Thump Coffee, Denver CO

A new coffee shop opened a few weeks ago in the Capital Hill area of Denver that’s definitely worth checking out. They’re new to Denver, but Thump is from Bend Oregon where they’ve had a shop and a roasting facility.

I’m always both excited and apprehensive to try a new place. I love trying new coffee and seeing what different places do with their space and how they feel. But, what if their coffee isn’t any good?

No such worries at Thump. After just walking in the door, I knew that it was going to be great. We were greeted with a very pleasant open space with a lot of seating that was completely occupied on a Sunday afternoon. I immediately was drawn to the Steampunk, a new siphon-like machine they have for their single origins. I was so interested in seeing one of these machines in person, that it took me a while to notice that they had Slayer espresso machines.

Steampunk or Slayer? It’s impossible to choose, there’s only one answer: both. I had an Ethiopian Yirgacheffe out of the Steampunk, and a Cortado out of the Slayer. Both were fantastic.

My 6 year old had a hot chocolate with chocolate syrup that they make at Thump, and his verdict? He finished it off, and with a big chocolate mustache, he said: “That was ridiculously yummy.”

When we went in, there were no seats left, and we decided just to stand in the back with a little railing. It turns out we stood next to where their roaster is going to go: it’s on its way. Right now, the beans are shipped in from Oregon, but once it arrives, they’re be roasting in the store.

We stood there for a bit enjoying our drinks, and were perfectly happy. But, they noticed we were standing and apologized that there weren’t any seats left and brought out extra chairs from the back for us. How great is that?

So, both for the very friendly staff and for the excellent coffee (and hot chocolate), definitely go and welcome Thump to Denver.

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Espresso Pressure Profiling and the Bezzera Strega

In the last 4-6 years, pressure profiling of espresso has been a cutting-edge technique to extract different interesting tastes out of espresso. The latest crop of the best commercial espresso machines all have pressure profiling capabilities: the Synesso Hydra, the La Marzocco Strada, the Slayer and others. These machines have high-tech approaches to change the pressure electronically during the shot. So, what is pressure profiling, and what does it accomplish?

Pressure profiling is the ability to vary the extraction pressure over time during an espresso shot. Typical pump-driven espresso machines extract at a constant 9 bars of water pressure during a shot. With pressure profiling, the pressure can be changed at will during the shot from 0-9 bars.

I haven’t had the opportunity to work with these machines myself, but the consensus that I’ve heard is that pressure profiling undoubtedly changes the taste of a shot. However, that change can be better or worse depending on what you do with the profile and the particular espresso blend you’re working with.

The only consensus that I’ve heard is that a gradual pre-infusion ramp to 9 bars almost always is a good thing, and then a declining pressure curve from 9 bars to a lower number at the end of the shot also generally improves a shot.

The funny thing to me about this consensus is that older lever machines have had both these characteristics for a very long time. Spring-driven levers inherently have a declining pressure curve: they typically have a peak of 9 bars and then decline to 4-5 at the end of the shot. Also, levers are usually plumbed in, and their design results in an initial pre-infusion at the water pressure of the line.

I’d worked with a Synesso Cyncra for years with Flying Five Coffee, and after Flying Five closed, I didn’t have an espresso machine for a few years while I tried to figure out a home machine that could measure up. After a two different Denver coffee shops switched away from their lever machines to Hydra’s and Strada’s, I was nostalgic for the lever taste that I had been enjoying. 

After lots of research and hand-wringing, I came across the Bezzera Strega, a “prosumer” lever machine. I’ve really enjoyed this machine, and I think the engineers at Bezzera are telling us something with its design.

Two features of the Bezzera in my opinion bring the Strega into the modern age and produce shots that vie with commercial pressure-profiled shots. First, they added a group-head heater to keep the temperature of the shot within about 5 degrees. This isn’t Hydra or Strada accuracy, but it is in the right neighborhood, and the results are great. With my old Synesso, I could taste differences as low as 2 degrees, and I can taste differences now with my Strega, so better temperature control would be a nice thing. But, what they’ve accomplished now is definitely good enough.

The second feature is a built-in vibration pump. Ostensibly, this pump allows the machine not to have to be plumbed in, but rather pull water from its built-in reservoir. But, in making the pump a 9 bar pump instead of putting in a 3 bar pump to mimic a typical water line pressure, I think the engineers at Strega are taking a cue from the pressure profiling world. The vibe pump creates a nice pre-infusion to 9 bars, which then switches over to the spring in the lever, starting at the same 9 bar pressure. The result is a nice continuous pressure curve that appears to match up with the pressure profiling consensus.

