A considerable research effort is focused on developing effective delivery systems for hydrophobic nutraceuticals. β-carotene, a pro-vitamin A carotenoid, requires encapsulation to improve its water dispersibility and chemical stability in foods. In this study, β-carotene was encapsulated in oil-in-water nanoemulsions fabricated using high-pressure dual-channel microfluidization. Two types of natural emulsifier, quillaja saponins (Q-Naturale) and whey protein isolate (WPI), were capable of producing nanoemulsions (d32=0.14-0.16μm) using this novel homogenization method. The physical and chemical stability of these nanoemulsions were characterized during storage at neutral pH conditions at refrigeration (4°C), ambient (25°C), and elevated (55°C) temperatures. At 4 and 25°C, all nanoemulsions remained physically stable throughout 14days storage, with little change in particle size or evidence of creaming. At 55°C, WPI nanoemulsions were also physically stable, but a small amount of droplet aggregation occurred in saponin nanoemulsions. The rate of β-carotene degradation increased with increasing storage temperature, but did not depend strongly on emulsifier type. This study showed that dual-channel microfluidization is an efficient method of continuously producing carotenoid-loaded nanoemulsions from natural emulsifiers. This knowledge may be useful for developing nutraceutical delivery systems for application within commercial food, beverage, and pharmaceutical products.
Keywords: Dual-channel microfluidization; Nanoemulsion; Q-Naturale; Storage stability; WPI; β-carotene.
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