Sunflower oil was added to donkey milk to increase the low energetic intake and improve both texture and healthy characteristics. This milk-based emulsion was fermented using a binary association of two strains of Streptococcus thermophilus showing distinctive abilities. One strain (St 907) produced ropy exopolysaccharide (EPS), whereas the other strain (St 563) produced folic acid. Fermentation was stopped at pH 5.0 to prevent whey separation. The refrigerated product was stable at least for 20 days and showed improved viscoelastic properties due to the EPS combined with the oil droplets. The volatile profile was constituted of ketones, aldehydes, alcohols and fatty acids, mainly originated from microbial fermentation, whereas few other compounds suggested the presence of oxidative processes. The folic acid content in the fermented beverage was increased by more than 10 times (2.03 ± 0.17 μg/100 mL) with respect to that found in donkey milk (0.16 ± 0.03 μg/100 mL).
An emulsion based on donkey milk and sunflower oil (1.6% v/v) was fermented by two strains of Streptococcus thermophilus showing distinctive abilities, i.e. the production of exopolysaccharides (EPS) and folates. A controlled fermentation was carried out to obtain a stable product for 20 days, showing improved viscoelastic properties and an increased folic acid content.