In a sense, with pressure profiling, we’ve learned some reasons why lever machines still have such a fanatical following today. It’s poetic that after some high tech development, the pressure profiling consensus found its way back to where espresso was born. The first espresso with crema was produced by Achille Gaggia with a lever in the 1940’s. 

Everything old is new again.

Freezing Coffee Beans

If you ask people who care about quality coffee whether to freeze their beans to help preserve their taste, you’ll get two wildly different answers. Some will say: yes, freeze them, freeze them immediately, and you’re a fool if you don’t. Others will say that freezing is always bad, and why would you even consider doing such a terrible thing to your freshly roasted coffee? With such different and strong opinions, is it possible that there’s the middle ground here?

Freshly roasted coffee is a wonderful thing. When you first encounter coffee just a few days out of the roaster, it’s like drinking an entirely new beverage. It’s fairly widely accepted in quality coffee that you should always buy freshly roasted beans and drink them up within a week or two from the roast date. And, I completely agree: fresh beans are always best.

The freeze camp was probably started by Mike Sivetz, the very scientific coffee inventor and researcher that invented the fluid bed air roaster. Mike has some very interesting patents on freezing coffee that lay out the case for freezing. Vastly simplified, the argument looks like this: coffee’s main enemy is oxidation, and chemical reactions slow down as the temperature goes down, and so oxidation is reduced at low temperatures. Mike took it much farther than that of course , essentially proving that freezing measurably slows oxidation down, and also slows the escape of CO2 from coffee as well.

The never-freeze camp says that freezing coffee causes trapped water to expand when it freezes, and this expansion breaks down the cell walls in the beans, releasing some trapped flavor oils and altering its structure.

Puzzled by this split-decision of the coffee industry, a number of years ago I set out to form my own opinion. I took some freshly roasted coffee, and froze some immediately after roasting, and kept some unfrozen. Then, I did day-by-day cuppings of both to attempt to prove to myself which was right.

The result? My opinion is that both camps are right. Freezing results in an immediate slight degradation in taste. But, you can’t fight oxidation, and so slowly the frozen coffee catches up to its unfrozen siblings. My take is that about between days 7-10 out of the roaster, it crosses over, and the frozen coffee preserves the taste and represents the coffee better than the unfrozen coffee.

The other interesting thing I found is that freeze-thaw cycles seem to each have their own penalty. Every time you freeze and thaw, you lose a bit in taste, perhaps something like 5 or so days of sitting idle.

For me, the result is a fairly simple answer: I keep whatever beans I’m going to drink in the next 7-10 days unfrozen, and then I freeze the rest. Then, after I’ve gone through then unfrozen part, I unfreeze a few days worth of beans at a time.

 

Scales

I’ve been using scales for brewing coffee for years. My friend who owns a bakery first clued me into this way of controlling not only the amount of grounds, but also the amount of water that go into a particular brew.

At first glance, it would seem like measuring water with a scale is overkill: it’s easy to measure water with a cup measure. However, when brewing drip/pour-over with fresh coffee, the bloom of the coffee prevents you from being able to accurately measure the water going into the brewing vessel. Same deal with espresso: the crema in your shot expands the volume so that you can’t measure it effectively. So, scales to the rescue: they precisely measure the amount of water regardless of bloom or crema. 

For pour-over or french press, I’m typically brewing for just myself. For a French Press, I measure out 14g of beans and then put a scale underneath the press. I then pour in 210g of water. How did I arrive at these numbers? I started with how much coffee I like to drink in the morning: about 7-ish ounces. I then used a 15:1 brewing ratio of water to grounds and converted it all to grams. This concept of a brewing ratio is a useful one: you can use it to find what ratios you enjoy, and then scale up or down the amount of coffee you like to drink.

For espresso, I’m even a bit more obsessive than most with scales. I use them at the grinding and brewing end. For my grinder, I measure out a bit more than 18g of beans, and then after I grind it, I tare it down to 18g precisely. Why take this extra step? It’s because of my grinder: despite my best efforts, some grinds tend to get trapped, and so the amount that comes out varies a decent bit.

