Black Drink
http://en.wikipedia.org/wiki/Black_drink
About a tablespoon of finely ground roasted
Yaupon leaf is boiled in a pint of water for five minutes, and allowed to cool and settle. Hot liquid is decanted off sediments and served. This is medium-strength.
Taste is bitter and has astringency similar to Green Tea. Aroma is distinctive, earthy.
Yaupon leaf decoction is diuretic and stimulative because of the caffeine. High levels of antioxidants are reported.
There is no emetic or laxative effect.
Absence of evidence collected by the FDA requires insertion of the standard non-evaluation disclaimer for non-patentable plants as useful medicines. Yaupon has centuries of safe use in America and should be on the Generally Regarded As Safe (GRAS) list (my opinions).
There are numerous ways to brew black drink. Starting with the harvest of the leaf, and the time of year, generally concentration of caffeine and dark phenolic compounds increase during the summer (my observations, hypothesis in need of proof). Leaf begins to get strong and has dark phenolic compounds in June, but much more so by late August. Best time to harvest is August up to October. Once you have Yaupon leaf there are several ways to prepare black drink. Raw leaf decoctions and infusions (cold and hot), or Dried leaf preparations (PPO active, or roasted), or a mixture.
Yaupon leaf has, I believe (my observations, hypothesis in need of proof), Polyphenol Oxidase (PPO) activity http://en.wikipedia.org/wiki/Polyphenol_oxidase. PPO is the same enzyme responsible for the "fermentation" of tea leaves to make black tea. N.B. this is a plant enzymatic "fermentation," not a microbial activity. PPO activity is optimal at about 135 F, and requires a minimum amount of moisture to function. My current preparation method, I believe, allows PPO activity. As soon as possible after picking leaves, they go into small food dehydrator which blows warm air over the leaves, and has a temperature control 100 F up to 150 F. At lowest temperatures, drying takes a very long time, and the leaves stay green and never turn black. At 135 F the leaves are mostly blackened around thirty minutes, and by two hours almost 50% of the moisture by weight has been lost and the leaves are crunchy and ready to grind. At higher temperatures (say 200-300 F in an oven) PPO gets inactivated, and the leaves stay greener. Once I harvested too many leaves to go into the dehydrator that evening, and the second batch remained at room temperature overnite, and when they were dried at 135 F, the leaves never blackened (why, I don't know, but I suspect proteolytic inactivation of PPO). Another way I prepare Yaupon leaf is to roast them in a wok or dutch oven on a stove or over a woodfire at higher temperatures with stirring. The leaf mix may exhibit some enzymatic blackening, but mostly browning, and some charring. Prepared this way, smoky flavors and caramel flavors are more pronounced. It is also possible to let the leaf blacken at 135 F for thirty minutes, and then to take the leaf and bruise it by hand or mortar and pestle, and then roast the still moist bruised blackened leaf over higher temperatures. Bruising can be used at any point in the preparation help promote rupture of the plant cell walls and release of compounds.
In 1923 George F. Mitchell, and J.W. Sale published a series of pamphlets for the Bureau of Chemistry of the USDA. These are available from the National Agricultural Library http://www.nal.usda.gov/ via your local library using the InterLibrary Loan (ILL). Presently (Aug 31, 2012) I have not seen these documents. Mitchell and Sales describe three "curing" processes to create: green, black, and cassina mate.
At the time Mitchell and Sale were calling the Yaupon by its other name Cassina.
The Chemistry Bureau was the precursor to the FDA which was formerly named in 1930.
These pamphlets are titled:
Beverages produced from Cassina
Manufacture of concentrated Cassina extract
The American Cassina Plant as the Source of a Table Beverage
Also look for this document from the NAL:
Ilex cassine: The Aboriginal North American Tea, Its History, Distribution, and Use Among the Native North American Indians, written by Edwin Moses Hale, which was published by USDA Division of Botany as Bulletin #14 in 1891.
This is available online at http://babel.hathitrust.org/cgi/pt?id=uiug.30112106909457, ebooks and google, but is difficult to print. Hale reports that Southern Indians brewed an alcoholic beverage from cassine (Yaupon).
