Effect of dried nut fortification on functional, physicochemical, textural, and microbiological properties of yogurt

In this study, walnut, hazelnut, almond, or pistachio were incorporated to produce functional yogurts. The effects on physicochemical and instrumental textural characteristics and syneresis, contents of folic acid, selenium, tocopherols, and n-3 and n-6 (omega) fatty acids, and viable counts of Streptococcus thermophilus and Lactobacillus bulgaricus were evaluated during storage. Fortified yogurts demonstrated higher protein and total solid contents and lower syneresis compared with control yogurt on d 21. Addition of nuts, except walnut, also increased S. thermophilus and L. bulgaricus counts. The concentrations of folic acid, alpha-tocopherol, selenium, and n-3 and n-6 fatty acids were higher in fortified yogurts compared with the levels found in the respective nut types. However, a decreasing trend was observed in all components during storage. Consequently, each nut could be incorporated into yogurt because of a specific functional property. For instance, walnut could be preferred for omega acid enrichment.