Evaluation of soy oil lutein isotherms obtained with selected adsorbents in hexane miscellas

Abstract

Bleaching of soy oil hexane/miscellas by adsorption of the lutein was examined. Quantitative differences in the adsorption behavior between a bleaching clay, alkaline rice hull ash and acid rice hull ash were measured by comparing the constants, K and n , of Freundlich isotherms. All the isotherms were dose‐dependent with K being inversely related and n directly related, to adsorbent mass. Overall, the bleaching clay performed better than the ashes. Alkaline ash had a larger K value than acid ash, but the n value of acid ash was greater. Equations of lutein adsorption were derived based on initial concentrations on lutein and the amount adsorbed per gram. Logarithmic plots produced constants, K i and ni which were the intercept and slope, respectively. As adsorbent dose increased, K i decreased and n i increased for each adsorbent studied. These findings may have applications in the processing of dilute miscellas where low temperature, low viscosity oil refining is desired.