Production of probiotic kefir fortified with encapsulated structured lipids and investigation of matrix effects by means of oxidation and in vitro digestion studies.

The aim of the present study is to encapsulate structured lipids (SLs) by complex coacervation of gelatin and gum arabic with or without using transglutaminase enzymes and to develop a functional kefir product via the addition of encapsulated SLs in the form of suspension and freeze-dried coacervates. Encapsulated SLs were evaluated for their oxidative stability during 30 days of cold storage. The data showed that coacervate solutions were more sensitive to lipid oxidation compared to freeze-dried capsules. Traditionally produced kefir samples that were fortified with complex coacervation products were stored for 10 days at 4 °C. The pH values of the samples decreased, whereas titratable acidity consistently increased during the storage period. Moreover, an in vitro controlled release study was conducted with a fortified kefir sample containing freeze-dried capsules. According to the results, kefir had no significant matrix effect on oil release from the freeze-dried capsules (p > 0.05).