Copper Question

CothermanDistilling

thank you! we were using 33.6 or 33.8 on the high end, but 82.4-91.4(28-33) is a pretty wide range and something I think we can easily stay in...

The big thing I see is that they were pumping the fermenting wash continuously... Are any of you craft rum makers out there doing that?

MotherOfDragon

Very interesting indeed. I live in a cold climate. This summer was very warm for this area. We had temperatures about 28-30 degrees C (82-86 F) for a long period. But we had a very cold winter instead and I thought at that time that I should produce a rum with less quality than before. (Started out in September 2017).

What happened was that I had to ferment a longer time, but the final product had just the same quality than before and in fact even a bit better than the rum I have produced this hot summer.

grim

The most interesting thing about Arroyo is that by the time of his death in 1949, he appears to almost entirely give up on the Heavy Rum patent, seeming to (reluctantly) capitulate it didn't work, did not produce consistent quality, wasn't repeatable, and that he wouldn't recommend anyone use it. A paper published after his death indicates his last work was on utilization of multiple strains of Sacc. as well as development of hybrid yeast strains for rum. This was based on realization that mixed culture fermentation was far too inconsistent for market demands and production planning. He was looking for another way to achieve the same end goal of high-ester (aka heavy) rums.

He doesn't entirely dump the idea, as he develops a process by which distillers would do a test distillation on a small sample of a fermented wash. Based on this test they would decide to distill the product, or would dump the wash without distillation. Yes, you read that correctly, he was saying that it was better to dump an entire ferment if it wouldn't yield the ideal output. Given the long aging time that was required to produce inconsistent heavy rums (3-5 years), the cooperage, warehouse space, time - that it would be garbage in, garbage out, so just toss it up-front.

If you look back through the old rum literature, you'll see the issue in real practice. Distillers were selling multiple grades of rum, in some cases there were documented to be 4 or 5 different grades of rum, or more.

The fact is, this wasn't intentional, every distillery wanted to make the top grade rums, they were the most expensive and most in demand, but the reality was they couldn't. The inconsistencies were simply too great. They realized that they could hold lower grades in cooperage for longer periods of time to increase the quality, but that was simply too costly. Low quality rum was typically sold for low prices in the local markets, and the highest quality rums - the ones that commanded the highest prices, were all export. There were tons of variations in between, which were used as blending stock/flavorings for cleaner continuous rums.

Seasonal variation in temperatures during production absolutely made an impact in Caribbean rum production. Keep in mind sugarcane would have been traditionally harvested starting in December, running through March - during the coolest/driest months. We're talking about low-80s daytime temps to low-70s nighttime temps across most of these regions. Fields were planted in a staggered fashion to stretch the harvest season as long as possible - keep the cane in the field. The cane that was harvested last would have been the rum that would have been subjected to the highest temperature fermentations. Early cane would have fermented in cooler weather, especially cool nights.

Cane juice can't sit, most of these historic rum distilleries were not distilling year round, and certainly not fermenting during the hottest summer months.

grim

We've run rum ferments with the fermenter tank mixer on intermittent agitation, I think agitation easily cuts a day, day and a half, off fermentation times. Forcing the yeast to stay in suspension versus starting to floc and settle is the primary reason here.

grim

Huge resource on historical rum grades by ester content, including the especially funky Hampden:

Jamaican Rum Marques Roundup @ Cocktail Wonk

Look at the absurd levels of variations. Look, we know these distilleries made at least 3 variations on purpose, but Hampden making 8? Long Pond making 12? Look at the ester level variation across the variations. They didn't just make a rum, they made every possible variation of rum, from super clean white rums, to undrinkable high ester rums like Continental and DOK.

grim

Clarendon in Jamaica is a great example. For high ester they are fermenting for weeks in uncontrolled wooden fermenters that would send a health inspector into convulsions, then distilled in traditional double retort stills, meanwhile their clean rums are run through closed and actively cooled stainless fermenters with 200,000 gallons of capacity, and run through columns. The fermentation chiller is the size of a house.

Two completely different theories, two completely different approaches, happening at the same exact place. You could not get further apart in methods of rum production. Fully stainless continuous distillation right next to Funky Jamaican copper double thumpers.

From the link above. You see the super clean, temp controlled, continuous fermented rum at the top, and the funky high ester at the bottom. It's fairly plausible that the rums in the middle are blends of the clean and high ester:

zymurgybob

"premature exhaustion...through vital over-excitement." Are we talking yeast or teenagers?

Smaug

Old people Bob....Old people.

zymurgybob

That makes sense, too.