Better living through chemistry?
September 26, 2012 6:57 AM   Subscribe

Are there unpleasant compounds in plastic (specifically Britta filters) that are soluble in pure ethanol that I don't want to drink?

I enjoy making home-made liquors (specifically infusions) like limoncello. I use a 190 proof Everclear as my solvent to extract the lemon oils (or fruit or whatever). Based on a tip I read online, my habit is to filter the alcohol in a new Britta filter before I soak the flavoring agent in the alcohol. I know that Everclear is only distilled once and I believe that it contains some impurities that contribute to a very harsh character. I further believe that the charcoal filtration has led to a much smoother taste in my finished product.

However, last night whilst studying to make my latest creation (a raspberry liquor), I came across a claim that highly concentrated alcohol is a very effective solvent for dissolving chemicals out of the plastic. The most knowledgeable sounding folks suggest that it will specifically dissolve the "plasticizer." However, other folks say that the liquor industry uses plastics to ship and store their alcohol and that it must therefore be approved by the FDA.

I'm told that the plastic used by Britta is either NAS (some kind of styrene) or SAN (Styrene Acrylonitrile). I think my pitcher is of the SAN variety, but I'm not entirely certain.

I've tried to find some kind of definitive food safety website, but get myself entangled in lots of unrelated stuff about BPA. My stuff is never heated, but it does make some sense that alcohol is an effective solvent and that Britta probably didn't design for that purpose. For what its worth, the alcohol is in contact with the plastic for perhaps a couple of hours at most. All subsequent steps are in glass. What do you think of the relative risk level?
posted by Lame_username to Food & Drink (34 answers total) 1 user marked this as a favorite
Can you set the filter part over a glass jar or pitcher?
posted by StickyCarpet at 7:00 AM on September 26, 2012 [1 favorite]

What kind of impurities are you expecting? I would think maybe a little ether or other volatile distillates, and those might evaporate just from decanting it. Oven-drying some epsom salts, adding that, then filtering it out would remove water, which is probably the bulk of the %5 impurity. Don't know what that would do to taste though.
posted by StickyCarpet at 7:04 AM on September 26, 2012

And for that matter, you can buy activated charcoal that's not in a filter--i.e., sort of a carbon stick--that you could just put in a food-safe, non-plastic, containter. Seems like there's no reason to run the liquor through a Britta filter at all.
posted by Admiral Haddock at 7:06 AM on September 26, 2012

Response by poster:
Can you set the filter part over a glass jar or pitcher?
Yes, but the filter housing itself is also made from plastic and the alcohol pools there as it slowly drips through the filter.
What kind of impurities are you expecting? I would think maybe a little ether or other volatile distillates
I must admit that its a bit of voodoo to me. I do know that people can distinguish (and strongly prefer) the filtered product from the un-flitered product in blind taste tests. I've repeated that a number of times.

I'm not intending to thread-sit, just to respond to direct questions.
posted by Lame_username at 7:15 AM on September 26, 2012

Don't know what that would do to taste though.

The salts will take on the water, but won't dissolve in alcohol. So if you get all the water there should be no change in taste.

Carbon filters are mainly for particulates. Things like ether would probably go through better than alcohol. Maybe what you are seeing is from decanting. Try a taste test: pour it from vessel to vessel a few times and compare that to the out-of-the-bottle.

I use Everclear as a cleaner for instrumentation, and it never leaves any noticeable residue.
posted by StickyCarpet at 7:23 AM on September 26, 2012

One other thing, Everclear straight can cause chemical burns in your mouth. Maybe what improves is that the alcohol itself is evaporating (which it does quite rapidly) and you just prefer more water.
posted by StickyCarpet at 7:32 AM on September 26, 2012

Response by poster:
Maybe what improves is that the alcohol itself is evaporating (which it does quite rapidly) and you just prefer more water.
By the time we taste it, it has been diluted with an equal volume of simple syrup. It is true that it is open to the air during the filtration process (and not at any other time).
posted by Lame_username at 7:37 AM on September 26, 2012

Maybe distilled water would be a more revealing mixer.

As you may have guessed, I'm a big fan of Everclear, as the base in shellac, as a cleaner, all kinds of things. The fumes are non-toxic, and even pleasant!

The problems are: have to go to Jersey to buy it; expensive; some shrinkage due to the humans getting into it.
posted by StickyCarpet at 7:44 AM on September 26, 2012

Best answer: OK Warning Chemistry follows:

Plastics consist of long chains of molecules which are going to be wholly insoluble in ethanol. Plasticizers are compounds that "dissolve" in the polymer and cause its properties to change. A good example is dioctylphthalate which adds more pliability when added into a polymer matrix.

