Steep and Release - The Bonavita Immersion Dripper

Melanie Pinola of Lifehacker recently posted an article about a new dripper from Bonavita, the Bonavita Porcelain Immersion Dripper. As its very long name implies, this is an immersion style dripper, similar to the Clever Coffee Dripper, but instead made of porcelain rather than plastic. The porcelain helps retain heat throughout the brew process.

An immersion style dripper is a cone that has a valve at the base that can be closed during the brew then opened. With the valve closed, coarsely ground coffee is immersed in hot water for approximately three minutes. This process is identical to a French Press. After three minutes the valve is opened and the coffee flows through a paper filter into the cup over a 30-45 second period. The result is French Press like body without the sediment. Total brew time is also similar to a French Press.

So why would one elect to use the Bonavita over a French Press? Several reasons. One, the porcelain combined with the cap allow the slurry to maintain a fairly constant temperature throughout the brew unlike the thin glass walls of a traditional French Press. Also, some may not prefer the gritty mouthfeel of a French Press brew. The Bonavita takes a paper filter, nearly eliminating coffee sediment.

(Photo credit: Lifehacker)

Does water temperature really matter?

When I make a cup of coffee I measure everything. I measure the weight of the ground coffee, the grind size, the water temperature, the weight of the water, and the brew time. By tracking all the variables I'm able to brew a consistent cup of coffee time and time again. This was especially important a couple weeks ago when I brought the Chemex and Kalita to work. I wanted to make sure everyone's experience was the same. The only way to ensure that reliably is to measure everything.

The amount of coffee I use, the grind setting, and even the water temperature were not simply drawn from a hat. I've been brewing pour over coffee for over a year. Up until a few months ago I had been tracking every single cup of coffee I made. Every cup of coffee. No seriously...every cup. The result of that experiment is an Evernote notebook filled with hundreds of notes. Over time I was able to dial in the specifics for each device I own.

But tracking everything is expensive. Many hours went into driving the residuals to my personal machine zero. Then I started thinking, what parameter could I ignore and still achieve the same, or similar, result. I may have found the answer browsing the video archive of Verve Coffee Roasters. They kill it again with another awesome video, this time on brew water temperature.

It doesn't matter what you read, you're going to find the same advice everywhere. Coffee should be brewed between 195F and 205F. What I failed to realized is that this is referring to the slurry temperature, or the temperature of the water/grounds mixture. That makes sense as brewing coffee is a process where solubles are extracted from the exposed surface area of the ground coffee. Water temperature drives what is extracted.

For the first half of the video they focus on demonstrating the temperature loss of the water as it comes in contact with the brew vessel. Using water just off the boil, they pour water into a preheated press pot to find a drop in temperature of about 6-7 degrees. Pouring the water into a pot that hasn't been preheated and you'd loose another 5 degrees of temperature. They did the same experiment, this time with ground coffee in a preheated press pot. The loss in temperature was much higher than I would have imagined. The temperature dropped from boiling down to 198F. That's 14 degrees cooler.

What does it all mean? Essentially, you you can take water right off the boil, pour it into your ground coffee, and be right at the low end of the recommended temperature range for brewing coffee. This is assuming you're using a preheated press or cone. If you want to be near the high end of the temperature range, you'd have to get the water beyond boiling, probably around 220F.

In the end, Verve's experiment demonstrated that water right off the boil and up to 1:30 off the boil produced a good cup of coffee. Even a cup brewed with water up to 4:30 off the boil produced a good cup. But, the closer the water temperature to right off the boil, the better. Hot water in a kettle maintains its temperature very well. Just be sure to keep that lid on.

I've been using 195F water to brew my coffee. That means my slurry temperature is roughly around the 180F mark. Having played with everything between 195-205F, I found 195F to be the sweet spot for my brews. I prefer slightly less bitterness and a muted acidity. That's something I've been able to achieve with the lower brew temperature. Although, any lower and it's probably considered a cold brew.

(Video credit: Verve Coffee Roasters)

Michael Allen Smith posted a review of a press pot he received. His article focuses on an additional variable he finds important when trying to decide which press pot to purchase. That variable is insulation. But does press pot insulation really matter?

I’ve been told that if you brew using a press pot, the chamber should not be used to store the brewed coffee. The reason being that the grounds are still sitting at the bottom of the pot and as long as there is still water, the coffee will continue to brew. This means that over time the coffee can become bitter and over extracted.

Now, the author does make the point that insulation probably isn’t of importance for those that immediately consume their coffee. But, for those out camping insulation might be important. I’d still say no. A traditional press pot should not be used to store coffee for an extended period of time no matter where you are unless you like drinking nasty coffee.

CoffeeGeek describes a unique press pot technique that nearly eliminates cup sediment, enhancing the finer coffee flavors. If you're a fan of a full bodied cup of press pot coffee, this might not be the technique for you.

The technique is similar to a traditional press pot technique until the last thirty seconds or so. Grind coarse, steep, and then remove the crust. Removing the crust that's formed will eliminate the majority fo the sediment present in the final brew presenting a much cleaner cup.

Once the crust has been removed, there is another layer called the scum. This layer is what's left of the bloom that occurred early on during the steeping process when the coffee was off gassing carbon dioxide. The video suggests removing the scum following the removal of the crust. In a typical pour over technique the filter would capture the scum.