Acta Scientiarum Polonorum Technologia Alimentaria

Background. This study aimed to evaluate the physicochemical properties and antioxidant activity of enriched yogurt with different concentrations of fennel extract (0, 1, and 3%) and Persian gum (0, 0.1, and 0.2%) during refrigerated storage (1 and 21 days).
Material and methods. Prepared milks with or without fennel extract and Persian gum were incubated with a mixed starter culture YF-3331 (Lactobacillus bulgaricus and Streptococcus thermophiles) in a volume of 200 ml in triplicate. The produced yogurt matrix was evaluated for pH/acidity, syneresis, viscosity, total phenolic content (Folin-Ciocalteu), antioxidant activity (DPPH), and sensory properties (12 participants).
Results. The pH, acidity, total phenolic content (TPC), antioxidant activity (AO), and viscosity of enriched yogurt were in the range of 4.29–4.8, 0.74–1.29%, 19.83–46.24% (mg gallic acid/g), 24.62–57.69% and 1329–3825 (cP) respectively. The results showed that increasing the amounts of fennel extract and Persian gum had a significant effect on the pH, acidity, TPC, AO, syneresis (%) and viscosity of enriched yogurt (p ˂ 0.05). The sensory analysis of samples revealed that the amount of fennel extract had a significant effect on the general acceptability of yogurt samples (p ˂ 0.05), but the effect of Persian gum was insignificant.
Conclusion. The results showed that enrichment of yogurt with fennel extract and Persian gum could improve physicochemical, phenolic compound and antioxidant properties; however, the extent to which additives were used was highly influenced by changes in sensory characteristics and consumer acceptability. In view of this, a yogurt sample containing 1% fennel extract and 0.2% Persian gum was more acceptable than the other samples on the 21st day of storage.