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Hydrocolloids preventing fruit from shrinkage while drying


Key words Fruit, shrinkage, drying, hydrocolloid.
Latest version 2012/03/22
Completed by FRIP

How does it work?

Primary objective Prevention of fruit shrinkage during fluidized bed drying.
Working principle Edible composite packaging materials, mainly consisting of polysaccharides, proteins, lipids or resins are supplemented with hydrocolloids (e.g. guar gum, pectin, carboxymethyl cellulose, gum acacia, pectin, sodium alginate and other polysaccharides). In general, hydrocolloids are used to affect the functional properties of food, especially its structure and texture. The important property of hydrocolloids in foods is the binding of water. Bound water slows down its evaporation and shape shrinkage.

The hydrocolloids are used because of their emulsifying, jellifying, stabilizing, and film-forming ability. They create the new film on the food that has an effect on slower drying rate of original food product. Their functional properties, complementary to that of the edible film’s components, are used to form or modify specific film characteristics and coatings. Usually a combination of lipid compounds and hydrocolloid-based structural matrices is used; where the hydrocolloids take effect on the strength and structural integrity of the film (higher viscosity lowers the mass transfer around new film and lowers also the drying rate of the original food). Addition of hydrocolloids effects in strengthening the extensibility support the energy to rupture the fruit leather (e.g. the drying rate can be lowered during first 2 hours of mango drying due to higher viscosity of the new film lowering the mass transfer. On the other side there are other aspects to be considered as well – methods of the heat transfer, not only the new film building. The quality of the drying process (which depends on the product characteristic and expected use) itself significantly depends on the drying conditions (air temperature level, air velocity, dew point temperature). Microwave and infrared drying methods showed better outcomes than convection method in terms of lesser shrinkage and lower product volume. Sequential infrared and freeze-drying was found to be suitable for crispy fruit pieces [1-6].

Additional effects The use of hydrocolloids can have significant positive effect on product safety, on nutritional and sensory attributes, stability and generally on food protection. E.g. no risk of the final food surface break is observed, overheating of the surface or additional water in food release is not a risk etc.
Important process parameters Heating intensity, time, temperature, method.
Important product parameters specific blending biocomponents and its’ amount due to the product specification. Each food composition and thermal treatment conditions need to use specific hydrocolloid components to create good new film that help to keep the original food quality.

What can it be used for?

Products Various kinds of fruit and vegetables.
Operations Drying, fruit pieces preparation,
Solutions for short comings The development of this new approach to biotechnology means a significant step forward for the food producers as well as for the consumers. The improvement of product properties is obvious (avoiding overheating and local burning of dried fruit pieces, uniforming the water content in dried food and keeping the convenient shape). This technology is a complement to the conventional technology (as drying).

What can it NOT be used for?

Products Not determined yet.
Operations In research process.
Other limitations Specific limitations can be obvious when the specific matrix or biomaterial is known; the requirement of valid legislative should be taken into account as well as specific conditions of product processing (used temperature i.e.).
Risks or hazards Risk of the food safety view it is lower than classical drying of food pieces but it is still subject of research.


Maturity Requiring future research before full scale application (proper material type has to be predicted for given food to create convenient film properties during drying).
Modularity /Implementation This technology can be inserted in an existing production line after preliminary pilot scale testing.
Consumer aspects Consumers appreciate lower fruit shrinkage and better taste characteristics. Nevertheless any further survey could be done.
Legal aspects Order No. 4/2008 Coll., which establish types and conditions of use of additives and solvent extraction in food (in the conditions of the Czech Republic) due to the Directive 2006/52/EC of the European Parliament and of the Council of 5 July 2006 amending Directive 95/2/EC on food additives other than colors and sweeteners and Directive 94/35/EC on sweeteners for use in foodstuffs.
Environmental aspects Not known.

Further Information

Institutes Warsaw University of Life Sciences, CIDCA, University of São Paulo, UCDavis, IMR International
Companies CP Kelco, Hebrew University of Jerusalem
References [1] López, O., García, M., & Zaritzky, N. E. (2010). Novel sources of edible films and coatings. Stewart Postharvest Review, 6(3), 1-8.

[2] Oliveira, W. P., & Souza, C. R. F. (2008). Spouted and fluidized bed drying of biomaterials. Stewart Postharvest Review, 4(1).

[3] Ratti, C., & Crapiste, G. H. (2009). Modeling of batch dryers for shrinkable biological materials. Food and Bioprocess Technology, 2(3), 248-256.

[4] Witrowa-Rajchert, D., & Rzaca, M. (2009). Effect of drying method on the microstructure and physical properties of dried apples. Drying Technology, 27(7), 903-909.

[5] Shih, C., Pan, Z., McHugh, T. H., Wood, D., & Hirschberg, E. (2008). Sequential infrared radiation and freeze-drying method for producing crispy strawberries. Transactions of the ASABE, 51(1), 205-216.

[6] Gujral, H. S., & Brar, S. S. (2003). Effect of hydrocolloids on the dehydration kinetics, color, and texture of mango leather. International Journal of Food Properties, 6(2), 269-279.

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Created by Milan123 on 6 April 2012, at 12:19