While I was making an AG batch this weekend I had a 154 degree mash for 60 min but my mash-out temp only got up to 162 instead of 170. What sort of effect will this low mash-out temp have on the beer? The actual OG was only 0.001 lower than the expected OG.
A 1 point gravity deviation is well within the limits of measurement. I really doubt the "mash out" temp had anything to do with it. For a true "mashout" you not only have to hit 170+, but hold it for 20 min. or so to denature enzymes. My experience is that it doesn't really matter much. The main advantage of raising the temp at the end of the mash is to solubulize and hopefully convert any remaining starches in the mash. That's where any gravity increase comes from. The temp you hit was certainly hot enough to do that. There's a persistent myth that raising the temp will also decrease the viscosity of the wort and aid runoff, but experiments with room temp sparging have given lie to that.