What to expect if i dont hit mash temp?

Hi fellow homebrewers,

What flavors, aromas or characteristics should I expect in a beer if I don’t hit the mash temp?

As of now, I have made some great tasting all grain beers but my first 3 batches were a disaster. I was doing several stuff wrong… I had several fluctuations in the mash temperature because I was not familiar with my equipment (BIAB by the way). Nor I did iodine test neither check the PH of the water.

Newbie mistakes… I know… but I let ferment the beers. In the 3 batches I ended with very strong green-apple acidic flavor. I haven’t had that problem again since I changed my technique. The other day, one of my friends brought me a sample of his first all grain beer. It had the exact same flavor profile.

I assume the problem was the mash temp leading to an incomplete sugar conversion but I couldn’t provide a technical response to my friend. Have someone else experienced the same effect in your beer? Does someone know why this flavor develops in the beer? What is the technical response?

I know it could be an infection too but the common denominator of the 3 batches was missing the mash temp and I brew frequently enough to say I don’t have infection problems in my process.

I appreciate your comments and experience.

Sounds like fermentation temps are your issue. If you're getting green-apple flavors, that's likely acetaldehyde, which is a byproduct of fermentation, I believe caused by fermenting too hot.

Mash temps determine the types of sugars produced, either complex or simple. The lower the temp, the more simple sugars are produced, allowing the yeast to convert more to alcohol, producing a lower FG, drier, "thinner" bodied beer. Higher temps produce more complex sugars, allowing less to be converted to alcohol, producing a higher FG, sweeter, "thicker" bodied beer.

By the way, I've never done an iodine test ore measured mash PH and haven't had any problems. Not saying you shouldn't, but I wouldn't call it a "newbie mistake."

What were your fermentation temps, and do you have a way to control it?

Green apple flavor is usually Acetaldehyde. It is fermentation related, not mash related. Underpitching, fermenting too warm, and removing the beer for the yeast cake too soon are all likely culprites. If you stepped up to full boils, it may be you didn't aerate well and had poor yeast growth.

Missing mash temps or ph may cause different impacts depending on which direction you miss. eg too low a temp will yield a very fermentable and dry beer. Going to high will get a sweeter, less fermentable brew. Missing really high for ph and temp could lead to husky or astringent tastes.

If you don't hit a temperature where conversion can occur you will not have sugars to ferment.

I note that you live in San Jose--I assume that's San Jose, CA where I also live and brew. What are you using for water in your brew? I've noticed some astringent qualities in my AG beers that I attribute to using less-than-optimal tap water. My understanding is that, particularly during the summers, the pH can be higher here than in many areas.

To address your questions directly:

If you miss your mash temperatures by a couple degrees to the low end (ie, shoot for 152, but hit closer to 148), you'll wind up with a much more fermentable wort. In the end, you'll have a boozier beer with less body.

If you miss your mash temperatures by a couple degrees to the high end (ie, shoot for 152, but hit closer to 156), you'll wind up with a less fermentable wort. This will lead to a lower alcohol beer with a bigger body.

Basically, as long as you're somewhere in the range of the mid 140's to about 160, you're still going to get beer. Much cooler than that, or much warmer than that, and either you won't activate enough enzymes to convert and break down fermentable sugars, or you'll denature those enzymes - either way, you won't have much in the way of fermentables in your wort, and you'll be stuck with a batch of mostly-unfermentable sugar water.

Now, as folks have pointed out, what you're describing definitely sounds like fermentation issues and not mash temperature issues, and should be addressed in that light - if you're not doing so already, look into controlling your fermentation temperatures!

larce11 said:

I assume the problem was the mash temp leading to an incomplete sugar conversion but I couldn’t provide a technical response to my friend.

Click to expand...

I agree with the others that it does not sound like a mash issue. Did you take gravity readings before and after fermentation? If your O.G. was within range of what was expected, then the appropriate conversions took place. The fermentability of these sugars is unknown at this time, but conversion took place. If your final gravity reading is within the expected range after fermentation was complete, then congratulations! You properly mashed your grains. I never do an iodine test, but I always take gravity readings to get an idea of the conversion taking place.

I do take pH readings, but I have taken to starting with distilled water and building my desired mineral profile. The pH readings let me know I've done the math right and hit the 5.2 - 5.4 range.