My HARIO–MAVO cold-brew comparison: TDS and filtering

After countless failed attempts at cold brew, I finally found the secret to cold brew.

1. Don’t stir or shake. Don’t stir or shake. Don’t stir or shake. This is extremely important: once you shake it, the taste gets worse. The most obvious change for me is that it becomes bitter. I suspect that too many fine grounds pass through the filter and that the excess fines are being washed around. If a cold brew turns bitter and muddy, I personally think it’s less hassle to make pour-over and add stainless-steel ice cubes.
2. Filter it with lyocell-fiber paper. A lot of people don’t want to make cold brew because they don’t want to filter it; they find filtering slow and troublesome. That was a main reason I avoided making it too. With a 500 ml bottle of cold brew, four or five regular filter papers weren’t enough because they kept clogging. This paper gets it filtered in no time.
3. Use a grind just a little coarser than for a regular pour-over.

A few thoughts on these two cold-brew makers: I used to think the HARIO was poorly designed because its grounds basket sat too high and its mesh count was too low, letting very fine grounds through. Only after using the MAVO did I realize that these were all deliberate advantages of the HARIO. 1. The high basket helps maintain a larger concentration difference between the inside and outside over time, because the more concentrated cold brew and the finest grounds sit at the bottom. 2. The HARIO basket’s mesh count is just right for exchange between the inside and outside; the MAVO’s is a little too high. In my comparison under the same conditions at a 1:12 coffee-to-water ratio, the HARIO measured about 1.55% TDS and the MAVO about 1.15%.

With this method, you’ll get a very clean cup with low bitterness and great taste. The first time I drank it, I thought the concentrate could only be about 1.2%, but after filtering it still measured above 1.5%. Diluted with ice, it landed at a reasonable strength. The only downside, if there is one, is that it goes down so easily—and it’s a caffeine bomb.

Parameters: SSP 98LU burrs, ground at 850 rpm; HARIO filter bottle; 54 g of coffee and 650 ml of water; steeped for 12 hours. I poured room-temperature water directly into the grounds basket and didn’t shake or stir at any point. Don’t worry about the last little bit of liquid in the basket: pour the cold brew from the bottle into the filter without shaking, then discard the remaining liquid and grounds. Since the HARIO mesh isn’t very fine, I don’t think much concentrate is lost. HIFLUX paper filters far more efficiently than traditional filter paper. Regular paper used to clog almost immediately and stop draining, which was frustrating. With this paper, filtering finished as I poured out the cold brew.