Here is a GoogleBook transcript of the Hearings for the Agricultural Appropriation Bill of 1924: Investigation of Yaupon as a Beverage. They discuss steam treatment of Yaupon leaf and how to 'ferment' steam-treated Yaupon leaf. http://tinyurl.com/qad8x5m
Brewing methods: Several years ago becoming comfortable with Yaupon Holly Black Drink, I would make weak decoctions, i.e. the above 1 tbs (ground leaf) per pint (browner than black). Now, I prefer Black Drink with a stronger kick to it, and will boil at least three tablespoons into a quart of water. When you boil the ground dried Yaupon leaf, initially it is very hydrophobic and must be stirred just to get surfaces of the grounds wet and hydrated. As it heats and approaches boil, fine bubbles appear, and then foamy froth. The bubbly brew will boil-over quite quickly with high heat and you do not watch and stir the kettle. Try medium high heat. On my electric stove, setting 5 out of 9 is ideal to avoid boil-over. A strong boil with frequent stirring has better extraction yields. An alternative to stirring is to keep a cup of cool water to quench the frothy foam (consider your final volume). You can make a concentrated extract, and then dilute it later (takes longer concentrate a dilute brew). For a single day, three tablespoons is enough for one person. Sometimes I brew bigger batches for friends, or to tide myself over for several days (3/4 cup per gallon). The Yaupon decoction is quite stable at 4C in the refrigerator. A ratio of nine tablespoons of ground leaf and a final volume of two to three quarts is potent enough to promote wakefullness. The American natives boiled the leaf by all historic accounts. Boiling bursts intact cell-walls and extracts and solubilizes chlorogenic-caffeine complexes; these complexes will precipitate as tea cream when the Black Drink cools.
Bring the water to a boil for several minutes before adding the ground Yaupon leaf and reduce the heat to half. This reduces the tendency to boil-over. Also if you are on municipal water supply, it will drive off the chlorine so chlorinated compounds do not badly flavor the decoction. Usually I use water which is treated by reverse osmosis for purity.
Formation of trihalomethanes in foods and beverages.
Huang AT, Batterman S
Food Addit Contam Part A Chem Anal Control Expo Risk Assess. 2009 Jul;26(7):947-57.
Department of Environmental Health Sciences, University of Michigan, Ann Arbor, 48109-2029, USA.
Trihalomethanes (THMs) are suspected carcinogens and reproductive toxicants commonly found in chlorinated drinking water. This study investigates THM formation during the preparation of beverages and foods using chlorinated drinking water. A total of 11 foods and 17 beverages were tested. Under the experimental conditions, each food and beverage formed THMs, primarily chloroform, although low or trace levels of brominated THMs were also detected. Tea formed the highest THM levels (e.g., chloroform levels from 3 to 67 microg l(-1)), followed by coffee (from 3 to 13 microg l(-1)), rice (9 microg l(-1)), soups (from 0.4 to 3.0 microg l(-1)), vegetables (<1 microg l(-1)), and baby food (<0.7 microg l(-1)). Chloroform formation with instant tea, used as a highly reproducible model system, increased with free chlorine concentration, decreased with higher food (tea) concentration, and was unaffected by reaction (steeping) time and bromide ion concentration. These findings indicate that chlorine-food reactions are fast, but that formation decreases as the chlorine demand of the food system increases. THMs are formed in the preparation and cooking of a wide variety of foods if free chlorine is present, and our results suggest that tea can be a significant source of exposure to THMs.
PMID:19680970 [PubMed - indexed for MEDLINE]
Infusions: I've never tried cold infusions (with coffee this takes time, several days). Tisanes or teas (hot infusions in nearly boiling water) yield weak tawny teas, just as short decoctions yield weaker brown brews. There is a greener generic plant taste to a Yaupon tea because fewer bitter compounds and complexes are present. Boiling might be necessary to degrade undesirable compounds or drive off smaller volatile molecules.
Steam infusion: What does work is to use a little home espresso machine, load it with one to two tablespoons of slightly course ground leaf and to to a steam infusion extraction with deionized water (about a cup). This yields a brew which is about as active as a strong cup of coffee. I recommend a courser grind for espresso because you will clog the filter up, especially with fine grounds harvested late in the season. Sticky resinous residue is evident on the filter of steam infusions. This method extracts the most water soluble compounds in a rapid period of time.
Percolation is a favored brewing method of many coffee brewers (Greene Deane (EattheWeeds)), I have yet to try this myself (I don't possess the apparatus). A friend who tried my Yaupon Holly Black Drink decoction for the first time at a bold strength ended up staying awake for over 48 hours. When I gave him Yaupon leaf (coarsely hand crushed) the brew he percolated was brown, not black, and he was disappointed that it did not keep him awake for writing work. Like all these methods, the fineness of the grind matters. Fine grind gives you smaller particles and greater total surface area and better extraction (more cell walls have already been pulverized), but you run the risk of clogging up the filter holding the bed of grounds. Courser grind is more porous, but takes longer to extract.
