Interactions of buttermilk with curcuminoids

The ability of buttermilk to carry and stabilise a preparation of curcuminoids was examined. The quenching of intrinsic protein fluorescence confirmed that the curcuminoids interacted with proteins in buttermilk. The Stern-Volmer quenching constant was >= 9.4 x 10(3) M-1. The apparent binding constant of curcuminoids to whole buttermilk was >= 2.2 x 10(4) M-1. Centrifugation of buttermilk (5% total solids, TS) - curcuminoid mixtures demonstrated that curcuminoids were partitioned into the cream (18.0% w/w, 0.64% TS), milk serum (73.3% w/w, 2.86% TS) and the casein-rich precipitate (6.76% w/w, 1.87% TS) fractions in the ratio of 1:3.7:3.5. The interaction of curcuminoids with components in the buttermilk improved its stability, as evidenced by the faster degradation of curcuminoids in phosphate buffer (pH = 6.8) than in buttermilk. The ability of buttermilk to carry and stabilise curcuminoids has the potential to enable the delivery of these components into functional foods. (C) 2013 Elsevier Ltd. All rights reserved.