Lutein-enriched emulsion-based delivery systems: Impact of Maillard conjugation on physicochemical stability and gastrointestinal fate

Abstract

The utilization of lutein as a natural colorant or nutraceutical in many foods, supplements, and 17 other commercial products is currently limited because of its low water-solubility and chemical instability. The purpose of this study was to evaluate the effect of Maillard conjugates on the physical and chemical stability of lutein-enriched emulsions exposed to different temperatures 20 and pH values, as well as on their potential gastrointestinal fate. Oil-in-water emulsions were prepared using either casein or casein-dextran conjugates as emulsifiers. Both types of emulsions showed a slight increase in particle aggregation at temperatures exceeding 37 ˚C, and 23 became more prone to color fading (lutein degradation) as the temperature was increased. 24 Casein-coated oil droplets were highly unstable to flocculation near their isoelectric point (pH 4 25 to 5) due to the reduction in electrostatic repulsion. However, casein-dextran-coated droplets 26 were stable from pH 3 to 7, which was attributed to strong steric repulsion by the dextran moiety. 27 The casein-coated droplets were unstable to aggregation in the gastric phase of the simulated 28 GIT, whereas the casein-dextrin-coated ones were stable, which was again attributed to increased steric repulsion. Emulsifier type did not strongly influence lutein bioaccessibility. This work shows that Maillard conjugates can improve the physical stability of lutein-enriched emulsions without adversely affecting the bioaccessibility of the bioactive agent.

Food‐Grade Covalent Complexes and Their Application as Nutraceutical Delivery Systems: A Review

“…This type of information can facilitate the rational development of conjugates as nutraceutical delivery systems (McClements ). For example, DLS and ELS have been used to characterize the stability of lutein emulsions prepared using either casein or casein–dextran conjugates as emulsifiers (Gumus and others ). This study demonstrated that casein‐coated oil droplets were highly unstable to flocculation near their isoelectric point (4 to 5) due to a reduction in electrostatic repulsion.…”

“…These 2 systems consist of emulsifier‐coated oil droplets dispersed in water, but only the smaller droplets in nanoemulsions can lead to more desirable functional attributes, such as improved stability to aggregation and creaming, and higher optical clarity (Tadros and others ). There has recently been considerable interest in the application of conjugate‐based emulsifiers to create emulsion‐based delivery systems to encapsulate bioactive agents such as carotenoids, curcumin, and lutein (Gumus and others ; Liu and others ; Wang and others ). Some potential advantages and limitations of using emulsions and nanoemulsions stabilized by conjugates are summarized here:…”

Development and evaluation of lutein‐loaded alginate microspheres with improved stability and antioxidant

“…The chemical degradation of lutein leads to undesirable color fading and loss of bioactivity . Moreover, lutein has lipophilic character with low water solubility, which leads to low absorption in the gastrointestinal tract, compromising its bioavailability . Emulsions have been reported to improve the absorption of lutein .…”

Preparation and potential applications of casein–polysaccharide conjugates: a review

“…SCN and locust bean gum (LBG) conjugates formed emulsions of smaller particle size and better emulsion stability than SCN and the unreacted SCN–LBG mixture . Stable lutein‐enriched nano‐emulsions at pH 3–7 were formed using casein–DX conjugates without any adverse effect on the bioaccessibility of lutein …”