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Chilling your mash


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#1 stevea

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Posted 28 March 2015 - 05:19 AM

I've tried both boiling mash and not. Verdict: not.

 

I'm from a brewing & sci background, and lack experience wrt distilling.

 

Your point begs the question.  If boiling is unnecessary (and I believe you are correct) then it's unlikely that temps much above the gelatinization temperate are useful.  Is 99C any better than 80C ?  Gelatinization (as well as pasteurization) is a matter of time and temperature,  You might need a bit more time at 80C than 99C, but heating & cooling energy reduction ...

 

 

Sorry 'bout that- www.mgthermalconsulting.com

 

I see others dismiss plate heat exchangers out of hand (given the grist) but I wonder if that is accurate.   Plate HX are used to chill trubby wort.  Are there plate HX available with sufficient clearance to handle grist ?  Plate HX several advantages of tube&shell that makes the idea worth considering.

  

 

Yes, you are wasting time and energy and, more importantly, diastatic enzymes by boiling. By boiling, you are not only denaturing alpha and beta amylase, but also gamma amylase, which is surprisingly effective at breaking down starch at fermentation temperatures. Your fermentations should be finishing near 0, unlike a brewer's fermentations. It takes a while to get away from the brewer's mindset, but you'll get used to it. 

 

Plant source gamma amylase (better known as alpha glucosidase) has peak performance around 45C & pH of 3, so it's mostly gone by the time you get to gelatinization temps of raw grist.  You might get some activity on the way up for low gelat temp starches.  Limit dextrinase (~60C & pH5.4) is a more credible cause of debranching.



#2 stevea

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Posted 28 March 2015 - 11:11 AM

It's been so long since I looked into this that I had to look it up on a couple of my favorite books: Whisky Technology, Production, and Marketing by Inge Russel and The Science and Technology of Whiskies by Piggott, Sharp, and Duncan. I highly recommend these books to anyone interested in learning about whiskey. Although they're expensive, I'd guess that they're significantly less expensive than a warehouse full of gross whiskey.

Like you, I haven't had much personal experience with DMTS problems. Most modern malts have low levels of s-methylmethionine (the chemical precursor of DMS and DMTS), so that's a good thing. However, if someone were to make an all malt whiskey out of a six row barley, or some other cultivar with high SMM levels, they might have more problems than we've had.

Also, I've used stills built from copious amounts of copper. This apparently helps with the DMTS issues as well. Additionally, aging periods in excess of one year will decrease DMS, DMDS, and DMTS levels, with DMTS being the most persistent and flavoractive of the three. Piggott et. al. show a table indicating that in scotch malt whiskey hogsheads, DMTS has a half-life in the neighborhood of 1-4 years, depending on the treatment of the barrel. The scraped and charred barrels reduced DMTS much faster than untreated barrels.

I'd need a lot more data to confirm my suspicion, but I personally suspect that a traditional double distillation of a malt whiskey will reduce DMTS levels significantly more than a single distillation. Since heat makes SMM decay into DMS, I've noticed that the very start of my stripping runs volatilize very little perceivable DMS (DMDS, DMTS, whatever. The stinky stuff). However, as the distillation progresses and the SMM present in the wort has more time to break down into DMS, I begin to perceive more DMS making its way through the still. Eventually, the levels seem to die down (just as a brewer will exhaust the SMM present in his wort by volatilizing it with a prolonged, vigorous boil) and disappear. It is my belief that this primary distillation volatilizes and releases much DMS that would otherwise be captured in a single-pass malt distillation.

Just some thoughts...

Nick

Nick -

 

Those are two excellent books, and Piggott is a flavor/food scientist I've been following for several decades (he must be near retirement).  My Sci&Tech of Whislkies is a xerox copy from ~15+ years ago (was out of print, maybe still is).   Another is the ""Malting & Brewing Science" books wrt beer brewing, but with some overlap.

