Characterization of a Casein-Sodium Alginate Emulsion Gel and its Application in 3d Food Printing

Emulsion gels with an oil fraction of 65-80% were prepared by one-step, or two-step homogenization, using micellar casein (MC), or sodium caseinate (SC), combined with sodium alginate (SA) as the stabilizer. The stability, moisture distribution, rheological properties and 3D printing characteristics of the emulsion gels were determined. Light microscopy showed that the oil droplet size was influenced by the preparation method and decreased with increasing oil content, more so after the one-step homogenization. The emulsion gels had excellent storage stability and no phase separation was seen after storage for 230 days; they also had high pH- and heat-stability. SC-SA emulsion gels contained more immobilized water than MC-SA gels, but the free water was mostly removed by centrifugation, followed by partial migration of immobilized water into the free water phase. As a result, the storage and loss moduli (G′ and G") of the gels increased markedly after centrifugation; the resulting, more concentrated gels had better self-supporting properties and consequently, were more suitable for 3D printing. The emulsion gels were highly resistant to simulated gastric digestion, but were almost completely disrupted after simulated intestinal digestion. Emulsion gels based on MC/SC-SA appear to have great potential for use in 3D food printing.