Rheological properties of frozen vegetable purees. Effect of freeze-thaw cycles and thawing conditions

Autor: Maria Dolores Alvarez Torres, Wenceslao Canet
Rok vydání: 2001
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Zdroj: Digital.CSIC. Repositorio Institucional del CSIC
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ISSN: 1438-2385
1438-2377
DOI: 10.1007/s002170100314
Popis: Results are presented on the effect of the number of successive freeze-thaw cycles and different final thawing conditions on rheological properties of frozen vegetable purees using a specific mixing device (helical ribbon impeller) to follow changes in dynamic properties. The number of freeze-thaw cycles ranged from zero (that is, thawing only) to four and were applied to three types of commercial product (broccoli-potato, carrot-potato and celery-potato). After freeze-thaw cycles, purees were thawed at room temperature, by microwave at three different settings, and in a saucepan. Rheological properties were affected more by the thawing conditions than by the number of cycles applied. Saucepan thawing increased the values of these properties as a result of an apparent heavy water loss during heating. The storage modulus (G') was the rheological property most affected by either effect in both broccoli- and carrot-potato purees, showing that their behaviour is predominantly elastic, with phase angles in the region of 5-12°. After one or two cycles (depending on thawing conditions), broccoli-potato presented much greater elasticity and apparent freeze-thaw stability than the others. Celery-potato puree presented the highest fluidity, possibly because its initial higher water content meant that loss modulus values were more significantly affected by thawing conditions. Results showed a complex dependence of the dynamic properties on structural factors of the purees as well as on processing parameters. © Springer-Verlag 2001.
Databáze: OpenAIRE