Design and Evaluation of a Microcomputer-based Vacuum Drying System for Shiitake Mushrooms

마이크로컴퓨터 시스템을 이용한 표고버섯의 감압건조에 대한 연구

  • Choi, Jae-Yong (Department of Biotechnology, Ajou University) ;
  • Kim, Kong-Hwan (Department of Biotechnology, Ajou University) ;
  • Chun, Jae-Kun (Department of Food Science & Technology, Seoul National University)
  • Published : 1987.12.01


Strain gauges attached on the Bourdon tube and load cell were used as the sensors for measuring the vacuum pressure in drying chamber and the weight loss of Shiitake mushrooms respectively. The vacuum drying system was interfaced further with the Bear II microcomputer. The interface devices used were built with such IC chips as MC 6821, ADC 0809, SN 74244 and SN 7424. The relationship between readings of vacuum gauge (P, mmHg) and digital outputs (D) from the microcomputer was represented by P =3.08 D-13.4875(r=0.9999). The weights of drying sample (W) were also related with the digital outputs (D) by W=0.4076 D-6.4762 (r=0.9999). During the vacuum drying of Shiitake mushrooms. the data on pressure and weight were recorded at regular intervals using an acquisition program on the microcomputer system. The Page model was fitted well to the drying data of Shiitake mushrooms. resulting in the following empirical equations : $(M-M_e)/(M_o-M_e)=\exp(-0.1569t^{1.0048})$ at 400 mm Hg up to 14 hours and $(M-M_e)/(M_o-M_e)=\exp(-0.1385_t^{1.2688})$ at 600 mm Hg up to 8 hours.