Effect of Storage on Rheology of Water-Soluble, Chelate-Soluble and Diluted Alkali-Soluble Pectin in Carrot Cell Walls
2015
Mierczyńska, Joanna | Cybulska, Justyna | Pieczywek, Piotr M. | Zdunek, Artur
The properties and functionality of pectins from plant cell walls depend on their structure. Therefore, the objective of this work was to determine the rheological properties of pectins extracted from plant cell walls with different solvents in relation to postharvest storage time. Water (WSP), chelate (CSP) and diluted alkali (DASP) soluble pectins were studied, taken from carrot cell walls (‘Nerac’ variety), at harvest and at five time points during storage. The rheology of pectins was studied in relation to flow properties and viscosity, and the storage effect was studied in relation to enzyme activity. The results showed that rheology of pectins depend on the solvent used for extraction. The viscosity of each pectin fraction increased during storage. WSP had the highest viscosity (maximum 0.045 Pas) compared to CSP (0.023 Pas) and DASP (0.011 Pas). DASP revealed thixotropic properties that increased from 3 % at harvest to 14 % after 5 months of storage. Flow behaviour of DASP did not change with storage time, whereas WSP and CSP showed a change from dilatant to pseudoplastic flow. The changes in rheological properties may be related to an enzymatic-induced molecular transformation, which promotes a gelling ability.
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