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Advisor(s)
Abstract(s)
The objective of this work was to study the influence of freezing on the visco-elastic properties of strawberries. Food structure plays an important role in food quality and functionality. It is important for the
consumers to find an identical sensation when they eat a fresh strawberry and when the strawberry is defrosted. The visco-elastic properties of a food product are an indirect measure of its structure.
Experimental measurements of these properties may correlate to changes on the physical attributes of the product. In this work, a dynamic mechanical analyser was used to assess changes on loss (E’’) and storage (E’) modulus, applying a compressive test with a Ø1.5 cm parallel plate geometry.
Strawberries were acquired in a local market and frozen in a blast and fluidized bed freezer at –30 ºC for 1 hour. Samples were stored at –30 ºC in freezing chambers.
Analyses were performed on fresh strawberries, after freezing and during storage. The samples were cut in small cylinders (1.5cm x 1.5cm) and left to relax during 1 hour at room temperature.
Preliminary tests were performed in order to evaluate the linear visco-elastic region and the loss and storage modulus were determined. A dynamic frequency sweep test was also performed. Results showed that the behaviour of fresh strawberry sample varies significantly when compared with a defrosted sample. The influence of the storage still cannot be evaluated and is currently under study. Overall, it can be concluded that the freezing process greatly influenced the visco-elastic properties of the strawberries.
Description
Keywords
Strawberry Visco-elastic properties Freezing
Citation
FUNDO, J... [et al.] - Study of the effect of freezing on the visco-elastic properties of strawberries. In Encontro Ibérico de Reologia, IBEREO'04, Beja, Portugal, 9-11 Setembro, 2004. 6 p. - Progress in Rheology of biological and synthetic polymer systems, IBEREO'04. Beja : Instituto Politécnico de Beja, 2004. ISBN 972-99301-0-4. 6 p.
Publisher
Grupo Español de Reologia / Sociedade Portuguesa de Reologia