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Messages - Richard

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Kegging and Bottling / Re: CO2 Stratification
« on: February 16, 2018, 11:58:33 PM »
So yes, stratification is real, but a red herring with respect to the topic of keg purging.

I don't think it is completely a red herring. The equations that say it takes 30+ purging cycles seem to be assuming complete mixing of the gases in some equilibrium state. The truth is somewhere in between, so it takes more than 1 but less than 30 purging cycles. Stratification definitely helps, but it isn't a magic solution (except for the Romans).

Kegging and Bottling / CO2 Stratification
« on: February 16, 2018, 09:48:02 PM »
There was a recent thread about purging of kegs where the stratification of CO2 in kegs was questioned. One post says that we would all be dead if CO2 sank down and formed a blanket below oxygen. Here is a link to an article in Science magazine which describes exactly that in a geologically active region in ancient Rome.

Here is an excerpt:
 Pfanz and his colleagues measured the CO2 concentration in the arena over time. During the day, the sun’s warmth dissipates the gas. But at night the gas—slightly heavier than air—billows out and forms a CO2 “lake” on the sheltered arena floor. It is particularly deadly at dawn, when the CO2 concentration 40 centimeters above the arena floor reaches 35%, enough to asphyxiate and kill animals or even people within a few minutes, Pfanz says. But concentrations fall rapidly with height.

CO2 stratification is real and can be deadly (or useful, if you are careful).

Commercial Beer Reviews / Re: Gordon Biersch Chum dry-hopped Irish Red Ale
« on: February 12, 2018, 09:07:27 PM »
I went to the grand opening of San Francisco Beer Week last Friday (2/9/18), and got to taste lots of beer, including some fresh Chum. It tasted nothing like the Chum I had before. I heard a rumor that they had problems with batch-to-batch consistency, so perhaps that was the problem with my first taste. I think it is more likely that the first 6-pack I had was old and going stale. In any case, the fresh Chum didn't have the taste that I found objectionable the first time I tried this beer.

Refractometers are calibrated to read correctly for water with a simple content of sugar. We need wort correction factors because wort has many sugars and other things that the refractometer was not designed to measure. Same for alcohol, so we need to correct refractometer readings after fermentation has started. If you add yeast to the solution you will need to correct for it because it isn't the sugar the refractometer was calibrated with. I don't know if the typical quantity of yeast per volume is enough to change the reading significantly, but I do know that cloudy liquids scatter the light in a refractometer and give very fuzzy lines which make it hard to get a decent reading.

Let's go with the poodles thought experiment. The principle of flotation says that an object afloat will displace a volume of liquid with weight equal to the weight of the object. Note that it is only the liquid displaced by the floating object that matters, not the average density of the contents of the container. If you have rocks or flocculated yeast at the bottom of your container they will affect the weight-to-volume ratio of the container as a whole but if the float does not go low enough to touch the rocks or yeast, then only the density of the liquid on top matters.

Now to the poodles. If you have a bunch of normal-sized poodles in a swimming pool and you drop a normal-sized hydrometer float in between them, your reading will be the same as if the poodles aren't there because they aren't being displaced significantly by your float. If you drop your float right on top of a poodle it will not sink at all, and your reading will be grossly affected (giving a very high density reading). Now imagine the poodle getting smaller and smaller until the weight of the float is comparable to the weight of the poodle. Now the extra weight on top of the poodle will begin to push it down in the water and your float will sink a bit, giving intermediate readings. Now imagine that you have billions of microscopic poodles per liter of water and you drop your float on top of them. It will displace many poodles along with the water, and give a reading that reflects the density of (poodle weight in displaced volume + water weight in displaced volume)/displaced volume. Assuming that the poodles are denser than water (my experience is that some poodles are denser than others) then the density reading will go up as more poodles are added per liter. That is the case for yeast. For real microscopic poodles (??), which were assumed to be floating at the start, their density is less than water so a lower reading would be obtained.

Jim's experiment is consistent with this. When he had flour particles in suspension, they were displaced by his float and raised the reading. After the all sank to the bottom they were no longer displaced by his float and his reading was back to that of water.

