From - Sat Apr 4 16:09:34 1998 Path: senator-bedfellow.mit.edu!bloom-beacon.mit.edu!news.kodak.com!news-pen-14.sprintlink.net!206.229.87.26!news-east.sprintlink.net!news-peer.sprintlink.net!news.sprintlink.net!Sprint!newsfeed.internetmci.com!192.52.106.6!ncar!noao!stsci.edu!usenet From: hodge@bowline.stsci.edu (Phil Hodge) Newsgroups: rec.food.drink.tea Subject: Re: caffiene in tea vs. steeping time Date: 30 Mar 1998 18:02:10 GMT Organization: Space Telescope Science Institute Lines: 102 Message-ID: <6fomn2$462@tnm.stsci.edu> References: <351F2E7F.DC4647A5@llnl.gov> NNTP-Posting-Host: bowline.stsci.edu Matt Harbowy posted an article (10964) about a year and a half ago that is relevant to this question. I include his article below. My interpretation of this is that the extraction of caffeine does extend over a sufficiently long period of time (many minutes) that only a small fraction would be extracted in the first half minute. So discarding the brew after 30 seconds does not significantly reduce the caffeine content. Phil Article: 10964 of rec.food.drink.tea From: harbowy@ix.netcom.com (matthew e. harbowy) Subject: Tea and caffeine (an update) Date: Fri, 13 Dec 1996 03:20:17 GMT Organization: ocha no kagakusha desu Reply-To: matt@teatime.com (sent to r.f.d.t and teatime-list, visit http://www.teatime.com/social for more info on the teatime-list mailing list on tea) In a recent article in Food research International, Vol 29, 325-330 (1996), the content of caffeine in various teas and styles of brew were compared. One of the formosa oolongs had less caffeine than the green and black teas on a dry weight basis, but when all were prepared to supplied directions, they had similar caffeine levels. When brewed for a series of three repeated brews, the caffeine concentration was higher in the first brew for one of the other Formosa oolongs than other green, black, and oolong teas. The caffeine content decreased dramatically from the first to the third brew, about 50-70mg/cup in first cup, 15-25 in second, and 5-10 in third, each brew about 5 minutes in length. Bag teas had slightly less caffeine than loose teas. This could be due to the use of broken and poorer quality leaves in bags. Theobromine was also measured, which was very low: 1.5-3mg/cup for first brew, 0.5-1 in second, 0.2-0.5 in third. Black teas had slightly more thobromine, attributed to the fact that younger leaves have more theobromine, and the young leaves are chosen for black tea production due to higher polyphenol levels. One other interesting result was that no (less than dection limit, 0.1mg/cup) theophylline was detected in any of the brews. This paper was of interest to me because it challenges many of the popular assertions about the caffeine content of teas. I will reinforce previous assertions I have made about caffeine contents of teas: 1. All teas have roughly similar caffeine contents, and one cannot rely on the belief that green tea has less caffeine, as asserted by many popular claims. One such claim is that degree of fermentation governs caffeine content, with green having 1/3 and oolong having 2/3 the caffeine content of black tea. This has been debunked repeatedly in this forum. Small differences in average caffeine contents of green vesus black tea may be due to the use of China varietals for green and Assam varietals for black, a line which comes closer to elimination with indian green teas and darjoolongs. Another is the use of younger or more mature leaves, where ther is some variation. Caffeine is a product of the natural metabolism of RNA in the plant and thus will vary with senescence. Some caffeine may also be made during fermentation, but it is not a sufficiently orderly process to clearly delineate such even multiples as 1/3, 2/3, etc. Fermentation time is decided by taste and plantation experience, not by biochemistry, and is not controlled to scientific tolerances. 2. Caffeine content does depend on brew technique and leaf size and variety, and that without an accurate analysis as such available from a qualified laboratory, one cannot assert that some teas have a lower or greater caffeine dose. 3. One popular assertion suggests that tea can be decaffeinated by brewing quickly and discarding the first brew. Since tea must be decaffeinated greater than 90% to be considered decaf (and most commercial decafs are >98% decaffeinated), the second brew, although lower in caffeine, is *not* decaffeinated (65-75% of caffeine coming out in the first five minute brew). Making informed decisions about what is a suitable level of caffeine in one's diet is a personal decision, and although doses of less than 200mg/day of caffeine have generally not been associated with health risks, one should *always* consult with a doctor and *not* consider any of this (or other literature) to be advice on your personal health. I urge the informed tea drinkers to be wary of advice on caffeine levels in tea, particularly results which say that green or oolong tea has less caffeine, and complain vociferously when such advice is given to those misinformed tropes who ply such nonsense. Thank you for your continued informed interest in this topic: please do not reprint this in anything but electronic form. matt (matt@teatime.com) "I'm the bear that went over the mountain" http://www.teatime.com/matt/