Monday, October 7, 2013
You might be wondering why there hasn't been a blog post in a while. I've been focusing my efforts of the production of a "Brewing Engineering." A book to capture the last year of research that I have conducted. Over 200 pages and nearly 50 tables designed to simplify the brewing process.
It's available now!
Brewing Engineering is the culmination of extensive work done to understand how each part of the brewing process works. Understanding is developed into application and presented in a way that brewers can utilize, regardless of background. If you are a beer geek like me, I’m sure you’ll find reading about brewing science quite entertaining. If you are more of an artist, don’t worry: each exploration wraps up into practical application of the concept. If you have visited my blog, much of this information will look familiar. The most valuable posts have been included in this book. Each one carefully edited, and in some cases expanded on and even re-written. In addition, some of the information in this book you will not be able to find on my blog, or anywhere else for that matter!
Tuesday, April 16, 2013
Boiling and cooling priming sugar can be a pain. There are advantages to this, but how much does it benefit the beer?
A further analysis of why these steps are preformed might help derive a better processes. I think it is possible to retain all of the benefits of boiling and cooling priming sugar without adding any time to the processes.
The benefits are two fold. Boiling the water and priming sugar allows the sugar to dissolve more easily and kills any microorganisms that may have been introduced. Cooling it keeps the yeast from being killed by the boiling liquid, and also keeps off flavors from being added into the beer that would leached out by pouring boiling water into the plastic bucket. HDPE used for food grade plastic buckets is rated for temperatures up to 190°F.(1) Exceeding that temperature could leach unwanted flavors out of the plastic and into the beer.
Killing BacteriaMost bacteria can be killed by flash pasteurizing. (2)(3) Tap water contains very little bacteria to begin with because there is no nutrients. For bacteria to grow both nutrients and water are required. Dry sugar also contains very little bacteria because there is no water. Therefore the amount of bacteria that may need to be killed is small. Heating to 165°F or above for a minute or longer is sufficient for most brewers.
Not Killing YeastYeast will be killed nearly instantaneously if shocked with 165°F degree water, so the common thought is that the priming sugar needs to be cooled before adding it to the bottling bucket. While it is true that the yeast will be killed at 165°F, it's also true that the temperature drops very quickly as cold beer is added to the bucket. Yeast, like most bacteria, will thrive at 110°F. (However, It will produce off flavors if fermented for a period of time at that temperature which is why most ales are fermented at 65°F an bellow.) The beer will likely be about 65°F or cooler at the time of bottling. 1 half gallon of beer plus 1 quart of hot sugar water at 165°F will yield a combined temperature of 98°F.
The Processes1) Add your priming sugar and water to a microwavable container. I prefer a mason jar.
For the correct amount of water and sugar to use
so as not to change the ABV of the beer see this post:
3) Remove from the microwave, secure the lid and swirl to dissolve most of the sugar.
4) Remove the lid and place back in the microwave for another minute.
5) Repeat steps 3 and 4 until the sugar is dissolved, and the temperature is above 165°F
6) Start the siphon of beer into the bottling bucket.
7) Once there is aproximently half a gallon of beer in the bucket add the sugar solution being careful not to splash the liquids.
Monday, March 25, 2013
- 6.5 gallon Fermenttion Bucket
- Air Lock
- Bottling Bucket
- 1 Hydrometer
- 6 feet of 5/16" Vinyl Tubing
- Butterfly Capper
This is the kit I cut my teeth on:
What you'll need to round up
- Your spaghetti pot. (6 quarts is a reasonable size)
- Two cases of pop top brown beer bottles with a long neck and a skirt.
The three most common mistakes made by first time home brewers are:
- Lack of fermentation temperature control.
- Insufficient yeast.
- Use of tap water with extracts kits.
When choosing a kit look for one that uses dry yeast and has an ABV of 5% or less.
One packet of dry yeast contains about 150 billion cells. This is sufficient for up to a 1.050 starting gravity which is less than 7 pounds of extract in a five gallon (19 liter) batch. The result will be a beer less than 5% alcohol by volume.
Because extract is made from an all grain mash it has all of the minerals needed for the beer concentrated in it. The major manufactures, Briess and Muntons, both are located in areas that have great brewing water that already have enough minerals. By using tap water, or spring water you are adding extra salts that will end up leaving your beer with a kind of a twang. Use Distilled or Reverse Osmosis water for extract brewing. You should be able to find it for less than a dollar a gallon.
Step up your game
- Autosiphons ($10)
- Thermometer for measuring pitching temperature ($8)
- Kegging setup
These are the ones I have and they work great!
Making better beer and brewing toys.
- bin or cooler to use as a water bath for fermentation temperature control.
- Refractometer. Much easier, faster, and smaller sample size required.
- aquarium heater to ferment ale's in the winter
- scale for grain and extract
- scale for salts and hops
Wednesday, March 20, 2013
Yeast require oxygen in order to synthesize compounds during growth. The lack of oxygen will therefore become evident if the yeast are put in conditions that with adequate oxygen would produce large amounts of growth. In order to highlight the use of oxygen in these tests a high gravity wort will be used and drastically under pitched. If the free oxygen in hydrogen peroxide can be utilized by the yeast then this should make it evident.
The TestThe hydrogen peroxide solution at the pharmacy here is 3%. For each molecule of 2(HO) there is one Oxygen molecule that can disassociate. It takes two of them to make oxygen gas. With some molar math this means that the solution available at the drug store is equivalent to a 7000ppm O2 solution.
