fermentable sugars and heat

[irishrover32]

im wondering do extracted fermentable sugars change with heat. for example if i mash between 140-150F for 1 hour i extract very fermenatable sugars from the grain, but if i up the temp to between 155-167F for a further 30 minutes will i change the sugars that i got from my 1 hour mash or will i just extract extra less fermentable sugars from my grain. if you'v any trouble understanding what im asking dont be afraid to question me.

 

[riderkb]

The enzymes that are active at high temps can't undo the work of the low temp enzymes. As can't recall the details, but some enzymes can't work close to the branches of the starch molecule and others can't work on short pieces. None of them will put the small sugars back together, so once the starch is converted the sugar profile is pretty much fixed.

On the other hand, the temp ranges for the various enzymes overlap a lot. That is one of the reasons why all of the temperature changes in a decoration mash give a different profile than a step mash.

 

[corax]

The sugars produced at lower temperatures are simple and fully fermentable. Raising the temperature after they are produced won't make any difference -- the sugars already produced won' go away, and they won't change to more complex, less fermentable sugars.

Going from high to low might make a difference. You would start out with complex, less fermentable sugars from the higher temp. mash. Then when you lower the temperature, assuming you didn't deactivate the low temperature enzymes, they would go to work and convert the complex sugars to simple, fermentable sugars.