A couple temperature questions

[slipkid]

Have a couple temperature-related questions I hope someone can help me with.

1. Today while I was mashing (small BIAB batch) I accidentally let the mash get too hot for a little while. My target mash temp was 153F-154F, and I hit 170F for a few minutes before I caught it and brought the temp back down. I know that high mash temperatures create unfermentable, dextrinous sugars and I've read that temperatures around 140F to 150F create more fermentable sugars. My question is: if I accidentally let my mash get too hot for a while, could I compensate by going low temporarily to get more fermentable sugar, or should I just try to get back to my target mash temperature ASAP instead?

2. During fermentation, I've read a hundred times that temperature control is very important. I know that means keeping the temperature in the sweet spot for the yeast, but is it equally important to keep the temperature changes to a minimum? I usually keep my fermentation vessel inside a larger container with water in it to act as a thermal barrier. If it starts getting warm, I'll usually toss some ice in the water to bring the bath temp down. I imagine that results in a pretty quick temperature drop in the wort/beer. Are quick temperature changes undesirable even if the changes are inside the safe temperature range?

Thanks!

 

[Grizzlybrew]

if I accidentally let my mash get too hot for a while, could I compensate by going low temporarily to get more fermentable sugar, or should I just try to get back to my target mash temperature ASAP instead?

No, not really (it's just not worth the effort of cooling and then trying to re-heat your mash). At that temperature (170°) some of the enzymes will start to become denatured. Bringing that temperature down doesn't reinvigorate them at that point. Just work harder to hit and hold your target temp.

is it equally important to keep the temperature changes to a minimum?

There are arguments that say the fluctuation will stress the yeast and I guess result in more undesirable esters/phenolics. Keep it cool for the first 48 hours and then it's not nearly as critical...

 

[ballz50401]

I like to keep most of my ales in the mid 60's during the first few days. Try swapping out frozen water bottles to keep temps down instead of throwing ice cubes in. Easier to control water volumes this way.