Food and Bioprocess Technology

, Volume 8, Issue 2, pp 266–276 | Cite as

Microwave–Vacuum Drying of Strawberries with Automatic Temperature Control

  • R. BórquezEmail author
  • D. Melo
  • C. Saavedra
Original Paper


A microwave–vacuum drying system with the ability of automatic temperature control was developed for strawberry drying in order to obtain a high-quality product, in terms of appearance, color, and texture. Changes in quality attributes of strawberries were determined by measuring the color, texture, shrinkage, and rehydration. Microwave–vacuum drying (47 mm Hg) yielded an elastic product of improved mechanical resistance with just a slight loss of color and appropriate rehydration performance using automatic temperature control around 50 °C and 700-W power. The specific energy consumed during strawberry drying using automatic temperature control varied between 1.30 and 2.30 Wh/g. The efficiency of process in automatic mode was 13.5 times higher than efficiency in manual mode. A drying protocol for strawberries, based on automatic on–off temperature control, was developed. Thus, the drying temperature and dead band could be easily changed during the trials, and there is no need to tune the controller when drying a different kind of fruit.


Strawberries Dehydration Automatic temperature control Microwave–vacuum drying 



This study received financial support from FONDECYT Grant 1110097.


  1. Albanese, D., Cinquanta, L., Cuccurullo, G., & Di Matteo, M. (2013). Effects of microwave and hot-air drying methods on color, β-carotene and radical scavenging activity of apricots. International Journal of Food Science and Technology, 48(6), 1327–1333.CrossRefGoogle Scholar
  2. Arnold, P. C., & Mohsenin, N. N. (1971). Proposed techniques for axial compression tests on intact agricultural products of convex shape. Transactions of the American Society of Agricultural Engineers, 14, 78–84.CrossRefGoogle Scholar
  3. ASAE. Compression test of food materials of convex shape. Published by ASAE December 2000, St. Joseph, Michigan: American Society of Agricultural Engineers.Google Scholar
  4. Bórquez, R. M., Canales, E. R., & Redon, J. P. (2010). Osmotic dehydration of raspberries with vacuum pretreatment followed by microwave-vacuum drying. Journal of Food Engineering, 99, 121–127.CrossRefGoogle Scholar
  5. Clary, C., Wang, S., & Petrucci, V. (2005). Fixed and incremental levels of microwave power application on drying grapes under vacuum. Journal of Food Science, 70(5), 344–349.CrossRefGoogle Scholar
  6. Contreras, C., Martín-Esparza, M. E., & Chiralt, A. (2008). Influence of microwave application on convective drying: effects on drying kinetics, and optical and mechanical properties of apple and strawberry. Journal of Food Engineering, 88, 55–64.CrossRefGoogle Scholar
  7. Contreras, C., Martín-Esparza, M. E., & Martínez-Navarrete, N. (2012). Influence of drying method on the rehydration properties of apricot and apple. Journal Food Process Engineering, 35, 178–190.CrossRefGoogle Scholar
  8. Cuccurullo, G., Giordano, L., Albanese, D., Cinquanta, L., & Di Matteo, M. (2012). Infrared thermography assisted control for apples microwave drying. Journal Food Engineering, 112(4), 319–325.CrossRefGoogle Scholar
  9. Changrue, V., Orsat, V., & Raghavan, G. V. S. (2008). Osmotically dehydrated microwave-vacuum drying of strawberries. Journal of Food Process Preservation, 32, 798–816.CrossRefGoogle Scholar
  10. Chong, C., Figiel, A., Law, C., & Wojdylo, A. (2014). Combined drying of apple cubes by using of heat pump, vacuum-microwave, and intermittent techniques. Food and Bioprocess Technology, 7, 975–989.CrossRefGoogle Scholar
  11. De Bruijn, J., & Bórquez, R. (2014). Quality retention in strawberries dried by emerging dehydration methods. Food Research International, 63, 42–48.CrossRefGoogle Scholar
