I do like to get my German Pilsners in the %.2-5.3 range so they really “pop”. Dark beers up around 5.5-5.6.
I played with adjusting Mash PH at room temp per styles and have come to the conclusion that mash PH at room temp of 5.5 to 5.6 works best for me and I can’t tell a difference in the finial beer. Hell it seems that each individual yeast strain has its own buffering ability and as long as I keep alkalinity in check I am golden.
Also I feel boil PH plays a larger roll in all my beers on perceived hop bitterness and desired finial “product”. Specifically I shoot for a boil PH measured at room temp of 5.5 meaning boil should be 5.2ish. This gives me a softer hop character. Some may like that harsher hop profile in IPAs and APA but I can definitely tell when someone’s boil is possibly high on PH:). This works for me anyways. Hell most of this is probably wrong anyways:).
I have found that S. pastorianus strains do not lower the initial pH as much as do S. cerevisiae strains.
That’s an interesting nugget of info. I will definitely be filing that one away for future reference.
http://braukaiser.com/blog/blog/2011/03/02/about-ph-targets-and-temperature/
some additional good reading on this topic of room temp vs mash temp PH. Kai highlights the difficulties many home brewers have faced understanding optimal mash PH, and if optimal is referencing mash temp PH or room temp PH. Kai also suggests the variance between mash temp and room temp PH is about .35 (mash temp being lower) (EDIT: all calcs i see for PH correction suggest .20 differential). He found that in general, all recent day references to optimal PH for mash are stated in room temp range, and lists the following:
“I believe that the optimal mash pH range is 5.3-5.5 for light beers and 5.4-5.6 for darker beers when testing a room temperature sample of the mash. This pH range is a good compromise between optimal enzyme activity, good boil pH and good cast-out wort pH.” -Kai
Great link. A few more I found interesting, even if they are older.
https://www.google.com/url?sa=t&source=web&rct=j&ei=5gzKVK2CLcehyATulIDoCA&url=https://www.ibd.org.uk/cms/file/307&ved=0CEkQFjAI&usg=AFQjCNHb-kMai8lpZ4KgnEtlrpdsnga6sw&sig2=ZuKFYsbej3W9vfpocUud8Q
here’s something I find very interesting regarding PH at mash temp vs room temp. I’ve mashed many a beer with PH at room temp readings of 5.3 and 5.2. That would mean my actual PH of the mash when corrected, would have been about 5.1 and 5.0. This would seem less than optimal, yet my conversion was still in the 80%+ range.
seems like while most of us talk in terms of acceptable PH range at room temp and 5.2-5.6, there must then be a similar acceptable range for mash temp PH of about 5.0-5.4.
Agreed. I’ve seen reports that show lager yeasts are not as aggressive in reducing beer pH as ale yeasts. My understanding from a Wyeast presentation is that the German Ale yeast 1007 is their most acidic producer. It is reputed as a good yeast for final fermentation of Berliners and Gose.
Here’s a paper that I recently read about the effect of gravity on proton efflux rate: http://onlinelibrary.wiley.com/doi/10.1002/j.2050-0416.2011.tb00457.x/pdf
I was expecting a paper on String Theory given that description ;D
There’s more than extraction rate at play when it comes to the hydrolysis of starch (a fancy name for mashing). Temperature combined with pH affects the composition of wort.
Here’s the text of a posting that I made about wort chemistry a few months ago.
"Let’s start with a very basic overview of organic chemistry (the study of carbon-based compounds). All sugars belong to a class of substances known as carbohydrates. Carbohydrates are a combination of carbon and water (hydrated carbon). The simple sugars found in wort are multiples of CH2O. Simple sugars are known as monosaccharides. The simple sugars found in wort are primarily glucose and to a lesser extent fructose and galactose (an “ose” is a sugar). These sugars are classified as hexoses because they contain six carbon atoms. The chemical formula for all three sugars is C6H12O6. They only differ in form.
The sugars found in wort that are more complex than the hexoses are known as disaccharides and trisaccharides. A disaccharide is a sugar that contains two monosaccharide molecules bound by what is known as a glycosidic bond. A trisaccharide is a sugar that contains three monosaccharide molecules bound by two glycosidic bonds.
Glycosidic bonds result in the loss of one H2O molecule per bond. For example, maltose is a disaccharide that consists of two glucose molecules bound via a glycosidic bond. While the chemical formula for glucose is C6H12O6, the chemical formula for maltose is not C12H24O12 (2 x C6H12O6). It is C12H22O11. That’s because we loose an H2O molecule when we combine two glucose molecules to form maltose.