 

Anyway one think to consider wrtt these British books is thatthey are primarily about malt whiskies (tho' S&ToW discuss the neutral grain spirits used in Scotland for blending )and that give an occasional nod to US & Canadian Whisk[e]ys.  IOW they are not very interested in the aromas from raw grain, although you can find a few articles in the BRI.

 

The other thing to note is that their flavor descriptions are European.  They can't call a mercaptan "skunky" b/c they don't have skunks (they call it "catty" or similar terms), and they won't describe DMS as "creamed corn" aroma b/c they don't typically eat sweet corn.much (a little more recently) ,so they refer to cabbage and vegetable aromas.  Yes DMS can get overpowering and bad, but  a lot of lagers have 100ppm, and most whiskies about 1/10th that. You can certainly sense it in some whiskies (new make corn esp).

 

This is the seminal paper on DMS.

 http://onlinelibrary...2.tb04101.x/pdf

 

The outline is this. in germinating seeds the amino acid methionine is converted to SMM (for transport).  The kilning & drying regime of malt can destroy a lot of the SMM precursor to DMS.   SMM is heat labile and converts readily to DMS at modest temperatures (<boiling)..  The DMS has a low bp (~38C), but there is a lot of SMM in malt, so it takes an extended boil to drive it all into DMS and off into vapor.   Note that in raw grains there is relatively little SMM (tho some) so this is mostly an issue of malt source SMM, not raw grain.

 

The DMS can boil off or can oxidize into DMSO (relatively high bp), but the yeast in anaerobic fermentation have an ion imbalance and have to reduce things in there environment - including the conversion of DMSO back into DMS.    Other fermenter bacteria can produce DMS from sulfates & sulfites as well, and some in prodigious quantity.

--

 

There is no direct relationship between DMS and dimethyl-disulfide, dimethyl-trisulfide, dimethyl-tetrasulfide, nor with the various ethyl-sulfide compounds.

DMTriS.  Is discussed as a component in whiskey flavors, but at ~10-ppm in whiskey and a flavor threshold down around 0.1ppb you simply are not going to get rid of it.  It's a part of whiskey.

 

So any finished DMS in your fermenter will appear in the heads, and it isn't abnormal to have quite a bit in new make.



#3 Artisan Still Design

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Posted 28 March 2015 - 12:23 PM

flow through wort chiller that is set up for a grain in mash.

if you have the cooling capacity, this can take your wort down to safe temps in a single pass.

 

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#4 Blackheart

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Posted 12 April 2015 - 07:08 AM

We use the wort chiller above that Steven noted. Takes about 25 mins to get from 155 to 90 using chilled water (circa 60 degrees F) that we keep in a cold liquor tank.

This is is the bomb. Love it.

#5 Shindig

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Posted 12 April 2015 - 08:52 AM

Steve/blackheart

 

How much is that chiller $?



#6 MG Thermal Consulting

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Posted 12 April 2015 - 09:07 AM

Stevea- I can get the "wide gap" plate exchangers you talk about, but the size starts out at way above the Btus required here.

 

With and external exchanger (and I have used Jess' quite a few times), an 8 to 10 HP refrigerated chiller will be needed plus a poly (most economical) reservoir. so that the intense load from the mash doesn't overload the ref. chiller.

 

You can use city water on these type exchangers, but the trick is to have city water at least below 60F to get the job done successfully, but you pay the price for a lot of water used.

 

When you move off city water, you need to integrate the entire cooling water system to closed loop if you can to save $$, in which case the HP required may changer if you are running stills the same time you are cooking mash.

 

Mike



#7 MG Thermal Consulting

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Posted 12 April 2015 - 09:10 AM

I have heard of smaller Wide Gap exchangers, but have no experience using them with "thicker" mash.

 

I have seen the shell & tubes run from $5 to $15K.

 

Does this help?



#8 Artisan Still Design

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Posted 29 April 2015 - 11:10 AM

the above pictured tube in shell unit is $5k

Blackheart mentioned a 25 min cooling time, that is with a 300 gallon mash, for referance.

I have another distillery doing a 1200 gallon mash, with even cooler water, and it still under 1/2 hour. flowing from one vessel to the next rather than recirculating






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