Microencapsulation of astaxanthin by ionic gelation: effect of different gelling polymers on the carotenoid load, stability and bioaccessibility

Astaxanthin (ASX) is a carotenoid characterised by numerous health-promoting properties but biased by scarce chemical stability. Our aim was to microencapsulate ASX through ionic gelation to improve its stability and bioaccessibility, evaluating the performance of low-methoxyl pectin (LMP) and chitosan, besides the most common alginate. Three formulations were tested: 3% pectin (Pec), 3% pectin + chitosan shell (PecChi) and 1.5% alginate-1.5% LMP + chitosan shell. The results showed that chitosan deposited onto PecAlChi and PecChi beads improved particle sphericity and limited oil oxidation during processing. PecAlChi provided the highest encapsulation efficiency (87%) and bioaccessibility (58%). The stability test at 65 degrees C x 24 days showed different polymer-dependent degradation kinetics, with PecChi providing the highest stability (48%). In conclusion, encapsulation performance strongly depended on the chitosan shell and the gelling polymers. This suggests that tuning the alginate/pectin ratio may lead to the best compromise between stability and bioaccessibility.

Automated summary

This study aimed to microencapsulate astaxanthin (ASX) using ionic gelation with low-methoxyl pectin (LMP), chitosan, and alginate. The results showed that adding chitosan improved particle sphericity and limited oil oxidation. The combination of LMP and chitosan achieved the highest encapsulation efficiency and bioaccessibility.