Comparison of the dried properties of Ganoderma lucidum produced by the convective dryer and infrared dryer.

Ganoderma lucidum is a promising medicine with a high amount of antioxidants and calcium. The selection of appropriate drying process methods in food science has a chief role to reach the best final characteristics. This study aimed to investigate the effects of air velocity and temperature in the convective dryer, sample distance, and infrared power in infrared dryers on the drying kinetics and quality of Ganoderma lucidum slices. In addition, Response Surface Methodology based on central composition design was used to optimize and analyze drying conditions. The ranges of temperature and air velocity were 40-60 °C and 0.5-1.5 m/s, respectively in the convective drying process while the range of distance and infrared power was 4-16 cm and 500-1500 W, respectively in the infrared drying process. It is worth mentioning that antioxidant and calcium contents were greatly enhanced during the drying procedures. Moreover, the values of the total color difference ranged between 8.21 and 19.66 for the convective dryer and 8.14 and 28.85 for the infrared dryer. A kinetic study indicated that dried samples by the infrared dryer could rapidly reach equilibrium moisture content due to exposure to IR radiation. Consequently, the results indicated that the infrared dryer has better performance than the convective dryer regarding drying time, energy consumption, and amount of calcium and antioxidant.

Modelling and experimental analysis of rice drying in new fluidized bed assisted hybrid infrared-microwave dryer.

This study aimed to investigate how infrared (1000-2000 W) and microwave power (100-900 W), air velocity (1-5 m/s) and temperature (40-80 °C) affected the specific energy consumption, the moisture removal rate, and the product's quality (whiteness index, head rice yield, water uptake ratio, and elongation ratio) in hybrid dryer. Rising temperature, velocity and microwave power and lower temperatures resulted in improving head rice yield of paddy samples. The experiments proved that the new hybrid system significantly increased the moisture removal rate (from 100 to 700%), head rice yield (from 5 to 40 %) and decreased the specific energy consumption (from 10 to 80%) compared to the single fluidized bed dryer. The water uptake ratio and elongation ratio of the dried samples in the hybrid dryer were higher than the single dryer, however their whiteness index was not significantly different. The best drying conditions are associated with the lowest specific energy consumption and the highest moisture removal ratio and rice quality. Experimental data were fitted into empirical drying models to explain moisture ratio variations during drying. Nomhorm and verma,s model was found to be the best for moisture ratio prediction. Also, the central composite design of response surface methodology was applied to forecast outputs. A modified cubic model was observed in all responses with high R2 values (greater than0.9). The drying parameters were optimized for the specified constraints, resulting in 68 °C temperature, 5 m/s air velocity, 900 w microwave power, and 1479 w infrared power. The experimental values were found to be 0.368607 g/s for the moisture removal rate, 7.16988 MJ/kg water for the specific energy consumption, 90.6% for the head rice yield, 58 for the whiteness index, 3.63 for the water uptake ratio, and 2.28627 for the elongation ratio, at the optimum treatment conditions.

Infrared drying effects on the quality of eggplant slices and process optimization using response surface methodology.

The aim of this work was to study the effect of thickness of samples, air velocity and infrared power on the drying kinetics and quality attributes of blanched eggplant slices during infrared drying. The drying experiments were made by Response Surface Methodology (RSM) based on a Box-Behnken design (BBD). Experiments were conducted at a thickness of 3, 5, and 7 mm, air velocity of 0.5, 1.25, and 2 m/s, as well as at infrared power 1000, 1500, and 2000 W. The drying time was affected by operating parameters. The drying processes increased total phenolic content and potassium content, significantly. The total color difference (ΔE) was in the range of 10.22-25.14. In the end, this process was optimized for reaching the best experimental condition.

Optimization and quality evaluation of infrared-dried kiwifruit slices.

Infrared drying characteristics of kiwifruits under natural and forced drying air convection with different conditions were investigated. An experimental study along with statistical analysis aimed to evaluate quality characteristics of infrared-dried kiwifruit slices, in terms of drying time, rehydration ratio and shrinkage as a function of infrared power levels, slice thicknesses, slice distance from the infrared lamps, and air velocity. Response surface methodology was used for optimization of drying parameters with employing desirability function. Minimum drying time, shrinkage, and maximum rehydration ratio assumed as criteria for optimizing drying conditions of kiwifruit slices were strongly dependent on the drying conditions. All operating variables had a significant effect on total responses, but slice thickness almost was the most prominent factor. The slices dried at the highest power level, the lowest distance from the Infrared lamp, the least thickness, and air velocity showed a higher rehydration capacity than slices dried at the other conditions.

Mathematical modelling of infrared-dried kiwifruit slices under natural and forced convection.

In this work, the effect of the radiation intensity, slice thickness, and the distance between slices and infrared lamps under natural drying air and the effect of slice thickness and air velocity under forced drying air on the moisture diffusion characteristics and the drying rate of kiwifruit slices during infrared drying were investigated. The drying of kiwifruit happened in the falling rate period, and no constant-rate period was observed in the drying curves. One hundred models were fitted to the drying data. Among the models, the exponential dsecay function model and modified two-term exponential-V model and the artificial neural networks with 4-5-7-1 and 3-5-5-1 topologies, hyperbolic tangent sigmoid transfer function, and Levenberg-Marquardt training algorithm presented the best results and showed the goodness of fit with the experimental data for the former and latter systems, respectively. The diffusivities varied between 1.216 × 10-10-8.997 × 10-10 m2/s and 2.567 × 10-10-10.335 × 10-10 m2/s for natural and forced drying air systems, respectively.