Starch–Carboxymethyl Cellulose (CMC) Mixtures Processed by Extrusion

Abstract

Some properties of native starch limit its applications and thus, modifications to its structure or association with other ingredients is recommended. The objective of this work is to study the effects of extrusion on mixtures of corn starch with 1, 5, and 10% w/w of carboxymethyl cellulose (CMC). CMC acts as a lubricant during processing, making it less drastic and preserving some starch granules against rupture. Increases in CMC concentration generate an increase in viscosity but have no significant effect on thermal properties. No new covalent linkages are observed, suggesting that interactions between polymers occurs via hydrogen bonds. The sample containing 5% w/w CMC added to starch prior to extrusion forms firmer and more stable instant gels compared to the sample in which the same level of CMC is added to the starch extruded without gum. Therefore, extruded mixtures of corn starch-CMC can be considered as new thickening and gelling ingredients for application, mainly, in instant foods.