Myofibrillar protein with κ- or λ-carrageenans as novel shell materials for microencapsulation of tuna oil through complex coacervation

Abstract

The myofibrillar protein (MP) extracted from Ctenopharyngodon idellus was used as a novel shell material for microencapsulation of tuna oil by using the complex coacervation method in the presence of κ- or λ-carrageenan. The optimum conditions for the complex coacervation process were found to be pH 5.0 and a 4:1 ratio of MP to carrageenan (κ- or λ-carrageenan). The occurrence of complexation between the biopolymers (liquid microcapsules) was compared to the final emulsion of individual MP and confirmed by confocal laser scanning microscopy (CSLM). After spray-drying, the obtained microcapsules were analyzed in terms of morphology, size, encapsulation efficiency (EE), surface oil (SO), encapsulation yield (EY), payload (PL), moisture content, hygroscopicity, wettability, solubility, flowability, color and oxidative stability. CSLM confirmed the occurrence of complexation between the biopolymers. The morphology of the resultant microcapsules was influenced by polymer type. The average size of all microcapsules was no more than 6.0 μm with EE, SO, EY and PL ranging from 91.11 to 98.65%, 0.01–0.07%, 82.67–99%, and 41.33–49.5%, respectively. When compared to the individual MP microcapsules, the complex coacervate microcapsules were lower in hygroscopicity and wettability, but higher in moisture content and solubility. The λ-carrageenan improved the solubility of microcapsules greatly, followed by κ-carrageenan. The optimal complex coacervate microcapsules performed better in protection against oxidative deterioration during storage. This research reveals MP as a promising microencapsulating agent for microencapsulation and protection of bioactive compounds, especially with κ- or λ-carrageenan as complex coacervates.