I brewed up a dry stout as my first brew session of 2014. I thought this would be the perfect time to try top mashing. The grain bill is very straight forward and only has one pound of roasted barley for specialty malt.

So what is top mashing?

Top Mashing is the process of adding grain late in the mash process to extract color and flavor after the main mash has finished converting. Normally, one would reserve grains that didn’t need to be mashed for this process.

Why perform a top mash?

The primary reason is mash chemistry. Great starch conversion is dependent on two things: temperature and mash pH. Temperature is pretty easy to control by the home brewer and easy to understand. However, pH can be difficult to understand, predict, and control. There has been a tremendous amount of chatter and debate lately about water chemistry and mash chemistry. Many people try and make predictions about what grain and how much they effect the pH of your wort. From those predictions, one can calculate different amounts of brewing salts (gypsum, carbonates, chlorides) required to put your pH back in check for optimum conversion.

Top mashing attempts to simplify this process by taking the very malts out of the mash that can have a dramatic pH lowering effect. Letting the base malt and a simpler mash chemistry do the work on the largest part of the grist…the base.

There are other debatable benefits of top mashing. Some may say that a smoother profile is capture by top mashing. Exposing certain malts to the heat of the mash for a shorter time may indeed extract less tannic or harsh flavors from them. Seeing how brewers have been mashing their entire grists for years without too much issue in this area, I don’t give this reason much credence.

What are the drawbacks of top mashing?

Primarily, it may take a bit more malt to get to the same color and flavor point than if the malts were in a mash for a full 60 minutes. In the video, I think that final stout wort is pretty black and I didn’t use more malt than I would have in a full mash scenario. I did crush the dark malts finely in anticipation of decreased ‘yield’. So beware and ‘your milage may vary’ with this technique.

This was the first time I had top mashed. We’ll see how it comes out when we taste it. However, both the un-hopped and post hopped wort tasted great with plenty of roast character.

Have you tried Top Mashing? Am I just crazy? Let us know in the comments section.