Encapsulation of curcumin in milk powders by spray-drying: Physicochemistry, rehydration properties, and stability during storage

Abstract

Curcumin is a natural polyphenol that has strong antioxidant, anti-inflammatory and anti-carcinogenic properties, however, it is sensitive to light, oxygen and heat, and also presents very low solubility in water. Several studies have focused on curcumin preservation and bioavailability due to its health importance, especially by encapsulation. Milk may constitute a good matrix for the encapsulation of curcumin, because it contains a significant proportion of casein micelles which are amphiphilic and porous, making them suitable for carrying hydrophobic substances such as curcumin. This work aims at evaluating the efficiency of milk for encapsulating curcumin, releasing it in an aqueous medium during powder reconstitution, and improving its preservation during storage. Curcumin was encapsulated by spray-drying at pilot scale, extracted by different solvents, and quantified by UV/Vis. spectrophotometry. Physicochemical characteristics (particle size distribution, water content, water activity, and color) and rehydration properties (wettability, dispersibility, and solubility indices) of curcumin-loaded milk powder were characterized. A powder storage study was also conducted to evaluate the stability of curcumin over time at different temperatures (10, 25 and 50 °C). Drying conditions were set to obtain a product of water activity close to 0.2. A method for curcumin extraction and dosage was also validated using diethyl ether as extraction solvent. Milk powder loaded with curcumin showed no significant differences in most characteristics compared to raw milk powder, except that its wettability was decreased by the presence of curcumin. Moreover, the good encapsulation yields and the stability of curcumin antioxidant activity during storage showed the suitability of skim milk for curcumin encapsulation.