Developing a strawberry yogurt fortified with marine fish oil1

Fortified dairy products appeal to a wide variety of consumers and have the potential to increase sales in the yogurt industry and help increase intake of long-chain n-3 fatty acids. The objectives of this study were to develop a strawberry yogurt containing microencapsulated salmon oil (MSO; 2% wt/vol) and evaluate its characteristics during 1 mo of storage. Unpurified salmon oil (USO) was purified (PSO) and both USO and PSO were analyzed for peroxide value (PV), anisidine value (AV), total oxidation, free fatty acids (FFA), and moisture content. A stable emulsion was prepared with 7% PSO, 22% gum arabic, 11% maltodextrin, and 60% water. The emulsion was spray-dried to produce MSO. The MSO was added to strawberry-flavored yogurt (SYMSO) before pasteurization and homogenization, and a control (SY) without MSO was produced. Both yogurts were stored for 1 mo at 4°C and we determined the quality characteristics including acidity (pH), syneresis, thiobarbituric acid (TBA), fatty acid methyl ester composition, color, and lactic acid bacteria (LAB) count. The entire experiment was replicated 3 times. Total oxidation (unitless) of USO, PSO, and MSO was calculated to be 20.7 ± 1.26, 10.9 ± 0.1, and 13.4 ± 0.25, respectively. Free fatty acid contents were 1.61 ± 0.19%, 0.59 ± 0.02%, and 0.77 ± 0.02% for USO, PSO, and MSO, respectively. Eicosapentaenoic acid and docosahexaenoic acid were the predominant polyunsaturated fatty acids in MSO and in SYMSO, but neither was detected in SY. Fortification of SY with MSO had no significant effect on yogurt pH or syneresis. A decrease in concentration of lactic acid bacteria was observed during the storage of all yogurts. Thiobarbituric acid values significantly increased as storage time increased and SY had a significantly lighter (higher L*) and less yellow (lower b*) color than SYMSO. Although some slight differences were observed in the color and oxidation of SYMSO compared with SY, the study demonstrated that SY could be fortified with salmon oil.