Mashing efficiency test

[Dodes]

Hi,
in the last three batches, I had a low efficiency. And because my new pH meter has arrived, I've decided to make a little test for the efficiency. Every 20 minutes I've measured the pH of the wort, the Plato of the wort and the temperature. I had a hypothesis, that my efficiency was suboptimal because of the alkaline water.

TL;DR - Even with "good" pH of the mash, I have to mash for 2 hours to get the 98% mash conversion efficiency, the same time as without the proper pH.

Because my water is alkaline, I've decided to make a 1st mash without any adjunct to lower the pH and the 2nd mash with the acidulated malt. Both had the same water/grist ratio of 2.8 l/kg.
pH meter was calibrated before the first mash with 4.01 pH and 7.01 pH solutions at temperature 24.3 C.
Malt was milled with gap setting of 0.75 mm.
I've used the pot on the induction heater as a mash tun. The temperature was regulated to be between 62 - 65 C. In the second test, the temperature was scattered a little bit more. I've stirred the mash in the Mash-in step, and then every 5 minute for about the 20 - 30 seconds.
The max yield (FWmax) should be 21.5 Plato in the first case and a little bit lower in the second case.

First, my water:

pH:     7.7        Alkalinity: 142 ppm as CaCO3
Ca:    57.7 ppm    RA:          94 ppm as CaCO3
Mg:    11.2 ppm
Na:     5.0 ppm
SO4:   33.8 ppm
Cl:     5.0 ppm
HCO3: 173.0 ppm

1. test mash:

1 kg Pilsner Malt (Yield: 80.6 %)
2.8 l Water

Computed pH by BeerSmith: 5.87

min. | Notes
---------------
 00  | Water is 63.5 C, added malt
 20  | Temp 62.2 C, pH = 5.9 (26.3 C), FW = 17.4 P
 40  | Temp 63.2 C, pH = 5.85 (26.1 C), FW = 18.4 P
 60  | Temp 63.1 C, pH = 5.82 (25.8 C), FW = 19.6 P
 80  | Temp 63.2 C, pH = 5.80 (26.3 C), FW = 19.6 P
100  | Temp 62.5 C, pH = 5.77 (26.6 C), FW = 20.4 P
120  | Temp 62.2 C, pH = 5.76 (26.8 C), FW = 21.2 P

2. test mash, with acid malt

0.95 kg (95 %) Pilsner Malt (Yield: 80.6 %)
0.05 kg ( 5 %) Acidulated Malt (Yield: 65.2 %)
2.8 l Water

Computed pH by BeerSmith: 5.38

min. | Notes
---------------
 00  | Water is 62.9 C, added malt
 20  | Temp 63.6 C, pH = 5.35 (26.4 C), FW = 16.9 P
 40  | Temp 61.2 C, pH = 5.34 (27.4 C), FW = 18.5 P
 60  | Temp 62.0 C, pH = 5.34 (27.6 C), FW = 18.5 P
 80  | Temp 65.5 C, pH = 5.33 (27.5 C), FW = 20.1 P
100  | Temp 66.4 C, pH = 5.32 (27.1 C), FW = 20.4 P
120  | Temp 65.3 C, pH = 5.31 (26.8 C), FW = 21.0 P

The last 3 temp measurements are higher than in the first test, because I wanted to try what happen when I raised the temp a bit.

I was thinking, that if I lower my mash, as in the 2nd test, that the full conversion would be made a lot faster. But as you can see, the duration is same as in the 1st test.

Question is, where could be the problem? The first thing that comes to my mind is bad crush, but I think that 0.9 mm gap setting is ok. In the second test, the pH is also in the range. And I've seen that people get full conversion in shorter time than my 2 hours.

Anyone got some opinion?

Thank You.

 

[chickypad]

Looks like you are hovering at pretty low mash temps about 142-145F range, so maybe that's contributing? Kai runs through factors that affect conversion efficiency on this page.

 

[doug293cz]

Interesting data. Under the conditions of your experiment, pH did not have a significant affect on conversion rate. As @chickypad notes, it might be interesting to run a similar test mash at higher temps, say about 67° - 69°C (152.6° - 156.2°F) using the same crush. Another interesting experiment would be to reduce your crush size to 0.5 - 0.6 mm (0.020" - 0.024"), using the same temps as the original experiments.

