Yogurt Fortification With Lyophilized Liposomes Coencapsulating Vitamins D ₃ and B ₁₂ : Physicochemical Characterization, Sensory Evaluation and Static In Vitro Digestion

Liposomes are lipid-based delivery systems of interest in pharmaceutical, food, and nutraceutical industries due to their ability to encapsulate bioactive compounds, such as vitamins, improving stability, solubility, and bioavailability. This study aimed to develop functional yogurt enriched with vitamins D₃ and B₁₂ by encapsulating these micronutrients in liposomal dispersions produced with food-grade phospholipids, coated with pectin, and subjected to lyophilization. An optimal sucrose concentration was selected as a cryoprotectant to minimize detrimental effects of freeze-drying on vesicle integrity. Lyophilized vesicles were characterized by bioactive retention and physicochemical properties. High retention of both vitamins was observed across most formulations, except those containing only hydrogenated saturated phospholipids, which showed reduced encapsulation efficiency. These vesicles were incorporated into yogurt, and the enriched product was evaluated for bioactive content, physicochemical and rheological properties, and sensory acceptability. The addition of vesicles did not negatively affect yogurt stability or consumer acceptance. In vitro digestion using the INFOGEST 2.0 protocol revealed increased vitamin D₃ bioaccessibility after the gastric phase only in samples containing Phospholipon 90G-based liposomes; however, after the intestinal phase, all formulations showed enhanced availability. Vitamin B₁₂ bioaccessibility remained consistent throughout digestion. Overall, results demonstrate a viable approach for coencapsulation and protection of hydrophobic and hydrophilic vitamins within a commonly consumed dairy product, offering a promising strategy for developing functional foods supporting daily nutritional supplementation. PRACTICAL APPLICATIONS: Pectin-coated and uncoated liposomes were successfully freeze-dried with sucrose as a cryoprotectant. Purified phospholipids improved the bioaccessibility of vitamin D₃ after gastric digestion. Liposome enrichment did not alter yogurt stability or sensory acceptance. The strategy allows the co-administration of hydrophilic and hydrophobic vitamins in dairy products.