I've thought about experimenting with that, and maybe lactic acid (not familiar with either) but haven't. If you can brew all grain, you can do a full sour mash. Instead of waiting an hour on the mash, wait 18-24 hours, then continue as normal. My previous batches doing 24hrs were coming out more sour than planned so I dropped it to 18hrs and it was perfect. Going to see what the next few are like. Some people like sour beers so make this pretty sour. I don't like it like that, I like it to be barely perceptible, but just enough to change up the characteristics of the beer. It's supposed to be a session beer for the common person, and I don't see too many people downing sour beers all night. Just my opinion, but to each his own!