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natbouman

High Acid or Low Acid?

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I've heard that apple that are high in acid tend to produce a distillate that is harsh and thin with lower aroma. Yet, Cognac producers seem to select grape varieties that are highly acidic as these are "perfect" for distilling. What's the deal? I've been cramming a lot of reading on wine/cidre chemistry into the last few days but have been unable to figure out whether acidic fruits (and I'm particularly concerned with apples) are better or worse for distilling--and more importantly, why they are better or worse.

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Just had this discussion with a brandy and cider maker about this the other day. While he didn't say much about acidity he definitely stays away from the sweeter varieties that he referred to as "sugar filled water balloons" claiming they have less flavor than less sweet varieties. I only wish I could remember the specific variety he said he used.

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So, I just found this post http://bostonapothecary.com/?p=596

which helped me understand acid's role in the creation of esters in distillation. That was very helpful. So, highly acidic apples could create a distillate that is richer the kinds of esters created in distilling. However, if I want to (as much as is possible) translate the flavor/aroma of the apple over to the distillate do I necessarily want to maximize distillation specific esters? The Bartlett/Williams pear aroma is produced (partly) by a volatile ester found in the fruit. Eau-de-vie made from the Bartlett is quite rich in pear aroma. So, should I be looking for apples that might be naturally high in volatile esters?

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Nat, I have a sneeking suspicion that high acid varieties are used for grapes to make the wine more stable in the time between when it becomes wine and when the distiller can get around to it. Calvados would be less heady if it were from a low pH cider.

Look carefully at the esters being discussed. I think you'll find a lot of ethyl esters. I'm pretty sure that those can develop from suitable higher order alcohols and free fatty acids in the presense of ethyl alcohol - and that it is acid catalyzed. But recall that none of the fruit acid is going to make it into the distillate. You also get esterification from Acyl-CoA floating around during fermentation (if slow enough) and from pyruvate - also during fermentation.

I've just started looking into fresh apple aroma chemistry. It is butyl alcohol and ketone dominated - other than some specific cultivar notes. I think - but am not sure yet - that yeast find those 'aromas' imminently edible.

I think building a blend with aromatic apples is a good idea. You can always 'adjust' the pH with malic acid if you need some shelf life during distillation.

The bigger hurdle is getting apple cultivar aroma through fermentation. I find that a higher alcohol level either helps stabilize it, or helps solublize it. If you've got a winery/distillery pair, it's right in the regs that you can transfer heads back to the winery and add them to fermentations. The yeast mop up a lot of aldehydes and acetates. It's a thought.

(By the way Bartlett pear aroma looks like the ethyl ester of a mid-weight unsaturated free fatty acid to me. A lot of grape varietal characters are terpenes - which seem to be rare in apples.)

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All that makes a fair amount of sense. Perhaps a high acid fermentation also helps guide a native microflora fermentation a bit better as well. However, if yeast eat fresh apple aroma chemistry, then how can a good calvados end up with an apple-like aroma?

I definitely like the notion of adding heads back to the cidre--makes sense that that might be beneficial as long as one isn't knocking out the yeast before they finish the work.

I found it interesting that Domaines Dupont uses 40% acidic apples to make their Calvados whereas other producers use far less--10-20%. Dupont is a pretty forward thinking producer (more new oak than any other Calvados producer, all basse tigue trees, only 13 varieties). I know that Dupont is trying to make a more refined spirit. I think they've succeeded. I'm not, however, the biggest fan of their products.

Many traditional Calvados makers age their distillate in huge oak casks that are ancient and no longer contribute much wood to the brandy. Often, they'll age or ferment their cidres in these tonneau so that the cidre will leave tannin behind in the wood which will then transfer to the brandy. I'd guess that wood soaked in aromatic cidre contributes more than just tannin to an aging brandy.

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Nat - on that subject of Calvados producers using old oak for distillates - they also do the same thing for their ciders, for up to a full year. As I understand it, it is a question of necessity: Fill your tank with cider, and let it sit (ferment) until you have more cider to put in next season. Otherwise, they cask dries out and you get problems with leaking.

The effect of leaving low-alcohol, un-sulphured cider around for a full year is a big increase in volatile acidity. Whenever I hear folks comparing American and French apple brandy, they are always quick to talk about terroir and varieties - All true, of course. What is being overlooked, as I see it, is the difference in VA between American and French ciders right before they go into the still. Americans have a distilling culture - ultra-hygienic, selected yeast + acids + enzymes, ferment and distill as quickly as possible - that is very different indeed from the good traditional Calvados producers. The only time I have made something that even faintly reminded me of Calvados, it was cider gifted to be by a winemaker that had sat around for nearly two years. Total nail-polish bomb. 

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Hi,

With the help of acidity, terpenoids fragrant substances comes free and creates aromas.

brendi tez.pdf

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I haven't heard that apples contain terpenoids.

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