One of the editors here at SciShow  was just having a heated debate with her partner about who  makes tea the right way.

She leaves a bag of herbal tea in the  mug the entire time she drinks it, while her partner lets their  loose leaf black tea steep for 2 minutes max and then adds milk. One thing led to another… Insults were slung, relationships  were damaged, tea was drunk.

There are about as many ways to  make tea as there are tea drinkers. And since tea is the second  most widely consumed beverage in the world after water, there’s bound to be a lot  of connoisseurs out there with opinions as strong as their tea. In this video, we’re going to explore what science has to say about those debates.

So here’s the tea on steeping the perfect cup. [Intro music] Our editor, let's call her Sally, Sally's tea time debates started  with what kind of tea reigns supreme. She and her partner have totally different preferences for Earl Grey versus chamomile. And from a scientific perspective, this debate is just about as  simple to answer as it gets.

Earl Grey wins every time  because chamomile isn’t even tea. Believe it or not, all true  tea comes from the same plant: Camellia sinensis. Although, there are different  varieties of that plant.

For example, green teas often  come from the small leafed variety and black teas from the broad leafed variety. But you can make green or black … or white or yellow or red… tea from either. Herbal teas don’t come from that plant.

They’re made of things like  chamomile, hibiscus, or mint. And their preparation methods and health benefits can vary based on the herb  or flower you’re steeping. But even across non-herbal teas, there’s quite a variety that  all stem from C. sinensis.

Somehow, the flavors are different enough  that our editor’s partner loves black tea and refuses to drink green tea. That’s because how it’s prepared  separates the greens from the blacks. Black tea is made by fully  oxidizing the leaves as they dry.

Sometimes the oxidation process  is referred to as “fermentation.” But it isn’t the kind of fermentation  that happens in bread or kimchi. That’s facilitated by yeast or  bacteria. Instead, tea oxidation happens when enzymes break down the leaf material and allow the molecules to form new compounds.

Green tea, on the other hand, is the product of harvesting fresh tea leaves and steaming them before drying  them, to prevent oxidation. Oolongs are somewhere in between. The tea leaves are dried  slowly and partially oxidized.

The extent of oxidation across tea types  is what makes them taste different. Unoxidized leaves in green teas  tend to taste a little bitter, with hints of umami and sweet aftertastes. That’s because they’re full of  flavor-contributing molecules called catechins.

And when those catechins are  oxidized to make black tea, they get converted into  different tasting molecules like bisflavanols, theaflavins, and thearubigins. Black teas can also be bitter,  but often less than green teas. And they can be less astringent.

You know that dry feeling in your mouth that you might get after  drinking wine or, well, tea? Black teas can even be sweet and often have roasted, malty,  or floral flavors, as well. Then to make the specific iconic tea types you and our Sally’s partner know and love, like Earl Grey, flavors like bergamot can  be added to the tea leaves.

But before that step, something else  happens during the oxidation process. The theaflavins and thearubigins  take on an orange-y red color. So the fact that black tea is darker does not mean that it has any more flavor  molecules or caffeine in it.

While black teas often have more  caffeine, that’s not always the case. Green and black teas go up to a  similar maximum caffeine level. And for reference, it’s about one third to  half the amount of caffeine that coffee has.

As it turns out, caffeine  contributes to tea’s bitter taste. Which means with more buzz  you might get a bitterer brew. But, if the bitterness bothers you, you can add some sugar to greatly reduce  the perceived bitterness of caffeine.

Not necessarily because you’re  tasting the sugar either. Now, some of the studies  we’ve cited tested coffee. Which I know is not tea but stay with me.

They found that you can add sugar and make the drink taste less  bitter without tasting sweeter. This effect works because the sugar molecules crowd the bitter caffeine  molecules into little clumps. When they’re clumped up, it’s harder for the caffeine to bind to your  taste receptors and register as “bitter.” If you aren’t drinking tea for the caffeine, then a decaffeinated blend could  also make a noticeable difference when it comes to bitterness.

