New Brewing Research Conclusions....

Physics, chemistry and biology of brewing. The causes and the effects.

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New Brewing Research Conclusions....

Postby Mesa Maltworks » Tue Apr 20, 2004 7:46 pm

I'm probably going to set off alot of debate with this posting, but this is current brewing science knowledge that I gained through my recent training by Weihenstephan (Freising, Germany & world's oldest brewer founded in 1096!) and UC Davis, two of the most respected brewing science institutions in the world. Some of these concepts are even contrary to my Siebel training, but as most know, brewing is a science and art that continues to evolve.

Here we go:

1) First Wort Hopping:

Don't ! This was a technique adopted by German brewmasters in the early 80's under the premise that it produced a "finer bitterness" than traditional early kettle hopping. NONE do it anymore! The reason is that they found out that this method of hopping is detrimental to head retention. The current technique is to begin hop charges 10 minutes after the onset of a vigorous boil. Weihenstephan's professors contend that if you perceive a harshness in your bittering additions, it is a hop variety or crop issue, not the application of the hops themselves. This rings true in the traditional sense since German brewers have always maintained that the use of low alpha varieties (nobles) produces a finer hop character in beer.

2) Step mashing as a method of increasing dextrines to increase the viscosity (mouthfeel) of beer:

Even though it is true that this mash technique does increase dextrins as an end result, it has been discovered that the perception of rich body in beer by humans is not related to dextrin content, but rather is a psychological reaction to some yet to be identified property in beer. They determined this through extensive blind trials where identical beers were sampled, half as-is and half with added dextrins. 100% of the respondants rated the body of the beers as identical!

Now what does this mean to us as brewers? With the fully modified malts available to us today, it is pointless to do anything other than a single step infusion mash. And, with the great excess of enzymes that are present in our malts (remember almost all fully modified malts are designed for big brewers with high adjunct rates), this means conversion can be achieved much faster than once believed. The current recommendations for all fully modified malts is a mash at 68~70C/154~158 with a pH of 5.3 for only 20 minutes prior to recirculation until the runnings are clear. Then sparge with 168 degree water, stopping the runnings at 2.5P/1.010SG. Then top up to kettle volume. Running beyond this gravity floor will only extract tannis and lipids. The idea here is to maximize extraction while minimizing grain contact. This goes a long way toward the elimination of tannins (harsh, husky flavors) and lipids (head killers and can create clarity issues) being entrained in the wort. The complete science regarding this technique is outlined in both Charlie Bamforth's and Michael Lewis's new books that are available from the Association of Brewer's publishing arm, Brewer's Publications. You can order them online from www.beertown.org.

3) Wort Aeration:

If possible, don't! The reason is that it is not the wort that needs the oxygen, it is the yeast. By oxgenating the wort instead of the yeast starter, it will cause an over production of cells due to the excessive oxygen presence. This then leads to the production of unwanted esters and higher alcohols that will compromise beer flavor.

When oxygenating starters, you cannot use pure O2... the reason is that the uptake occurs too fast and without a dissolved O2 meter ($$$), you cannot tell when to stop. The way to properly do this one is to aerate using a high pressure aquarium pump, sterile air filter and a stainless steel aeration stone, all of which are redily available. It is virtually impossible to over-aerate using air, so you will avoid oxygen toxicity problems that will occur if trying to do this with pure oxygen.

I know these topics are contrary to what most people have learned and read about (me included!) and particularly go against traditionalist notions. In the case of the 20 minute, single rest, high temperature infusion mashing technique, remember that all of the mandates we learned were based historically when barley varieties and malting was very poor. This reality required heroic steps to produce a good wort, but they have been proven to no longer be necessary, and in some ways, detrimental.

Upon returning from this recent training, I instituted these practices in my brewery and they definitely work. My biggest concern was centered around the mashing regimin change. I kept obsessing that the short mashing time might lead to a reduction in wort color or hue. Nope! Not only did the wort turn out great, but I chopped 70 minutes out of my day!

Give these a whirl. I think you will be pleased with the results and you didn't have to pay thousands of dollars to find out like I did.

Eric
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interesting

Postby ecze » Wed Apr 21, 2004 1:21 am

wow those sure are some iconoclastic ideas. especially the dextrin thing. I mean, a doppelbock with a FG of 1025 definitely tastes thicker and richer than a pils with an FG of 1007. Would you say then that the melanoidins could have something to do with it?
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Interesting to say the least ...