Metals: because chlorogenic compounds can chelate metals, be aware of your brewing containers. American natives boiled Yaupon Black Drink in clay vessels. Chlorogenic chelates of iron are considered antioxidant because it keeps the iron in a high spin state incapable of scavenging radicals and forming hydroxy radicals via Fenton reactions. Copper complexes with chlorogenic on the other-hand are pro-oxidant. All this complex chemistry confuses, so simply: use pure water (reverse-osmosis, rain-water) and stainless steel, if you don't have ceramic cookery.
Additions: I like to add citrus to my Yaupon. I learned this on my own, and later discovered that folks in North Carolina Outer Banks do the same thing (see the book Black Drink ed. Hudson). Citrus such as Calamondin http://en.wikipedia.org/wiki/Calamondin tastes best, followed by lime, lemon, orange, and grapefruit. The citrus is a tastant, and the combination will taste much better than either Yaupon alone, or citrus water alone. The citrus will change the color of the infusion from deep dark black towards orange colors. This is known as a bathochromic shift and is due to the pi-bonds changing position in the polyphenols as carboxyl groups are acidulated. It is a known phenomena in tea when lemon is added. Mate is often drunk with lemon in South America, and in Brazil, coffee with lemon is a popular. Also catechins in tea have increased bioavailability in citrated tea drinks than plain tea. Yaupon with lemon tastes alot like good old southern iced tea. http://dx.doi.org/10.1002/mnfr.200700086
The ascorbic acid and citric acid in citrus will acidulate free carboxylate-ion groups in the polyphenolic compounds such as the caffeoylquinic acids (chlorogenic acid and its relatives). A carboxylate-ion group with free electrons can coordinate with metals. Chlorogenic acid actually binds iron tightly, keeps it in a high-spin state and unavailable for reaction - (Fenton chemistry (known), microbes (unknown)). One can actually become anemic if one were to imbibe too many chlorogenic acids (i.e. from coffee, or yaupon).
Here is a long article on the Chlorogenic acid. http://jn.nutrition.org/content/137/10/2196.long Chlorogenic Acid Compounds from Coffee Are Differentially Absorbed and Metabolized in Humans
It is recommended to actually eat solid foods in conjuction with these beverages instead of relying on the energizing activity of caffeine. I find it is easy to fast when drinking Yaupon, and my lunch meals move late into the afternoon because I feel like I have the energy to keep going. This summer I've actully lost five pounds down from 150 while drinking Yaupon, but I feel better for it.
Other additions I like to my Yaupon include Mints, Stevia (both of which are also used in South America with Mate). Honey works well also, and one might include a little bit of seasalt. A recipe of mine is Yaupon, Honey, Mint, and a little but of Rum - this I call a Rummyeopon, and is quite enjoyable.
Sugars dissolved in hot Yaupon black drink evolve a small quantity of gas (my observation).
Be Aware, Caffeine is toxic at high concentrations, and that Caffeine concentrations do vary in different populations of Yaupon depending on genetics, gender, location, fertilization, age, sunlight, and time-of-year. The strength of a brew prepared from weak leaves in March will not be equivalent to that from October for the same plant. The darkness of the decoction is some indication of strength, but it is hard to judge without serial dilutions or spectrophotometer. Strong Yaupon decoctions do not make me regularly want to retch like strong infusions of Coffee Bean or Green Tea. I count twice that I have had to hurl after Yaupon in the past three years of daily drinking Yaupon and both times my body was stressed from either too much exertion (heavy hiking in Cattaloochie), or staying up and partying too much without sleep. Whereas dozens of times coffee has induced nauseau (often just from the aroma), and little less so for Green Tea. Recently I brewed up a strong decoction of Yaupon Black Drink (~10 tbs per 2 qt) and was drinking it into the afternoon; I had a hard time falling asleep that night. The rule of thumb is not to consume Caffeine four hours before needed sleep. Incidently there are two populations when it comes to Caffeine metabolism - fast and slow acetylators (N-acetyltransferase). If you are especially sensitive to caffeine you may be a slow acetylator and have a more difficult time clearing Caffeine. Women generally clear caffeine slower than men, and women on oral contraceptives clear Caffeine significantly slower.
