In situ quantification of β-carotene partitioning in oil-in-water emulsions by confocal Raman microscopy

Confocal Raman microscopy (CRM) was able to quantify the beta-carotene concentration in oil droplets and determine the partitioning characteristics of beta-carotene within the emulsion system in situ. The results were validated by a conventional method involving solvent extraction of beta-carotene separately from the total emulsion as well as the aqueous phase separated by centrifugation, and quantification by absorption spectrophotometry. CRM also enabled the localization of beta-carotene in an emulsion. From the Raman image, the beta-carotene partitioning between the aqueous and oil phases of palm olein-in-water emulsions stabilized by whey protein isolate (WPI) was observed. Increasing the concentration of beta-carotene in an emulsion (from 0.1 to 0.3 g/kg emulsion) with a fixed gross composition (10% palm olein:2% WPI) decreased the concentration of beta-carotene in the oil droplet. CRM is a powerful tool for in situ analyses of components in heterogeneous systems such as emulsions. (C) 2017 Elsevier Ltd. All rights reserved.