Postby Azorean Brewer » Wed Apr 21, 2004 6:47 am

Eric,

Thanks for the insight, I have to agree with you, as I read the post I kept saying "20 minute" mash is he nuts, but you have never steered us wrong yet. We appreciate it. You'll get payback quick on the money you spent to find all of this out ... I have only done two first wort hoppings both in my "Big Bang IPA" and because there are so much hops in there already, I don't think it will matter going to a normal hop schedule. (Recipe calls for 1 oz. Fuggles first wort, 1 oz. Nugget 90 min., 1 oz Fuggles, 15 & 1 min. ea.), I'll just change it to 1 oz. Fuggles at 30, 15, 1 min. intervals.

Many Regards,

Paul.
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Great dissertation

Postby fitz » Wed Apr 21, 2004 7:38 am

With this news, I may be able to go back to doing more all grain. The time thing doesn't kill with that schedule. I've already told you that I am partial to German beers, so in my eyes, they know what they are doing.
Thanks for the great Info Eric.
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Melanoidins...

Postby Mesa Maltworks » Wed Apr 21, 2004 9:37 am

Well... it is possible that this is a contributor, but as they stated, they don't quite know yet. I do know, in the case of you r bock, a portion of the viscosity impression is due to the residual sugar. In this case there would be a slightly measurable increase in viscosity, but in humans, sugar is also known as a psychological trigger for an increase in this perception due to the building upon childhood memories of syrups. It is not the only causal factor though as they pointed out. The dextrin study was just concluded a recently. They now are attempting to determine the actual mechanisms, so I'll keep up with where they are and once they have a conclusion I'll post back. Knowing that the dextrin study took 2 years, I'll bet the next one takes alot longer since there are so many variables involved instead of 1!

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Mash Thickness??

Postby TassieBrewer » Wed Apr 21, 2004 6:57 pm

Eric,

Thanks for the info, could you please tell us what mash thickness is recomended.

I'm currently using around 3L per kg and can't get conversion @ 68C in 20min based on an Iodine test.

Cheers
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Mash Thickness...

Postby Mesa Maltworks » Wed Apr 21, 2004 9:51 pm

Petr;

As long as you are using fresh, fully modified malt the conclusions I reach are that 1) Your mash thickness may be too thin to maintain an appropriate temperature to achieve complete conversion via such a short rest, or/and 2) You need to raise your dough in temperature and insulate your mash tun.

Thickenss: You need to be between 1.23 L to 1.33 Litres per .45Kg grain. (Equates to 1.3~1.4 Qts per Lb. grain). I would mash in between these amounts... say 1.28L water to .45Kg grain.

Mash Tun: One of the difficulties of instituting this concept in a homebrew setting is that homebrew mash tuns tend to be much deeper and narrower than commercial ones. This geometry creates a greater convection effect which can create a substantial temperature differential between the top of the mash and the bottom, so mash thickeness becomes the controllable variable in this situation.

In your case, dough in to achieve a target mash temperature landing on the higher side of the temperature range (69~70C). Make sure to cover the tun and then insulate it if possible. A thick blanket should do the trick. (Another way of maintaining mash temperature is to place the covered tun (IF METAL!!!) into an oven on the warm setting. I used to do this when I homebrewed.)

If you still get an iodine negative reaction, warm the first runnings (slowly or it may scorch!) to 75.5C and perform the vorlauf until clear. Try the iodine test after the runnings are clear. If it is negative, sparge at 75.5C until your runnings are at 2.5P/1.010SG and top up to volume for the boil.

Hint: To assure that you don't get false positives via iodine tests, run the test sample through two back-to-back coffee filters to eliminate the possibility that grain particulate is in the sample when tested.

If this doesn't work, your only choice is to extend the mashing time.

Let me know how it goes !


Eric
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WOW!

Postby Goliath » Thu Apr 22, 2004 2:39 am

First ever post from me.

Just when you think youv'e got it all nutted out in your head, along comes something else that turns your world upside down!

We'll try to give it a go at Big Brew 2004

Regards
Dave
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Some questions to answer

Postby Raydownunder » Thu Apr 22, 2004 5:24 am

Hi Eric

Excellent topic and I supplied the link to the Australian Craftbrewers forum and the questions are now coming in, if you don't mind maybe you could answer some. The feedback so far is very positive.
Cheers
Ray Mills
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question about aeration of wort versus starter

Postby billvelek » Thu Apr 22, 2004 5:29 am

First, are you saying that it would be better, if we have a good starter, to not have ANY oxygen at all in the wort? In other words, not only NOT use an airstone in wort, but should we take steps to _avoid_ ANY form of aeration, such as splashing the wort into the fermenter or otherwise causing foaming of the wort before pitching?

