International E-publication: Publish Projects, Dissertation, Theses, Books, Souvenir, Conference Proceeding with ISBN.  International E-Bulletin: Information/News regarding: Academics and Research

OSMO-Convective Drying of Onion Slices

Author Affiliations

  • 1 Dept. of Processing and food Eng., College of Technology and Eng. Maharana Pratap Uni. of Agriculture and Tech. Udaipur, INDIA

Res. J. Recent Sci., Volume 1, Issue (1), Pages 51-59, January,2 (2012)


The present study is carried out to standardize the pretreatment of onion slices and study drying characteristics during convective drying. The effect of process parameters during osmotic dehydration such as osmosis, concentration and temperature of syrup on mass reduction, water loss and salt gain increased with increase of syrup concentration and temperature. The water loss and solid gain during osmosis at 5, 12.5 and 20 \rBrix was varied in the range of 15.88 to 25.65 and 6.63 to 10.15 per cent at 35, 45 and 55\r C temperatures respectively. The drying temperature and pretreatment as osmotic dehydration had a significant effect on the rehydration ratio and colour. The drying times of un-osmoses and osmoses onion slices by convective drying at 40 and 60 per cent drying temperature were 12, 10 and 8 and 6 hrs respectively. Quality of dried product in respect to colour and rehydration was superior. The osmo-convective dehydrated samples were found more acceptable than convective dried ones. The onion dried at 20\rC brix solution concentration, 55\rC osmosis temperature and 70C drying temperature was more acceptable on the basis of colour and rehydration.


  1. Baroni A.F. and M. B. Hubinger, Drying of onion: Effects of pretreatment on moisture transport. Drying technology 16, 9,10, (1998)
  2. Jain S.K., R.C. Verma, L. K. Murdia and P. K. Dashara, Mass transfer and drying characteristics of osmotically dehydrated papaya cubes followed by Airdrying, National convention held at hyderabad in 2004-2005, (2004)
  3. Jannot Y., T. Andre, J. Rodolphe, and J. Nganhou, Modelling of banana convective dring by the drying characteristic curve (DCC) method. Drying technology 22(8), 1949-1968, (2004)
  4. Krokida, MK., Karathanos VT. and Maroulis ZB, Effect of osmotic dehydration on colour and sorption characteristics of apple and banana. Drying Technology, 18(4&5), 937:50, (2000)
  5. Pavasovic, V.,Stefanovic, M., and Stefanovic, R. Osmotic dehydration of fruit. : Drying 86. Ed. Mujumdar, A.S. Hemishpere Publ.CO., New York, Vol., 76, 1986.
  6. Rahman M. S. and Jack Lamb, Osmotic dehydration, Drying technology, 19(6): 1163-1176, (1990)
  7. Ranganna S., Handbook of analysis and quality control for fruits and vegetable produce, Tata mcgraw hill publishing co-operation limited; New Delhi, (2000)
  8. Brooker D. B., F. W. Bakker and C. W. Hall, Drying and storage of grains and oil seeds, The AVI publishing company, Inc. west port, Connecticut: 56-71, (1974)