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 pr oposed. PSs in a 0.25 M sulfuric acid medium are titrated photometrically w ith Triton X-100. The dye Coomassie brilliant blue G (CBBG) is used as a ph otometric probe for the rapid determination of critical micelle concentrati on values. The detection limits achieved for the PSs studied (viz. PS 20, P S 40, PS 60, PS 65 and PS 80) ranged from 0.05 to 0.08 mu M. The relative s tandard 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, bisc uits, butter, margarine, chocolate and noodle soup) with distilled water at room temperature. Average recoveries ranged from 98.0 to 99.3%. (C) 1999 E lsevier Science B.V. All rights reserved.