Emulsification properties of amylose-fatty sodium salt inclusion complexes

Abstract

Amylose complexes formed with fatty sodium salts were evaluated for their emulsification, foaming, and rheological properties. Amylose inclusion complexes (AIC) were produced in a pressurized microwave reactor using the sodium salts of fatty acids having carbon chain lengths of 12–22. The AIC were isolated by freeze drying, re-dissolved into aqueous solutions (0.1–3.0% solids) and their surface and rheological properties were then characterized. The AICs successfully formed emulsions with corn oil. The emulsifying properties of the various AIC, as well as long-term emulsion storage stability were determined. The AIC have superior emulsifying activity at neutral and alkaline pH, and superior stability at alkaline pH, compared with commercial octenyl succinic anhydride (OSA) starch. In neutral aqueous solutions, the sodium arachidate (C20) AIC had 31% greater emulsifying activity, and the sodium behenate (C22) AIC had 60% greater emulsion stability than OSA starch. Emulsions formed with the AIC were stable during long-term storage as the oil droplets were resistant to coalescence. Stability increased with fatty acid salt chain length due to viscosity differences, with solutions of the higher molecular weight fatty acid salt AICs having greater viscosity. All AIC emulsions had enhanced emulsifying activity with increased alkalinity of the continuous phase. The AIC are surface active polymeric emulsifiers which did not produce foams. The AIC are effective biodegradable emulsifiers produced from readily available inexpensive food grade ingredients formed via van der Waals rather than chemical bonds.