Enzyme resistance and biostability of hydroxyalkylated cellulose and galactomannan as thickeners in waterborne paints

Autor: C. Formantici, S. Cheroni, B. Gatti, Y.M. Galante, G. Margheritis, L. Perrone
Rok vydání: 2012
Předmět:
Zdroj: International Biodeterioration & Biodegradation. 69:106-112
ISSN: 0964-8305
DOI: 10.1016/j.ibiod.2011.06.009
Popis: Chemically modified polysaccharides are widely used as rheology modifiers in several applications, such as food and feed, personal care, detergents, textile printing, building materials, paints and coating, paper manufacturing, and oil operations. Hydroxyalkylation, performed with ethylene or propylene oxide, is one of the most common chemical reactions applied to modulate the rheological profile and other properties of polysaccharides. Hydroxyethyl cellulose (HEC) and hydroxypropyl guar (HPG) are widely used as thickening and stability agents in waterborne paints. Hydroxyalkylation also increases the resistance of polysaccharides to enzyme degradation due to steric hindrance by the substituents on the susceptible bonds along the polysaccharide backbone. This feature of “enzyme resistance” is often referred to as “biostability,” yet it does not mimic a real-life situation of microbial contamination that can occur in a production plant or storehouse. We have compared viscosity decreases of HECs and HPGs in the presence of their specific hydrolyzing enzyme (cellulase and mannanase, respectively) to actual microbial contamination by consortia of fungi or bacteria. We found that the behaviour of HEC and HPG solutions inoculated with microorganisms differs and cannot be predicted from enzyme challenge data alone. Thus, “enzyme resistance” and “biostability” are not equivalent properties. For practical purposes, it is important to bear this in mind when selecting the most appropriate polysaccharide thickener, the manufacturing conditions of waterborne paints and the optimal stage of biocide addition.
Databáze: OpenAIRE
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