Dioctylphthalate is soluble in ethanol, but the amount present in any plastic is going to be quite low. It is essentially like adding a bit of grease between the molecules of polymer and if you add too much it will just all fall apart. If you are concerned you can order some activated charcoal from nearly anywhere along with some coffee filters and make your own filter system that will work as well.

Straight everclear shouldn't cause chemical burns in your mouth (depending on your idea of chemical burns) as I have drank laboratory ethanol many times before and didn't get anything even remotely resembling a burn. THF and ether burn a lot if you get them in your mouth, along with dichloromethane and chloroform but ethanol and methanol just sting a bit.

You also don't need to try and remove the last 5% and the ethanol will just absorb water from the air until it gets to around 95% pure anyways.

If I were you I would just keep on using the brita pitcher, unless you are getting too paranoid at which point I would order a kilo of charcoal from aldrich along with a nice large funnel and some good filter papers and set up a filtration system of my own.
posted by koolkat at 8:14 AM on September 26, 2012 [4 favorites]

Can I use laboratory ethanol to make limoncello? How do I know if it has methanol/additives to make sure that people don't drink it?
posted by Strass at 8:46 AM on September 26, 2012

It depends. If it is potable then you will be fine. If it has been denatured than you will die because it will have isopropanol in it. If it is anhydrous then you will get cancer because it would have been dried using benzene (traditionally they might do something different to dry it now I know I dry it by distilling from magnesium turnings).

The thing to look out for is USP (united states potable) in which case it means safe to drink, but not recommended without further treatment to improve the flavor.
posted by koolkat at 9:15 AM on September 26, 2012

I'm in Canada. Should I be looking for CSP instead? I will check it out when I get back to lab later...
posted by Strass at 9:22 AM on September 26, 2012

^ just CP. dur...
posted by Strass at 9:24 AM on September 26, 2012

Not sure I bet it would still be USP as that is what I can buy in the UK as well.
posted by koolkat at 9:35 AM on September 26, 2012

Actually USP means United States Pharmacopeia aka can be used in pharmaceutical settings fit for human consumption.
posted by koolkat at 9:38 AM on September 26, 2012

Response by poster: Koolkat, I'm looking at filter paper and you have opened my eyes to a whole new world. I'm looking for a filter that will eliminate particles from the final solution. I currently use coffee filters, but they are suboptimal because they quite quickly get clogged and refuse to pass any more liquid through. I have to change them many times for any given batch and they take quite some time to pass all the liquid through. Google tells me that coffee filters trap particles from 10-15 micrometers. I'm trying to find coarser filters that I can use for the first pass that might clean larger particulates before I switch to coffee filters, but I'm overwhelmed by the filter paper marketplace. I think I want qualitative filters (I don't care about the stuff I trap) and fast/slow seems obvious. Do I need ashless? High wet strength? I need a Buchner funnel! Holy crap -- vacuum filtering, there is so much I didn't know anything about. Thanks a million!
posted by Lame_username at 10:39 AM on September 26, 2012

I would stay away from vacuum filtration because while it speeds up filtration, the low pressure will cause the alcohol to evaporate more quickly.
posted by Strass at 10:49 AM on September 26, 2012

Best answer: The Everclear probably tastes harsh because of fusel oil, and the method of choice to remove that appears to be activated carbon.

I think you're wise to move beyond Brita's, not least because they are relatively expensive.

If you can find an old Revere Ware drip coffee maker, such as this one (currently at auction on ebay with a single bid of $9.99, and closing in a couple of days) you can put up to several pounds of well-washed-- and dried, for your purposes-- activated carbon in the upper vessel (scroll down to see it in disassembly) and simply pour the Everclear through as many times as you think necessary. That upper vessel is all stainless steel, and has hundreds of tiny holes drilled in its base which act as the filter, and the alcohol should go through in less than a minute.

I'm using a stack of two of these and a pair (so I can fill one from the tap and pour into the stack sitting in the other) of stainless 70 oz. Vollrath pitchers as my drinking water purifier.

I recommend coconut shell or wood activated carbon for you rather than the coal based stuff which seems to be popular for aquariums. Amazon will sell you coconut shell activated carbon by the pound at a rate around five times what you might pay buying in hundred pound quantities from an industrial supplier.

