Changes

(in progress)

Another antimicrobial mechanism resulting from oxidative stress has been attributed to both iso-α-acids and humulinic acids<ref name="Schurr et al, 2015"> [http://www.sciencedirect.com/science/article/pii/S0740002014002470 Schurr et al., (2015)] </ref>. Humulinic acids are either not bitter tasting or much less bitter than iso-α-acids but are similar in structure to and are formed from the degradation of iso-α-acids. This oxidative stress-driven antimicrobial activity is due to potential for oxidation-reduction (redox) reactions between Mn2+ ions and specific hop acids within the cell. Iso-α-acids or humulinic acids pass into the cell, where environmental conditions promote redox reactions between Mn2+ and the acids<ref name="Schurr et al, 2015"> [http://www.sciencedirect.com/science/article/pii/S0740002014002470 Schurr et al., (2015)] </ref>. These redox reactions result in the transfer of electrons out of the cell (-----look up Behr and Vogel, 2010). By targeted molecular modifications [http://www.sciencedirect.com/science/article/pii/S0740002014002470 Schurr et al. (2015)] determined that the Mn oxidative stress-driven antimicrobial effect of iso-α-acids was more important than antimicrobial effect of the ionophore proton transfer discussed above in the overall anitmicrobial activity of hops on microbes<ref name="Schurr et al, 2015"> [http://www.sciencedirect.com/science/article/pii/S0740002014002470 Schurr et al., (2015)] </ref>.

==Aged Hops==