Scholarly article: maturation in Mini Casks vs Lg Casks

[SpiritOf76]

I was searching for "mini casks" and ran into this article. Thought somebody might benefit from it. Can't post the PDF (bboard says "PDF extension not allowed), so I hope the link is good for a long time:

COMPARISON OF SCOTCH MALT WHISKY MATURATION IN OAK MINIATURE CASKS
http://www.scientificsocieties.org/JIB/ ... _5_359.pdf" onclick="window.open(this.href);return false;" rel="nofollow

[kiwistiller]

To save people the download I thought I'd copy and paste the abstract and conclusion (hell, its all I generally read of a scholarly article anyway ) cheers for the post

ABSTRACT
The sensory and chemical attributes of Scotch malt distillate matured in uncharred, American white
oak casks, were compared with distillate matured in miniature casks of similar wood with a capacity
of 6 Litres. The maturation profiles of the two types of casks differed in the pattern of extraction of
wood components and in the flavour characteristics of the final distillates. The product from the
miniature cask maturations was not comparable with a Scotch malt whisky, due to differences in the
ratios of concentrations of extractives. This may relate to differences in oxidation rates in the two
cask types.

CONCLUSION
The composition of the final distillate from maturation in miniature and full-size casks differed significantly. An increased surface to volume ratio of the miniature cask, and increased oxygen concentration, appeared to enhance both extraction and further transformation of wood components, resulting in the dominance of a single characteristic, sweet, after 21 months of maturation.

Earlier work has shown that wood lignins have a limited number of bonds susceptible to cleavage and exhaustion of these in the staves of the miniature casks, prior to the completion of the maturation process, may account for the subsequent reduction in concentration. Spirit matured in miniature casks was free from the pungent and sour notes present in that from the full-size casks in the absence of wood charring. Maturation of Scotch malt distillate in miniature casks did not enhance the sensory quality of the final product, nor did miniature casks provide a suitable model of an accelerated Scotch whisky maturation process.

[SpiritOf76]

Yes, good call on posting the abstract.

But for anybody interested - the article has some detailed information about the chemical exchanges - at least the names of many chemicals - which could be a starting point for deeper research/understanding of maturation on oak.

Also of potential interest is a list of flavor/taste adjectives by which each sample of whiskey was evaluated. For me, this list of adjectives was at least as interesting as the rest of the article.

[Slow & Steady]

ABSTRACT
The sensory and chemical attributes of Scotch malt distillate matured in uncharred, American white
oak casks, were compared with distillate matured in miniature casks of similar wood with a capacity
of 6 Litres. The maturation profiles of the two types of casks differed in the pattern of extraction of
wood components and in the flavour characteristics of the final distillates. The product from the
miniature cask maturations was not comparable with a Scotch malt whisky, due to differences in the
ratios of concentrations of extractives. This may relate to differences in oxidation rates in the two
cask types.

Did anyone else find the part of the abstract I have underlined strange... Scotch Whiskey for the most part is matured in once used Bourbon Barrels, and Bourbon Barrels are charred. I have toured cooperages in Scotland and all of the disassembled staves from used barrels were charred.

[kiwistiller]

It does seem a little funny, doesn't it... I suppose it is to control for the differences in char and previous product that they couldn't keep the same or couldn't be bothered waiting for...

[SpiritOf76]

I would assume that it's just a matter of controlling variables for the sake of the study. It probably isn't possible to find small size used bourbon barrels. So in order to evaluate the interaction between the spirit and the wood with the isolated variable being barrel size, they'd need to use uncharred large barrels.

[Slow & Steady]

Yeah... the study is still a valuable work, however, using the term Scotch is at best a rocky road. With over 100 distilleries in Scotland producing a wide range of nose/taste profiles, I wonder why the researcher would taint his Abstract & Conclusion with statements like "Maturation of Scotch malt distillate in miniature casks did not enhance the sensory quality of the final product".

The aging of the malt distillate at 21 months produced sweet as the dominant change. I can understand this. The sugar (arabinose, glucose, xylose, galactose and rhamnose [suspect source Hemicellulose break down]) and color are normally extracted/produced in greater amounts early in the aging process (first 12 months). Glycerol and fructose appear much later in the maturation process. The congeners: Acids, Tannins, Esters, and Aldehydes increase in a linear fashion and require time to build to the levels we taste in a 10 year old Scotch. What would the character of the mini cask have been at 4, 5, or even 6 years. We can't even call it Scotch until it has been aged in Scotland for a minimum of 3 years.

I don't have problems with the conclusions the research proposes. I would like to see what the conclusions would be with a wide range of higher entry proof levels... say 130, 140, 150, 160, 170. The extraction of sugars/solids and color decrease sharply as the entry proof is raised, tannins and volatile acids decrease to a lesser extent, Esters and Aldehydes continue to accumulate at the same rate regardless of entry level. I think one could find a good proof level to produce an acceptable result with the mini casks. Not Scotch mind you but a good single malt maybe possible with the right combination of Mini Cask Size, Single Malt distillate entry proof and Time.

[SpiritOf76]

Ok so here is something different. In the current edition of the ADI newsletter, Dry Fly principal makes the following statement regarding their soon-to-be-released whiskey:

"Dry Fly's wheat whiskey is aged in 15-gallon barrels; one year in a 15-gallon barrel equals three or more years in a full size 53-gallon barrel, Poffenroth said."

Does anyone here have any experience or know of a thread that makes a comparison of small vs. large barrels? It would be nice if Mr. Poffenroth is right. But does that mean that 4 months in a 5-gallon barrel is equal to one year in a 15-gallon barrel which is equal to 3 years in a full size 53-gallon barrel?

[Slow & Steady]

I think it is safe to say that the "Scholarly article" concluded that the small cask didn't truly accelerate the aging processes compared to a longer aged large barrel, only the sweet/sugar notes were notable in the flavor profile. Makes sense to me... many of the processes going on during aging take "time and oxygen" to accumulate an aged taste and nose.