Evaluation of Rice-based Alternatives to Titanium Dioxide for Colour-masking in Iron-Fortified Salts

Abstract

Titanium dioxide (TiO₂) is a common whitening agent used in the food industry, used in candies, baked goods and confectionaries. Several food regulatory agencies have banned or severely restricted TiO₂ use due to potential carcinogenic/ genotoxicity. Rice starch and rice flour were investigated as alternatives to TiO₂, since they are cheap, opaque, white and are widely used in industry. Due to its amorphous granules and resulting low electrostatic forces, the adhesion of rice starch to extruded materials was much weaker than that of TiO₂.  Adhesives were synthesized from crosslinking citric acid with rice starch and rice flour through esterification reaction pathways. The results were tested on extruded ferrous fumarate cylinders used in salt fortification and compared with TiO₂ was as control. The results show that rice starch as a whitening agent with a modified rice starch adhesive was a promising option for replacing TiO₂ as a colour masking/whitening agent. It was observed that higher mass fractions of citric acid in the adhesive produced better results. Rice flour performed comparably to the rice starch in adhesives however, the ease of use was poorer due to higher viscosity and clumping. The cost for using rice starch was a cost-effective alternative to TiO₂ as rice starch is a cheaper, widely available food additive.