Production and evaluation of sweet almond and sesame oil nanoemulsion and their effects on physico-chemical, rheological and microbial characteristics of enriched yogurt

This study investigated the qualitative properties of fortified yogurt produced with a sweet almond and sesame oil nanoemulsion as well as an emulsifier (0.25–0.5% Span 80 and Tween 80). The pH, acidity, syneresis, rheological properties, microbial composition, fatty acid composition, oxidative stability, antioxidant activity, and sensory properties of the fortified yogurt were investigated during 15 days of storage at 4 °C. The results showed pH and syneresis were reduced by the incorporation of sweet almond and sesame oil nanoemulsion containing 0.5% emulsifier, while the acidity, malondialdehyde formation, and antioxidant activity were increased. The use of the oil nanoemulsions exerted no significant effect on the Lactobacillus delbrueckii subsp. bulgaricus count but decreased the amount of Streptococcus salivarius subsp. thermophiles. By the addition of sesame and sweet almond oils, the yogurt viscosity decreased but the elastic modulus and viscous modulus values increased. Among the treated samples, the highest sensory score during 15 days of storage was related to the yogurt fortified with sesame oil. Overall, sesame oil with 0.25% of the emulsifier is suggested for the production of fortified yogurt.