Second, for those of us who don't currently have an airstone and have only aerated by shaking the vessel, will that create a sufficiently large starter to follow your recommendation, above? If so, what size should the starter be for a 5 gallon batch?

Third, if your answer to ques.#2, above, is no, and the starter is therefore not of an _ideal_ population, then how adviseable or detrimental is aeration of the wort using the common methods of splashing/shaking/mixing/aggitating the wort in the fermenter? It would seem almost a necessity if we want a quick and vigorous start. Is the difference in results likely to be noticeable enough that you would recommend switching methods to an airstone aerated starter and no aeration wort? ... and how much would you stress that recommendation (slight? ... highly?)

I found your article extremely interesting. Thanks for sharing and for any help you can give re my questions.

Cheers.

Bill Velek
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Alternative to coffee filters

Postby joncz » Thu Apr 22, 2004 7:41 am

I took a folded up paper towel, iodine tested it to verify it was indeed starch-free and then dropped a few drops of wort onto it. The wort wicks outward and the particulate remains in the center of the drops. If you then drop iodine at the edge of the wort, you can avoid all the particulate matter.
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Aerate the Starter (if possible)...

Postby Mesa Maltworks » Thu Apr 22, 2004 8:17 am

Bill;

Yes, as I stated, it is best to only aerate the starter if you are so equipped to do this. The reason is that once the yeast has all the oxygen it needs to build strong cell walls and reproduce, it does not need any more. Any additional oxygen beyond that point will cause them to stay in a reproductive state rather than begin a fermentative state. If you can do this, you will notice a refined smoothness to your beers due to a reduction in ester production and therefore your beer will condition faster.

Since shaking a starter vigorously only produces large bubbles, it is an inefficient and inconsistent practice. I assume if you would do it for a LONG time... say 30 minutes, it would probably be sufficient, but 1) who wants to shake a starter for 30 minutes? & 2) since the air is not sterile, you would definitely risk contamination.

The cost for a pump, tubing, filter and stone shouldn't be more than $35 and the stone can serve as device to force carbonate in kegs that would only take 20 minutes or so. But if this investment is not in your future, go back to the splashing method in the carboy.

Starter sizes are actually cell count/viability dependant. The best practice is to pitch 1 million cells per ml wort per 1 degree plato for ales and 1.5 million cells per ml of wort per degree plato of wort with a cell viability of 96% or more.

Since most homebrewers can't measure cell counts or don't viability tests, The best practice otherwise is to step the yeast culture up one day at a time to 100 ml, 200 ml, 400 ml, 800 ml and finally to 1,000 ml (5 total days of stepping) using a 5 deg. plato hopped wort (remember you want REPRODUCTION not fermentation, this is why the wort gravity is low.) While doing this, aerate 24 hours a day (builds strong cell walls/keeps yeast in a reproductive state) using the air pump/sterile filter method. For a 5 gallon batch, this should be adequate. If you do this, there is absolutely no need to aerate the wort.
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Austrailian Forum...

Postby Mesa Maltworks » Thu Apr 22, 2004 8:36 am

Ray;

I read some of the responses to the article on your forum and have a couple of points and a suggestion.

One postee stated he could not understand how you can over-oxygenate the wort/starters using pure O2. Actually, this is incredibly easy to do with a gas stone since it produces very fine bubbles. The majority of oxygen uptake required by yeast takes place within 10 minutes! If you left the oxygen on this long, you would definitely over oxygenate the wort and in a starter you would kill alot of the cells.

As far as homebrewers not being able to apply the mash technique, I disagree strongly. These concepts are NOT brewing system volume dependant. If you seem unable to do this it is either that your mash tun heat loss is too high, pH is wrong, milling is too coarse or your grain has degraded in it's extract/enzymatic capability. It could also be a blend of these factors.

Now... the suggestion: Could you have these guys post their responses/questions here? Otherwise I will end up answering alot of things twice, which I really don't have the time to do very often. This will also allow everyone to benefit from the posts as well.

Eric
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Thanks; now I have follow-up questions, please.

Postby billvelek » Thu Apr 22, 2004 2:19 pm

You said "... step the yeast culture up one day at a time to 100 ml, 200 ml, 400 ml, 800 ml and finally to 1,000 ml (5 total days of stepping) using a 5 deg. plato hopped wort ... aerate 24 hours a day."

1. Should I start with 100ml, regardless of the size of my yeast sample? E.g., would I treat a dry yeast packet the same as Wyeast smack-pack (which I presume I would wait until swollen before moving it to the 100ml starter), and the same as a yeast sample from a beer bottle?

