Decent tea portafilter coming
Essentially these are portafilters with an exit valve that opens at 4 bar. With the right DE1 program, we can control that valve opening time.
Here are the advantages of making tea with an espresso machine:
- totally automated 3 minute brew
- works with a teabag and loose tea.
- Easy cleanup even with loose tea.
- different water temperatures can be used for different teas (some teas benefit from lower temperatures)
- concentration (ie dilution) of the tea can be standardized
- multiple pass recipe through the tea bag gets more tea extracted, as clean water is put in each time.
- you can choose to throw out the first extraction, as is common practice with nice tea.
- another benefit of throwing out the first flush is that this serves to warm the basket and portafilter, so that the rest of the brews are at a higher temperature.
- improved tea flavor by getting the timings and temperature exactly as you want them.
I developed a program that makes passes at brewing, ending up with about 250ml of tea in the mug. Here it is:
I fill the basket and exit on pressure, and then hold to brew. I then flush at 4ml/s, and then hold at 2 bar, then once again, and then a final flush.
Our new firmware is doing a fairly good job of getting the tea in the portafilter close to 100ºC.
Here are the steps in the profile:
One thing I don't like is that the rim of this portafilter head is flat, not rounded like a basket. This flat top requires the portafilter to be locked in tighter than usual to form a seal, otherwise there is a bit of leakage.
and then ran the program again to make my tea, as I quite like weak english breakfast tea without milk:
I will be evaluating several other models of tea portafilter heads in the next few weeks.
The intent is to have a new portafilter from Decent, as well as a variety of tea recipes, optimized for different kinds of tea.
# TALKING TO THE MANUFACTURER:
We spoke to the manufacturer of this portafilter head, and they said “but we don't have a valve in our portafilter!”
They made the portafilter to artificially create pressure in brewing tea-concentrate, and that's how they think of their device, because they only have a 9 bar espresso machine.
Look at this exploded parts image:
The spring on the washer causes water to need about 4 bar of pressure to exit. That causes the tea to extract at pressure.
However, with the Decent we can control the pressure, and also stop water flow, so we can use that spring as a non-electrical open/close valve.
We're not using the portafilter as they intended, but that's fine. You can of course as the Decent to make a 9 bar shot, and then extract tea at around 4 bar, which is about what the the spring resistance gives.
# FUTURE TEA RESEARCH
Decent customer Dylan suggested an interesting idea, of starting the tea brew with quick, successive rinses at 2 bar, and then using the flush valve to automatically throw that “first rinse” tea out. I'm going to try that out, and see if it works. If so, that makes the Chinese practice of throwing the first rinse out fully automated, and we can pick the settings that work best.
Updated 2020/08/29