About a year ago, when I was younger and more naive about just how passionate internet forums can get, I quoted a bunch of medical studies which had identified the serious health hazards of drinking metal-filtered or unfiltered coffee.
I was attacked on all fronts. The coffeekid himself led the charge and accused me of ignoring the teachings of the experts. Of course, all of the studies I quoted were written by Phd scientists and were refereed and published in leading medical journals. But that didn't seem to matter to him or to my other attackers.
Perhaps some of you who have come late to this debate weren't aware of these studies. It is for your benefit that I include the attached Microsoft Word file.
I would also like to state in advance that I do not plan to participate in debates about the validity of these medical studies. I simply make them available and leave it to you to decide how to use the information. However I was sufficiently impressed by the depth of this scientific work to decide that I could never sell metal filters with a clear conscience.
I am simply the messenger. Don't shoot the messenger.
Thanks, Alan. Although I'm personally not as concerned about this issue as I suspect you'd think I ought to be, what I've always appreciated is how you let your convictions about the conclusions you've reached on this question guide your decisions with integrity in a market where a lot of companies would be pleased to satisfy any demand for a product that could net a profit.
richedie Senior Member Joined: 17 Jun 2006 Posts: 681 Location: Pennsylvania Expertise: I love coffee
Posted Tue Nov 28, 2006, 10:10pm Subject: Re: Aerobie Aeropress
Thanks Alan,
I'll read through it as soon as I have more time. It sounds like, based on this document.....it is wise to only drinknk basically drip coffee? How many methods use a paper filter? Even the Chemex and Melitta filters allow some oils through for flavor. How does this relate to espresso!?
Posted Tue Nov 28, 2006, 10:20pm Subject: Re: Aerobie Aeropress
Yirga Said:
What I'd like to know is, starting with paper filters, what inspired metal, then polyester -- especially, polyester! Why not cotton, silk, nylon, rayon, or eel skin?
In March of this year, Alan had posted some results with low-grade spun polyester felt, which "pass about as much particulate as the metal filters." That didn't interest me and I didn't participate in the thread, which quickly drifted into cholesterol arguments.
I started trying polyester felt designed for filtering a couple months later -- I believe the "Aeropress versus French Press: Tipping the balance?" thread was the catalyst. I tried 50, 25 (I think), 10, 5 and 1 micron felts (some of those covered in the "Polyester felt filtering material in Aeropress" thread where this was chronicled). The 1 was a bit difficult to work with in an Aero, and proved unnecessarily fine. 10 passed fines. 5 was sweet.
The first thing that makes felts, specifically, more interesting than either metal, paper, or woven fabrics such as cotton is that felts have depth to them, whereas these others are surface filters. It makes a huge difference in performance. Felts are far less prone to stall in the presence of fines, which quickly clog surface filters. Felts trap particles in a depth of fibers, so they end up having more surface area to fill before the media clogs up. Thus, felt is far more forgiving of bad grinders from a standpoint of throughput, though of course extraction problems attending a wide particle size distribution (such as bad grinders produce) aren't in the least helped by one's choice of media.
The first thing that recommends polyester as opposed to other felts is low cost and a sound temperature range. There are no significant advantages to alternative fibers, that I've seen, that would justify the additional expense of other fibers. Among other things, since nylon felts (to cite an example) are not as common, they're not available in as wide a range of porosities. Other industries long ago ferreted out the cheapest and most effective media, and polyester came out as quite a winner.
Polypropylene felt is another serious candidate, but would only work for cold brewing or, possibly, brewing in the low register of the Aeropress's published temperature range. At somewhere upwards of 200 degrees the fibers would collapse and the filter would, as far as I can tell (haven't tried), completely fail (probably just totally clog)
In short then: felt because it offers more reliable, faster throughput than surface filters (whether paper, metal, or woven fabric). Polyester because it's relatively cheap and works well at brewing temperatures. 5 microns because that's the nominal rating that represents a threshhold of fines not being present in the cup.
Posted Tue Nov 28, 2006, 11:23pm Subject: Re: Aerobie Aeropress
Hi Rich,
Every study that I'm aware of has reported that paper filtering virtually eliminates the harmful lipids. You'll see that when you read my attachment.
I also sent two AeroPresses to The Department of Agrotechnology and Food Science, Wageningen University in the Netherlands. They conducted the same tests on the AeroPress brew which they had conducted on all of the other brewing methods in their prior study which I quoted in the attachment.
They found that the AeroPress brew had similar levels of lipids as paper filtered drip brew. This seems reasonable to me. We use the same oxygen bleached paper that is used in high-quality cone filters.