Sure, you might be like Sally’s partner, wondering what anyone would possibly be  drinking tea for if not for the caffeine. But Sally drinks decaffeinated  tea for the health benefits. See, there are these things called free radicals that can be floating around your body.

Free radicals are molecules  that have unpaired electrons. Since electrons are more settled  when they’re paired up and bonded, the free radicals are quite reactive and will attempt to bond with whatever they can. That’s what tea puts a stop  to, or at least reduces.

It’s full of antioxidants, which are good at scooping up those free radicals and reacting with them before  they can react with anything else, like the proteins or nucleic  acids that your body needs. So by rounding up all those  free-wheeling free radicals, antioxidants help prevent damage to  the important stuff in your body. When it comes to tea, polyphenols  play this antioxidative role.

Tea polyphenols have been  linked to preventing cancer and cardiovascular diseases; they could help manage diabetes and obesity; and they might contribute to  longevity and neurological health! Green teas have more of the polyphenols  that link to all these good benefits, so if you’re particularly interested  in this broad spectrum health bonus, green tea might be your cuppa. Especially compared to a lot of  herbal teas including chamomile.

While some herbal teas have a  comparable antioxidant boost when stacked up against black  tea, a lot of them just don’t. So on top of not coming from the real tea plant, these poorer antioxidants makes many  of them truly the knockoff option. In that way, Sally is absolutely  on the wrong side of the debate.

Choosing chamomile over Earl Grey, she’s not even getting as many health benefits … and that’s the whole reason she drinks the stuff! So maybe she needs to pick a sampler pack of tea to find her new go-to variety. And while she is deciding, we're gonna take a quick ad break Thanks for watching this SciShow video!

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Now, if Sally switched to  Earl Grey as her new daily brew, she still might not make tea  the same way as her partner does She’d have to decide w here she stands  in the very divisive milk debate. I know! I know.

Most of the British are going to  insist that there is no debate. It’s not a cuppa tea without milk. But some people are purists.

And to them, we say that researchers in Scotland looked into this debate and  determined that adding milk doesn’t seem to affect the integrity of the drink. All those sweet antioxidants and caffeine  can still dissolve into the brew just fine. The bad news for the pro-milk community  is that adding milk to your tea might prevent your body from getting  the benefits of the tea’s antioxidants.

Many studies have shown that milk-free tea has greater health benefits  compared to the milky alternative, probably because of the way milk  proteins interact with tea polyphenols. Which means, and I kinda love to  be the one to break this news, milk does not belong in tea. It scientifically makes it worse.

That’s one point for Sally over her partner! That said, if a warm and comforting  milky beverage is your primary tea goal, then by all means have milk! Just know that you might not  get all the advertised perks.

Even though you’ve already  left me angry comments by now, here’s a bit of redemption  for you milky tea drinkers: despite being full of proteins that   might interfere with how your  body takes on antioxidants, cold milk should at least help  prevent the antioxidants in your tea from being destroyed in the first place. It could do that by changing  its steeping temper ture. After all, temperature has  a strong influence on what   kinds of molecules actually make it into your tea.

Including those coveted polyphenols. Water that’s above 90°C can  damage these delicate molecules, decreasing the overall health benefits of the tea. So if antioxidants are one of  your reasons for drinking tea, then you don’t want your water to be boiling hot.

Now, I threw you milk lovers a  bone by assuming your milk is cold. But if you really want the antioxidants, there are ways to lower the tea’s temperature  without introducing protein-heavy milk. To maximize antioxidants, or  at least improve their yield, one solution is cold brewing.

One study from Italy compared tea brewed hot, between 75°C - 90°C, for 3-4  minutes to tea brewed cold, at 4°C, for 12 hours. They found that long, cold brew times  allowed antioxidants deep in the tea leaves to seep out while also reducing  some of the bitter tea components from the final brew. But if you don’t want to  wait 12 hours for your tea, they also found you could start the brew  hot, then shock it cold before drinking.

