Fabrication of core–shell structured macrocapsules by electro‐coextrusion with agar–hydrocolloid mixtures for precooked food applications: textural and release characteristics

Abstract

SummaryTextural and release characteristics of three types of core–shell macrocapsules, fabricated by electro‐coextrusion with agar only, an agar/fish gelatin (80:20) mixture or an agar/κ‐carrageenan (80:20) mixture at a total hydrocolloid concentration of 2% (w/v) and different applied voltages (0–8 kV), were investigated. The capsule diameter (1.1–1.6 mm) and shell thickness (15.1–38.4 μm) decreased with increasing applied voltage. Mixing agar with fish gelatin or κ‐carrageenan reduced slightly the capsule hardness and breaking energy; however, the capsule integrity was solid enough for safe handling. The release of core (olive oil containing a dye) in boiling water followed first‐order kinetics and was retarded significantly when κ‐carrageenan was mixed with agar but accelerated with fish gelatin addition (only 2.5–3.4 min for the release of 80% of the core). The agar/fish gelatin macrocapsules can be applied in precooked foods, because they are mechanically stable and can rapidly release the core upon contact with hot water.