Determination of polysorbates in foods by formation of mixed micelles

A new approach to the determination of polysorbates (PSs) in foods based on measurements of the critical micelle concentration of mixed micelles is proposed. PSs in a 0.25 M sulfuric acid medium are titrated photometrically with Triton X-100. The dye Coomassie brilliant blue G (CBBG) is used as a photometric probe for the rapid determination of critical micelle concentration values. The detection limits achieved for the PSs studied (viz. PS 20, PS 40, PS 60, PS 65 and PS 80) ranged from 0.05 to 0.08 mu M. The relative standard deviation for 0.3 mu M PS 60 was 2.8%. Food samples can be analyzed directly after dissolving PS from foodstuffs (baked bread, doughnuts, biscuits, butter, margarine, chocolate and noodle soup) with distilled water at room temperature. Average recoveries ranged from 98.0 to 99.3%. (C) 1999 Elsevier Science B.V. All rights reserved.