Equipment and Software / Re: Improved Refractometer Correction calculator
« on: February 09, 2018, 04:07:12 AM »
I read the Zymurgy article, and there is an equation listed in it. I put that into my spreadsheet right next to Terril's old cubic that I had been using. For my current batch, the Novotny formula gave values about 2 points higher down to a gravity of 1.032, then 1 point higher below that. At the end of fermentation the ST formula gives 1.008, the Novotny formula gives 1.009 and my hydrometer gives 1.009. I would say that these are all so close to each other that it is hard to really say that one is better than the other. I need lots more brews to be sure, not that I needed any extra motivation to brew.

All Grain Brewing / Re: How is Munich malt made?
« on: February 06, 2018, 02:46:05 AM »
Yeah, I love the taste of Munich but it only has a diastatic power of 40-50 Lintner depending on which kind you get. Adding a bit of highly modified malt will help your conversion a lot.

Equipment and Software / Re: no chill in stainless steal
« on: February 04, 2018, 10:29:52 PM »
If you are careful you can chill the normal way with no "waste". I am in California where water efficiency is always on our minds. The most water that I put down the drain from brewing is from cleaning because that can't be captured and repurposed. For chilling wort I use a standard immersion chiller, along with a whirlpool to keep the wort moving across the coil. I collect the hottest water in the sink for cleaning with later, then collect water in buckets to use for watering household plants and the vegetable garden It is perfectly clean water. When the discharge water from the chiller drops to the temperature of my tap water, I switch to a closed system that has ice water in a small cooler and a submersible pump to move it through the coil and back into the cooler. There are other techniques also, but the key point is to capture any clean water and use it later. The only water that goes down the drain is soapy or dirty in some form, and that is a small fraction of the total.

General Homebrew Discussion / Re: Learning about water
« on: February 02, 2018, 10:19:48 PM »
I know if I did a 900 foot well I would get seawater! Maybe I could mix it with Jim's lava to get distilled water.

Kegging and Bottling / Re: Bottle Cap Ingress: Is it real?
« on: February 02, 2018, 02:26:41 AM »
“When I use a word,” Humpty Dumpty said, in rather a scornful tone, “it means just what I choose it to mean—neither more nor less.” “The question is,” said Alice, “whether you can make words mean so many different things.”

Yeast and Fermentation / Re: High temp fermentation
« on: February 01, 2018, 11:44:05 PM »
Could anything bad happen from this? Definitely a possibility
Did anything bad actually happen from this? Dunno, depends on the length of time

High temps during primary definitely affect the flavor profile coming from the yeast. In secondary that is not an issue. Considering that it was fermented at 85, it seems unlikely that a reasonably short excursion to 94 would totally ruin it.

The best way to tell if there are off flavors is to taste it.

Kegging and Bottling / Re: Bottle Cap Ingress: Is it real?
« on: February 01, 2018, 05:29:51 PM »
So the graph you linked is nice, but it just tells us the obvious: you need to beat the hell out of a beer to get it to start noticably staling, i.e. “Stage C”.

I guess I just don't understand what you are saying. If it isn't noticeable, then who cares?

Kegging and Bottling / Re: Bottle Cap Ingress: Is it real?
« on: February 01, 2018, 04:32:44 PM »
The neat thing about this is , believing and science don’t need to coincide for it to happen. A little google work will show you all the studies of cap ingress and beer staling limits.  Gas laws are gas laws.  Staling limits are staling limits.  After that it’s simple math for when they coincide.
A little googling turned up this reference ( to a graph from Bamforth's 2004 book (Beer:Health and Nutrition):

Did you have some other reference in mind? Would you care to share it?

To be clear: I accept that oxygen will get into the bottle, and I accept that oxygen will eventually cause staling. I also accept that the rate of chemical reactions is  a function of temperature.

General Homebrew Discussion / Re: RO water good for making beer?
« on: February 01, 2018, 05:39:27 AM »
I assume you mean to say that you have been brewing for years with RO water modified by the addition of minerals, not straight RO water. I personally would no longer call it RO water after adding stuff to it.

Kegging and Bottling / Re: Bottle Cap Ingress: Is it real?
« on: February 01, 2018, 03:14:53 AM »
I'm not surprised there is O2 ingress, but I have some skepticism about the experiment.
  • To rehash another thread, how many times was the keg purged with CO2 before sealing? How much oxygen was left in the keg?
  • I believe that O2 will gradually enter the bottle, but I find it hard to believe that enough could enter AND react with the beer to stale it within 90 days at 35F
As a follow up I would like to see different temperatures and different lengths of time. I would also like to see a more quantitative measurement of oxidation (not just oxygen, but the actual compounds that result from staling), although that could get quite pricey.

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