True, acidity is a good thing in coffee. It provides the sweetly tart spark essential to lifting the sensory experience of a fine Arabica coffee from grainy, dull inertness to lively complexity. It signals the presence of certain organic acids with powerful anti-oxidant properties that have helped turn perception of coffee from a health threat to a health drink. Nevertheless, there are many who deeply love coffee—and caffeine—but whose digestive systems simply can't handle a whole lot of those lively, healthy organic acids. Some of these acid-sensitive coffee lovers write emails to Coffee Review asking for help: How can I find a coffee that gives me the sensory pleasure (and the caffeine) I look forward to every day without the burning and acid reflux?
There are two directions in which to look for such a paradoxical product. First, coffees explicitly advertised as low-acid coffees. A handful of companies now specialize in low-acid coffees, and have come to constitute a tiny, but recognizable, market niche in today's coffee industry. For this month's cupping we tested twelve coffees from five of these specialized companies. All explicitly advertise their low acidity. These companies use proprietary, if rather lo-tech, methods to reduce acidity, involving either very slow or interrupted roasting (which reduces both acidity and aromatics) or treating the green beans before roasting by removing the waxy outer layer through steaming, which also reduces acidity while muting aromatics. In most cases, these companies also appear to have loaded the dice in favor of lower acidity by buying their green coffee from origins like certain regions of Brazil that produce naturally lower acid beans
Inadvertently Low-Acid Coffees
Another option for the acid-sensitive coffee lover is to look for coffees that may not be specially treated to reduce acidity, or advertised as lower in acidity, but which may be expected to be low in acidity for unintended or "natural" reasons. Dark roasting, for example, particularly very dark roasting, dramatically reduces acidity.
The quest may be trickier for those of us who prefer medium or light roasted coffees; here the search must be directed at coffees that traditionally are lower in acidity in their raw, unroasted state owing to lower growing elevations (the lower the elevation the less intense the acidity) supplemented by certain fruit removal methods that may reduce acidity, like drying in the whole fruit (the dry or natural method) or drying in the fruit pulp (the pulped natural or honey method).
Brazils lead the pack of suspects for naturally low acid coffees, with Sumatras a probable second choice. However, regrettably for those in search of certainty, lower grown coffees from almost any origin can turn out to be relatively low in acidity, while both Brazils and Sumatras often turn out to be rather acidy depending on where they were grown and how they were processed.
Matching High Ratings and Low Acidity
We tested twenty additional coffees that we suspected could turn out to be low acid coffees, but which were not advertised as such. We looked for coffees that combined attractive sensory properties with low acidity confirmed by an instrument reading of pH, the standard measurement for relative acidity/alkalinity. We found three such coffees, inadvertently low in acidity but high in sensory potential, all reviewed here: A Tully's French Roast (rating 85; low acidity mainly owing to very dark roasting, although low-acid green coffees may have contributed as well), a Peet's Sumatra Blue Batak (rating 88; low acidity mainly owing to dark roasting and also perhaps owing to lower-than-normal acidity in the green coffee), and—the real find of the month, in my view—a lovely, lyrically delicate medium-roasted Water Avenue Coffee Brazil Esperanza (91) with low acidity both perceived and confirmed by pH
Scorecard for the Advertised Low-Acid Coffees
How well did the twelve advertised low-acid coffees fare in our tests?
The good news is that they genuinely did display low acidity, both as perceived during cupping and as confirmed afterwards by testing for pH.
The bad news is that most did not taste very good. Ratings for the twelve advertised low-acid coffees we tested averaged 79; the twenty coffees we tested that were not advertised as low acid averaged 87
The taste problems with the advertised low-acid coffees were only partly owing to the flavor-dampening impact of the procedures designed to lower acidity (slow or interrupted roasting in the case of Puroast, HealthWise, Tyler's and Simpatico; green bean treatment in the case of Hevla). With many of these coffees, the main problem was a familiar, old-fashioned one: taste-tainted green beans. The Tyler's Acid Free Coffee Regular (68) was by far the worst tainted of the twelve, a text-book example of a hard, medicinal cup. All three Hevla samples also showed taints, ranging from the 69-rated Dark Roast (musty, rotten ferment) to the considerably more palatable 79-rated Espresso WB (mildly musty). The Puroast House Blend (77) also appeared to be mildly musty, though the Dark Roast Guatemala (84), also from Puroast, was a sound coffee, suggesting that, at least with the Puroast samples, the low-acid treatment (very slow roasting) was not the most influential flavor-destroying culprit. With the HealthWise samples the acid-muting procedures seemed particularly foregrounded, however. Both the 79-rated Gourmet Low Acid 100% Colombia and the 75-rated Gourmet Low Acid Organic Colombia were flat and woody, though the latter added a clear hint of rotten ferment. The flavor winners by far among the advertised low-acid coffees were the Simpatico Nice Coffee samples, both of which were relatively low in acidity as measured by pH and pleasantly free of green coffee taint. The Simpatico Espresso Roast is reviewed here at 87; the mixed-roast Black & Tan Blend came off the table at 86.
