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menschmaschine · 04-03-2009, 01:36 AM

I thought it would be informative to have a thread dedicated to some of the myths still floating around out there regarding any aspect of homebrewing and the science behind the current points of view from reliable sources.

To keep the thread most organized here is a suggested format:

-Put a title on your post with the myth description. If you're responding to someone else's post/myth, leave the title line blank.

-State/describe the myth.

-Explain why it's a myth using science or current/widely accepted information.

menschmaschine · 04-03-2009, 01:37 AM

Myth:
Many homebrew recipes and books indicate, when doing step mashes, to do a protein rest at ~122°F.

Response:
The purpose of a protein rest is to allow proteolytic enzymes (proteinase and peptidase) to breakdown various proteins down into smaller constituents. These enzymes are most active between 113°F (45°C) and 131°F (55°C).

In short, larger proteins cause haze (insoluble), mid-sized proteins cause foam/head retention, and small proteins don't do much of anything except add some body. Some of these proteins are inherent in the malt (barley type) and some are formed/broken down during malting. The more modified a malt is, the more these proteins are broken down. This is indicated (or calculated) on the malt analysis by the Kolbach Index or the Soluble Nitrogen Ratio.

In the "olden days", when malts were variably under-modified, if you wanted a haze-free beer, you needed to do a protein rest. Today's well-modified base malts have relatively high proportions of soluble proteins. Doing a protein rest can break these proteins down further so that the final beer is void of the mid-sized proteins you want for foam/head retention and malt flavor.

So, don't follow a recipe or book blindly when it comes to protein rests. Chances are you don't need it and doing one can reduce head retention and leave dull malt flavors. Your lowest rest temperature (unless doing an acid rest) should be in the mid 130s°F, but more likely the low 140s°F (and, subsequently, a rest in the upper 150s°F). Doing a rest in the low 140s°F can straddle the line between a protein rest and a saccharification rest. It will facilitate a small amount of proteolytic enzyme activity and break down a few large proteins to help with head retention while not breaking down too many mid-sized proteins to harm it.

mrfurlly · 04-10-2009, 02:39 AM

Quote:

Response

:

my head felt the same way after reading that as it did trying to read stephen hawkings a brief history of time !!!!!

**Yuri_Rage** · 04-10-2009, 03:08 AM

The myth:
One should always use liquid yeast over dry yeast.

The facts:
(from Mr Malty, Wyeast, White Labs, and several online supply stores)

A single 11g dry yeast packet, properly rehydrated, will result in a pitching rate of approximately 200 billion cells.

A single Wyeast Activator pack contains approximately 100 billion cells.

A single White Labs vial contains between 70 and 140 billion cells.

When making starters from vials or smack packs:
1 liter starter = about 150 billion cells
2 liter starter = about 200 billion cells
1 liter starter, then pitched into 4 liter starter = 400 billion cells

A five gallon batch of beer at an OG of 1.055 requires approximately 200 billion yeast cells for proper/healthy fermentation.

A properly prepared 2L liquid yeast starter is required to get the correct pitching rate for the aforementioned five gallon batch. Any error in procedure will decrease the cell count and/or introduce contaminants.

Many of the same strains are available in both dry and liquid form.

Dry yeast packets usually cost less than $2.

Liquid yeast vials/packs usually cost around $7, not including the cost of producing starter wort.

So, if the required strain is available in both dry and liquid form:
Choose dry yeast to minimize cost, minimize effort, and maximize pitching rate.

PseudoChef · 04-10-2009, 03:15 AM

Albeit not in the format requested, I posted this topic a while ago:

http://www.homebrewtalk.com/f14/adding-sugar-your-beer-not-going-make-taste-like-freakin-cider-90498/

beerjunky828 · 04-10-2009, 04:40 AM

When you talk about using liquid yeast over dry yeast, are you just saying that proper fermentation will be carried out using dry yeast just as well and even better than liquid yeast?

From a personal standpoint, I have found the flavor of the beer that was fermented with liquid yeast is slightly better.

Have you noticed any flavor differences when you have used dry yeast over liquid yeast for the same recipe?

**Yuri_Rage** · 04-10-2009, 12:12 PM

Not only will the fermentation be just as healthy if not better, but the resulting flavor should be just as good if not better. I have experienced that with several recipes, including my pumpkin ale. In fact, my results using dry yeast have been so good that I avoid liquid yeast if at all possible.

**Brewmasters Warehouse** · 04-10-2009, 12:22 PM

I will say that a little realized fact, IMHO, is that many commercial brewers use dry yeasts to ferment. Every type of dry yeast is available in kilo sized or larger bricks that are sold to breweries and brew pubs. I am not saying that every commercial brewery uses dry yeast exclusively, but many use dry yeast quite often.

SpanishCastleAle · 04-10-2009, 12:34 PM

See...I wanted to post that protein rests sort of get a bad rep these days and that a short one isn't always bad (and I'm not even talking about haze at all). But I certainly can't 'out-science' menschmachine. I just find that I sometimes like the 'body/mouthfeel' better and don't notice any head retention problems as long as it's short...in very unscientific tests.

**GilaMinumBeer** · 04-10-2009, 01:35 PM

Quote:

Originally Posted by menschmaschine

Myth:
Many homebrew recipes and books indicate, when doing step mashes, to do a protein rest at ~122°F.

From my readings in the opinionated texts, there is still much debate on this.

Some authors stiull suggest that even a short 10 minute rest at the range you've cited is good at breaking down those haze forming proteins without a sacrifice to head retention or body. Some others even suggest that such a practice improves the "malt character" of the beer akin to that of a decoction.

Now, I would go not that far (to relate the maltiness to deco) but, I do routinely employ a protein rest for most anything but Pale Ales. 10 minutes at 120 and my beer is crystal clear in record time, I have less to no need for IM. And I still maintain a huge malt backbone and a head that takes days to recede.

So, I agree and disagree. I think the amount of time spent at said rest range is more detrimental than the act of the rest alone. For well modified malts I use no more than 15 minutes. I treat the rest as a "smoke break" on the way to the "buffet".