Monitoring of the moisture content during dehydration of parsley with near infrared spectroscopy
- Publication Type
- Contribution to conference
- Authors
- Romano G, Böhner M, Rose P, Heindl A, Müller J
- Year of publication
- 2009
- Published in
- Proceedings of the 5th CIGR International Technical Symposium
- Page (from - to)
- 29-33
- Conference name
- 5th CIGR VI Section Symposium on Food Processing, Monitoring Technology in Bioprocesses and Food Quality Management
- Conference location
- Potsdam (Germany)
- Conference date
- 31.08.-02.09.2009
Dried leaves of parsley (Petroselinum crispum) with optimal levels of moisture content are widely required by food industries to produce convenient food like instant soups. Near Infrared Spectroscopy (NIRs) offers potential to control the quality of finished products.
For this study a conveyor belt dryer for medicinal and spice plants was used. The objective of this research was to assess the performance of near infrared spectroscopy as a fast and non-destructive method for on-line measurements of moisture content of parsley bulk. To reach this goal, two NIR instruments were mounted on the dryer. One at the center of the feeder to measure the moisture content of the fresh incoming material, which was between 50% and 85% (w.b.) and the other one mounted at the exit of the drier, which gave readings of moisture content between 5% and 40% (w.b.).
To protect the instrument from the high temperatures present at the dryer output, the NIR was equipped with a cooling system. Calibration was necessary to determine the relationship between the ratio of the absorbance of “near-infrared” radiation at 1940 nm and the moisture content of the bulk. Additionally these non-destructive measurements of moisture content of parsley bulk during drying were high when correlated with those obtained using the destructive oven drying technique with coefficient of determination of 0.96. The standard error obtained for the prediction of moisture content ranged between 1.57 and 2.69 for fresh and dried samples respectively.
We conclude that the NIR technique could have the potential for rapid and effective control of moisture content when dehydrating medicinal and spice plants.