Int. J. Mol. Sci. 2011, 12(9), 6089-6103; doi:10.3390/ijms12096089
Article

Identification of a Protein with Antioxidant Activity that is Important for the Protection against Beer Ageing

1,* email, 2email, 3email, 4email, 4email, 1email and 5,* email
Received: 16 August 2011; in revised form: 1 September 2011 / Accepted: 9 September 2011 / Published: 19 September 2011
(This article belongs to the Special Issue Antioxidants)
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract: This study was carried out with fresh Australian lager beer which was sampled directly off the production line, the same samples aged for 12 weeks at 30 °C, and the vintage beer which was kept at 20 °C for 5 years. Characteristic Australian lager flavour was maintained in the fresh and vintage beers but was lost in the aged beer. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and free thiol group labelling analyses of beer proteins found that this flavour stability correlated with the presence of an unknown 10 kilodaltons (kDa) protein with a higher level of free thiols. The protein was purified by size-exclusion chromatography, then peptide sequencing and database matching identified it as the barley lipid transfer protein (LTP1). Further characterisation using diphenylpicrylhydrazyl (DPPH) free radical scavenging and a Saccharomyces cerevisiae-based antioxidant screening assay demonstrated that the LTP1 protein was active in DPPH reduction and antioxidant activity. The absence of free thiol in the aged beer indicates that the thiol functional groups within the LTP1 protein were saturated and suggests that it is important in the flavour stability of beer by maintaining reduction capacity during the ageing process.
Keywords: beer thiol protein; flavour; free radical; antioxidant; LTP1; yeast; Saccharomyces cerevisiae
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MDPI and ACS Style

Wu, M.J.; Clarke, F.M.; Rogers, P.J.; Young, P.; Sales, N.; O’Doherty, P.J.; Higgins, V.J. Identification of a Protein with Antioxidant Activity that is Important for the Protection against Beer Ageing. Int. J. Mol. Sci. 2011, 12, 6089-6103.

AMA Style

Wu MJ, Clarke FM, Rogers PJ, Young P, Sales N, O’Doherty PJ, Higgins VJ. Identification of a Protein with Antioxidant Activity that is Important for the Protection against Beer Ageing. International Journal of Molecular Sciences. 2011; 12(9):6089-6103.

Chicago/Turabian Style

Wu, Ming J.; Clarke, Frank M.; Rogers, Peter J.; Young, Paul; Sales, Narelle; O’Doherty, Patrick J.; Higgins, Vincent J. 2011. "Identification of a Protein with Antioxidant Activity that is Important for the Protection against Beer Ageing." Int. J. Mol. Sci. 12, no. 9: 6089-6103.

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