Effect of Supercritical Extract from Black Poplar and Basket Willow on the Quality of Natural and Probiotic Drinkable Yogurt.

Yogurt is a fermented milk drink produced by , ssp. , or , which can be enriched with polyphenolic compounds to enhance its antioxidant properties. Supercritical (scCO/HO) extracts obtained from the mixture of bark and wood of black poplar () and basket willow () are the source of bioactive compounds. The aim of the study was to assess the effect of supercritical extracts from the and on the fermentation, quality, and bioactive properties of drinkable natural and probiotic yogurts. The incorporation of scCO/HO extracts at a dose of 0.01% (w/v) into milk for the production of natural and probiotic yogurts increases their functional properties by enhancing the antioxidant activity without causing negative effects on the physicochemical and organoleptic properties of products. The antioxidant activity of yogurt with scCO/HO extract from and was higher than control yogurts by 1.3-13.2% and 4.4-37.5%, respectively. The addition of a supercritical extract reduced the time of natural and probiotic yogurt fermentation. Natural and probiotic yogurt with scCO/HO extracts added was characterised by a bacterial population size of over 7 log cfu/g, and the microflora was active throughout the cold storage period. FTIR analysis confirmed the presence of scCO/HO extracts from or in both types of yogurt. A secondary structure analysis confirmed interactions between compounds of scCO/HO extract from and extract with milk proteins. These interactions affect the compounds' structural and functional properties by changing, e.g., their digestibility and antioxidant properties.