Natural astaxanthin encapsulation: Use of response surface methodology for the design of alginate beads

Nowadays, consumers are more conscious about healthier products consumption benefits. Astaxanthin obtained from the microalgae Haematococcus pluvialis represents a natural ingredient for the nutraceutical and functional food industries. It is claimed that astaxanthin has much stronger antioxidant activity than vitamin E and β-carotene, providing different health benefits. However, the unstable structure of the molecule limits its application in functional foods development. Therefore, the present study evaluates the effect of five independent formulation and process variables for natural astaxanthin oleoresin encapsulation using an external ionic gelation technique. Response surface methodology can be used for studying the effect of several factors at different levels and their influences on each other, which overcomes the shortcoming of the traditional orthogonal method. The results showed that alginate and CaCl₂ concentrations have a significant effect on particles size obtained, while alginate/oleoresin ratio and surfactant concentration greatly influence the astaxanthin oleoresin release rate. In vitro studies under simulated intestinal conditions showed that astaxanthin oleoresin release process can be described by Hopfenberg model. Three mathematical models were obtained for predicting particle size, astaxanthin release rate and encapsulation yield under different process conditions, providing a platform for microencapsulation technology optimization for healthy food design.