In order for a yeast cell to use a disaccharide or a trisaccharide, these sugars must undergo an important process known as hydrolysis. That word should look familiar to anyone who has dealt with a primary fermentation bogeyman; namely, autolysis. Hydrolysis is the combination of “hydro” (water) and “lysis” (break apart). Hence, hydrolysis is the breaking apart of carbohydrate via the addition of water. We need to add one water molecule per glycosidic bond in order to release the simple sugar molecules.
C12H22O11 + H2O → C6H12O6 + C6H12O6
To take a step backwards, mashing is the simple name for a biochemical process known as hydrolysis of starch. Like hydrolysis of starch, hydrolysis of sugar requires enzymes. Enzymes serve as hydrolysis catalysts. Catalysts are substances that speed up chemical reactions. Yeast cells produce the enzymes necessary to hydrolyze disaccharides and trisaccharides into monosaccharides.
Now, here’s where yeast genetics come into play. Enzymes are proteins. Proteins are made up of amino acids. Genes are responsible for encoding amino acids into enzymes. Different yeast strains encode the enzymes that catalyze the hydrolysis of complex sugars into simple sugars to different degrees. Some yeast stains do not encode the enzymes necessary to hydrolyze certain sugars. For example, the Windsor yeast strain cannot break down the trisaccharide maltotriose (C18H32O16), which is composed of three glucose molecules bound by two glycosidic bonds. That’s why it leaves a higher than normal terminal gravity.
By wort composition, I do not mean the composition of the grist that we used to make a batch of wort. I mean the proportions of monosaccharides, disaccharides, trisaccharides, and dextrins in a batch the wort.
According to Fix (Principles of Brewing Science), mashes produced at 60C (140F) and 70C (158F) have the following compositions:
60C/140F Wort
Monosaccharide – 10%
Disaccharide – 61%
Trisaccharide – 9%
Dextrin – 20%
70C/158F Wort
Monosaccharide – 8%
Disaccharide – 41%
Trisaccharide – 16%
Dextrin – 35%
As one can clearly see, not only does the percentage of dextrins in wort rise with respect to mashing temperature, the percentage of trisaccharides rises as well. To a great extent, the ability to ferment the trisaccharide maltotriose determines the relative attenuation of any given yeast strain for a specific wort composition. Bry 96 (a.k.a. “Chico,” 1056, WLP001, US-05, or simply Ballantine) is very good at breaking maltotriose down into glucose. Pretty much all that is left after it has completed fermentation is dextrin and a small amount of melibiose."
With the text of the earlier posting complete, we need to discuss dextrin. A higher-order polysaccharide that is left over at the end of hydrolysis of starch is called limit dextrin. Most of us have been taught to mash low for a highly fermentable wort because beta amylase is active at lower temperatures. However, this view is not complete because limit dextrin contains α-1,6 glycosidic bonds, which amylases cannot break. An enzyme that is also active at lower mash temperatures is called limit dextrinase. Limit dextrinase can break the α-1,6 glycosidic bond found in limit dextrin; thereby, reducing limit dextrin to simpler saccharides.
You and I both!
“A New Approach to Limit Dextrinase and its Role in Mashing”
http://onlinelibrary.wiley.com/doi/10.1002/j.2050-0416.1999.tb00020.x/pdf
It’s easy to miss, but the pH values discussed in the section concerning pH optimum were measured at 20 degrees Celsius.
So if i’m reading this correctly (and it was a struggle) optimal room temp PH is 5.6, favoring apparent fermentability and w/o affecting a-amylase…
“Lowering the mash pH from
5.7 to 5.4 increased the apparent fermentability, but as
the pH decreased below 5.4 a decrease in the
fermentability value was observed. Lowering the pH
from 5.7 increased the limit dextrinase activity (Fig. 4),
but did not affect the a-amylase activity and slightly
decreased the p”-amylase activity (results not shown).
When the mash pH dropped below 5.4 the increase in
limit dextrinase activity was counteracted by a marked
decrease in both a-amylase and P-amylase activities
resulting in lower apparent fermentabilities."
Limit dextrinase doesn’t have a huge effect on the mash at the temps most of us use. It’s peak activity is between 140-145F, and drops off rapidly at higher temps. It could have some impact during a long, low-temp mash for something like a light lager (which is probably why it appears in the literature), or if you’re doing a low-temp mash for something like a big barleywine or belgian.
I found a paper written by Charlie Bamforth that sheds new light on limit dextrinase at lunch. I am going to read the paper this evening and attempt to distill it down to something that one does not need a Ph.D. in biochemistry to understand. That’s the problem with most brewing science-related papers. We are not the intended audience.
