Are published pH ranges for beer styles at mash temp or room temp? I see pH 5.2-5.3 recommended for a Kolsch (Googled, of course...) but at what temperature? I always measure pH at 68 F. I also wait at least 20 minutes into a mash before pulling a sample for measuring.
Much of it depends upon whom you trust to be doing the real science and research into flavor and other key parameters, I.E., the big names among the commercials or the (ahem) big names among home brewers. I've come to the opinion that the commercials (if they reference it at all, which does not appear to happen often) reference pH measurement at mash temperature, and the far more recognized (at our level) home brewing oriented types have misconstrued this somehow to be at room temperature. YMMV, but seek for peer reviewed research data from industry types and ye shall find. For example:
Malting and Brewing Science (Briggs, Hough, Stevens, and Young) definitively states the ideal mash pH range as 5.2-5.5 pH at mash temp (which is in the same source immediately ballparked to be 5.5-5.8 pH at room temp [wherein the ideal mash pH midrange target would thereby be 5.65 at room temperature]). No less than Bamforth subsequently states that the rest of the scant data one finds with specific regard to the proper mash pH measurement temperature and its associated ideal pH range (generally along the lines of 5.2-5.6 pH as measured at 68 or 75 degrees) is coming from nothing more than circular reasoning of totally unknown origin, whereas someone at some unknown juncture in the past took the actual research done at mash temperature and said out of the blue (plus put it into print, lending credence beyond measure) that it must have been done at room temperature, and from then on the parrots all jumped on board and repeated this unfortunate mantra of unknown origin until it became literally cannonized gospel (as I interpret Bamforth).
You are free to feel safe and secure among the home brewers parroting 5.2-5.6 pH as measured at 68 or 75 degrees, or you can step into the world of endless bashing and let the parrots of the mantra bash you at will. The choice is yours.
I've further, and in my opinion far more importantly, come to the opinion that the commercials are far more interested in kettle pH than mash pH (which might be why they don't talk much of mash pH). For example: Rochefort, one of the Trappist Monasteries, states that it mashes at 5.8 to 5.9 pH (due to combined grist and water alkalinity), and subsequently adjusts pH only downstream in the kettle to pH 5.2. AJ deLange once stated that he asked a bunch of commercials about mash pH, and (if I'm reading him correctly) the (paraphrased, most common, or collective) answer he received was (in essence) "That sort of thing seems to be of far more importance to you home brewer types".