edited August 31, Sep 1, 2012 , sep9
Yaupon leaf has, I believe (my observations, hypothesis in need of proof), Polyphenol Oxidase (PPO) activity http://en.wikipedia.org/wiki/Polyphenol_oxidase. PPO is the same enzyme responsible for the "fermentation" of tea leaves to make black tea. N.B. this is a plant enzymatic "fermentation," not a microbial activity. PPO activity is optimal at about 135 F, and requires a minimum amount of moisture to function. My current preparation method, I believe, allows PPO activity. As soon as possible after picking leaves, they go into small food dehydrator which blows warm air over the leaves, and has a temperature control 100 F up to 150 F. At lowest temperatures, drying takes a very long time, and the leaves stay green and never turn black. At 135 F the leaves are mostly blackened around thirty minutes, and by two hours almost 50% of the moisture by weight has been lost and the leaves are crunchy and ready to grind. At higher temperatures (say 200-300 F in an oven) PPO gets inactivated, and the leaves stay greener. Once I harvested too many leaves to go into the dehydrator that evening, and the second batch remained at room temperature overnite, and when they were dried at 135 F, the leaves never blackened (why, I don't know, but I suspect proteolytic inactivation of PPO). Another way I prepare Yaupon leaf is to roast them in a wok or dutch oven on a stove or over a woodfire at higher temperatures with stirring. The leaf mix may exhibit some enzymatic blackening, but mostly browning, and some charring. Prepared this way, smoky flavors and caramel flavors are more pronounced. It is also possible to let the leaf blacken at 135 F for thirty minutes, and then to take the leaf and bruise it by hand or mortar and pestle, and then roast the still moist bruised blackened leaf over higher temperatures. Bruising can be used at any point in the preparation help promote rupture of the plant cell walls and release of compounds.
In 1923 George F. Mitchell, and J.W. Sale published a series of pamphlets for the Bureau of Chemistry of the USDA. These are available from the National Agricultural Library http://www.nal.usda.gov/ via your local library using the InterLibrary Loan (ILL). Presently (Aug 31, 2012) I have not seen these documents. Mitchell and Sales describe three "curing" processes to create: green, black, and cassina mate.
At the time Mitchell and Sale were calling the Yaupon by its other name Cassina.
The Chemistry Bureau was the precursor to the FDA which was formerly named in 1930.
These pamphlets are titled:
Beverages produced from Cassina
Manufacture of concentrated Cassina extract
The American Cassina Plant as the Source of a Table Beverage
Also look for this document from the NAL:
Ilex cassine: The Aboriginal North American Tea, Its History, Distribution, and Use Among the Native North American Indians, written by Edwin Moses Hale, which was published by USDA Division of Botany as Bulletin #14 in 1891.
This is available online at http://babel.hathitrust.org/cgi/pt?id=uiug.30112106909457, ebooks and google, but is difficult to print. Hale reports that Southern Indians brewed an alcoholic beverage from cassine (Yaupon).
Here is a GoogleBook transcript of the Hearings for the Agricultural Appropriation Bill of 1924: Investigation of Yaupon as a Beverage. They discuss steam treatment of Yaupon leaf and how to 'ferment' steam-treated Yaupon leaf. http://tinyurl.com/qad8x5m
Brewing methods: Several years ago becoming comfortable with Yaupon Holly Black Drink, I would make weak decoctions, i.e. the above 1 tbs (ground leaf) per pint (browner than black). Now, I prefer Black Drink with a stronger kick to it, and will boil at least three tablespoons into a quart of water. When you boil the ground dried Yaupon leaf, initially it is very hydrophobic and must be stirred just to get surfaces of the grounds wet and hydrated. As it heats and approaches boil, fine bubbles appear, and then foamy froth. The bubbly brew will boil-over quite quickly with high heat and you do not watch and stir the kettle. Try medium high heat. On my electric stove, setting 5 out of 9 is ideal to avoid boil-over. A strong boil with frequent stirring has better extraction yields. An alternative to stirring is to keep a cup of cool water to quench the frothy foam (consider your final volume). You can make a concentrated extract, and then dilute it later (takes longer concentrate a dilute brew). For a single day, three tablespoons is enough for one person. Sometimes I brew bigger batches for friends, or to tide myself over for several days (3/4 cup per gallon). The Yaupon decoction is quite stable at 4C in the refrigerator. A ratio of nine tablespoons of ground leaf and a final volume of two to three quarts is potent enough to promote wakefullness. The American natives boiled the leaf by all historic accounts. Boiling bursts intact cell-walls and extracts and solubilizes chlorogenic-caffeine complexes; these complexes will precipitate as tea cream when the Black Drink cools.
