Submitted to: National Meeting of Institute of Food Technologists/Food Expo
Publication Type: Abstract Only
Publication Acceptance Date: June 2, 2006
Publication Date: June 24, 2006
Citation: Luzio, G.A., Cameron, R.G. 2006. Functional and rheological properties of highly esterified pectin after treatment with an orange pectin methylesterase. National Meeting of Institute of Food Technologists/Food Expo. Abstract No. 014-06. Technical Abstract: Degree of esterification (DE) is a primary determinate of many of the functional properties of commercial pectin. Pectin is widely marketed based on DE values and the requirements for gelling are dependent on the DE. More recently, the yield stress behavior of pectin in the presence of calcium ions is dependent on the type of deesterification (ordered vs. random) as well as the DE, but these pectin structures were not characterized. Recent work indicates that pectin structural information can be obtained and these structural changes can be matched with the functional properties. In this work, the rheological data resulting from the stepwise decrease in DE of non-calcium sensitive pectin after demethylation at pH 4.5 and 7.5 with the salt-independent PME from citrus fruit peel was correlated with pectin structural properties. Yield stress measurements using an AR2000 rheometer together with calcium sensitivity values were matched with block size and number as determined by ion chromatography HPLC from EPG block deesterified pectins. Pectins were deesterified with salt-independent PME at pH 4.5 and 7.5. Starting with 94 DE pectin, DE had to be reduced to a value of 70 or less before yield stress behavior was observed in the presence of calcium ion. Yield stress values were first observed in pH 4.5 samples at 70 DE and pH 7.5 samples first exhibited yield stress after DE was reduced to a value of 60. Minimum block size for calcium reactivity appears to be between a value of 10 to 20 unesterified units. It may now be feasible to structurally characterize deesterification patterns produced by pectin methylesterase (PME) and relate this to its functional properties.