Encapsulation of pomegranate polyphenols by ionic gelation: Strategies for improved retention and controlled release.

This study aimed at producing pectin hydrogel beads by ionic gelation proce to carry pomegranate extract (PE) evaluating approaches to increase its retention and protect the polyphenols from environmental conditions that interfere in the stability and color of these compounds, such as the pH of the medium. Several strategies were tested to reduce the mass transfer and consequently increase its retention. The insertion of a filler (gelatinized starch), the employment of different concentrations from the external environment, the adsorption using blank pectin-starch beads, and the electrostatic coating using chitosan were performed. The release of entrapped compounds over time was employed to evaluate the release pattern of PE in water media. Diffusion coefficients calculated from these experiments were then used to estimate the PE release behavior. The encapsulation efficiency (EE) was significantly improved (42 % to 101 %) when equalizing the concentration of the external medium with that from the beads formulation. Furthermore, the increase in the PE concentration was proportional to the rise in the mechanical strength (MS) of the beads which indicates a modification of internal structure due to the presence of polyphenols. The adsorption was efficient in entrapping the active compound, and despite the high PE content observed for all beads (average value of 2960.26 mg of gallic acid equivalent/100 g sample), they had the lowest diffusion coefficient from the release in water media. Finally, the coating was able to reduce the release rate in most of the tests (DAB uncoated = 0.5 DAB coated), however, during the electrostatic deposition a loss of about 32 % of the phenolic compounds in the chitosan solution was observed which led to a reduced EE. Despite the obtention of retarded release, coating studies need to be improved. Some adjustments in the execution of this technique are necessary so that the losses are reduced and the process becomes viable for the use of beads in food.

Flavoring properties that affect the retention of volatile components during encapsulation process.

Flavorings are widely used in food and beverage industries and spray drying is the most cost-effective encapsulation technique to deliver stable products. Generally, the same slurry is used to encapsulate both hydrophilic and hydrophobic flavors which led sometimes to lower retention. The same slurry formulation composed by Modified Starch and Maltodextrin 20DE was loaded with 35% of two different flavorings (orange and passion fruit) and, spray dried under the same conditions. The flavorings selected had different octanol/water partition coefficients and their composition affected the emulsion stability. Orange flavoring presented clearly better emulsion stability than passion fruit flavoring, confirmed by size distribution and Turbiscan Stability Index (TSI orange ≪ TSI passion fruit). A key learning from this work is that the best infeed emulsion achieved by the most hydrophobic flavoring, presented the lowest droplet size and yielded in final bigger particle size and the best encapsulation efficiency result (>92%).