This is something that concerned me early on in brewing, but try as I might, I found it made little difference in the final beer or in long term stability of the beer. Being a homebrewer with limited access to DO probes capable of standing up to the heat of the mash, I never got readings to verify what I was doing was really reducing HSA. So, I gave up trying. Later I learned and I fully believe today that HSA is a non issue if you have excellent fermentation. The yeast are opportunistic and will scavenge and oxygen and many oxidized compounds. At UC Davis, I know that Bamforth and Lewis taught that yeast could resolve any HSA during fermentation.
Let me tell you a story about how Brettanomyces can remove oxidation from a beer. We make a beer called Worry, which is a Belgian strong golden aged in Grgich Hills chardonnay barrels for two years. When the beer goes into the barrel, we give it a dose of several strains of Brettanomyces (including one that we harvested from our local area). The Brett utilizes some of the remaining sugars and develops some interesting character that goes nicely with the chardonnay and oak notes. I was tasting through some barrels around 18 months into the process when I came across 4 barrels where someone forgot to add the Brett when filling them. The beer, normally light golden in color, was a nasty brown. Think 3 SRM versus 14. It also tasted very stale and heavily oxidized. My guys wanted to dump it, but I told them that if we added the Brett, it would fix it. They thought I had lost my mind, but they added the Brett to the four barrels anyway. In about 3 months, the beer was back to a light golden color with no signs of oxidation or staling. The Brettanomyces opportunistically utilized those oxidation compounds and reversed the staling.
So, it shows the power of yeast in preventing and even reversing oxidation. I think, for that reason, HSA is a non issue.