The antioxidant activity of mamaki tea was quantified and three of its phenolic acids (catechins, chlorogenic acid, and rutin) were identified in a study titled Major Phenolic Acids and Total Antioxidant Activity in Mamaki Leaves, Pipturus albidus published in Journal of Food Science.
Of significance is that this study distinguishes between the nutrient profiles three of the four mamaki varieties identified and picture in Kartika’s 2006 thesis.
The concentrations of (+)catechins in Mamaki leaf are significantly higher (P < 0.05) than those reported for other commercial tea leaves, especially the Gyokuro green tea leaves, Chinese oolong tea leaves, and Kenya black tea leaves (Sakakibara and others 2003).
(+)catechins is commonly found in green tea and plays a role as an antioxidant against cancer, obesity, diabetes, cardiovascular disease, aging, and neurodegenerative diseases (Zaveri and others 2006).
Chlorogenic acid is commonly found in root vegetables such as carrot, radish, turnip,and burdock (Sakakibara and others 2003). Chlorogenic acid in hawthorn fruit is found to be beneficial as an antioxidant against low-density liproprotein oxidation (Zhang and others 2001;Wang and others 2007). Chlorogenic acid is also found in blueberries and plays roles in browning reaction and polymerization (Kader and others 1997).
The concentrations of rutin in Mamaki leaf are also significantly higher (P < 0.01) than those for other tea leaves (Sakakibara and others 2003).
Rutin is commonly found in red wine, buckwheat, citrus,and tomato skin (Heims and others 2002). An animal study showed that rutin plays a role as an antioxidant and is effective in controlling the animal body weight (Gao and others 2003).
Another interesting find of the study is that antioxidant activity in the leaves changes with the seasons. The purple and green varieties are a little stronger over winter. The hybrid variety is a little more steady between seasons, but experiences a slight bump in antioxidant activity during summer. Will this one day lead to tea snobs who demand a certain variety of mamaki that is harvested during the appropriate season? Perhaps it’s simply easier to stick with the hybrid variety knowing that it’s a happy medium no matter when it it harvested. (Especially considering that harvesting can happen year-round in Hawaii, four or five times per year.)
Finally, anyone that has brewed a big batch of mamaki tea has been delighted when they realized that it can set in the fridge of a week or so without getting “sour” like lesser teas that often go bad overnight. This study confirmed it and apparently proves the source of mamaki tea’s long shelf life…it’s antioxidants hang around, keeping it fresh.
Unfortunately, only the purple variety was used for this test. And, at first glance the chart seems to show that the brewed tea looses half its antioxidant power after three days. But take time to consider the room for error with the plus or minus figures on the right side…
While it seems likely that you get extra benefit by drinking the tea freshly brewed, something seems to kick in as the tea ages that causes the unpredictability to fade away as it is replaced with dependability. The tea seems to find a happy medium. Could we also interpret the data as indicating a possible increase in protective antioxidants? I took the liberty of graphing out the data for a better visual. One wonders how far out the graph would need to go before the tea actually goes bad and breaks out of the funnel.
Looks like prime territory for future study. Along with the study that is needed to determine if the hybrid and green varieties have the same effect.