Oil-soluble food ingredients sensitive to degradation can be protected from their environment by microencapsulation. In an O/W1/W2 system, these oil soluble compounds are dissolved in small oil droplets, dispersed within a gelled matrix microbead (W1), which forms a barrier from outside inﬂuences. The stability and degree of protection delivered by the gel matrix depends on its structure and strength, and these in turn depend on the gelling process. For heat sensitive ingredients this process is typically a cold-set gelling process. Here we investigated the eﬀect of variations in matrix polymer (alginate and WPI aggregates), the gelator (acid and calcium nano- particles), and method of gelation (internal and external) [1 - 3], on the ability of microcapsules to retain oil droplets, and maintain their integrity during the production process. The eﬀects of these parameters on gel strength were tested on macroscopic gels, the smoothness of the surface of microcapsules without oil was investigated with SEM, and the integrity of microcapsules with oil was investigated with CLSM. External gelation with calcium chloride nanoparticles gave the smoothest and strongest microcapsules for both the protein and alginate microcapsules. Internal calcium gelation of microcapsules (induced with calcium carbonate nanoparticles and GDL) produced a mixture of smooth and rough microcapsules, most likely because of the diﬃculty of ensuring a completely homogeneous distribution of the calcium nanoparticles and GDL on the small scale of a microcapsule. The internally gelled alginate microcapsules were all destroyed in the production process while about half of the internally gelled protein microcapsules were destroyed. Microcapsules produced by acid induced gelation of WPI aggregates (using GDL to lower the internal pH), gave slightly rough microcapsules of which about half were destroyed during the production process. When the pH was brought further from the isoelectric point, the capsules became rougher and showed less integrity. These observations will help in designing new gel-based microcapsules with stability and release patterns tailored for a wide range of sensitive, oil-soluble ingredients.
|Number of pages||1|
|Publication status||Published - 2015|
|Event||ISFRS 2015 - Zurich, Switzerland|
Duration: 7 Jun 2015 → 11 Jun 2015
|Period||7/06/15 → 11/06/15|