German Brewing

Since going to a step mash (145/160f) my fermentations have been very strange. All take off very well even at very cold Temps and run to 55-60% att, where they slow down to a creep and very very slowly finish. This is not normal for my fermentations and is not a yeast health issue. This only started when step mashing started. Any suggestions?

30/30/10 normally, have done 45/30/10 with the same results

Any other new variables? Like too much SMS or cold fermentations?

My best guess is mash temp stratification, maybe parts are dropping back to the 130s? Maybe messing with the fan levels? I don't find much info on this topic.

Do you do full volume mashes?

I hope your thermometer is calibrated. Otherwise a change in the vintage of the malt sometimes requires an intensely stepped mash in the beta amylase range. Your maltings shoukd be able to advise.

I had quite a bit of trouble with attenuation when switching to lodo brewing. Tinkering around with mash temps and times, nutrients, yeast health and bigger pitches helped a little but there was still something else going on. I suspected the sulfites and their effect on the yeast, however that wasn't it. What ended up being the biggest factor in loss of attenuation was the switch to full volume mash and how mash thickness effects the enzyme efficiency.

Anyway solving this problem was simple with my system which consists of two kettles. The first is used to prepare the DO water and then transfer via gravity into a second kettle that is used for the recirculated mash. When mashing is complete I simply transfer back to the first kettle which now serves as the boiler.

I used to start with 7.5 gal (full volume) in the 1st kettle then DO boil, cool, add sulfites and transfer the whole thing into 2nd kettle for the mash. Now I have changed to using only 6 gal in the initial DO boil, cool then transfer to the mash and carry on there as usual. Then about 30 min before mash out, I bring the remaining 1.5 gal of water to boil in the first kettle. After 5 minutes of boil, I then underlet the finished mash wort from 2nd kettle back into the now boiling water in kettle 1 thus getting a jump on bringing the entire volume up to boil.

This method not only satisfies the low oxygen requirements but also cuts down on time and accelerates the process efficiency. Most importantly though the thicker mashes make the enzymes work much better.

Another benefit to my system was a lower liquid level in the mash which makes my floating mash cap ride lower in the kettle. This then allows me to place another lid on top of the kettle offering more protection from ambient oxygen and also insulation from temperature loss during mashing.

All in all these changes resulted in the greatest improvement to my system, process and product since switching to low oxygen brewing.