Hack Your Mr. Coffee

Is it possible to make actually great coffee from the most mundane of coffee machines? What if we took an old stalwart–that Mr. Coffee brewer that costs about twenty bucks–and applied the best of what we know about the craft of coffee brewing?

Back when Mr. Coffee was invented, percolators (which recirculated the brew over and over through the coffee grounds) were the most popular way to make coffee. The drip brewer was a big improvement, but there a few key problems with Mr. Coffee and similar home coffeemakers that keep it from making a truly delicious cup. Mr. Coffee was coffee’s Atari 2600 of its time–a game-changer in its day, but with today’s higher-quality software (whole-bean specialty coffee), the hardware’s more than a bit outdated.

But don’t give up hope. If you’re visiting family this holiday season and all they’ve got is a good ol’ Mr. Coffee, there are a few tricks you can use to make the results taste much, much better.

Before You Start: Clean It!

A perfectly-brewed cup is just about 98.5% water and only about 1.5% dissolved coffee stuff. “Making coffee” means passing that water over your ground coffee, extracting the coffee stuff in just the right way, so clean water is critical. Tap water is often just fine, but in high-mineral or softened water supply situations, bottled spring water may be better.

But even if you’re starting with clean water, you’re going to throw your coffee brewing out of whack if you use your dirty (or barely rinsed) pot or carafe to pour water into your Mr. Coffee’s water reservoir. You may wonder, “What’s the big deal? It’s all coffee anyway.” Well, the purity of the brewing water will not only affect how it acts as the substance that dissolves the desirable coffee solubles in your grounds, it will also gunk up the plumbing of your Mr. Coffee. So just be sure to use a clean carafe or container to pour in your water. Might sound obvious, but you’d be surprised how many people use a coffee-stained carafe for their brew water!

One more note that may not sound like much of a hack, but is key to the best results: give that Mr. Coffee a good, thorough cleaning before you even think about brewing a cup. Coffee contains a small amount of naturally occurring sugars, as well as an even smaller amount of oils. We call oxidized oils “rancid,” and there’s enough sugar to feed moldy fungus. Wash (by hand or dishwasher if it’s safe) the removable parts as often as you would the cups you’re drinking coffee from, and keep the other parts clean by wiping them with a damp cloth.

Stay Off the Burner

Most of the lower-priced Mr. Coffee models include a hot plate that warms the carafe that holds the finished brew. While that appears to be an add-on feature, the underside of the hot plate actually holds the mechanism that heats the brewing water in the first place.

The chemistry of brewed coffee isn’t very stable, and added heat will accelerate the breakdown of key components, so bitter or astringent compounds will dominate the flavor. On the other hand, poorly brewed coffee can taste unpleasant when cooled off, simply because your palate is more sensitive to flavors of liquids that are closer to body temperature.

So the hot plate is really a trade-off, but I’d recommend skipping it. If you can fit a trivet or something that won’t catch fire under the carafe, insulating it from the hot plate, do so. Otherwise, once your pot has finished brewing, remove it from the hot plate and don’t put it back.

Find the Sweet Spot

Mr. Coffee may be handsome, but he’s dumb. What I mean is that when you switch on most models of Mr. Coffee* and similar coffeemakers, water is heated and sprayed continuously until the water reservoir is empty. So if your 4-cup setting takes 5 minutes, 8 cups will take 10 minutes, and 12 cups will take 15 minutes.

If your toaster worked this way, and kicked on four times longer to make four slices of toast than just one, you’d throw that thing into the street! Like most forms of cooking with heat, temperature and time are very important variables. Without some control over time, you really have no control at all.

The good news is that there’s actually a workaround. The bad news is that the workaround is that you should only use your Mr. Coffee to brew one size batch.

Every brew method (and coffee) has an optimal range of brew times that maximize desirable flavors like sweetness and pleasant acidity and minimize unpleasant flavors like bitterness or astringency. Five minutes is a good match for most auto-drip methods, especially because the brew water temperature tends to hover between 185 and 200°F during this time frame. So all you have to do is trick your Mr. Coffee’s into sticking with that sweet spot.

