Rheological properties and volatile composition of fermented milk prepared by exopolysaccharide-producing Lactobacillus acidophilus n.v. Er2 317/402 strain Narine

Fermented milk products were made using a probiotic strain of human origin, Lactobacillus acidophilus n.v. Er2 317/402 strain Narine. The effects of the strain on the texture, rheology, microstructure, and volatile profiling of fermented milk products over a period of 25 days under refrigerated storage conditions were investigated using steady and dynamic rheological tests, confocal laser scanning microscopy (CLSM), and headspace solid-phase microextraction gas chromatography mass spectrometry, respectively. CLSM images confirmed that exopolysaccharides (EPSs) from Narine were large in size and interacted with proteins. EPSs (50 mg) were obtained after 8 h of incubation. Volatome profiling of Narine fermented milk revealed 15 volatile compounds, including 2-heptanone, 2-nonanone, acetoin, isobutyric acid, isovaleric acid, and 2-phenylethanol. EPSs produced from L. acidophilus n.v. Er2 317/402 strain Narine gave the fermented milk a smooth ropy texture. The natural, soft-bodied, drinkable, and pleasant flavor of Narine makes it an attractive food ingredient.