Insight into the co-solvent induced conformational changes and aggregation of bovine β-lactoglobulin

•Bovine β-lactoglobulin (β-lg) was incubated separately with two commonly used organic solvents MeCN and BA at room temperature at pH 7.0.•Partial unfolding and increase of α-helical structure of β-lg at moderate concentrations of MeCN (5–50% v/v) and at very low concentrations of BA (0.1–1.5%).•At higher concentrations of MeCN (50–80%) and at low concentrations of BA (1.5–3.0%), structural transitions from α-helical to non-native β-sheet structure leading to the self-assembly of β-lg.•TEM study revealed the formation of amyloid fibrillar aggregates of β-lg in organic co-solvents.