Effect of maltodextrins on the stability and release of volatile compounds of oil-in-water emulsions subjected to freeze-thaw treatment

Whey protein stabilized O/W emulsions with and without maltodextrins were subjected to three cycles of freeze-thawing, and changes in particle size, creaming index (CI), free oil (oiling off), microstructures, and volatile release behavior were evaluated. After freeze-thawing, emulsions without maltodextrins experienced extensive droplet aggregation, and considerable level of creaming and oiling off were observed. Differential scanning calorimetry suggested that emulsion destabilization was mainly due to water crystallization. Among the three maltodextrins tested, maltodextrin with a dextrose equivalent (DE) value of 6 (DE 6) has the highest molecular weight and it offered the emulsion the least change in droplet size, CI and oiling off after the temperature processing. When volatile compounds were incorporated into the emulsions, the presence of maltodextrins modified their release behavior before and after freeze-thawing. Most volatiles had lower air-emulsion partition coefficients (K-A/E) in emulsions containing maltodextrins, and the K-A/E decreased with the increase of DE value of maltodextrins for some volatiles. In the emulsion without maltodextrins, freeze-thaw treatment resulted in lower release of propanol, pentanone, heptanone and higher release of diacetyl and hexanal in comparison to the release from controls without freeze-thawing. In emulsions with maltodextrins, no significant difference was found in the release of propanol, pentanone, heptanone between freeze-thawed emulsions and the untreated emulsion (p > 0.05). (C) 2015 Elsevier Ltd. All rights reserved.