Brew on

 

[Dodes]

Thank you for your replies.

I think I'll try to reduce the mill gap a little more and would try another experiment or a real batch. As @chickypad noted, the temperature could be a problem, but I had a beers with even lower temps and conversion was done in no more than 1 hour (but, I was using corona mill then and the crush was really tight).

 

[Dodes]

I've just rechecked the mill gap settings, and it's set to 0.75 mm actually.

 

[doug293cz]

Grit size plays a huge role in gelatinization rate, and gelatinization is the rate limiting step in the mash. Gelatinization occurs on at the surface of the grits and proceeds towards the center. The smaller the grits the faster and easier it is to gelatinize all the way to the center of the grits, which must occur to get 100% conversion.

One of the low oxygen brewing guys mentioned that the recent crop of European malts has a slightly higher gelatinization temp then past years' crops. This would make your low mash temps even more of a factor.

Brew on

 

[Big Monk]

First thing I would want to know is the malster.

 

[Silver_Is_Money]

That appears to be almost textbook perfect acidification. You were lucky to receive a quite mainstream normal lot of acidulated. Was it Weyermann?

 

[Dodes]

Hey,
thanks for the replies

@doug293cz, do I understand you correctly, that the low temperature could be really the cause in my case?

@RPIScotty, the Pilsner malt was from local malt house. Do you want some specific values for the malt?

@Silver_Is_Money, oh yes, till yesterday, I was skeptical about acidulated malt. Because I've used it for almost the 2 years and my efficiency wasn't always perfect. I thought that maybe it is not working. But now I knew it WAS working indeed. Yes, it was Weyermann.

Maybe I could try this experiment with the Weyermann Pilsner malt and see how it goes.

 

[Silver_Is_Money]

Maybe I could try this experiment with the Weyermann Pilsner malt and see how it goes.

I'm of the opinion that you have already quite effectively shown that mash pH does not impact efficiency. The answer to efficiency increase must lie elsewhere.

 

[Weezy]

It's generally held that pH is not critical at all with regards to mash efficiency. It just needs to be in the appropriate range (5.2-5.7). You first test is high. Others have pointed out the critical points: maltster/ quality of the malt, crush, and temp.

 

[doug293cz]

Hey,
thanks for the replies

@doug293cz, do I understand you correctly, that the low temperature could be really the cause in my case?

...

Yes. Gelatinization can definitely be slower at lower temperatures. One of the benefits of decoction is that it very effectively gelatinizes the most stubborn starch granules due to the much higher temps.

Brew on

 

[Dodes]

I'm of the opinion that you have already quite effectively shown that mash pH does not impact efficiency. The answer to efficiency increase must lie elsewhere.

I think that there is a probability, that I was using under-modified malt, because the malt used was a floor malt. Therefor my suggestion to use another pilsner malt.

It's generally held that pH is not critical at all with regards to mash efficiency. It just needs to be in the appropriate range (5.2-5.7). You first test is high. Others have pointed out the critical points: maltster/ quality of the malt, crush, and temp.

I think that the only possibility here is a quality of the malt.
The crush is probably ok, as the people with even greater mill gap have better result than me.
With the temperature, it's the same as with crush. A lot of people used even lower temperatures, and get full conversion a lot faster.
So it looks like the malt could be problem as I've noted above. I cannot find the kolbach index in my malt specification so I've emailed to get one. If it will be low then it could be answer for the full conversion time question.

 

[Dodes]

So, I've received the answer about Kolbach index and it is 39. So it is on the edge between the under-modified/moderate-modified malt.

Maybe I should try protein rest or mash at higher temps.

 

[Silver_Is_Money]

So, I've received the answer about Kolbach index and it is 39. So it is on the edge between the under-modified/moderate-modified malt.

Maybe I should try protein rest or mash at higher temps.

Does your data sheet list the WK value? I can convert that into Lintner.

 

[Dodes]

No, other values I have (related) are RE45=40.5, Friability=87. In relation to WK, I have the "starch conversion time in minutes" and it is 12 minutes.

 

[Weezy]

How does the malt taste? I wouldn't waste a second of my time on undermalted grain unless there was a taste worth getting.

 

[Dodes]

Malt is tasting fine. In no way would I throw out 20 kg of malt

 

[Weezy]

Malt is tasting fine. In no way would I throw out 20 kg of malt

Of course not. I meant that I wouldn't buy it again unless it's stellar.

