|Savary, Brett -|
Submitted to: Pacifichem Symposium
Publication Type: Abstract Only
Publication Acceptance Date: October 16, 2010
Publication Date: N/A
Technical Abstract: During deesterification, the ester groups on the pectin from citrus peel byproducts can be removed in a random or block wise (sequential) manner. Pectins containing blocks of unesterified groups on the chain are highly reactive to divalent cations such as calcium ion. In solution with calcium, pectins deesterified pectins by various pectin methylesterases (PME) can exhibit unique rheological properties depending on the enzyme used and its origin. One such property is that they can produce solutions that have pseudoplastic properties that are needed for suspension aids. A non-calcium sensitive pectin with a 94 % degree of methylation was demethylated at pH 4.5 and pH 7.5 to DM values ranging from 30 to 80% using enzymes isolated from plant and fungal sources. Rheology measurements on these pectins indicated that to reach a maximum value storage modulus, G', a cure time of 20 hours is needed while gelling under the geometry Data indicates that the modulus is mostly comprised of an elastic component which is important for suspension applications that are typically subjected to shear. A maximum value of storage modulus was observed at mole ratios (calcium ion to free unesterified carboxyl groups) of 1.0 to 1.2. Recovery of G' and G'' and after shear will be discussed together with comparison of modulus values based on the type of PME used.