Economical moisture measurement system for dried longan aril using electrical capacitance

• Main Authors: Amaroek S., Theera-Umpon N.
• Format: Article
• Published: Farm Machinery Industrial Research Corp. 2015
• Subjects: Agricultural and Biological Sciences (miscellaneous); Engineering (all)
• Online Access: http://www.scopus.com/inward/record.url?partnerID=HzOxMe3b&scp=84859982152&origin=inward; http://cmuir.cmu.ac.th/handle/6653943832/38991
• Institution: Chiang Mai University

Presently, there is no specific instrument for moisture content measurement of dried longan aril. It can only be measured directly by an extensive measurement method. It takes at least 8 hours and must be performed by a skilled agriculturist. This research has developed a system to measure the moisture content. A new circuit design for measuring capacitance and the design and construction of a longan aril container to mimic a capacitor were proposed and, subsequently, a prototype moisture measurement system for dried longan aril was successfully invented. The estimated capacitance yielded the moisture content and dielectric constant of dried longan aril inside the container. The system was tested on the total of 1,500 samples to determine the relationship among moisture content, dielectric constant, and electrical capacitance of dried longan aril. The results showed that the electrical capacitance and the dielectric constant of dried longan aril increased with moisture content. The moisture content could be calculated from the capacitance of the dried longan aril-based capacitor by using a specific polynomial equation. The 1,500 samples tested had a very low mean absolute error of 0.652 % w.b. The system worked very well and achieved a mean absolute error of 0.721 % w.b. in the blind test experiments. The total budget to build this economical moisture tester was less than 60 US Dollars.