This method quickly extracted caffeine while preserving some of those polyphenols. In black tea, it led to even  more antioxidants in your tea than either the hot or cold brew  options. Not bad for a rush job.

I hope the temperature effect  diffused some of the tension I created as a full throated American nevermilker. And while temperature is one way  to speed up your steeping tea so it doesn’t take 12 hours, there’s another way that not everyone, including Sally, is going to like: use loose leaf tea. We all know why we use tea bags.

They’re more convenient. But tea bags throw an extra obstacle in your cup, slowing down all the good stuff in  the leaves as it tries to become tea. The tea bag’s shape and how  packed full of tea leaves it is affect the diffusion time.

Hot water gets trapped inside the tea bag, and can’t move around enough to get all the  tea stuff out of the bag and into the cup. On the other hand, loose leaf  means your tea has room to move! Water can get in there way  more easily and swirl around, speeding up diffusion so that  your tea is ready faster.

Not to mention that whatever  your tea bag is made of… there’s a chance some of that  could get into your tea as well. Standard tea bags are stable at  temperatures lower than about 250°C, and it’s super unlikely you’re brewing  tea at a temperature that high! But, if you’re worried about something  hitching a ride on your tea bag, then you might as well switch to loose leaf.

That’s a point for Sally’s partner. Loose leaf is superior to bags. But if she insists on making the  wrong choice and using tea bags, at least she’ll have an  easier time dunking the tea … because she’ll need to do more dunking than she would if you just used loose leaf.

Dunking the tea bag or stirring  the water while steeping helps speed up the diffusion process. By disturbing the water, you’re creating little currents and eddies that spread the dissolved  tea particles more quickly. It prevents the tea-saturated water  from getting stuck around the leaves.

When stirred or dunked, the  water with fewer tea particles can sweep in to get more, creating a uniform tea solution way quicker. According to a computer model,  dunking a tea bag for 60 seconds could be up to four times as  efficient as letting the tea bag take an undisturbed bath! It doesn’t get much clearer than that.

You should definitely dunk. So Sally, who leaves the bag  in there all day without agitation, is wrong. I’m getting agitated just thinking about it.

But if Sally really doesn’t want to  put in the effort to dunk or stir her tea, researchers have worked out how  long she needs to let it sit. The caveat is that there’s a bit of  difference between balls of oolong that have to be steeped longer or  multiple times as the leaves unfurl. Versus matcha, which is  completely ground up tea leaves that infuse into water almost immediately.

But let’s say your tea is somewhere in the middle, like a loose leaf black tea. To increase some of the polyphenols, you might need a steeping time  between 10 and 60 minutes. Maybe Sally was onto something with her long steep time after all.

And if waiting an hour seems  absolutely unreasonable, you can probably cheat and get most of  the benefits from a much shorter steep. One study found that the majority of infusion for loose leaf black tea  happens in the first 90 seconds. In their study, the tea solution was  basically saturated after only two minutes.

And if you have a few more minutes, it’ll probably taste better. Another study calculated that  the approval of a black tea by trained taste testers was optimal  when brewed for 6 minutes at 89°C. However, when selecting for a mellow taste, 100°C water and a steep time of almost 10 minutes, but with more water used per tea bag was best.

Finally, when selecting for sweetness and umami, the ideal tea steeped at 77°C, with less water per tea bag, and  a steep time of only 2.29 minutes. So that explains

Sally’s  partner with the two minute cutoff. So to have your perfect cup of tea You're gonna need a stopwatch and a thermometer and 60 seconds of dunking unless you put in more water and then add ice you know what, I'll personally just stick to whiskey Considering the variety of  benefits that tea provides, the advice you choose to follow in the end depends on what fortune you seek in those leaves.

If you do it for the sake of  nostalgic comfort, throw in some milk. If you do it to add a jolt to your  day, grab a bitter tea with some sugar. If you do it to stay healthy,  try a cold brewed true tea.

Just remember that with so many ways to drink  this internationally recognized delight, someone else’s cup of tea  might not be your cup of tea. [ outro ]