impact of mash temp on mash extraction / efficiency

[hoppyscotty]

Do we assume the same sugar extraction at all mash temps or is there something that says you achieve a different mash efficiency at lower mash temps? Just asking as I've just finished fermenting a Saison with an OG a goof 4 points low (64% mash efficiency vs 79% target efficiency) and FG finished a good 6 points lower than target. My mash temp was a bit lower than I normally brew at and usually hit OG within a point or so, therefore 4 points is a bit more of a miss than I might expect.

There was a honey addition late on in the boil so maybe its a Brewfather assumption of Honey contribution?

Thanks.

 

[dcbrookes]

It is not the quantity of sugars produced so much as the type. A lower mash temperature will rpoduce more fermentable sugars, whereas a higher mash temperature will produce more (unfermentable) dextrines. All other things being equal a lower mash temperature should produce a lower FG and a higher percentage of alcohol.