For the tests these will be diluted down to more reasonable amounts of oxygen. 350, 175, 88, 44, 22, 11, 5, 3 and zero will be used. Each test will be done in triplicate.
All tubes will be inoculated with a 21°P wort and 1 million cells per ml. (under pitching by a factor of twenty in a very high gravity wort.)
All tubes will be done in triplicate.
All of the tubes initial gravity, final gravity and final cell volume will be recorded. A cell count will be conducted on three of the tubes with the lowest volume of cells and three tubes with the highest volume of cells. From this information final cell counts will be derived for all 27 tubes.
In addition, daily cell counts will be preformed on two additional tubes. One containing no additional hydrogen peroxide and the other containing the 11ppm oxygen equivalent using hydrogen peroxide. Daily cell count and gravity will be checked.
The resultsHydrogen peroxide was effective at adding oxygen to the wort, but did not improve attenuation. The toxicity of the hydrogen peroxide was detrimental to yeast growth. The optimum level was an equivalent of 50ppm of oxygen although at this level the results were similar to adding no oxygen. The high gravity wort with low pitch rate took 12 days to complete with and without the added oxygen, although fermentation without added oxygen in the form of hydrogen peroxide was significantly faster.
Monday, March 18, 2013
The Practical Brewer has been an excellent resource for brewing. The chapters are all written by renowned member of the professional brewing community composed of both brewers, instructors and scientists. This is the best text book on brewing that I have read. Everything is covered in detail from wort production to fermentation.
If you are serious about brewing, whether as a home brewer or professionally, this is a book you'll want to have in your library.
Friday, March 15, 2013
Perhaps the title is a little far fetched, but this is entertaining and informative none the less. This feature length video makes for a nice way to unwind on the weekend. Take a trip through time to discover how beer has shaped civilization and led to numerous inventions.
Wednesday, March 13, 2013
The primary goal of fermentation is the production of alcohol, while the goal of propagation is increasing the yeast biomass. On one hand, anaerobic yeast respiration converts sugar into alcohol, carbon dioxide, and some energy. Aerobic reparation, on the other hand, converts sugar and oxygen into water, carbon dioxide and about twenty times as much energy. The real difference between these two is that with oxygen more energy is produced. Without oxygen more alcohol is produced.
The two things that yeast need from the wort to make new cells is material (sugar) and energy. While both of these are available during both aerobic and anaerobic respiration there is much more energy during aerobic respiration. This is why a stir plate, that provides constant oxygenation, is commonly used for starters.
Oxygen is good for propagation, but how much is required, and how can it be used to maximize cell growth?
Aerobic yeast respiration is as follows:
C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + 31 ATP (see footnote 1)
180g C6H12O6 + 192g O2 → 264g CO2 + 108g H2O + 31 ATP
Converting from moles to grams we can see that for every gram of fermentable extract 1.07 grams of oxygen are required for aerobic respiration. For a 10°P (1.040) wort that would be a whopping 107,000ppm! With pure oxygen gas the saturation point of water is only 50ppm. So in terms of aerobic respiration, there is no practical limit to the amount of oxygen that can be utilized. Oxygen, however, is toxic to yeast in high concentrations.
Because oxygen is always in short supply anaerobic respiration dominates the metabolic activities. For this reason, the anaerobic reaction very closely resembles Balling observation. When the reaction is converted to moles it can be seen that the "losses" that balling describes are the sugar converting to other materials.
C6H12O6 → 2 CH3CH2OH + 2 CO2 + 2 ATP(see footnote 2)
1.9553g C6H12O6→ 1g CH3CH2OH + 0.9553g CO2 + 2 units ATP
2.0665g C6H12O6 → 1g CH3CH2OH + 0.9565g CO2 + 0.11g biomass (see footnote 3)
The Carbon Dioxide is virtually identical and the difference in glucose mass is almost exactly the yeast biomass.
If the two things that yeast need are sugar and energy to reproduce then how much more yeast would be generated from aerobic respiration. For every 2 units of ATP 0.11g of yeast are generated. If there were 31 units of yeast then 1.705g of yeast could be generated. This would require 3.6603g of sugar and adequate oxygen. Anaerobic respiration produces 0.053g of yeast per gram of fermentable extract. At 20 billion cells (dry mass) per gram that's 1 billion cells generated per gram of extract. Aerobic respiration could produce 0.4658g of yeast per gram of fermentable extract. This makes 9.316 billion cells per gram.
With adequate oxygen the yeast propagation could be almost 10 fold above what is typical of fermenting beer!
So how can we get anywhere near the 107 thousand parts per million, and what is the maximum the yeast can tolerate? Don't worry, I've got a plan and a set of experiments to prove it.
(3) Balling C. J. N. 1865. “Die Bierbrauerei” Verlag von
Friedrich Temski, Prague, CHZ. As cited in:
MODELING OF ALCOHOL FERMENTATION IN BREWING – SOME
PRACTICAL APPROACHES, Ivan Parcunev, Vessela Naydenova, Georgi Kostov, Yanislav Yanakiev, Zhivka Popova, Maria Kaneva, Ivan Ignatov http://www.scs-europe.net/conf/ecms2012/ecms2012%20accepted%20papers/mct_ECMS_0032.pdf