Impact of high mash temp on OG

LAB thermometer off 5*F!!! Mashed in at 154-155 instead of target 149. Didn't figure it out for 45 minutes, thus killing off much of the beta-amylase enzymes.

I understand that hitting the higher temps emphasizes alpha-amylase and this in turn produces higher TG/FG due to more unfermentable dextrins. How would this change in the alpha-amylase/beta-amylase ratio impact the O.G.??? Raise it or lower it?

BTW - iodine test indicated conversion.

Can you first describe the process you used to calibrate your lab thermometer? When you checked it at boiling, did you only immerse it to the immersion line? Did you also toss in some pebbles or a pinch of chalk, etc for some nucleation sites? (you can get several degree error if you forget that). And you also checked at 32 f in an ice bath with mostly crushed ice?

It shouldn't affect the OG a bit. Conversion is conversion. The OG should be the same whether you mash at 147 or 160. The amount of maltose/maltiose would vary due to mash temperatures, but not the actual OG if you got complete conversion.

Thank you moderator for info on OG not being influenced by ratio of maltose to other sugars resulting from alpha/beta-amylase ratio.

Appreciate also extra ideas on calibration. The lab thermometer has to be calibrated at the factory. Ugh.

I did immerse the other three in the kettle at nucleation points to arrive at 212*F. I'll check later on the temp with ice. Too immersed in brewing process at time of last brew to address this.

Thanks to both of you!

Yeah, I had to question you about checking your lab thermometer because it seems to me they sometimes get a bad rap. But I've owned a couple and they were dead nuts , so I have to wonder if people are sometimes checking them wrong.

BTW, not sure what you meant about calibrating the lab thermometer. When brewers say "lab thermometer" they mean the liquid filled glass kind that you can't calibrate. And you don't really ever need to adjust a thermometer anyway-- the important thing is to know the error so you can add/subtract for your readings. E.g. I have a digital that I can't adjust, but I know it reads 3f high at mash temps. Good enough.

You'll raise the FG some, but nothing to be worried about.... Unless you were trying to make a dry beer. Then your kinda screwed