Multivalent carboxylic acids to modify the properties of zein

Methods must be developed to improve both the processability and physical properties of zein-based articles. Typical plasticizing gents that improve processability have a negative impact on physical properties at elevated humidities. Continued efforts must be mployed to discover improved plasticizers. Carboxylic acids having more than one carboxylic acid moiety have been evaluated in ein melt formulations produced in a torque rheometer. These reagents were effective plasticizers for zein, lowering zein viscosity, nd delaying the onset of rapid viscosity increase. These reagents altered viscosity differently than the traditional plasticizers such s triethylene glycol. These additives also lowered the tensile strength (TS) of zein formulations at 50% RH. Surprisingly, TS at 0% RH was higher than that at 50% RH at elevated levels of these additives. NMR analysis of Soxhlet extracted samples showed hat these multivalent carboxylic acids do not cross-link the zein under the reaction conditions employed. 2006 Elsevier B.V. All rights reserved.