Effect of the ethanolic extract and essential oil of Ferulago angulata (Schlecht.) Boiss. on protein, physicochemical, sensory, and microbial characteristics of probiotic yogurt during storage time

BACKGROUND The use of functional food, such as probiotic products, is important due to their health benefits against various diseases. Phenolic and aromatic compounds originating from medical plants can contribute to the growth of probiotic bacteria. METHODS The ethanolic extract (0.2% and 0.4%) and essential oil (0.01% and 0.03%) of Ferulago angulata (FAEE and FAEO, respectively) were added to probiotic yogurt (Lactobacillus acidophilus and Bifidobacterium bifidum bacteria) to investigate their effects on the survival of probiotic bacteria during storage time (21 days) and assess its physicochemical, protein, and organoleptic properties. RESULTS Upon increasing the concentration of FAEE and FAEO, the value of total phenol content, acidity, viscosity, and water absorption of yogurt treatments increased, and the pH, syneresis, and solubility of treatments showed a decreasing trend (p < .05). Also, adding 0.01% FAEO and 0.2% FAEE improved the organoleptic properties of yogurt (p < .05) compared to the control treatment. The survivability of the investigated probiotic bacteria demonstrated a decreased trend during storage in all treatments, but at the end of the study, the number of both probiotic bacteria in all treatments was significantly higher than that of the control samples. CONCLUSION Based on the results of protein, physicochemical, microbial, and sensory tests of herbal probiotic yogurts, the addition of 0.03% essential oil is the best way to realize the goals of the research