Then, when brewing, I put a scale underneath the cup I’m pulling the shot into, and measure the amount of espresso in the shot, which is 1.5 oz. This isn’t the usual approach: I’ve seen many coffee shops that do a very good job pull shots into a measured shot glass and measure the shot by volume. While this is a pretty good approach, it’s inaccurate because of the crema expanding the shot and making it difficult to measure. Also, it means that you have to pour the espresso from that shot glass into the drinking cup, and in that process some of the precious crema is left behind in the shot glass. Popping a scale underneath the cup, and pulling the shot right into the cup gives you both precision and collects every morsel of crema.

Is this obsession with precise measurement really necessary? That depends. For me, the precise control of the brewing process provides solid platform that greatly increases my enjoyment of quality coffee. 

Here’s how I think of it: accurate brewing measurements create a technical foundation for the artistic and culinary aspects of quality coffee. Given that solid foundation, it’s fun to explore the possibilities of different coffees and go exploring for different tastes.

Bezerra Strega

Last December, I bought a Bezerra Strega home espresso machine for my office after not having an espresso machine for a number of years. Back with Flying Five Coffee, we had a Synesso, which I consider one of the best commercial espresso machines in the world, and I just couldn’t bring myself to go backwards to older less precise machines.

The Strega has rescued me from the espresso doldrums. It’s a “prosumer” lever machine that combines the old-school lever with some new-school features that gives temperature-stable commercial machines a run for their money.

The thing I really enjoy about the Strega is that it enables you to just use the machine and enjoy the benefits of great espresso without needing to go overboard in technical details. This is something that I’m very prone to do. In just using the machine normally, you’ll be reaping the benefits of good-enough temperature stability and modern pressure-profiling of the extraction.

If you read the Strega thread on home-barista, you might be intimidated about the technical detail discussed there and think that it’s complex to learn and use. I don’t think this is the case. Even when I was just starting out with the Strega, I had immediate good results with it.

Initially, you can just turn on the Strega, let it warm up for 20-25 minutes, grind, tamp and extract. The Strega is always in the right temperature ballpark for good extraction, and just “going for it” and pulling shots works very well. You’ll have great espresso pretty much immediately.

But, as always with espresso, careful attention to detail always improves things. I’ve learned some things over the last 9 months from reading the home-barista thread and from experimenting. Here’s how I use my Strega now:

First, I turn it on just 10-15 minutes before I want some espresso: it heats up really quickly, which I absolutely love. There’s nothing that bothers me more than waiting around when I’m ready for espresso!

Once I hear a short hiss from the machine (which is the vacuum breaker sealing), I wait about a minute more and then pull about 10 seconds of water by pulling the lever down, and then I raise the lever very slightly to stop the vibe pump. I do this to hold some of the  hot water up in the piston to warm it up. This is optional, and is just a time saver: it cuts a decent bit of time off the warm-up time.

Then, I grind and tamp 18g of espresso at 35 lbs. pressure. Before I put the portafilter in, I do a very short cooling flush with the lever: just long enough to release any pressure that’s built up in the line. Then, I put the portafilter in and pull the lever all the way down.

This engages the vibration pump, which fills the piston with water and starts pre-infusion. I let this go until the sound of the vibe pump changes, or espresso starts to drip out. Then, I release the lever and let it extract.

You can steam milk at any time: the Strega is a heat-exchanger.

For me, the result is quality espresso that I really enjoy. I’ve even been having fun pulling the same espresso from the Strega that I can get at shops in Denver out of Synesso’s and comparing the taste differences. Amazingly, the Strega stays neck-and-neck with its commercial counterparts.

Bodum Pavina Glasses

I’ve been using Bodum Pavina double-walled glasses for a number of years now. Actually, we sold these way back with Flying Five Coffee, so that means I’ve been using them since at least 2007/2008. I think these glasses are great, and not just because they look cool.

They’re hand-blown double-walled borosilicate glass. The obvious advantage of the double-walled glass is that it insulates the hot coffee from your hand. While this is a fantastic feature, I think there’s another more interesting advantage to this: you can control how the coffee cools.

One of the many things I love about drinking single origin coffees is how the flavor changes as the coffee cools down. With a “normal” cup, this is a passive journey. With the double-walled glasses, you can control the cooling somewhat. What I like to do is to blow across the top to cool the coffee and taste as I go. When I find a taste that I’m particularly enjoying, I’ll stop and pause for a while, and the insulating double-walled glass lets me linger on that taste for a while. Then, I’ll go find another one.