The exact AeroPress levels were:
For a new filter: Cafestol = 0.122 mg Kahweol = 0.125 mg
At my request they also used the same filter for ten pressings without washing. The lipid levels gradually rose with each pressing to the following after the tenth pressing: Cafestol = 0.36 mg Kahweol = 0.37 mg
They then washed the same filter and pressed an eleventh time. The lipid levels were: Cafestol = 0.20 mg Kahweol = 0.22 mg
All of the above levels are for a serving of 150 ml Americano or an undiluted single-scoop "AeroPresso". These serving sizes are identical to those used in their prior report.
Jasonian Senior Member Joined: 8 Aug 2005 Posts: 3,856 Location: Lubbock, TX Expertise: Professional
Posted Wed Nov 29, 2006, 2:32am Subject: Re: Aerobie Aeropress
It's your right to sell(or in this case, not sell) what you want for whatever reason you may have.
I think it shows good character that you attach research showing your reasoning for not providing metal filters.
Despite all of that, in support of the coffee purist in me, and fully subscribing to the idea that life in itself is deadly, I am still holding out for metal filters.
I did, however, have the chance to play around with an Aeropress over the holiday weekend.
It's not espresso. It's not drip. It's not FP. It's something quite different, and entirely unique. It takes a bit of getting used to having no frame of reference for the type of brew it is.
I was still able to get quite an "oil slick" with the provided paper filters, but still.. the coffee geek in me needs the permanent metal filter.
The first thing I did when I bought my most recent drip brewer (presto scandinavian) was to purchase a permanent metal mesh (gold tone, though not Swiss Gold) filter for the thing. It's never seen a paper filter.
My Melitta manual pourover, on the other hand, sees unbleached Melitta flavor-pore filters.
That's about the only paper I use for filtration, and even then, only for a Melitta manual pourover cone.
I find that more subtley of flavor is present in the cup through a filter with larger holes. Maybe it's just me.
Good luck, NOT getting SHOT! On a regular basis, it's often, lock and load, on here!
I'm thinking you are sincere at saving the sinners on here from the evils of LDL cholesterol from coffee oil. Trouble is, coffee oil for coffeegeeks is like the, spice, in the tale, Dune! The quest and use of it becomes the primary reason for existence! Mess with a man's spice, and he'll shoot you and throw you to the giant worms to finish off!
Unfortunately, oil in foodstuffs is the main carrier of taste and mouthfeel. Butter, cheese, beef, pork and mutton are savored considerably for their oil/fat flavors, regardless of how much the drums are beat concerning the cardiovascular risks that medical science reveals that these oils/fats pose.
I'm sure you realize coffeegeeks are mostly into taste and mouthfeel of coffee and not searching for health tips! To make a case against coffee oil is to attack taste and mouthfeel and that'd be at one's peril, as you've observed. What I was surprised at in one of the findings of your quoted Netherlands studies, is that the highest percentages of unhealthy stuff in brewed coffee came from French Press and NOT Italian espresso! Wouldn't espresso have more coffee oil than press pot?
Oh, and isn't Netherlands, Michael Jackson's estate he abandoned in California before escaping to Bahrain?
CaptainCowPie Senior Member Joined: 12 Dec 2005 Posts: 61 Location: Charlottesville, VA Expertise: I live coffee
Espresso: Mypressi Twist for now Grinder: Super Jolly Vac Pot: Not Yet Drip: Aeropress & Clever Coffee... Roaster: Heat Gun / Bread Machine
Posted Wed Nov 29, 2006, 8:13am Subject: Re: Aerobie Aeropress
Yirga Said:
I've been inspired by CaptainCowPie -- not by what he says but by his name! Could a cowpie Aero filter be a much better one than paper, metal or polyester?
I will volunteer to test a cowpie filter if you will test a mud filter. All in the name of great coffee. ;)
I am finding that I really like a finer grind with the polyester filter, finer than I used for espresso. I invert the Aeropress, pour in some water to cover the bottom, add the coffee, pour in some more water and quickly stir for about 10 seconds. After the bloom subsides a bit, I pour in more water to fill the Aeropress to the top. Then I press to get some oil out, invert it over the cup and press for about 30-45 seconds.
The coffee has really turned out great. The finer grind has allowed for a shorter extraction, and that seems to suit my tastes better. Next I am going to experiment with stirring the mixture more
Was surprised at one of the findings of your quoted Netherlands studies, is that the highest percentages of unhealthy stuff in brewed coffee came from French Press and NOT Italian espresso! Wouldn't espresso have more coffee oil than press pot?
A probable explanation for this is that the tamped puck in the espresso brewing process filters the brew pretty well -- despite the widespread belief that the high pressure extracts more oils than other brewing methods. Also, the exposure time of the grounds to hot water is typically about about 25 seconds in the espresso process and five minutes in the FP process. The Netherlands study used boiling water and five minutes steep time.
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