2. I'm probably making this harder than it is, but I want to make sure I understand. Do I make an entire liter of 5degPlato wort, and draw off the amount that you indicated for each day to add to my starter? Or do I check the gravity of the starter each day and then add the necessary amount to adjust the total volume of the starter back up to the 5degPlato (this will no doubt require adjustments in specific gravity for each addition)?

3. How much should the starter be hopped (IBUs), and do you recommend a certain variety, or does that depend on the recipe for which the starter will be used? Bittering or aroma hops?

4. How crucial is the temperature for making a starter, i.e., do I need to worry about evaporative cooling if the room temperature gets up into the mid 70's? I assume that with the starter comprising just 5% of the 5-gallon batch, and being mostly yeasties, at that, (as opposed to fermenting alcohol, and esters). Does the temp matter if we are starting lager yeast or ale yeast?

5. I notice that you also mentioned in para.2 of your answer to me that aeration by shaking risks contamination from air that is not sterile; I presume that this means that you would recommend that I somehow filter the air being pumped into the starter, because you have also already mentioned oxygen toxicity problems when using pure oxygen. Do you recommend any particular methods for filtering/sanitizing the air, and how crucial do you think that this extra precaution really is?

Thanks.

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Wow... Lemmie get a beer and answer !...

Postby Mesa Maltworks » Thu Apr 22, 2004 7:15 pm

Q1: "Should I start with 100ml, regardless of the size of my yeast sample? E.g., would I treat a dry yeast packet the same as Wyeast smack-pack (which I presume I would wait until swollen before moving it to the 100ml starter).

Answer: My directions were aimed at starters for fully activated smack packs. If you are doing actual culturing (starting with a single cell, not repitching trub or bottle sediment), you start with 10 ml & the step to 100 and so on.

Dry yeast should only be 1) hydrated in warm water without stirring for 15 minutes, then stirred vigorously and let set for an additional 10 minutes, then added directly to the wort. They only need water and a small amount of O2. As long as they are not too old, dry packs have a very high cell count to counter their low viability.

For smack packs: Once fully activated, pitch them into a STERILE, not sanitized flask and add 100 ml of 5 deg. hopped wort. Step up as directed every 24 hours. Obviously, the final volume will well exceed 1,000 ml, I was referring only to the wort additions with those instructions. The final volume will require a vessel that can hold at least 2,500 ml with a headspace.

Q2: "and the same as a yeast sample from a beer bottle?"

Answer: No. Yeast samples from a bottle should only be cultured by harvesting a single cell from an agar plate. The reason is that you don't know exactly how long the yeast has been under the beer which is VERY stressful on the little buggers. This can lead to very poor fermentatin results if you try to simply step up the lees from the bottle. (by the way, did you know that many commercial producers condition with yeast that is different from that that the beer was fermented with? This is VERY common with ales since they cannot condition under refrigeration. Particularly among Belgian beers, lager yeast is used for this reason as well as better, faster and tighter sedimentation. If you are sure the yeast in the bottle is the fermentation yeast, by all means, culture it, but I wouldn't use the lees.)

Q3. "...Do I make an entire liter of 5degPlato wort, and draw off the amount that you indicated for each day to add to my starter? Or do I check the gravity of the starter each day and then add the necessary amount to adjust the total volume of the starter back up to the 5degPlato..."

Answer: No, each addition of wort is at the volume indicated. Ie... add the activated smack pack to 100 ml of hopped wort... after 24 hours, add 200 ml of the hopped wort to that and so on...

Q4: How much should the starter be hopped (IBUs), and do you recommend a certain variety.."

Answer: If you make 2500 ML of sterile wort for the step up process, add .25 tablespoon of a high alpha hop. The only reason that you add hops is for their anti-microbial properties. At this level, there will be no effect on the beer into which the culture is pitched. Hint: The easy way to produce sterile wort for starters is to use DME, hops, canning jars and a pressure cooker for 20 minutes at 1 bar/15 psi.

Q5: "How crucial is the temperature..."

Answer: 70~72 degrees is fine. The yeast character will not be affected in the reproductive stage at this temperature. It is fermentation temperature you want to control.

Q6: "...I somehow filter the air being pumped into the starter..." & "...how crucial do you think that this extra precaution really is?"

Answer: You can get a .45 micron, inline air filter (~$8) from any larger homebrew supplier such as Beer, Beer & More Beer, Williams Brewing, Northern Brewer or possibly your local supplier. Crutial?... MANDITORY!!! You will be pumping air into this baby for days! If you try this unfiltered, you will culture everything that will eat sugars in your house!!!

I hope this cleared this up for you!

Eric
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