What is Really in Bottled Tea
Since I have been discussing bringing tea out in a thermos, some readers may think why the trouble? Why not just buy one of those many readily available bottled tea ( aka RTD tea — “Ready-To-Drink” tea )?
The tea researcher’s husband who is also a tea researcher in Hangzhou, if you remember him in the article Tea in a Thermos, gave up using higher quality tea because he found out that the nice aroma and taste disappeared once the liquid is bottled. (“Higher quality” is a relative term here; it actually means not so poor. ) That means if there is real tea in your bottle, it wouldn’t be good tea in the first place.
How much health content in a bottled tea
Okay, it’s not the tea taste you are after, it’s the health content. Well, there is much ( or less ) to find out in that bottle. As pointed out in the USDA Database for the Flavonoid Content of Selected Foods (1), the “mean” flavonoid content in bottled tea products is 9% of the “mean” cup of tea prepared from tea leaves or tea bags (2). That means a bottled tea has not even one-tenth of the health content than tea made from the “average” teabag or loose leaf tea.
USDA: “Mean” flavonoid content in a bottled tea is 9% of that in a cup of tea prepared from tealeaves or a teabag.
Other than the USDA survey mentioned above, few scientists have come up with solid data against the big money behind all those bottled flavoured beverages. The government agency has huge limitations in many aspects anyways. The sales of bottled “tea” has still been growing by leaps and bounds by the popular misperception of it being a healthier or more natural drink. In reality, most products are basically flavoured sugary water which sales are based on huge marketing and distribution budgets.
Natural depreciation of catechins takes time
When one prepares a normal cup of tea and put it aside, the health contents in it depreciate quite slowly, at least for the first couple of days (3). Please note that this conclusion concerns only the few health matters most have been researching about; taste matters and other minor but contributive substances such as the aromatic oils, sugars, minerals etc are rarely studied. We all know that empirically a cup of tea put there for a day or two is never as good as when it is fresh.
So what happens when tea is bottled in a factory, transported across land or sea, stored in a warehouse, and shelved in a supermarket before it gets into your mouth, many days after that critical first two days?
ascorbic acid reduces tea catechins
The first thing a manufacturer worries about is that the drink would be swarmed with germs and moulds, which would lead to huge reputation and then financial problems for the company.
The one most popular way to prevent this is heat treatment and adding of citric or ascorbic acid. In Hong Kong, where there is a proportionally huge market for bottled tea and a strong vernacular custom of tea drinking, a team in one of the top universities studied the changes of tea catechins as the tea liquid goes through these treatments when it is bottled (4). Here is something you need to know:
Ascorbic acid (vitamin C) or citric acid seems to be an even more popular ingredient in bottled tea drinks than tea itself. Other usual substances include various forms of sweeteners, fruit juices (the content of it in a declared 1% fruit juice tea can be more than tea itself), and flavouring. However, reading the label gives you only part of the picture.
The addition of ascorbic acid (aka vitamin C) to beverages as an antioxidant (i.e. as a preservative) is common practice. The scientists found that it is able to maintain the proportion of substances in the tea bottle only for the first month. After that, however, the total amount of catechins rapidly reduced and almost totally disappeared in 6 months. The alternative use of citric acid for the purpose seems slightly better, about 30% of the original amount of catechins still existed after the same duration.
Heat damages EGCG
However, the nature of the catechins has changed. The scientists looked particularly at EGCG, epigallocatechin gallate, the catechin that has been continuously proven to be the key contributor in the many health effects of tea. They found that when tea is heated for sterilization, or even steeped at 100°C, EGCG begins to change into GCG, gallocatechin gallate, another kind of tea catechins, but not key to tea’s health role.
Adding to the fact that only poorer quality tea and not so much of it is used in the production of RTD tea products, the effective amount of catechins that one can get from a bottled drink is practically non-existent.
There is no good bottling technology for tea yet
Some Japanese brands have been putting much effort in trying to use as much real tea in their products as possible using various approaches. The latest is perhaps Kirin’s cold extraction approach. They are not confident enough yet to showcase any data in terms of catechins or other flavonoid content. There is a bit of improvement in their products in terms of taste, but there seems to be yet a long road to deliver a bottled tea product that is remotely similar even to a thin tea in a thermos that you prepare by yourself using acceptable quality tealeaves.
Nothing better than a cup of tea made from whole leaves
