After each period, the teas were ground into powder and mixed with boiling water, before being cooled and analyzed.
"We found that among the teas we looked at there seems to be a progressive decrease in the amount of antioxidants as a function of time," lead author Friedman said.
The team found at least some drop-off in catechin antioxidant content early on in the storage process, and went on to observe that by the end of six months catechin concentrations had plummeted among all eight teas by an average of 32 percent -- a figure the authors characterized as "highly significant."
Specifically, the most prevalent form of catechin (EGCG) decreased by 28 percent after six months of storage, while the second most common catechin (ECG) dropped by 51 percent in the same timeframe.
Friedman described his work as preliminary, and expressed the hope that the findings would prompt more research into the storage-antioxidant question, given the large variety of teas on the market and the strong probability that not all teas would experience nutrient degradation in exactly the same way or pace.
For their part, the authors of the Italian olive oil study noted that to be considered "extra-virgin," olive oil must be sourced directly from olive tree fruit through a process confined solely to washing, decanting, filtration and high-speed mixing.
The final product is known to be rich in a specific blend of fatty acids and phenolic compounds, the latter acting as antioxidants. Consuming olive oil has long been considered beneficial with respect to lowering the risk for heart disease, stroke and several kinds of cancer.
To explore the durability of antioxidants found in extra-virgin olive oil, Antonella Baiano and colleagues at the University of Foggia in Italy looked at several varieties of the oil that ha
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