Lutein-enriched emulsion-based delivery systems: Influence of emulsifiers and antioxidants on physical and chemical stability

•Emulsifier & antioxidant type affected the stability of lutein-enriched emulsions.•The emulsions exhibited color fading during storage due to lutein degradation.•Quillaja saponins produced the most physically and chemically stable emulsions.•Ascorbic acid was an effective antioxidant in quillaja saponin-stabilized emulsions.•Catechin, α-tocopherol, and ascorbic acid palmitate acted as pro-oxidants.

The impact of emulsifier type (quillaja saponin, Tween 80, whey protein and casein) and antioxidant type (EDTA, ascorbic acid, catechin, alpha tocopherol, ascorbic acid palmitate) on the physical and chemical stability of lutein-fortified emulsions was investigated. Quillaja saponin produced emulsions with the best overall stability to droplet aggregation, creaming, and colour fading during storage at 45 °C for ten days. The impact of antioxidant type on the stability of lutein-fortified emulsions prepared using quillaja saponin was therefore investigated further. The extent of droplet aggregation and creaming was largely independent of antioxidant type. Surprisingly, most of the antioxidants promoted lutein degradation. Only ascorbic acid showed some ability to inhibit colour fading during storage, although EDTA had some inhibitory effects in the early stages of storage. This study suggests that lutein-enriched emulsions prepared using quillaja saponin as an emulsifier and ascorbic acid as an antioxidant may be the most suitable as delivery systems.