Development of probiotic yoghurt fortified with high-purity Chlorella vulgaris-derived lutein and its nanoencapsulated form for enhanced stability and functional efficacy

Lutein delivery from microalgae into probiotic yogurt is limited by poor aqueous solubility, oxidative degradation during fermentation, and reduced bioaccessibility. This study developed a scalable synbiotic yogurt fortified with high-purity lutein (92%, HPLC-confirmed) extracted from Chlorella vulgaris , using sodium caseinate-pectin nanoencapsulation (encapsulation efficiency 89.4%) to enhance stability and bioaccessibility while maintaining probiotic viability. Yogurts were fortified with free lutein (7.5 or 15 mg/100 g) or equivalent nanoencapsulated lutein, then evaluated for lutein retention (nanoencapsulated retained > 90% vs. 60% loss in free lutein after 21 days at 5 °C), Lactobacillus rhamnosus KU985435 viability (> 10¹⁰ CFU/mL over 21 days), in vitro lutein bioaccessibility (2.3-fold higher in nanoencapsulated samples), sensory attributes, and antioxidant capacity (DPPH scavenging 96.7% in T4 vs. 38.6% control at day 0). Nanoencapsulation provided superior storage stability, enhanced bioaccessibility, and sustained antioxidant activity without compromising probiotic counts or sensory acceptability (T4 scored highest: 92/100). These findings demonstrate a feasible nanoencapsulation strategy for functional yogurt delivering stable microalgal lutein with enhanced functional efficacy.