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Master Brewers Association of the Americas > BREWING RESOURCES > Ask the Brewmaster
April 17
Packaging and Filtration

Q: We produce 7,000bbls/year all draft. We cannot explain to the owner why we should or should not filter our beer into package except that "cause everyone does."  We currently only have a plate and frame filter. It is terrible and we find it strips flavor of our hoppy products, and we are a American craft brewery... everything is hoppy. So I guess my question is why should we filter?! I know about colloid stability. Our package shouldn't be sitting on shelves long because its only going 20 miles, I'm not to worried about that. What else do I need to be worried about? Our beers drop clear. Yes its not totally brilliant, but that is also something we don't really care about.  In summary is there anything you can add or give insight to about rationales about filtration into package?
A: Filtration is not a requirement for bottled or canned beers but keep in mind that even beer shipped only 20 miles away will probably end up sitting out at room temperature were yeast and sediments forming in the beer might form meaty-bready flavors which may not impress your customers. The answer to your question of whether to filter or not depends entirely with what you want your customers to experience.  Some beer styles are meant to have a haze, i.e. hefe-wizen, Saison and many IPA's are sold with a hazy golden hue that "glows in the glass." In today's beer world haze is much more acceptable than it used to be.  Brewers may want to preserve all the flavors they can without stripping anything out through a filtration process.  A little bit of yeast present will actually act to prevent oxidation and is not necessarily a bad thing in smaller packaging operations which tend to experience high air pick up.  If your beers are meant to be served brilliantly clear you will need to stabilize and filter.  If your customers do not expect a brilliantly clear beer but you do want some degree of clarity then you might be able to use finings to clarify out most of the yeast and chill haze prior to packaging and avoid sediment formations.  There are a variety of products on the market available for this purpose, it is a low technology solution for basic physical stability issues.  I would certainly recommend against using any kind of process that adversely affects the flavors that you want to sell.  More important for hop led package beers is to invest in crown caps with liners that will not scalp the hop flavors from your beers.  Consult your suppliers to see what they can offer. 
April 07
Measuring wort oxygen

​Q: I have a question for your blog about predicting dissolved oxygen levels.  I am looking for an equation that will predict with reasonable accuracy the dissolved oxygen levels of wort using an inline aeration assembly with a lpm regulator on the oxygen tank.  I have heard that anywhere from 4 to 6 lpm for 30 to 45 minutes with a 10bbl system with give about 8ppm dissolved oxygen, but this range is far to large.  Lets assume that my oxygen stone is clean, I run at 4lpm for 30 minutes into 10bbls of wort at 11 degrees celsius.  Is there an equation out there that will take into account these components and provides with a somewhat accurate prediction for DO levels?  Any help would be greatly appreciated!

A: Correct wort aeration is critical for yeast health and performance.  A fairly easy way to gauge O2 absorption to your flow meter is to simply put the O2 tank onto a scale and observe the net weight used for a typical wort run off.  Assuming the O2 is completely absorbed you can take the weight in milligrams and divide it by the total liters of wort run.  Compare this figure to the flow rate in liters per minute on your flowmeter and make the necessary adjustments to your aeration flow.  The target should be about 8-10 ppm (mg/L) dissolved oxygen. For 10 bbls of wort (1,172 liters) you should be adding 9.4to 12 grams of oxygen to achieve 8- 10 mg/L.  Make sure your aeration stone is kept clean, clean it regularly with a causitc-oxidizer solution and soak it in acid every once in a while to dissolve mineral deposits.

April 04
Single infusion mashing with hulless grains

​Q:  We use an infusion mashing vessel with a deep 3 foot bed.  We are having problems running off wheat beers with more than 20% wheat grist.  What options exist to make this easier?

A:  Infusion mash tuns were designed to make all-barley malt mashes in British brewing.  The barley used is normally very well modified and crushed more coarsely than a typical North American malt to form the grist.  The coarse grist including the non-soluble husk and gentle infusion mashing are able to form a permeable mash bed that is relatively deep and does not require rakes to facilitate run off.  Wheat (and rye) malt does not have a husk and the grain is usually not very well modified meaning that it not only does not help in forming a filter bed and has greater amounts of beta glucan material that will increase the viscosity of the wort. Beta glucan in malt is the cell wall material that encases the starch granules in the barley grain, it is partially broken down during malting in the germination process.   Large amounts of wheat and rye in the grist will tend to decrease permeability and yield run off problems.  There are two options commonly used to alleviate the issue of slow run-offs with high wheat or rye malt grists.  One is to add rice hulls to the grist which will help in forming a more permeable mash bed but this will not decrease the beta glucan present so it only offers a partial solution.  The other option, which can be used in conjunction with rice hulls on on its own, is to use a glucanase enzyme that will break down the remnant beta-glucan material in the mash.  By breaking down this material the viscosity of the wort will decrease significantly and the run-off is much easier even with higher wheat and rye grists.  The enzyme is deactivated during the subsequent kettle boil. b Either way look for barley malt specifications limiting the barley beta glucan levels to less than 100 ppm.

April 02
Pathogens and beer

Q:  Why doesn’t beer grow pathogenic bacteria?

A:  Once wort is fermented into beer it is a hostile environment for most micro-organisms to grow very well especially (and fortunately) pathogens which can caused infections in humans.  The primary limitations to growth of disease causing bacteria like Salmonella and Clostridium are:
• Low pH (under 4.6)
• Anaerobic conditions (no oxygen)
• High CO2 content (toxic)
• Low temperatures (pathogens prefer warm body temperature)
• Depletion of nutrients (the yeast have already digested most available carbohydrates and proteins)
• Ethanol concentrations above 2.5% ABV
• Hop acids (above 20 BU’s)

March 26
Cost of building a brewery

​Q:  I was just wondering if there is a flat rate cost per hectolitre for building a brewery? I understand this would only be a guideline but a general figure would be helpful.

A:  This is a  much more complicated question than it sounds and you would need to pin down many more details in determining even a ballpark estimate,  a few of which are:
•    How many hL per year production
•    Green or brown field, real estate and construction costs
•    New or used equipment
•    Level of automation
•    Packaging or draft only
•    Brewery pub attached
•    Level of regulatory issues
Sorry but there is no easy answer I can provide to you. I suggest you talk to people who have started breweries similar to what you are thinking of.  Go to your local MBAA district meeting, there are many people there who might be able to help guide you.

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Have you ever had a brewing, brewery, or technical question but didn't know who to ask?
Send your questions or comments or recipes to the MBAA Technical Director Karl Ockert.
Karl will post questions and answers as frequently as possible in a blog format as a benefit to all MBAA members.


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