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Chilling your mash


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#1 boognish

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Posted 05 October 2013 - 12:57 PM

Hey everyone! This is my first post here! Looks like this is a wonderful community and I look forward to being a part of it!

We are a startup distillery a few batches in. Pretty exciting and heady times for sure! Anyway, it is taking wayyyyyy too long for me to chill down my mash. We are fermenting and distilling on the grain, so a plate chiller isn't going to work here. I am worried about DMS formation (I come from the brewing world) although I can't seem to find any info on how DMS carries over into distillate, and the time (labor cost) that it takes to chill to pitching temps. We are mashing in a 420 gal steam jacketed reactor. To chill, we just switch from steam to cold water, but this isn't really working fast enough. Any ideas?

#2 jeffw

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Posted 05 October 2013 - 02:39 PM

What is your crash time? What is your cold water temp?

#3 Paul Tomaszewski

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Posted 05 October 2013 - 02:58 PM

Call Jesse Lupo at Trident Stills, he has the best thing I've heard of going for grain-in-mash heat exchangers (www.tridentstills.com).

#4 mendodistilling

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Posted 05 October 2013 - 08:05 PM

Yep, heat exchangers, possibly with cold liquor tank chilled water w/ glycol. Its a big temp drop on demand. your dropping the temps 70 degrees or more. The mash cookers I see use internal coils from vendome copper and brass works. You could try that route maybe.

#5 fldme

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Posted 06 October 2013 - 06:52 AM

Jesse can build you a cold water coil. Do not worry about DMS, beer brewing and mash for whiskey is two different animals. You could drop the temp a little then add cool backset to it in the fermenter.

#6 MG Thermal Consulting

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Posted 06 October 2013 - 07:02 AM

Problem with steam jackets is that they are not designed for any particular heat transfer rate, so you have indefinite times on cooling side. The best way I've come across is Jess' external exchanger, you can pipe it for city water or closed loop (Jess and I have just supplied one of his exchangers and my cooling system just being installed up in VT., a 500 Gal mash cool). I used a 10 ton chiller with a customer supplied indoor tank with isolation exchanger and added an optional drycooler to chill the glycol circuit to cut down on the KW used by the chiller when fermenting and condensing are the only loads. If the cold liquor tank is what you're considering, for a 420 gal mash cool, you'll need a big tank, it's better use of space to set up a chiller with a smaller poly reservoir, IMO. Either way, I recommend getting the Trident exchanger and fitting it to the city water line ( you can always Tee over to the jacket if your city water gets too warm. Give me a call and I can run through it with you. Mike 678-773-2794

#7 boognish

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Posted 06 October 2013 - 01:53 PM

These sound like the options I have seen, although I don't See that chiller on Tridents page. Thanks for the quick responses! I hadn't thought of using backset, that's an interesting option, but storage is going to make that untenable right now. We are going to be tight on cash until we can start packaging (waiting on label approval during federal shutdown) so at least I can stop worrying about DMS.
Here is kind of a related question.

The first batch we did we did not boil the mash. It got a pretty strong lacto character in the mash after a few days. Since then, the last few batches of mash I have boiled. When the first run was stripped, it seemed to not bring that lacto flavor over. Am I wasting time and energy boiling? It's easier to chill from 62 C than 100 C...

#8 Jedd Haas

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Posted 06 October 2013 - 08:13 PM

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

#9 fldme

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Posted 07 October 2013 - 04:52 AM

No need to boil. You probably are getting lac to going if it is taking a long time to cool. Backset would solve both issues. In the mean time, when you start cooling drop pH of mash to at least 4.5 to keep lac to out

#10 MG Thermal Consulting

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Posted 07 October 2013 - 05:33 AM

Is the "way too long" a function of you not being able to source a cold enough process water for cooling, or that you do not have enough exchanger to satisfy the heat load. The higher temp (from near boiling to 140F/60C) can be done fairly quickly with whatever heat exchanger you use, but as you near the target mash temp, it takes longer and longer to reach your target- this is a function of the heat exchanger and how cold your process water is. This is why it is a struggle to reach 80F mash down South when the city water source of cooling is 85F in the summer and higher production requirements push toward using refrigerated sources (cold liquor tanks or packaged chillers). To chill the mash without a source cold enough or a heat exchange source large enough makes you suffer on the production end, simple as that. Give Jesse a call, I have seen his work and it is top notch. He will ask you all the questions needed to supply a proper heat exchange system, whether it is a coil-in-tank or an external shell & tube.

#11 Natrat

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Posted 07 October 2013 - 06:07 AM

Hey Boognish, I came over from the brewing world, too, so I get your issue with cooling.

