Foam ?

[David R.]

Foam ?

by David R. » Nov 17th, '12, 12:38

When rinsing the leaves, some teas make more foam than others. Sometimes, when there is a lot, I can't help wondering if this is a bad sign or not. But the truth is that I have no idea what is actually going on. Does anyone have an explanation ?

[Drax]

Re: Foam ?

by Drax » Nov 17th, '12, 13:29

I'll be curious what traditional views of tea will say on the topic, but from a scientific standpoint, I think it's difficult to determine good or bad.

For example, saponins are a naturally occurring plant chemical that can cause a soapy or foamy appearance in liquid solutions. They are a combination of sugars and sapogenins (the latter of which are derived from isoprene usually; biochemical pathways similar to hormones). How do these things alter the taste, texture of the tea? I don't know...!

And of course, there could be other non-saponins causing the foam, so that's a consideration as well.

[David R.]

Re: Foam ?

by David R. » Nov 18th, '12, 04:43

Thanks Drax.

[HifideliTea]

Re: Foam ?

by HifideliTea » Nov 19th, '12, 04:05

Perhaps some of the many factors:

1) Temperature of the water
I am drinking a 92 raw yiwu today and it is flat, no sweetness at all, lots of aged temple taste (sandalwood incense and camphor pillars). I remembered that when I rinsed the first flush this morning, there was a lot of foam, and the water was not really hot (too lazy to reboil).

2) Sweetness of the teas
Sugar creates foam in teas?

3) Speed and height at which one pours the hot water to the teas
The higher and the faster the hot water is poured into the tea will cause foaming.

[tingjunkie]

Re: Foam ?

by tingjunkie » Nov 23rd, '12, 10:42

Can't comment on the chemistry or science, but the traditional wisdom assumes the foam carries the dirty stuff you don't want to drink, and that's why you're supposed to swipe it off with the gaiwan/teapot lid and get rid of it.

[David R.]

Re: Foam ?

by David R. » Nov 24th, '12, 12:19

Can't comment on the chemistry or science, but the traditional wisdom assumes the foam carries the dirty stuff you don't want to drink, and that's why you're supposed to swipe it off with the gaiwan/teapot lid and get rid of it.

Thanks. I do that, but I recently encountered a puerh which was still giving me bubbles after many brews. This is like the 8th brew or so :

.

[wyardley]

Re: Foam ?

by wyardley » Nov 24th, '12, 13:23

The foam from the first round or two should be skimmed. I thin later on, though, it's just the saponins in the tea.

[tingjunkie]

Re: Foam ?

by tingjunkie » Nov 25th, '12, 01:32

Yep, bubbles and foam are different things. Just do the rinse and maybe first infusion, and don't sweat it.

[David R.]

Re: Foam ?

by David R. » Nov 25th, '12, 08:21

Thanks you everyone !

[needaTEAcher]

Re: Foam ?

by needaTEAcher » Dec 1st, '12, 20:45

Can't comment on the chemistry or science, but the traditional wisdom assumes the foam carries the dirty stuff you don't want to drink, and that's why you're supposed to swipe it off with the gaiwan/teapot lid and get rid of it.

My teacher calls it "the breath of microbes", though from where I am sitting, I can't help but imagine millions of little critters drowning in a sea of boiling doom!

I am reading a book on tea and teaware from China, with English alongside the Chinese. They talk a bit about the foam, saying that in competitions way back when foam color and consistency were among the aspects judged. Apparently, white foam is a good thing, though I have never noticed a different color.

[brandon]

Re: Foam ?

by brandon » Dec 1st, '12, 23:05

You were reading about a head of foam on whipped tea being judged, not saponin. Pretty sure the OP question has nothing to do with microbes, though. You can get this on Yancha straight from the roasting, or sealed in vacuum for years, just for example.