 

[Dodes]

Of course not. I meant that I wouldn't buy it again unless it's stellar.

Yes, I'll try the other one next time I'll be buying.

 

[RM-MN]

Thank you for your replies.

I think I'll try to reduce the mill gap a little more and would try another experiment or a real batch. As @chickypad noted, the temperature could be a problem, but I had a beers with even lower temps and conversion was done in no more than 1 hour (but, I was using corona mill then and the crush was really tight).

You have a mill gap with your Corona? The plates rub on mine and I get conversion quickly, very quickly, like under 5 minutes. Tighten up that mill!!!:rockin:

 

[Dodes]

You have a mill gap with your Corona? The plates rub on mine and I get conversion quickly, very quickly, like under 5 minutes. Tighten up that mill!!!:rockin:

No, not corona. I have double roller malt mill.

 

[helibrewer]

That Kolbach number is right in the middle for British malts, do you happen to have the Fine grind/Course grind difference?

 

[Dodes]

Yes, it's 84.5% / 80.6%.

 

[ba-brewer]

I recently changed my system from a static mash in a cooler to a RIMS system in a kettle and my conversion times had been taking longer. The first 80% went pretty quick (20min)but then would slow down and getting to above 95% would take almost 90min instead of 100% in 60min. I used to use a water to grain ratio of 4gal/9.5lb or 1.68 qt/lb so kept using that in my new system. I have room in the kettle for more water and found if I increased the water to 5gal or ~2qt/lb and I am getting full conversion in 60min again.

Before doing the change to the water to grain ratio I played with the grind but it did not help.

 

[eric19312]

Looks like you are hovering at pretty low mash temps about 142-145F range, so maybe that's contributing? Kai runs through factors that affect conversion efficiency on this page.

This is a pretty low mash temperature.
Here is Kai's data
http://braukaiser.com/wiki/index.php/File:Windisch_data_mash_time_and_extract.gif

You can see that the mash at 60C after 2 hours to get to point where mash at 65 got in 15 minutes. Am sure crush and pH play a role too but it is just not surprising that mash will take longer at low end of typical brewing range.

 

[Dodes]

I recently changed my system from a static mash in a cooler to a RIMS system in a kettle and my conversion times had been taking longer. The first 80% went pretty quick (20min)but then would slow down and getting to above 95% would take almost 90min instead of 100% in 60min. I used to use a water to grain ratio of 4gal/9.5lb or 1.68 qt/lb so kept using that in my new system. I have room in the kettle for more water and found if I increased the water to 5gal or ~2qt/lb and I am getting full conversion in 60min again.

Before doing the change to the water to grain ratio I played with the grind but it did not help.

I see. Thanks, for your info.

But when you change water to grain ratio, you need to take the sparging into account, because your sparge efficiency could be hurt.

In my case, I'm making 20 L (~ 5 G) batches (in fermenter) and I'm using 2.8 l/kg (~ 1.3 qt/lb) so I've got "low enough" sparge water to rinse the grains. But even then, the efficiency of the sparging is low. If I raise water to grain ratio, the sparging efficiency would be even lower. It's all interconnected. One needs to make compromises.

 

[Dodes]

This is a pretty low mash temperature.
Here is Kai's data
http://braukaiser.com/wiki/index.php/File:Windisch_data_mash_time_and_extract.gif

You can see that the mash at 60C after 2 hours to get to point where mash at 65 got in 15 minutes. Am sure crush and pH play a role too but it is just not surprising that mash will take longer at low end of typical brewing range.

I see, thanks. I'll read the "connected" article.

 

[ba-brewer]

I see. Thanks, for your info.

But when you change water to grain ratio, you need to take the sparging into account, because your sparge efficiency could be hurt.

In my case, I'm making 20 L (~ 5 G) batches (in fermenter) and I'm using 2.8 l/kg (~ 1.3 qt/lb) so I've got "low enough" sparge water to rinse the grains. But even then, the efficiency of the sparging is low. If I raise water to grain ratio, the sparging efficiency would be even lower. It's all interconnected. One needs to make compromises.

I think the first goal is to get full conversion then worry about the sparging. Yes they are all connected if you add more water to the mash you need to subtract some sparge water for all to equal out. By adding extra water to my mash I made my two runs close to equal volume which is suppose to optimize efficiency.