  12. Drouzas, A. E., & Schubert, H. (1996). Microwave application in vacuum drying of fruits. Journal of Food Engineering, 28, 203–209.CrossRefGoogle Scholar
  13. Drouzas, A. E., Tsami, E., & Saravacos, G. D. (1999). Microwave/vacuum drying of model fruit gels. Journal of Food Engineering, 39, 117–122.CrossRefGoogle Scholar
  14. Erle, U., & Schubert, H. (2001). Combined osmotic and microwave-vacuum dehydration of apples and strawberries. Journal of Food Engineering, 49, 193–199.CrossRefGoogle Scholar
  15. Gekas, V. (1992). Transport phenomena of foods and biological materials. CRC Press, Inc. Printed in United States, chapters 5 and 6. Pages 133–185.Google Scholar
  16. Khraisheh, M. A., Cooper, T. J., & Magee, T. R. (1997). Shrinkage characteristic of potatoes dehydrated under combined microwave and convective air conditions. Drying Technology, 15, 1003–1022.CrossRefGoogle Scholar
  17. Li, Z., Raghavan, G. S. V., & Orsat, V. (2010a). Temperature and power control in microwave drying. Journal of Food Engineering, 97, 478–483.CrossRefGoogle Scholar
  18. Li, Z., Raghavan, G. S. V., & Orsat, V. (2010b). Optimal power control strategies in microwave drying. Journal of Food Engineering, 99, 263–268.CrossRefGoogle Scholar
  19. Lu, L., Tang, J., & Ran, X. (1999). Temperature and moisture changes during microwave drying of sliced food. Drying Technology, 17, 413–432.CrossRefGoogle Scholar
  20. Meda, L., & Ratti, C. (2005). Rehydration of freeze-dried strawberries at varying temperatures. Journal of Food Process Engineering, 28, 233–246.CrossRefGoogle Scholar
  21. Prabhanjan, D. G., Ramaswamy, H. S., & Raghavan, G. S. (1995). Microwave- assisted convective air drying of thin layer carrots. Journal of Food Engineering, 25, 283–293.CrossRefGoogle Scholar
  22. Raghavan, G. S. V., & Venkatachalapathy, K. (1999). Shrinkage of strawberries during microwave drying. Drying Technology, 17(10), 2309–2321.CrossRefGoogle Scholar
  23. Roknul, A., Zhang, M., Mujumdar, A., & Wang, Y. (2014). A comparative study of four drying methods on drying time and quality characteristics of stem lettuce slices (Lactuca sativa L.). Drying Technology, 32, 657–666.CrossRefGoogle Scholar
  24. Sunjka, P. S., Rennie, T. J., & Beaudry, C. (2004). Microwave-convective and microwave-vacuum drying of cranberries: a comparative study. Drying Technology, 22, 1217–1231.CrossRefGoogle Scholar
  25. Valdivambal, R., & Jayas, D. S. (2007). Changes in quality of microwave-treated agricultural products—a review. Biosystems Engineering, 98, 1–16.CrossRefGoogle Scholar
  26. Venkatachalapathy, K., & Raghavan, G. S. (1999). Combined osmotic and microwave drying of strawberries. Drying Technology, 17, 837–853.CrossRefGoogle Scholar
  27. Wang, S., Hu, Z., Han, Y., & Zhenxin, G. (2013). Effects of magnetron arrangement and power combination of microwave on drying uniformity of carrot. Drying Technology, 31, 1206–1211.CrossRefGoogle Scholar
  28. Wojdylo, A., Figiel, A., Lech, K., Nowicka, P., & Oszmianski, J. (2014). Effects of convective and vacuum- microwave drying on the bioactive compounds, color, and antioxidant capacity of sour cherries. Food and Bioprocess Technology, 7, 829–841.CrossRefGoogle Scholar
  29. Zhang, M., Tang, J., Mujumdar, A. S., & Wang, S. (2006). Trends in microwave related drying of fruits and vegetables. Trends in Food and Technology, 17, 524–534.CrossRefGoogle Scholar
  30. Zheng, X., Wang, Y., Liu, C., Sun, J., Liu, B., Zhang, B., Lin, Z., Sun, Y., & Liu, H. (2013). Microwave energy absorption behavior of foamed berry puree under microwave drying conditions. Drying Technology, 31, 785–794.CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media New York 2014

Authors and Affiliations

  1. 1.Department Chemical EngineeringUniversity of ConcepciónConcepciónChile

Personalised recommendations