Any downside to a protein rest?

[skibikejunkie]

I have been brewing all-grain using brew in a bag for several batches, a couple of which I have used a protein rest while mashing. I've noticed that the protein rested beers have had better clarity than my single step mash beers. According to Palmer's book, this makes sense, since the protein rest will break down some of the proteins that can cause chill haze. Elsewhere in Palmer's book, however, he suggests not doing a protein rest when using well-modified grains but doesn't explain why.

One of the downsides to brew in a bag is that you end up with more solids (presumably proteins) in your wort since you're not doing a true lautering process. Just wondering if there is a downside to doing a protein rest (other than the additional time) when brewing with well-modified grain. My anecdotal experience suggests a protein rest is a good way to improve beer clarity, but I don't want to do it if I'm going to fuck up something else in the process.

[spiderwrangler]

The most commonly mentioned concern is doing an extended protein rest to the point that proteins involved in head formation and retention are clipped too short to 'do their job'.

[brewinhard]

+1 to spider. Too long of a protein rest on today's modified malts can leave one with little head retention (depending on the malt used).

[Thirsty Boy]

keep your P rest shortish, and maybe a little hotter than traditional - say at 55°c for only 5-10 minutes.

really - with modern well modified malts, a p rest shouldn't actually make a noticeable difference to your clarity. It could simply be the fact that in order to do P rest, you have to mash for longer and you need to do some extra stirring during the ramp from protein to conversion temperatures. The extra time and the extra stirring meaning you are mashing a little more intensively and converting starch that might have been contributing to your beer being less clear.

as an experiment (if you can be bothered) try doing a mash that skips the P rest, but includes a bit of extra time and a chunk of extra stirring. see if maybe thats whats doing the trick.

word of caution - some BIAB brewers in Australia have been finding issues when they brew with a P rest. Its only brewers that use electric Hot water Urns with a specific type of element as their BIAB pot. Because the wort at Ap rest temp is below the gelatinization temperature of the starches... there are a lot of undissolved starches and proteins lurking about in that wort. and when they hit the button to add heat for a ramp, a bit of that googe is sticking to the element and burning on. By the time the whole brew is done, its done enough burning to give a "scorched" taste to the brew and sometimes wrecks the element.

so if you are brewing electrically - remember to inspect your elements after the boil and make sure that they aren't suffering form the issue when you do a Protein rest. if it does seem an issue, then about the only thing you can do with a fixed element system, is make sure you stir extra vigorously and concentrate around the vicinity of the elements - when you are raising from temps that are below gelatinization temps. the extra vigour and velocity from your enhanced stirring, will help scrub the elements a little and moderate the issue...maybe enough.

TB

[skibikejunkie]

as an experiment (if you can be bothered) try doing a mash that skips the P rest, but includes a bit of extra time and a chunk of extra stirring. see if maybe thats whats doing the trick.

Thank for the suggestion. I'll give that a try next time.

word of caution - some BIAB brewers in Australia have been finding issues when they brew with a P rest. Its only brewers that use electric Hot water Urns with a specific type of element as their BIAB pot. Because the wort at Ap rest temp is below the gelatinization temperature of the starches... there are a lot of undissolved starches and proteins lurking about in that wort. and when they hit the button to add heat for a ramp, a bit of that googe is sticking to the element and burning on. By the time the whole brew is done, its done enough burning to give a "scorched" taste to the brew and sometimes wrecks the element.

so if you are brewing electrically - remember to inspect your elements after the boil and make sure that they aren't suffering form the issue when you do a Protein rest. if it does seem an issue, then about the only thing you can do with a fixed element system, is make sure you stir extra vigorously and concentrate around the vicinity of the elements - when you are raising from temps that are below gelatinization temps. the extra vigour and velocity from your enhanced stirring, will help scrub the elements a little and moderate the issue...maybe enough.

TB

Not an issue for me, but thanks for pointing this out. I'm using a gas burner under a pot with a false bottom supporting the grain bag, so no scorching so far.

[dstar26t]

What basemalt are you using? If you're going to go the extra step to do protein rests, you should know your malt first. Get the analysis sheet from the maltster and look at the S/T (Soluble to Total protein/nitrogen) or Kolbach index, also look for total protein. Less than 38% soluble protein and you may want to start thinking about a protein rest. More than 12% total protein and you may want to start thinking about a protein rest. If the total protein is listed as nitrogen, multiply by 6.25 to get total protein. I would stay in the upper part of the temp range since that is where the longer proteins get broken down which cause the haze. Leave the short and intermediate ones alone as to not effect mouthfeel and head retention. And of course make sure you're getting full conversion before you blame protein for haze, as previously mentioned.
I've had issues with some Golden Promise in the past and a rest at 133 for 10-15 minutes was enough to clear it up. The soluble nitrogen ratio on that lot was 37.5%, total nitrogen was 1.45% or as protein, 9%.

Nate

[unsteadyneddy]

keep your P rest shortish, and maybe a little hotter than traditional - say at 55°c for only 5-10 minutes.

really - with modern well modified malts, a p rest shouldn't actually make a noticeable difference to your clarity. It could simply be the fact that in order to do P rest, you have to mash for longer and you need to do some extra stirring during the ramp from protein to conversion temperatures. The extra time and the extra stirring meaning you are mashing a little more intensively and converting starch that might have been contributing to your beer being less clear.

as an experiment (if you can be bothered) try doing a mash that skips the P rest, but includes a bit of extra time and a chunk of extra stirring. see if maybe thats whats doing the trick.

word of caution - some BIAB brewers in Australia have been finding issues when they brew with a P rest. Its only brewers that use electric Hot water Urns with a specific type of element as their BIAB pot. Because the wort at Ap rest temp is below the gelatinization temperature of the starches... there are a lot of undissolved starches and proteins lurking about in that wort. and when they hit the button to add heat for a ramp, a bit of that googe is sticking to the element and burning on. By the time the whole brew is done, its done enough burning to give a "scorched" taste to the brew and sometimes wrecks the element.

so if you are brewing electrically - remember to inspect your elements after the boil and make sure that they aren't suffering form the issue when you do a Protein rest. if it does seem an issue, then about the only thing you can do with a fixed element system, is make sure you stir extra vigorously and concentrate around the vicinity of the elements - when you are raising from temps that are below gelatinization temps. the extra vigour and velocity from your enhanced stirring, will help scrub the elements a little and moderate the issue...maybe enough.

TB

I have experienced this, but didn't know why it only happened when doing a protein rest. Now I know why. Thanks.