Here’s how you do it: fill up your water reservoir to about the 8 cup line. Without any coffee or filter, turn on your Mr. Coffee like you’re making a pot of coffee. When you see the first bit of water drip into your carafe, start a stopwatch. When your stopwatch hits 5 minutes, switch the brewer off. Leave everything alone and come back in about an hour when everything’s cooled down. Set the carafe aside. Turn Mr. Coffee upside-down over your kitchen sink and dump out the water from the reservoir. Then pour the carafe water (or the same amount of water) into the reservoir and take note of where the water level is. That’s how much water you’ll use now and forever more.

Now, how many “cups” is your water line indicating? I put “cups” in quotes because Mr. Coffee “cups” are five fluid ounces (not the normal eight ounce “cups”). A good recipe to start with is 10 grams of coffee (about two tablespoons) per (five fluid ounce) Mr. Coffee cup. So you can do the math and figure out how much ground coffee you should use to get your pot to brew for exactly five minutes. Start with a grind size that looks like coarse sugar and adjust your grind to taste. Too bitter? Grind coarser. Tasting weak? Grind finer.

This whole process may seem cumbersome, but it’s a one-time task that will help establish your Mr. Coffee’s sweet spot.

*Some of the newer and higher-priced Mr. Coffee models do have control mechanisms that de-couple the amount of water it’s brewing from the time it takes to brew, similar to professional-grade drip brewers.

Temperature Tweaking

Boiling water is what drives water up to Mr. Coffee’s spray head, so putting warmer water into your carafe will push water through faster. It won’t make much of a difference in the actual temperature of the brew water (because boiling is boiling), but it will make a difference in the brewing time. This is one way to change the “sweet spot” brew yield covered above.

Simply put, you could repeat the “find the sweet spot” process, but using a specific temperature of water. The flash heater brings a small quantity of water up to a boil, and the bubbling up drives water up the pipe and to the showerhead above the coffee. The higher the temperature of the water, the less time it takes to bring that water to a boil. The lower, the more. Get it?

It’s tricky and definitely geeky, but even if you don’t decide to try this, it’s still good to learn why this works. Your brewer may drift from the “sweet spot” because the water you’re putting into it is warmer or cooler than when you originally tested it.

The obvious way to make sure you know what temperature your brew water is would be to use a thermometer. Another option could be to load your Mr. Coffee with water well in advance of brewing with it, giving it time to settle to a happy room temperature. The simplest method, however, would be to use your hand on the side of whatever you’re using to transfer water. Get a sense of an average room temperature, and remember that. Like putting your hand on someone’s forehead, it doesn’t beat a thermometer, but it’s enough to tell you if you should be concerned or not.

Along this line, if you brew again soon after you just made a pot, Mr. Coffee will get to boiling faster since it’s already all hot and bothered. This will throw off that ideal five-minute brew, so you may want to wait a bit to let the pot cool off before starting again.

Help Wetting

The big gallon-sized fancy brewing machines that folks like me use in our cafes have specially designed spray heads to deliver water evenly across the coffee grounds, but most home machines dribble the water in a haphazard way.

Water flows down and flames flicker upwards, but despite that difference, the flow of water through the coffee in a drip coffee brewer is a lot like the heat from an barbecue grill. If your grill’s flame is severely uneven, with a hot spot over here and a cool spot over there, it’s really going to affect how evenly you’re cooking the food. So how would you handle that? Well, you could improve the situation through technique, moving the food around to coax a net result of some semblance of evenness, right?

Well, Mr. Coffee’s spray head is pretty sloppy. It’s just an open tube (sometimes multiple smaller holes) positioned over the coffee, with water periodically spurting out of it like ocean waves over rocks. On its own, rather than sending water evenly through your coffee grounds, Mr. Coffee’s brew water will dribble out of its spout and drip through via the path of least resistance. Most of the time, this means that the water will brew one side of bed of grounds, and barely wet the other side. This unevenness is exacerbated when you’re using coffee roasted within the past month or so, because the CO2 gas expelled from fresh coffee when it’s met by hot water pushes outward, and the bubbly damp grounds form a barrier and push aside the dry grounds, effectively protecting them from the brew water.

The easiest way to overcome this problem is to periodically open Mr. Coffee’s lid and with a spoon or other utensil, gently stir the coffee grounds to wet the entire bed of grounds and encourage evenness. Once everything’s saturated with water, osmosis and diffusion forces can kick in, working to help pull the flavor molecules out of the entire bed of coffee. Coffee brewing is like a hot-tub party for the coffee grounds. If you’re not wet, you’re not part of the party!

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