Submitted to: Proceedings of Florida State Horticultural Society
Publication Type: Proceedings
Publication Acceptance Date: February 13, 2004
Publication Date: April 1, 2004
Citation: Luzio, G.A. 2003. Effect of block deesterification on the pseudoplastic properties of pectin. Proceedings Of Florida State Horticultural Society. 116:425-429. Interpretive Summary: Plants contain enzymes that can modify pectin. Pectin is commonly used in the household to make homemade jellies and jams. In this work it was shown that, when these plant enzymes are used to modify the pectins, they have unique properties. These new pectins are different from commercial pectins, but they are still natural products. The enzymes that were used in this work are food grade. One unique property of these new pectins is that they can be used in fruit drinks and juices to keep the fruit pulp from settling to the bottom of the container. The product has an improved appearance during storage since no separation or settling occurs. It can also be shown that the juice drink has acceptable mouth feel when the modified pectin has been added.
Technical Abstract: During deesterification, the ester groups on the pectin can be removed in a random or block wise (sequential) manner. The removal of esters block wise is typically mediated by plant pectin esterases such as those found in papaya extracts. Pectins containing these blocks of unesterified groups on the chain are highly reactive to divalent cations such as calcium ion. In solution, in the presence of calcium ions, pectins deesterified by plant pectin esterases can exhibit unique rheological properties. One such property is that they can produce solutions that have pseudoplastic properties such as yield stress behavior. This yield stress behavior can be used for particle or pulp suspension. These pectins were used to suspend citrus pulp in the presence of calcium ions and the settling rate was 50 times slower than the control with no added pectin. Yield stress behavior can be important for pulp stabilization in fruit drinks, while providing low viscosity for acceptable mouth feel.