Bring the water to a boil for several minutes before adding the ground Yaupon leaf and reduce the heat to half. This reduces the tendency to boil-over. Also if you are on municipal water supply, it will drive off the chlorine so chlorinated compounds do not badly flavor the decoction. Usually I use water which is treated by reverse osmosis for purity.
Formation of trihalomethanes in foods and beverages.
Huang AT, Batterman S
Food Addit Contam Part A Chem Anal Control Expo Risk Assess. 2009 Jul;26(7):947-57.
Department of Environmental Health Sciences, University of Michigan, Ann Arbor, 48109-2029, USA.
Trihalomethanes (THMs) are suspected carcinogens and reproductive toxicants commonly found in chlorinated drinking water. This study investigates THM formation during the preparation of beverages and foods using chlorinated drinking water. A total of 11 foods and 17 beverages were tested. Under the experimental conditions, each food and beverage formed THMs, primarily chloroform, although low or trace levels of brominated THMs were also detected. Tea formed the highest THM levels (e.g., chloroform levels from 3 to 67 microg l(-1)), followed by coffee (from 3 to 13 microg l(-1)), rice (9 microg l(-1)), soups (from 0.4 to 3.0 microg l(-1)), vegetables (<1 microg l(-1)), and baby food (<0.7 microg l(-1)). Chloroform formation with instant tea, used as a highly reproducible model system, increased with free chlorine concentration, decreased with higher food (tea) concentration, and was unaffected by reaction (steeping) time and bromide ion concentration. These findings indicate that chlorine-food reactions are fast, but that formation decreases as the chlorine demand of the food system increases. THMs are formed in the preparation and cooking of a wide variety of foods if free chlorine is present, and our results suggest that tea can be a significant source of exposure to THMs.
PMID:19680970 [PubMed - indexed for MEDLINE]
Infusions: I've never tried cold infusions (with coffee this takes time, several days). Tisanes or teas (hot infusions in nearly boiling water) yield weak tawny teas, just as short decoctions yield weaker brown brews. There is a greener generic plant taste to a Yaupon tea because fewer bitter compounds and complexes are present. Boiling might be necessary to degrade undesirable compounds or drive off smaller volatile molecules.
Steam infusion: What does work is to use a little home espresso machine, load it with one to two tablespoons of slightly course ground leaf and to to a steam infusion extraction with deionized water (about a cup). This yields a brew which is about as active as a strong cup of coffee. I recommend a courser grind for espresso because you will clog the filter up, especially with fine grounds harvested late in the season. Sticky resinous residue is evident on the filter of steam infusions. This method extracts the most water soluble compounds in a rapid period of time.
Percolation is a favored brewing method of many coffee brewers (Greene Deane (EattheWeeds)), I have yet to try this myself (I don't possess the apparatus). A friend who tried my Yaupon Holly Black Drink decoction for the first time at a bold strength ended up staying awake for over 48 hours. When I gave him Yaupon leaf (coarsely hand crushed) the brew he percolated was brown, not black, and he was disappointed that it did not keep him awake for writing work. Like all these methods, the fineness of the grind matters. Fine grind gives you smaller particles and greater total surface area and better extraction (more cell walls have already been pulverized), but you run the risk of clogging up the filter holding the bed of grounds. Courser grind is more porous, but takes longer to extract.
Metals: because chlorogenic compounds can chelate metals, be aware of your brewing containers. American natives boiled Yaupon Black Drink in clay vessels. Chlorogenic chelates of iron are considered antioxidant because it keeps the iron in a high spin state incapable of scavenging radicals and forming hydroxy radicals via Fenton reactions. Copper complexes with chlorogenic on the other-hand are pro-oxidant. All this complex chemistry confuses, so simply: use pure water (reverse-osmosis, rain-water) and stainless steel, if you don't have ceramic cookery.
