Guest guest Posted June 28, 2004 Report Share Posted June 28, 2004 Someone on another list said she used to enjoy kombucha tea until she did some more research and found things like this article: http://www.fungi.com/info/articles/blob.html Here is part of it: ....One of the major problems with trying to culture Kombucha at home is the fact that the sugar medium is non-selective. The culturing of yogurt or sourdough can be done with a modicum of success, because the milk and flour media selectively favors the desired organisms. Not so with sugar, tea and water which is an " open slate " for the culturing of most microorganisms - including pathogenic Aspergillus, Candida, Cryptococcus, and Fusarium species. The first week is the most critical time during which contaminants in Kombucha race for dominance. As the PH of the broth descends into acidity, the risk of pathogenic organisms proliferating is real and measurable. The primary vectors of contamination are of course, the air. Cheese cloth is an ineffective filtration membrane for preventing airborne contamination. Airborne contamination can be prevented by forcing air through a sub-micron filter, the type which are commonly used in Laminar Flow Hoods in sterile tissue culture. Without such filtration (99.99% at ..3 microns), contamination is probable. It is easy to prove this danger by simply pouring the sugar media into sterile Petri dishes (with a gelatinizer like agar agar added). Exposing these dishes briefly to the air in your kitchen will result in a plethora of contamination growth in only 4-5 days. These organisms are made more visible on the surface of the media because of the gelatinizing agent-agar. In liquid culture, they are proliferating even more rapidly, but more invisibly, because they are submerged. The other vectors of contamination are: the mother culture, the insufficiently sterilized media, your hands, and the vessel in which the brew is made. Few people are aware that more than 1,000,000 particles exceeding .3 microns are floating in the air per cubic foot. These are generally not dangerous unless they become more concentrated or if the impacted human is immunocompromised. Although the majority of these contaminants may not be dangerous, it takes only one pathogenic species proliferating to a toxic level to cause serious harm. Making Kombucha under non-sterile conditions becomes, in a sense, a biological form of Russian Roulette. For those who are ill, drinking Kombucha prepared at home could be one of the worst things they could do! According to the recipe, I boiled water for 5 minutes to make a Black Tea (Earl Grey also works) fortified with what seemed to be an unusually ample amount of white sugar. To each liter (quart) of water, after boiling for 5 minutes, add 70 grams (2 1/2 oz) of sugar, add 1 tea bag (= 5 grams or 1/6 oz). Let steep. Once cool, pour about 1/10 equivalent of Kombucha tea as inoculum. Stuff the opening with cotton or gauze. Incubate for 7-10 days at room temperature. The fluid will bubble from carbon dioxide production during the active fermentation period. If not wishing to actively grow Kombucha, the fermenting jars can be stored in the refrigerator for prolonged periods. The gelatinous Blob will soon float on the surface as a cohesive sheath. Older colonies, with a higher density, will shelf off from underneath and sink to the bottom. Kombucha is unlikely to become contaminated with bacteria if the tea broth has a sufficiently high sucrose content (approximately 10+ percent sugar), making it a naturally inhospitable environment. Furthermore, the tea-with its high acidity, alcohol content and antibiotics-makes bacterial contamination even less probable. Another factor, beyond contamination, is that the extreme acidic nature of the broth has the potential to cause acidosis-a condition where the blood can not adjust its pH. This is one of the suspect causes being investigated with a woman in Iowa who died from drinking Kombucha (See Newsweek, April 25th, 1995, pg. 6). Ironically, the same acidic conditions that prevent bacterial contamination may give rise to its own toxic side-effects. High acidity of the broth aside, I have seen several of my vessels spontaneously contaminate with molds. Of most concern are the species of Aspergillus I have found floating around with Kombucha. I fear that amateurs could think that by merely pulling out the Aspergillus colonies with a fork, that the culture would be de-contaminated, a dangerous, even deadly presupposition. The water-soluble toxins of Aspergillus can be highly carcinogenic. Several species are known killers. Since the public can not be expected to distinguish a clean fermented culture from one which is not, I fear that the unreserved use of this tea will result, has resulted in illness, if not death. (See Newsweek, April 25th, 1995, pg. 6.) Should your Kombucha become contaminated-most often the contaminants are green, pink or black mold-islands floating on the surface of the tea-you can try to re-purify the culture by removing a portion of contiguous sheath and introducing it to a newly prepared batch of tea. Prior to insertion, you should thoroughly wash the sheath with cold water. If the sheath you chose falls apart, then you have likely selected one that is infected. The sheath should have good cohesiveness and feel rubbery to the touch. Once placed into the new batch of tea, incubate as before and watch. The general rule of " when in doubt, throw it out " holds true here. Even with this technique, one should not presume that the Kombucha Blob has been fully purified of contaminants. Herein lies my greatest concern: in all of the " home grown " literature-photocopies, mimeographs, and handwritten sheets-accompanying the many Kombucha samples I have received, not one mentions the possibility of contamination nor methods for re-isolation. Furthermore, with the complex associations between these multiple organisms, it is possible that other bacteria and yeast species may join in the symbiosis with unpredictable effects. In short, if you are dying from an illness not currently treatable with antibiotics, pure, uncontaminated cultures of Kombucha may help you. Otherwise, I think the danger of misuse should be a prevailing concern for us all. Quote Link to comment Share on other sites More sharing options...
Guest guest Posted June 28, 2004 Report Share Posted June 28, 2004 >Someone on another list said she used to enjoy kombucha tea until she did some more research and found things like this article: > ><http://www.fungi.com/info/articles/blob.html>http://www.fungi.com/info/article\ s/blob.html The CDC did a study on some cultures which I read sometime back, though it doesn't seem to be on their website anymore. They tested 100 cultures or so for nasties, and didn't find any. The acidity of the culture inhibits the pathogenic bacteria. Molds are another matter! I don't mess around with molds. I'd kind of wonder though, if mold forms, if the culture was healthy to begin with. I make kefiili and I make vinegar and I make kefir beer ... none of those has ever grown any mold, even though I've left kefiili cream in the fridge for several months (ditto with kimchi). Bottled beer never molds either, in my experience. I have had some cultures I've made mold, and then they get tossed! I don't worry too much about the " nonsterility " of the conditions. Yeah, some salmonella might float into my kefiili culture. If it does, and if the culture is healthy, it will kill the salmonella, or render it harmless. Dead bacteria, when ingested, act as a kind of vaccine, it is thought (that is how vaccines work ... they train the body to recognize baddies). Your intestines get live bad bacteria in them all the time ... unless the bacterial population is unhealthy there, or they are just totally overwhelmed, your system handles the baddies quite easily. Eating probiotic foods that are " used to " handling environmental pathogens makes you more able to withstand those pathogens too! However ... I've never made kombucha so I'm not commenting on that in particular. -- Heidi Jean Quote Link to comment Share on other sites More sharing options...
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