Oxidation status of encapsulated structured lipids applied in kefir product

Abstract

ABSTRACT Introduction Although there is increasing demand for enrichment of foods with long-chain polyunsaturated fatty acids (LC-PUFAs) containing oils, avoiding lipid oxidation still exist as a major challenge for food producers. Therefore, oil encapsulation technology has been increasingly attracting the attention to retard lipid auto-oxidation and increase the range of applications. The objective of this study was to investigate the oxidative stability of encapsulated MLM type structured lipids (SLs) and to assess the oxidative stability when incorporated into kefir product. . Method MLM-type SLs containing FAs of Echium oil at sn-2 position and caprylic acid at sn-1,3 positions were encapsulated by complex coacervation method in the presence of gelatin and gum Arabic. Effect of transglutaminase enzyme was also investigated as cross-linking agent. Oxidative stability tests (peroxide value, p-anisidine value) were conducted for the freeze dried coacervates and coacervate suspensions of SLs during 30 days of storage at 4 °C and ambient temperature. Kefir samples fortified with complex coacervation products were analysed for their stability during storage for 10 days at 4 °C. Moreover, in vitro release profile of encapsulated SL in kefir samples were conducted.Significance In our study, MLM-type SLs were added into kefir product and oxidative stability tests were conducted for the first time. In addition, release study was applied to encapsulated MLM-type SL for the first time to determine the possible food matrix effect.

Results The kefir sample fortified with free SL had the lowest oxidation value whereas coacervate and suspension fortification of kefir resulted in higher oxidation levels throughout the 10 days of cold storage. Moreover, transglutaminase-treated coacervates and suspensions were more vulnerable to lipid oxidation than non-treated coacervates and suspensions. Based on the findings, kefir was found to have no significant matrix effect on oil release kinetics of encapsulated SLs (p > 0.05).