Perhaps people who manage low-acid coffee companies are entrepreneurs with little experience evaluating coffee and so are victimized by green coffee importers or private labelers who unload cheap, tainted coffee on them. If so, the situation was probably exacerbated over the past year by the relative shortage of good quality Arabica coffees. Summarizing the Results
The table below summarizes ratings and pH measurements for fourteen of the least acidy of the total of thirty-two samples we tested. Unfortunately, we had to leave out some very fine-tasting coffees because their pH was too acidy for inclusion.
A word on interpreting pH numbers. Distilled water has a neutral pH (neither alkaline nor acidic) of 7.0. Numbers higher than 7.0 indicate solutions that are alkaline; numbers below 7.0 acid. So the higher the pH number the lower the acidity. Furthermore, the pH scale is logarithmic, so a relatively small difference in pH at the levels we are discussing may represent a large difference in intensity of acidity. A difference of around 0.3, for example, is quite meaningful, and a difference of 1.0 is dramatic.
The coffees appearing highest on the tabular list displayed lowest acidity as measured by pH. However, all of the listed coffees are considerably less acidy than most high-grown, medium-roasted coffees, which tend to register a pH of around 4.9 to 4.5.
pH - Coffee - Rating - Reasons for Lower Acidity
A caveat on pH: As confirmed by a useful conversation with Joseph Rivera, a consultant who specializes in coffee chemistry, a particular set of organic acids, chlorogenic acids, are probably the main contributors to compounds that produce stomach irritation in susceptible coffee drinkers. Unfortunately, paying a laboratory to measure chlorogenic acid in twenty or so samples of coffee turned out to be far too expensive for our limited budget at Coffee Review. But pH alone appears to be a sound starting point for measuring acidity, and is the measurement used by the U.S. Food and Drug Administration to define low-acid canned foods (pH higher than 4.6).
I also was struck by how closely our sensory readings of intensity of acidity in these samples tracked degree of acidity as measured by pH. So I suspect that those interested in finding a naturally low-acid coffee could rely on their own perception of acidity when trying out samples. Those consumers who enjoy darker roasted coffees should have few problems. Almost any Brazil or Sumatra and many Mexicos, Perus, Guatemala Antiguas and Nicaraguas brought to a darker roast should display relatively low acidity. Those who enjoy medium-roasted coffees may find the search more difficult, but experimenting starting with Brazils may work.
Lower Acidity through Brewing and Buffering
Finally, a note on two other ways to reduce the potential of coffee to irritate the stomach: How you brew it and what you put into it before you drink it.
The cold-water brewing method extracts considerably less of everything from coffee, including acids, than do hot-water brewing methods. The Toddy company produces an excellent little cold water brewing system (www.toddycafe.com). Most 90-plus coffees we review on our site brewed in the Toddy system should produce a light-bodied, sweet, low-acid, though perhaps aromatically simplified black coffee that should be relatively easy on sensitive stomachs. A naturally low-acid coffee like this month’s Water Avenue Brazil should be very, very mild in acidity if brewed by the cold water method.
Or there is the espresso-and-milk option. Start with a mild espresso coffee composed of inherently low-acid coffees – look for all-Brazil or Brazil-based espresso blends. Click on “Advanced Search” on the Coffee Review home page, choose “Espresso” in the “Type” column and enter “Brazil” in the keywords box. Or perform the same search, but try “Nicaragua” or “Sumatra” in the keywords box. All should give you a list of relatively low-acid espressos. If you don’t buy your coffee by Internet try to find Illy Caffè, a very low-acid espresso, at upscale grocers. Brew this coffee espresso-style in a short shot of an ounce or so and combine it with about three parts hot frothed milk for a beverage that still tastes like coffee but is quite easy on the digestive system (assuming the system’s owner is not lactose intolerant).