Additions: I like to add citrus to my Yaupon. I learned this on my own, and later discovered that folks in North Carolina Outer Banks do the same thing (see the book Black Drink ed. Hudson). Citrus such as Calamondin http://en.wikipedia.org/wiki/Calamondin tastes best, followed by lime, lemon, orange, and grapefruit. The citrus is a tastant, and the combination will taste much better than either Yaupon alone, or citrus water alone. The citrus will change the color of the infusion from deep dark black towards orange colors. This is known as a bathochromic shift and is due to the pi-bonds changing position in the polyphenols as carboxyl groups are acidulated. It is a known phenomena in tea when lemon is added. Mate is often drunk with lemon in South America, and in Brazil, coffee with lemon is a popular. Also catechins in tea have increased bioavailability in citrated tea drinks than plain tea. Yaupon with lemon tastes alot like good old southern iced tea. http://dx.doi.org/10.1002/mnfr.200700086
The ascorbic acid and citric acid in citrus will acidulate free carboxylate-ion groups in the polyphenolic compounds such as the caffeoylquinic acids (chlorogenic acid and its relatives). A carboxylate-ion group with free electrons can coordinate with metals. Chlorogenic acid actually binds iron tightly, keeps it in a high-spin state and unavailable for reaction - (Fenton chemistry (known), microbes (unknown)). One can actually become anemic if one were to imbibe too many chlorogenic acids (i.e. from coffee, or yaupon).
Here is a long article on the Chlorogenic acid. http://jn.nutrition.org/content/137/10/2196.long Chlorogenic Acid Compounds from Coffee Are Differentially Absorbed and Metabolized in Humans
It is recommended to actually eat solid foods in conjuction with these beverages instead of relying on the energizing activity of caffeine. I find it is easy to fast when drinking Yaupon, and my lunch meals move late into the afternoon because I feel like I have the energy to keep going. This summer I've actully lost five pounds down from 150 while drinking Yaupon, but I feel better for it.
Other additions I like to my Yaupon include Mints, Stevia (both of which are also used in South America with Mate). Honey works well also, and one might include a little bit of seasalt. A recipe of mine is Yaupon, Honey, Mint, and a little but of Rum - this I call a Rummyeopon, and is quite enjoyable.
Sugars dissolved in hot Yaupon black drink evolve a small quantity of gas (my observation).
Be Aware, Caffeine is toxic at high concentrations, and that Caffeine concentrations do vary in different populations of Yaupon depending on genetics, gender, location, fertilization, age, sunlight, and time-of-year. The strength of a brew prepared from weak leaves in March will not be equivalent to that from October for the same plant. The darkness of the decoction is some indication of strength, but it is hard to judge without serial dilutions or spectrophotometer. Strong Yaupon decoctions do not make me regularly want to retch like strong infusions of Coffee Bean or Green Tea. I count twice that I have had to hurl after Yaupon in the past three years of daily drinking Yaupon and both times my body was stressed from either too much exertion (heavy hiking in Cattaloochie), or staying up and partying too much without sleep. Whereas dozens of times coffee has induced nauseau (often just from the aroma), and little less so for Green Tea. Recently I brewed up a strong decoction of Yaupon Black Drink (~10 tbs per 2 qt) and was drinking it into the afternoon; I had a hard time falling asleep that night. The rule of thumb is not to consume Caffeine four hours before needed sleep. Incidently there are two populations when it comes to Caffeine metabolism - fast and slow acetylators (N-acetyltransferase). If you are especially sensitive to caffeine you may be a slow acetylator and have a more difficult time clearing Caffeine. Women generally clear caffeine slower than men, and women on oral contraceptives clear Caffeine significantly slower.
edited August 31, Sep 1, 2012 , sep9
Yaupon and Lemon
On the left is a Yaupon Black Drink, and on the right has been added 1% lemon juice, after which the chromophores (chlorogenics and quercetin, &?) do not absorb as much light. Precipitates form in the solution and there is more light scattering. It actually takes much less citrus juices to cause this transmittance shift (about 0.2% or seven drops per 100 mL).
See: http://www.ncbi.nlm.nih.gov/pubmed/20161530
for a discussion of ascorbic acid and catechins in tea.
Food Res Int. 2010 Jan 1;43(1):95-102. Formulation with ascorbic acid and sucrose modulates catechin bioavailability from green tea. Peters CM, Green RJ, Janle EM, Ferruzzi MG. Source Department of Foods and Nutrition, Purdue University, West Lafayette, IN 47907.
See: http://www.ncbi.nlm.nih.gov/pubmed/20161530
for a discussion of ascorbic acid and catechins in tea.
Food Res Int. 2010 Jan 1;43(1):95-102. Formulation with ascorbic acid and sucrose modulates catechin bioavailability from green tea. Peters CM, Green RJ, Janle EM, Ferruzzi MG. Source Department of Foods and Nutrition, Purdue University, West Lafayette, IN 47907.