What I think is interesting about the paper I linked to above are the differences in both optimum temperature and heat stability between purified LD and LD as found in a malt extract.
Also the LD in the malt extract was active at temperatures higher than what I had previously heard.
Edit:
Do you mind posting the link or the title?
The paper is entitled “Barley and Malt Starch in Brewing: A General Review” (http://writing.ucdavis.edu/sciencewriters/pdf/bamforth/Bamforth_Review_Barley_and_Malt_Starch.pdf). It covers more than limit dextrinase.
“Stenholm and Home (46) showed that a key factor is the
state of purity of the enzyme. Thus, when purified limit dextri
nase is heated, it loses all its activity in less than 10 min at
65°C. However, if crude extracts of malt are heated so as to
mimic mashing, then in fact, some 60% of the activity is still
present after an hour at conversion temperatures (Fig. 11). In
this respect, it may even be more inherently stable in mashing
than is b-amylase (32).
Research in several laboratories has shown that the key issue is not so much heat sensitivity (which was the message from received wisdom) as the extent to which limit dextrinase is available in the mash. It is now recognized that the enzyme is bound up with other components of the barley grain and is not active. Anything that increases the extractability of the total bound limit dextrinase, together with factors that promote the release of the enzyme from its inhibition by the binding agent, will promote free limit dextrinase and, therefore, increase fermentability. This is, of course, necessary in the production of light beers (the biggest growth sector worldwide); but also, high levels of dextrins in beer can lead to gel formation and difficulties with filtration, so the availability of limit dextrinase has implications beyond securing fermentability alone.”
Some more food for thought
“Of perhaps more commercial promise for increasing limit dextrinase is a change of pH. Stenholm and Home (46) showed that limit dextrinase activity is substantially increased by lowering the mashing pH (Fig. 13). They clearly showed that there was a much greater correlation between free limit dextrinase activity and fermentability than there was with total limit dextrinase. In turn, fermentability correlated rather less well with a- and b-amylase. Osman (38) showed that the pH optimum for b-amylase (pH 5.5) is significantly higher than it is for limit dextrinase (pH 5) (Fig. 14). However, there is still substantial b-amylase activity at the lower pH. Certainly, it appears from the work from Home’s lab (46) that a potent tool for enhancing fermentability is to lower the pH of mashes.”
Here is the part of the paper that I found illuminating because all-grain home brewers rely on the iodine test to check on the state of conversion:
“The other molecule that amylose can bind when in aqueous solution is polyiodide (iodine), yielding the familiar dark blue complex. Amylose can bind up to 20% of its weight as iodine; however, bound lipid interferes. How significant is this when the brewer tests for conversion by using the simple iodine test? Might a residuum of unconverted starch be undetected? Furthermore, it is often overlooked that the major proportion of starch molecules, namely the amylopectin, binds less than 1% of its weight as polyiodide and yields a dull brownish color and not a blue one. To me, at least, it seems that the iodine test is severely flawed. However, equally, I am unable to offer a better suggestion for a procedure that is rapid and reliable.”
I have treated that dull brownish color as dextrin since I started brewing all-grain beer.
Figure 13 was the most interesting to me as it showed that LD is still active at higher mash pHs. I also think figure 14 is pretty useful.
I never saw the point of performing an iodine conversion test.
Some thoughts I had as I read through this article:
A) It’s impossible to read this without hearing it narrated in Charlie’s voice. Especially when he uses the phrase “dead in the water”.
B) How steep is the dropoff in limit dextrinase activity beyond 65C? Obviously this research is largely targeted at light lager breweries, but it would be nice to see another data point or two above 65C.
C) There are a lot of unanswered questions for me still. I’m not jumping to the conclusion yet that any of this data will translate to a more fermentable wort, at least for the beers I typically brew.
There are two assertions here that really seem (to me) like there is a high probability of cancelling one another out to some extent. The first is that free LD is rapidly degraded at higher temps, while malt extracts seem to preserve LD activity. The second is that a considerable portion of LD is bound in the malt and inactive. When I connect the dots, I come to a possible conclusion that the reason LD activity remains over an extended time in malt is because it is bound. By liberating more free LD, you would potentially see a more rapid degradation if it is only “protected” by being bound within the malt. Unless you can liberate LD at a faster rate than it degrades, you may not really get so much bang for your buck.
It seems like malt enzyme content and possibly temperature would play a large factor here. A more highly kilned malt mashed in the 150’s may not see much of a benefit in fermentability by lowering mash pH. But at very low mash temps with lightly kilned malt, there seems to be a very likely benefit of targeting a lower mash pH to maximize free Limit Dextrinase in the mash.