Not to say that a passive journey in a normal cup isn’t a good thing – I enjoy that too. It’s just that it’s also fun to be able to control it and linger on interesting tastes.

Even before I found these glasses, I’ve always gone out of my way to drink coffee out of glass glasses. Call me crazy, but I just think coffee and espresso just taste better out of glass. It’s well accepted that coffee tastes better when you don’t put it in a to-go cup but drink it in a porcelain cup at the coffee shop. For me, it’s the same sort of analogy: I can’t exactly say why, but for me coffee in a glass just tastes better.

Finally, the hand-blown glass just looks and feels cool. Bodum did a really nice job with the Pavina glasses. It’s somewhat magical to see your coffee hovering above the “bottom” of the glass, and it’s always fun to watch the coffee brewing into the cup. The insulating walls make it very comfortable to grip the glasses without a handle, and the curve of the Pavina fits well in your hand.

Yes, they occasionally break: they’re glass. But, for me it’s worth it.

Moka Pot Brewing

The Moka Pot doesn’t get mentioned too often as a brewing method of choice for quality coffee. It’s not in the same company as V60 pour-overs, Chemexs, French Presses, Aeropresses, or other single serve approaches for those of us obsessed with finding fun quality brewing methods. But, I’ve found there’s some very interesting tastes to be found with Moka Pots.

Many times, people call Moka Pots “Stovetop Espresso Machines,” which isn’t strictly true. The steam pressure only creates a bar or two of pressure, whereas espresso machines extract at 9 bars. So, Moka Pots are really their own category of extraction at medium pressure.

I believe I might have a slight advantage in using Moka Pots – I live in Colorado at about 5400 ft. where the boiling temperature is 204 ºF. Moka Pots use steam pressure created by boiling water in a pressurized lower container to force water up through a pipe into a bed of grounds above. Many times, this water is super-heated above boiling and extracts a scalded, bitter taste: a result of extraction at too high a temperature. Here at altitude, though, I suspect the lower boiling temperature might make Moka Pots extract in the range of good coffee brewing – typically pegged at 195 – 205 ºF.

In case anyone wants to give the method I use a try, here’s what I do. I jump through a few hoops to avoid heating the grounds for a long time, and also shoot for a relatively slow extraction. I also take pains to only extract about 2 oz., and not let super-heated steam go through the Moka Pot at the end. Finally, I’ve settled on one drink that I make with the Moka Pot, that for me creates a really interesting drink with origin flavors.

Here’s my sequence:

1. I boil water in the bottom half of the Moka Pot without the top half not connected. Ie, I’m avoiding heating up the grounds for a long time while the water boils.

2. While the water is boiling, I put 1-2 Tbsp of half and half or cream in the upper half of the chamber. I’m making a sort of very short breve I suppose with this if you use espresso terms. I have a friend that calls this drink a “Breve Macchiato.” By putting it in the top half of the chamber, it lets the cream or 1/2 and 1/2 heat up during the extraction.

3. When the water boils, I turn off the heat, and use pot holders to assemble the Moka Pot, putting the grounds into the holder. This isn’t the most elegant process and requires some practice, but I think it’s worth it.

4. I then start the extraction on the tiny “simmer burner” on my stove. Am I the only one who pretty much never uses this burner? It doesn’t produce any heat and it’s way in the back, almost as if it’s embarrassed to be a stove burner. But, it’s perfect for a Moka Pot. I keep the heat pretty low: only about to 6 on my burner (which goes up to 10).

5. It takes about 30s-60s before any “espresso” comes out, and it bubbles out slowly. I keep the heat low, and sometimes back off just a tad. When about 1.5-2 oz have come out in about 30-45s, I turn off the heat and immediately pour into my cup. I usually judge the amount of extraction by the color as it comes out and mixes with the cream or 1/2 and 1/2.

The result is an espresso-looking creamy drink that doesn’t taste like espresso. I’ve been focusing on single origins with this lately, and different interesting origin notes come out of this method than pour-overs or French Presses. This year, I’ve been on a Honduras kick, which has yielded some really interesting fruity tastes. In the past, Yirgacheffe’s have yielded amazing flavor combinations.

Can the Moka Pot keep company with the V60s and Chemexs of the quality coffee brewing world? I’d say that it’s worth a look and taste.