Enrichment of some biochemical properties of yogurt with addition of Cornus mas L.

In this study, fruit yogurt was produced by adding cranberry fruit puree to yogurts at different levels of 5%, 10% and 15% (w/w). Fruit yogurts were stored at +4 oC for 21 days and the changes in the physicochemical and biochemical properties of the samples were examined at one-week intervals. A significant increase was achieved in the water holding capacity and viscosity values of fruit yogurts, while a decrease was observed in the serum separation values. Statistically significant changes were occurred in the rheology and texture profile analysis results of fruit yogurts with the addition of cranberry puree (P<0.05). It was determined that there was an increase in the total aerobic mesophilic bacteria and mold-yeast counts of fruit yogurt samples (P<0.05). There was a decrease in pH, protein, fat and ash values, while significant increases were determined in dry matter and titration acidity values of fruit yogurts (P<0.05). Due to the red color of the cranberry fruit, the L* and b* values of the fruit yogurt samples decreased, while the a* value increased statistically (P<0.05). It was determined that using cranberry fruit in yogurt manufacture had a significant effect on ABTS and DPPH antioxidant activity, total phenolic substance and anthocyanin amounts and these increasing were in proportion to the amount of cranberry added. ABTS antioxidant activity values of the samples increased from 8.85±0.25 mmol TE/g to 43.01±1.33 mmol TE/g depending on the cranberry ratio on the 1st day of storage. Similarly, there was an increase in DPPH antioxidant activity values from 719.32±1.21 to 1407.885±11.83 mmol TE/g. Depending on the addition rate of cranberry puree, similar increases were found in the biochemical analysis results on other days of storage. The highest antioxidant activity values were found in yogurt samples with 15% cranberry added. As a result, it was determined that 10% amount of cranberry added to the yogurt sample contributed positively to the physicochemical (TPA properties, rheological behavior, color and serum separation values) and biochemical (antioxidant activity, anthocyanin and phenolic compounds) properties of fruit yogurt. It was concluded that for the production of fruit yogurt, it would be appropriate to add 10% cranberry puree.