To filter the fruit solids out of your infusion, I think you could use an old Acme (now Waring) juicer (scroll down to number "three") with a strip paper filter in front of the holes in the stainless filter basket. Waring/Acme still sells the paper strips separately, as far as I know, but you also might want an inductive motor speed control to reduce splatter as you add the infusion to the spinning basket.
posted by jamjam at 11:58 AM on September 26, 2012 [1 favorite]

Best answer: I have background in chemistry (just a bachelor's and this is not my field, although I have studied plastics and plastic additives including plasticizers in the past).

The short answer is I don't know, and I doubt very much anyone in the forums you perused knows either. My guess would be no, you will not be leaching appreciable chemicals out of a Brita due to solvent effects.

I think jamjam is fundamentally on the right track. The thing is, carbon filtration of distilled spirits is a known technique in distilling. The secondary filtration method in a Brita (ion-exchange resin) is probably pretty much pointless for your aims. I think your better bet would be to buy bulk activated charcoal (or carbon the terms seem to be used interchangeably) specifically produced for brewing, wash it well, and soak your liquor in it and filter it. If you google activated carbon distillation you will find a bunch of product and information links. There's not really a need to get fancy with the equipment (jamjam's set-up makes sense when you are daily treating the liquid you must drink to survive, I think it might be a bit much for the occasional bottle of improved Everclear). Even if you wash the carbon really well you will likely need to filter the product to remove carbon particulates.

Another thing you may consider: just switching to a decent mid-grade vodka. Everclear is basically a nasty spirit distinguished only by its strength. I've worked with both for consumable projects and basically decided the added alcoholic purity of Everclear was not worth the bother of trying to redeem its nasty taste.

Again I think going down the route of scientific filtration supplies is probably expensive overkill (and there's little guarantee they will work better for the purpose). I would be looking at stuff like a chinoise, reusable cloth coffee filters, jelly bags doing some prefiltering with cruder strainers, cheescloth, etc. These things are made for straining food. Lab filters are made for isolating the products of chemical reactions.

Strass, most lab alcohol is denatured and will be labeled so. If it is not labeled you need to assume its denatured. Things are specifically set up to prevent people from drinking industrial alcohol. Let's face it: if college labs made food grade industrial ethanol easily available to students, they would drink it all. And again I just don't think its worth the trouble when decent vodka will do the job perfectly well.
posted by nanojath at 12:38 PM on September 26, 2012

(I meant distilling, not brewing in paragraph 3)
posted by nanojath at 12:39 PM on September 26, 2012

Response by poster: Nanojath, most people who produce fruit infusions do in fact use vodka and I intend to compare the two for my forays into fruit. I can say that most everyone I know who has tried limoncello with vodka and with grain prefers the results with the Everclear. It just tastes much more "lemony" to me.
posted by Lame_username at 1:18 PM on September 26, 2012

Just decanting isn't going to improve the flavor of your alcohol. I mean think about it, if that's all they had to do to make Everclear a premium product, they'd already be doing it at the distillery. It adds basically zero cost.

The brita filter does have activated carbon in addition to the ion exchange resin. It's the carbon that's improving the taste. The only difference between cheap vodka and premium vodka is how many times they filter it for you before they bottle the stuff.

I'm guessing the reason why your everclear limoncello is better than vodka is because it's higher proof, and closer to being just a pure solvent.

Building your own filter is probably a better solution just in terms of cost. Brita filters are expensive, and you're mostly paying for a kind of filtration you don't need.
posted by danny the boy at 2:08 PM on September 26, 2012 [1 favorite]

Response by poster:
Building your own filter is probably a better solution just in terms of cost. Brita filters are expensive, and you're mostly paying for a kind of filtration you don't need.
Although the cost is higher, most of it is a sunk cost at this point. It looks like I pay $5 for a replacement filter, so the cost delta isn't that great now. I am filtering a case of Everclear on one filter.

I do need a better solution for the post-soaking filtration. My first idea was to buy a big Buchner filter with some course filters and some fine filters and see if that works better than the coffee filters. The high speed of the vacuum filter was appealing and you can find kits for not a lot of money, but if it causes me to lose a large volume of alcohol due to evaporation that would be bad. I just weighed my first batch of 1.5l of alcohol after six passes of the Brita and evaporation loss was less than 0.5%, so I'm OK with that.
posted by Lame_username at 3:01 PM on September 26, 2012

Have you done any tests around when the Brita filters become exhausted? I don't know the answer to this, but it was my impression the last time I did research into filtering vodka, was that after a few passes of a 1.75L bottle the filter was consumed? Maybe I'm misremembering.

