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 Note that the free thiol concentration diminishes as they are exposed to oxygen, removing the antioxidative ability of LTP1 and the other cysteine-rich proteins.<ref name=lund/><ref name=lundm/><ref name=wu>Wu MJ, Rogers PJ, Clarke FM. [https://onlinelibrary.wiley.com/doi/pdf/10.1002/jib.17 125<sup>th</sup> anniversary review: The role of proteins in beer redox stability.] ''J Inst Brew.'' 2012;118(1):1–11.</ref> However, even if the wort is fully oxidized during mashing, the disulfides (bound thiols) are subsequently reduced during fermentation, thus converting them to active free thiol antioxidants in the beer.<ref name=lund/><ref name=lundm/><ref name=wu/> Of course, oxygen-limited packaging is also extremely important to prevent degradation of beer flavor.
-Reducing agents such as sulfite can re-activate oxidized thiols,<ref name=wu/><ref name=lundm> although adding sulfite at packaging is generally not something we recommend. See [[Packaging]].
+Reducing agents such as sulfite can re-activate oxidized thiols,<ref name=wu/><ref name=lundm/> although adding sulfite at packaging is generally not something we recommend. See [[Packaging]].
-<ref name=wumj/> To further confirm LTP1's free radical scavenging activity in a physiological context, it was tested against six reactive oxygen species using a Saccharomyces cerevisiae-based assay. The antioxidant activity of LTP1 protected the yeast against the toxic effects of all six oxidants (Figure 5b). LTP1 was most effective against menadione, increasing yeast growth by 11-fold, and it counteracted all the six oxidants and increased yeast growth approximately 4 or 5-fold against H2O2, linoleic acid hydroperoxide (LAH), peroxynitrite and diamide. These findings demonstrated barley LTP1 has free radical scavenging and antioxidant capacity. In terms of brewing, LTP1’s activity against hydrogen peroxide and LAH is significant. H2O2 and LAH are thought to major ROS involved in flavor deterioration process. Elimination of these ROS abrogates the cause of oxidative process. Linoleic acid is found to be the most abundant lipid derived from malt and its oxidation by hydrogen peroxide or hydroxyl radical can lead to formation of LAH which can in turn trigger oxidative reactions, resulting in generation of precursors of the stale-tasting aldehydes.
 This high content of thiol cysteines in the protein is the basis for its radical scavenging and antioxidant activities. However, native barley LTP1 would not have antioxidant activity because all its thiol groups are occupied in the formation of disulfide bonds. The labeling of LTP1 thiols in beer demonstrated that the disulfide bonds in the native LTP1 were disrupted and linearised, most likely due to denaturing steps of malting, wort boiling and brewing. These free thiols were maintained during brewing and in packaged beer by a variety of factors. One of them could be the glycation of glycine and lysine residues with sugars such as glucose and xylose via the Maillard reaction [21]. The foam stabilising property of LTP1 has also been attributed to its glycosylation [19]. A possible working mechanism for its ROS-scavenging ability is proposed: LTP thiol(s) is oxidised to the sulfenic acid by oxidants such as H2O2, which results in the destruction of a peroxide molecule in 1:1 stoichiometry. The free thiol can be recovered by two sequential reactions (reactions 2 and 3). The reaction 2 generates a disulfide (LTP-SSR) through reaction with a small molecule (HS-R) such as yeast thioredoxin. The reaction 3 uses sulfite or phenolic compounds to generate free thiol from the disulfide for the next round elimination of ROS.<ref name=wumj/> Beers with higher levels of free thiols taste better.