Drying of foods using supercritical carbon dioxide — Investigations with carrot

The use of supercritical carbon dioxide (scCO 2) for the removal of moisture from cylindrical pieces of carrot has been investigated. The experiments were carried out at 20 MPa pressure and the effects of temperature and co-solvent (ethanol) addition were examined. At the investigated conditions, co...

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Bibliographic Details
Published in:Innovative food science & emerging technologies 2008-07, Vol.9 (3), p.280-289
Main Authors: Brown, Z.K., Fryer, P.J., Norton, I.T., Bakalis, S., Bridson, R.H.
Format: Article
Language:English
Subjects:
Air-drying
carbon dioxide
Carrot
carrots
dried vegetables
drying
Drying kinetics
drying temperature
ethanol
food preservation
food processing
Microstructure
multivariate analysis
physical properties
pressure treatment
rehydration
shrinkage
simulation models
Supercritical carbon dioxide
texture
water content
X-ray microtomography
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Summary:The use of supercritical carbon dioxide (scCO 2) for the removal of moisture from cylindrical pieces of carrot has been investigated. The experiments were carried out at 20 MPa pressure and the effects of temperature and co-solvent (ethanol) addition were examined. At the investigated conditions, comparisons with air-drying indicated that drying kinetics and the associated drying mechanisms differed between the techniques. The microstructural characteristics of carrot pieces that had been dried using the different techniques were compared using X-ray microtomography and light microscopy. Carrots dried in the supercritical fluid environment were seen to retain their shape much better than air-dried carrots which underwent shrinkage. Samples dried in ethanol-modified scCO 2 possessed less dense structures and consequently displayed more favourable rehydrated textural properties than the air-dried equivalents. Drying is a common unit operation in food processing, but the rehydrated product is often of very poor quality. Comparatively little work has been done on optimising drying for quality of the final, rehydrated product. Supercritical drying is a possible way of maintaining product microstructure, and this paper describes experiments in which the supercritical drying of carrot is studied and compared with conventional processes.
ISSN:1466-8564
1878-5522
DOI:10.1016/j.ifset.2007.07.003