This research is the study of microwave distribution in the drying chamber to develop the belt-conveyor microwave dryer. The dimensions of the drying chamber are 90 cm width 3 cm length and 30 cm height. Two 800 W magnetrons were installed at the top of the chamber. It was found that the uniform of microwave distribution was observed at the center area of drying chamber. The uniform microwave distribution in the drying chamber at 400 W is achieved. A microwave leakage from the prototype is within the microwave oven safety standard of the US Department of Health and Human Services. This study can be used as a guideline for an industrial design for belt-conveyor microwave dryer.

Drying an agricultural product with hot air (HA) method causes a long drying time and results in high specific drying energy consumption (SEC). The dried product has high shrinkage percentage and low rehydration. Therefore this research aims to develop dried shiitake mushroom using belt-conveyor combined microwave-hot air drying method (MHB). The shiitake mushroom was dried by MHB at microwave power of 300 W 400 W 500 W and 600 W and air temperature of 65 oC with air velocity of 0.3 m/s and recycled air of 80% and by the HA drying method at air temperature of 65 oC. The samples were dried until their final moisture content less than 11.1% dry basis. The drying kinetics SEC of drying process and quality of dried shiitake mushroom were evaluated. The quality of dried product was considered in terms of color shrinkage rehydration texture water activity and microstructure. The results showed that the shiitake mushroom drying using MHB gave higher drying rate than that of HA drying method leading to short drying time and resulting in low SEC. The drying rate of un-blanched shiitake mushroom was higher than that of blanched shiitake mushroom. Dried shiitake mushroom from MHB drying gave lower values in shrinkage percentages and hardness but higher rehydration and larger pore size than that dried by HA drying. However the color values (L* +a* and +b*) of dried shiitake mushroom in all cases were not significantly different. Meanwhile dried shiitake mushroom from un-blanched case gave lower values in shrinkage percentage and hardness but higher values in all colors and rehydration and larger pore size than those of blanched case.

This research developed a new model to determine the moisture diffusion coefficient for the thin-layer paddy drying with the spouted free-fall bed dryer. The design and construction of the dryer was done to experiment with the drying kinetics. The experiment has studied under conditions of hot air temperature of 60-150 °C the initial paddy mass of 5 - 15 kg and hot air velocity of 19 m/s. The results showed that the higher hot air temperature and the lower initial paddy mass resulted in a significant reduction in drying time. The experimental results were used to calibrate 12 of the most popular thin-layer drying models to find a suitable one considering based on the root mean square error (RMSE) chi-squared value (χ2) and the correlation coefficient (r). It was found that the popular thin layer drying model was able to accurately predict the effect of the moisture ratio considering both the influence of hot air temperature and the initial paddy mass in linear models. The highest accuracy was RMSE = 0.0279 χ2 = 0.00084 and r = 0.9938. In addition the experimental results have been used to synthesize the new diffusion moisture coefficient which is a function of initial paddy mass temperature and drying time. This developed model was based on an exponential function with only 7 model constants. The simulated results observed that the new model achieved the average error only 1.8 percent compared with the best model that uses up to 24 model constants.

The development product of dried pickled passion fruit peel aimed to study appropriate production process of dried pickled passion fruit peel to study the preservation and examine the acceptance from the customers. The result showed that the appropriate way to produce dried pickled passion fruit peel was the 30% 40% and 50% of intensity in syrup. With the intensity of syrup started from 30% the appearance color and smell of final product got highest average score. Therefore the production should be slow pickled with 30% of syrup intensity. In terms of preservation there was no microorganism over Thai industrial standard institute of fruits and vegetables 161/2015. Finally most of the customers accepted this product

The objectives of this research were to study the effect of hot air velocity on the changes of the moisture content and temperature of preserved tomatoes undergoing combined conveyor system and hot air drying. Specific energy consumption physical properties in term of color and shrinkage and sensory evaluation of dried preserved tomatoes were also investigated. The preserved cherry tomatoes were dried at a drying temperature of 80oc and hot air velocity of 2 and 4 m/s until the moisture contents of the preserved tomatoes were lower than 18% wet basis. The experimental results showed that the hot air velocity had effect on the changes of the moisture content and temperature of preserved tomatoes. Specific energy consumption total color difference shrinkage percentage and sensory evaluation results of dried preserved tomatoes of the hot air velocity of 2 and 4 m/s were not significantly different (P>0.05).Moreover the dried preserved tomatoes obtained from this research had significantly lower sensory scores in term of color and appearance than those obtained from the local market (P≤0.05). However sensory scores in term of flavor texture and overall preference of the dried preserved tomatoes obtained from this research and the local market were not significantly different (P>0.05).