I'm not a big fan of running cold water into a hot jacket...most dimple jackets on mash tuns aren't capable of handling those heat stresses long term. I've seen leaky or bubbly jackets (signs that the dimple welds have failed) in a couple of distilleries, now, and although I havent' spoken with those distillers, judging from the plumbing on the tun, that's exactly the issue.

I've been transferring my mash into a glycol jacketed tank, but to go from 155 to 90 still takes 6 hours (jacket only on a fifth of the surface area in the tank)
I've been toying with the idea of building a tube and shell heat exchanger (this is the easiest way cool mash) and it might be as easy as running a hose through a cold liq tank, but I'm leaning towards using stainless in a barrel full of glycol.

Having said all of that, DMS, diacetyl, acetaldehyde, isoamines, all those potential fermentation off-tastes from beer don't seem to come through in the final distillate. Some of the fermentation by-products are definitely detectable in headshots and sometimes in the dunder, but I never get them in the product. Remember that you're BOILING (almost) your beer again, and most of those flavors are as volatile as hop aroma, so they scrub out pretty quickly, and don't re-condense.

If you are going to continue to use your jacket for cooling, then I'd encourage you to cycle your mash. Agitation definitely helps, but I found that pulling my mash out of the vessel and pumping it back in a loop increased the rate of my delta T by about 30%. I had a lackey spray water on the hoses, too...every BTU counts when you're in a hurry!

#12 MG Thermal Consulting

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Posted 07 October 2013 - 07:28 AM

Jess and I supplied our equipment independently- my chiller system, his exchanger. PM or email me and I can give you some idea of costs- the type equipment used on the VT distillery is on my website, however.

#13 MG Thermal Consulting

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Posted 07 October 2013 - 07:30 AM

Sorry 'bout that- www.mgthermalconsulting.com

#14 nick jones

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Posted 08 October 2013 - 01:10 AM

Am I wasting time and energy boiling? It's easier to chill from 62 C than 100 C...


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. In a well-managed 2-5 day ferment, lacto is not an enemy worth worrying about. In fact, there's plenty of research that demonstrates that lacto (in manageable levels) is a distiller's friend.


Having said all of that, DMS... don't seem to come through in the final distillate. [hillbilly accent out of context]


If you're looking for DMS in the distilling literature, you'll likely find DMTS (dimethyl trisulfide) instead. Natrat is correct that DMS isn't a big problem in distilled spirits, but DMTS will make it through a distillation and comes from the same precursors.

Given the low proportions of malt in most whiskies, DMTS is rarely a problem. But DMTS is something to watch out for in an all malt whiskey.

Nick

#15 boognish

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Posted 10 October 2013 - 03:21 PM

That is some great info there and confirms some other suspicions I had about boiling.

#16 Natrat

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Posted 21 October 2013 - 03:33 PM

Nick,

I'm interested in finding out more about DMTS...I know that sulfide and trisulfide precursors can be increased by the addition of hops (especially stale hops or hop oils), and I knew that malt had some contribution, but I was unaware that trisulfide could be a danger in a malt fermentation. I've even read that Dimethyl disulfide can be a significant flavor in an unaged whisky (apparently produced from interactions with copper) but that all the sulfides reacted positively in longer term barrel aging, though whether it is due to interactions with the barrel or related to oxidative reactions, I don't know.

What precautions against DMTS production do you recommend, and why? I do an all malt whisky, and I've never detected an oniony taste or smell, but I just know that I will in EVERYTHING now that you've pushed my hypochondriac off-taste button!

Natrat

#17 nick jones

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Posted 21 October 2013 - 05:11 PM

What precautions against DMTS production do you recommend, and why?


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

#18 Denver Distiller

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Posted 21 October 2013 - 06:43 PM

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.

Double distillation will help in the sense that, all things being equal, you're doubling the contact of the vapor with copper. Copper takes care of your SMM and sulphury notes in your new make. Obviously if you distill in one pass, you're likely using a plate still, so you'll hopefully get enough copper contact to reduce DMS. Personally, I wouldn't use fewer than either two passes in an alembic or one pass with at least 6 plates in an eaux de vie still. There's a reason eaux de vie distilleries use catalytic converters in conjunction with their 3 plate stills.... they need more copper contact both for sulphur reduction as well as EC reduction in stone fruit fermentations. Copper will reduce your sulphur issues everywhere save your spirit condenser (if you are using two separate stills).

Recall, too, that if you're working with barley, kilning reduces DMS-P greatly. If you're using green malt or distiller's malt, you'll have elevated DMS-P in your grain relative to traditionally kilned brewer's malts simply because the barley isn't heated enough to convert and . Your fermentation regime may all but eliminate this effect, however, leading to relatively little DMS in your fermented mash/wash.

#19 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.



#20 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.






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