Selective encapsulation of quercetin from dry onion peel crude extract in reassembled casein particles

Abstract

Quercetin, a lipophilic dietary flavonoid, used as a therapeutic agent and a food component was encapsulated with casein particles to improve its water solubility as well as bioavailability in the food and pharmaceutical formulations. The nano-structured casein particles were reassembled with pure quercetin from the synthetic solution and the encapsulation yield was assessed by studying the effect of pH and the concentration of casein and additives like salts and Cetyl trimethylammonium bromide (CTAB). A maximum encapsulation yield of 97% was obtained for the reassembled casein particles formed with the addition of 0.5% (w/v) sodium caseinate, 0.1 M of calcium chloride, 0.5 M of di potassium hydrogen phosphate, 0.1 mM CTAB and 1 M of sodium citrate at a pH of 7. The identified process condition was further used to encapsulate the quercetin from the aqueous crude extract of dried onion peels. The microwave-assisted extraction was able to produce the crude extract with maximum quercetin content of 39.37 ?M per ml of the extract. Further the response surface methodology (RSM) was used to optimize the significant encapsulation variables for the maximum encapsulation yield of quercetin from aqueous crude extract. A maximum encapsulation yield of 96% was achieved at the pH 7.09 by using 2.1% (w/v) of sodium caseinate. © 2019 Institution of Chemical Engineers