Summary The evolution of oxidative and structural characteristics of proteins, especially lipid transfer protein 1 (LTP1), in beer during forced‐ageing was examined. The oxidative characteristics of beer and proteins were evaluated by DPPH radical scavenging activity and ABTS radical cation scavenging activity. Results showed that the levels of proteins, thiols, LTP1 and antioxidant activity decreased gradually. This was accompanied by the degradation of macromolecular proteins in beer during forced‐ageing. Results from circular dichroism (CD), Fourier‐transform infrared spectroscopy (FTIR), surface hydrophobicity (S0) and ζ‐potential further indicated that the secondary and tertiary structure of LTP1 changed drastically during forced‐ageing, with the reduction of the S0, α‐helix and β‐sheet contents and the increase in negative ζ‐potential and random coil. Thus, the proteins, especially LTP1, might play important roles in maintaining oxidative stability of beer.

Oxygen is contributing to the deterioration of the beer and shortening the shelf-life of the packaged product. The effect of dissolved oxygen (DO) on oxidative and structural characteristics of protein in beer during forced ageing was examined. Results showed that increased DO decreased obviously protein content in beer, and further reduced antioxidant activities of beer and lipid transfer protein 1 (LTP1). Meanwhile, the increase of DO decreased significantly the free thiol groups content and enhanced the disulfide bonds level in beer and LTP1. Results from circular dichroism, surface hydrophobicity and zeta-potential illustrated that the increase of DO dramatically changed the secondary and tertiary structure of LTP1 with the decrease in the surface hydrophobicity, a-helix and b-turn contents, and the increase in the random coil and negative zeta potential. These results indicated that increased DO could damage the structure of LTP1 and had a negative impact on oxidative stability of beer.

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