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Testing the Impact of Various Filter Sizes on Bottled Whisky
I am trying to decide on what filter sizes to use for bottling our whisky (aged for 3 years and we are using non chill filtration). Apologies for another post on this topic as I have seen quite a few on here but they haven’t really answered my question.
From literature and posts here I see that a common filter pore size is around 1 micron, with many of you using 5 micron and then 0.5 micron.
I spoke to a filtration company who have lots of experience with this type of work and they informed me that small changes in the filter size (eg 1 micron to 1.2 micron) can make significant changes to colour and taste of whisky. As a result the best thing to do would be to send a sample and they would test different filter sizes and send back finished product from different filter sizes to us. This saves using the wrong filter size for our bottling and potentially harming our product.
Does anyone have any input or experience with testing filter sizes before committing to a full bottling run? My worries of not doing this is ending up with a whisky which will haze or go cloudy in time from a filter too large or a whisky which has had some of its hard earned taste removed at the final step.
If testing is the correct way how do we then deal with bottling of whisky from different ages and different casks etc in the future? – it seems excessive.
If anyone has any thoughts/input on anything relevant then please let me know!
Thanks
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3 Replies
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Some filter suppliers will offer to do bench runs of filter media for you to test to help you select your filtration. (Shout out to David Strauch at Strauch Chemical)
Personally we go as coarse as we can without any visual issues. For most of our whiskeys that means just going through a 5 micron cartridge. For our brandies we do see some haze so we use Beco Select A20 pads and chill filtration (around 4 C) or a similar cartridge with non-chill filtration depending on the expression.
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The elements that contribute to the flavor and color of your product are typically in solution, and won’t be removed with barrier filtration unless that filtration is very, very, very fine. Whiskey and spirits are very low-solids products. Most of my filter customers can go a long time on a single set of filters. Months or more depending on how they take care of them. All that being said, the difference between 1 micron and 1.2 microns is extremely minute for most spirits. I would be very surprised if changing from a filter size of 1.0 vs 1.2 microns had any perceptible effect whatsoever, either on the colo(u)r or flavo(u)r. I’m sure the claim is being made in good faith, but it sounds a bit exaggerated.
Filters are a “sticky” product. Once a customer has found the filter that works for them, the cost of switching to another brand is pretty high relative to the benefit of sticking with tried and true—even if they do save a few bucks on a per-filter basis. That being the case, I’ve heard more than a few exaggerated claims from filter salespeople in order to bring them into their ecosystem (Bear in mind the source of this claim, of course. TCW also sells filters). So, the 1.0 vs 1.2 micron distinction sounds like FUD to me.
Your apprehensions are very common. New distillers are worried about taking out too much (e.g. “removing flavor”) or not enough (e.g. ending up with haze).
Removing “too much” with standard, nominally-rated barrier filters—which is 90% of what we sell to distillers—is not easy to do. Staying from 1-5 microns should have no practical effect on your final product, unless fine carbon dust and bits of char are part of your brand.
The “not enough” side is tougher. Haze removal has been discussed quite a few times on this board. The short answer is there’s no magic bullet. If your product ends up with haze, you may wind up needing to make changes to the final product to remove the haze (or educating customers regarding why haze is a “good thing”). The changes don’t necessarily mean that the product will be harmed or diminished, but it may be altered. If you’re wary of chill filtering you can try filtering at normal temps with a more highly charged filter media that contains diatomaceous earth, or borosilicate glass. That may be enough.
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In my opinion, it is necessary to separate the marketing of the product and the technical parameters of the product (alcohol).If we are talking about “haze” (opacity, turbidity) inside a drink in a bottle, then from the point of view of Chemistry and Physics, this means that there are fine impurities in the solution.They can even appear simply from the fact that you diluted your alcohol with water after the distiller. A change in the concentration of alcohol leads to the fact that some of the soluble substances become poorly soluble, and create a “colloidal phase”, which is very fine and your filters will not protect against it.If we talk about “fruit drinks” (fruit flavor), turbidity (fog inside the bottle) can appear even when the product is diluted from 45% to 42%. You are not using deionized water, which means salts in the water (impurities) can also create a “fog” inside the drink, because they create new compounds. Therefore (from the point of view of alcohol production technology), one should strive to obtain a ready-made drink immediately, without numerous dilutions with water.If we talk about “very fine cleaning” from a technical point of view, filters are not always necessary. There is an excellent method for purifying small impurities using a centrifuge. You can use methods of purification from chromatography: a very long tube in a rotating drum, by the way, in this way it is even possible to obtain alcohol and all individual alcohols and components without heating and distillation at all, only by a mechanical method. I’m not kidding now.
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