I guess I wonder if the last bottle from your case tastes as good as the first bottle. Or are you mixing all those bottles into one giant batch?
posted by danny the boy at 3:49 PM on September 26, 2012

Just decanting isn't going to improve the flavor of your alcohol. I mean think about it, if that's all they had to do...

Works for a lot of wines, just sayin'.
posted by StickyCarpet at 4:11 PM on September 26, 2012

From jamjam's link:

Fusel oil, a contaminant found in alcohol, gives it a harsh and heavy taste on the palate. Fusel oil is a generic name and includes propanol, iso butanol and methyl butanol.

Our product range comprises both powdered activated carbon (PAC) and granular activated carbon (GAC) products for this application.

posted by StickyCarpet at 4:21 PM on September 26, 2012

Response by poster: That's a good question, actually. I always believed that a Brita filter was good for six bottles times 6 passes, but my wife just read the instructions and they say that a filter does 40 gallons (of water of course), so I was going to do the whole case with one filter. Now I'm paranoid. I might have to do another taste test. I'm filtering bottles 5 & 6 now.

We just did a double blind test of the second bottle and it was blindingly obvious. I might try a test of bottle 6, but there is some risk I will get too inebriated to trust the results.
posted by Lame_username at 4:24 PM on September 26, 2012

Response by poster: Wife prefers bottle 6, I prefer bottle 1. We still like both better than unfiltered. Not completely sure what to make of this result.
posted by Lame_username at 4:28 PM on September 26, 2012

It just tastes much more "lemony" to me.

Well you can't argue with results (though I'm becoming increasingly suspicious that you've merely discovered a convenient excuse to get your wife drunk on neutral grain spirits on a Wednesday night...) I still wonder if it mightn't be worth looking into just using activated carbon. I'd think it pretty much gets down to how much carbon you use and how long you leave it in contact. I've seen recommendations of leaving the carbon in distilled alcohol for a week. Might be worth some reading and an experiment.
posted by nanojath at 10:39 PM on September 26, 2012

Best answer: As far as a first pass filter I would get a large funnel and just use some cotton instead of filter paper. When the cotton gets clogged just take up a little bit of it to reveal a lower unclogged layer and it will keep going. FOr filter papers I would just get something student grade and not worry about ashless or anything else like that. (Ashless papers are neat because you can use them to determine the total mass of filtered solids by putting them in a high temperature oven until they burn up and disappear nothing that you are really interested in anyways.)

Buchner filtration would be a good idea, but then you would need a vacuum source (usually a venturi pump) and they can still get clogged. You needn't worry about the ethanol evaporating as it would still evaporate at the azeotropic ratio. You might get less of a yeild but only something like 1-2% so not that big of a deal overall.

If you are going to get really serious about doing liquor filtration I would recommend getting a proper column to hold your carbon. The frit at the bottom will prevent the carbon from coming through (I would cover the frit with sand as an extra precaution) and the extra vertical height will ensure more more efficient removal of higher order alcohols and esters.
posted by koolkat at 1:31 AM on September 27, 2012

Response by poster:
(though I'm becoming increasingly suspicious that you've merely discovered a convenient excuse to get your wife drunk on neutral grain spirits on a Wednesday night
Technically speaking, the taste test was her idea. Perhaps she was seeking to get me drunk and take advantage.
posted by Lame_username at 8:56 AM on September 27, 2012

Like I say, don't argue with results...
posted by nanojath at 12:04 PM on September 27, 2012

(Seriously though cotton jelly bags are awesome and pretty cheap, even if they're only good enough for a primary strain of the limoncello it will speed up your final run through something finer porosity).

koolkat is making me pine for the chemistry bench, I wouldn't have thought it possible...
posted by nanojath at 12:09 PM on September 27, 2012

Response by poster: Follow Up: I went ahead and changed the Britta filter after bottle 6 and filtered the remaining bottles as usual. Today I was able to assemble a panel of 7 taste testers. 6 of them can reliably distinguish filtered from unfiltered. None of them can reliably distinguish bottle 1 from bottle 6, although 4 people insist that they can. Despite their certainty of their preference, they don't reliably pick the same one in independent trials. The 7th tester is just going to have to be eliminated from future tests.
posted by Lame_username at 1:39 PM on September 29, 2012

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