The objective of this research was to study the influence of drying air velocity characteristics on paddy drying. The pneumatic dryer prototype was used in this study. Test drying 15 kg of Hom Pathum paddy at 22 – 25% initial wet basis moisture content was tested drying under the drying air temperature 80OC until its moisture is 14% wet basis with the two drying air velocity characteristics. The first characteristic of drying air velocity is constant at 12.80 m/s and another is reduced velocity every 15 minutes throughout the test process from 12.80 - 8.44 m/s. Drying in a vertical tube with a diameter of 3.81 cm and height 1 m for study the drying behavior drying rate (DR) specific energy consumption (SEC) and thermal efficiency of drying. The results showed that drying with constant air velocity gives a shorter time higher drying rate lower primary SEC consumption and higher thermal efficiency than drying with reducing air velocity.

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 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).

This research aims to study the appropriate drying condition and extraction solvent for extracting protein and antioxidants from the porcine placenta. Three levels of drying temperature were used in this study which were 50 60 and 70ºC the result shows that the best drying condition for porcine placenta was 70ºC for 4 hours because this condition provided the least drying time and the lowest moisture content of porcine placenta (3.80±3.36% dry basis). After that the fresh and dried porcine placenta were extracted by using three solvents which were deionized water (DI) phosphate buffered saline (PBS) and hexane. The efficiency of extraction was investigated by measuring the crude protein and antioxidant of the porcine placenta. It was found that there was no protein and antioxidant in fresh and dried porcine placenta extracted by hexane. However the protein was found as 0.05±0.01 and 0.04±0.01 mg of bovine serum albumin/100 mg fresh for fresh porcine placenta and 0.12±0.030 and 0.07±0.016 mg of bovine serum albumin/100 mg fresh for dried porcine placenta extracted by DI and PBS respectively. In additional the antioxidant was found as 1.13±0.03 and 1.29±0.04 mg of trolox/100 mg fresh for fresh porcine placenta and 3.37±0.02 and 3.59±0.01 mg of trolox/100 mg fresh for dried porcine placenta extracted using DI and PBS respectively.

This research objective was to apply thermoelectric module model TEC12710 as a preheater and dehumidifier for red chilies dryer. The heat side and cool side of Thermoelectric module affected by supplied electricity were used to produces the low humidity and warm air in preheater before charging to the main electric heater of dryer. Fresh red chilies were selected as a sample in the prototype testing during the use of preheater assisted main heater and using only main heater. The test results are compared with the sample dried under the natural sun drying. The experimental results show that the preheater can condense the moisture in air with the highest MER of 0.083 kgwaterh-1 at cold side of thermoelectric module and can heat the air up in 10°C of temperature with hot side of thermoelectric module. The final moisture content of sample is only 10%wb with the slightly changed in color when compared with the sample from sun drying. The using of preheater with main heater gives a higher specific moisture extraction rate lower specific energy consumption 14 MJ energy used and can dry faster than 10 h when compared with the using of only main heater.