Hot air drying of palm fruit is a simple method but results in low grade palm oil. The steaming of palm fruit results in high grade palm oil but it requires a wastewater treatment process. Both methods have both advantages and disadvantages, therefore if they were combined, it can result in the better grades of oil, which should be encouraged for farmers in Thailand to apply. This research aimed to determine mechanical characteristics of semi-damp dryer for oil palm. The results of a compression and relative humidity tests were used as the criteria for the tests. The oil palm semi-damp dryer was used in this research. The oil palm semi-damp dryer used the aerosolized technique with 100 °C hot water as a sprayer and a humidifier for the oil palm in the dryer. The purpose was to reduced palm fruit hardness. The study use tenera palm from Prachinburi province and neighborhood of Thailand. The drying time for testing was 1, 2, 3 and 4 hours. The temperature for testing was 70, 90 and more than 100 °C. The results of the compression force of oil palm by using a semi-damp dryer were lower than using a hot air drying. The compression was lower than using hot air drying. The best of mechanical characteristics palm was baking with semi-damp dry at 90 °C in 3 hours. Compression force was 0.675 kN and relative humidity value was 57.18%. The palm oil was tested for the %FFA and DOBI and showed that the grade of palm oil by using semi-damp drying was fair but still edible grade.
Process performance and quality attributes of temperature and step-down relative humidity controlled hot air drying of Panax notoginseng roots
