):  
Ying Ming Chew ◽  
V. An-Erl King

Abstract. Microwave drying (MD) of pitaya peel was performed at 75, 225, 375, 525, and 750 W. The drying effects on the effective moisture diffusivity (De), total polyphenol content (TPC), betalain content, DPPH scavenging ability, and rehydration abilities of pitaya peel were examined. The data were compared with hot-air drying (HD) at 100°C for 4 h and freeze-drying (FD) for 24 h. The results showed that the MD kinetics of pitaya peel fit Fick’s law and the Arrhenius equation with an activation energy (Ea) of 34.08 W g-1. The De values of MD, which ranged from 2.35E-07 m2 s-1 (at 75 W) to 5.56E-06 m2 s-1 (at 750 W), indicated that the effectiveness of MD was appreciably higher than that of HD (2.44E-08 m2 s-1) and FD (4.43E-09 m2 s-1). Although MD resulted in decreased betacyanin (9.31 mg L-1 extract) and betaxanthin (6.58 mg L-1 extract) contents, the DPPH inhibition of pitaya peel remained at 75% due to an increase in TPC (115 mg GAE per 100 FW). MD of pitaya peel can also provide higher rehydration ability than HD and was comparable to FD. This study concludes that MD of pitaya peel was highly effective while maintaining high levels of TPC and DPPH inhibition. Keywords: Arrhenius equation, Effective moisture diffusivity, Fick’s law, Microwave drying, Pitaya peel.


2016 ◽  
Vol 369 ◽  
pp. 119-124
Author(s):  
E.M.A. Pereira ◽  
J.V. Silva ◽  
J.P.S. Santos ◽  
T.H.F. Andrade ◽  
A.G. Barbosa de Lima

This work aims to conduct an experimental study of the drying kinetics of castor bean fruits (Ricinuscommunis L., “BRS Energia” variety). Experiments were conducted using an oven at air temperatures 50 and 70°C and air relative humidity values 16.34 and 6.24%, respectively. The castor bean fruits were considered as a triaxial spheroid. The experimental moisture content data as a function of time were fitted to different lumped models (namely Henderson and Pabis, Page, Midilli and two-term exponential models) available in the literature.The values of the effective moisture diffusivity were obtained from the Fick's diffusion model. Results shows that the two-term drying model could adequately describe the thin layer drying behavior of castor bean fruit, and that the effective moisture diffusivity increases with increasing drying air temperature.


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