Production of stable food-grade microencapsulated astaxanthin by vibrating nozzle technology

Astaxanthin is a carotenoid known for its strong antioxidant and health-promoting characteristics, but it is also highly degradable and thus unsuited for several applications. We developed a sustainable method for the extraction and the production of stable astaxanthin microencapsulates. Nearly 2% astaxanthin was extracted by high-pressure homogenization of dried Haematococcus pluvialis cells in soybean oil. Astaxanthin-enriched oil was encapsulated in alginate and low-methoxyl pectin by Ca²⁺-mediated vibrating-nozzle extrusion technology. The 3% pectin microbeads resulted the best compromise between sphericity and oil retention upon drying. We monitored the stability of these astaxanthin beads under four different conditions of light, temperature and oxygen exposition. After 52weeks, the microbeads showed a total-astaxanthin retention of 94.1±4.1% (+4°C/-light/+O₂), 83.1±3.2% (RT/-light/-O₂), 38.3±2.2% (RT/-light/+O2), and 57.0±0.4% (RT/+light/+O₂), with different degradation kinetics. Refrigeration, therefore, resulted the optimal storage condition to preserve astaxanthin stability.