What You Need to Know About Low Acid Coffee

Cup of dark roasted coffee surrounded by coffee beans

People around the world love their coffee. The worldwide population drinks an estimated two billion cups daily. In the United States, coffee drinkers down an average of 3.1 cups per day. This amount is still below the FDA recommended maximum daily caffeine intake (400 mg), equaling about four to five cups of coffee. However, some coffee drinkers may find even one cup brings on stomach irritations or heartburn. Instead of giving up their daily cup of coffee, these coffee drinkers may have looked to low acid coffee as a solution.

What is low acid coffee? 

Some people may not have even known low acid coffee existed. Others may have heard of low acid coffee but don’t fully understand what it is.

Low acid coffee has lower pH levels relative to regular coffee. A measurement used in the chemistry field, pH refers to a scale that indicates how acidic a liquid is. The scale runs from 0 to 14. More acidic liquids have a lower pH (below 7), a pH of 7 is considered neutral, and basic liquids fall above 7 on the scale.

Black coffee has a pH of about 5. For comparison, carbonated water has a pH of 3 while fruit juices have a pH of 6. An increase or decrease of one on this scale represents a 10-fold change in acid level. For example, the acid level of black coffee is 10 times higher than that of fruit juice.

Low acid coffee’s flavor profile is also different when compared to regular coffee. A lower pH level can result in a smoother tasting coffee, but the taste can become bland if the acid levels are too low. 

Let’s take a moment to distinguish between measured acidity and perceived acidity because it can get confusing.

You’ve likely heard coffee drinkers evaluate a coffee by describing its acidity. More often than not, they are referring to the coffee’s perceived acidity. It is also commonly known as brightness, and it contributes to a coffee’s complex flavor profile. Perceived acidity is the first taste you notice when you take a sip of coffee. It gives it a lively flavor, and without it, many would consider their coffee bland. 

Perceived acidity is different from measured acidity, which takes into account pH levels. What may be confusing for some is that the term “perceived acidity” is not frequently used. Instead, people use the general term “acidity” (or “brightness”) when describing a coffee’s flavor profile. Coffee drinkers are more often concerned with perceived acidity than measured acidity. 

Of course, if you have a sensitive stomach, you may be more inclined to be concerned about measured acidity – at least more so than most coffee drinkers would. However, most, if not all, coffee drinkers find perceived acidity important as well. After all, who would want to drink a dull flavored coffee? 

Now that we know the difference between perceived and measured acidity let’s learn how they are related

A study has shown that a coffee’s perceived acidity and measured acidity are correlated. This relationship makes sense since both acidity types are affected by the same acids: acetic, formic, malic, citric, lactic, quinic, and chlorogenic. 

Scientists have also noted that smaller changes in measured acidity can have a large impact on flavor.

So, can the measured acidity in coffee really cause stomach issues?

If you’ve researched low acid coffee as a solution to stomach issues, you may have come across some conflicting information. Although you will find plenty of articles saying that regular coffee can cause heartburn or stomach irritations, there is a smaller number emphasizing that coffee’s measured acidity is too low to be the culprit.

Some studies have shown that it isn’t the acids themselves that cause issues, but it’s how they react to stomach acid. Chlorogenic acids in coffee, in combination with caffeine, stimulate your stomach to produce more gastric acid. Too much gastric acid can lead to stomach aches, bloating, nausea, and heartburn and can contribute to acid reflux

However, another coffee component, N-methylpyridinium (NMP), curbs the amount of gastric acid secreted by your stomach.

Overall, studies have been inconclusive in determining if the measured acid in coffee directly causes heartburn and stomach irritations. But based on the information above, it would seem that coffee with more NMP and lower levels of chlorogenic acids may be less reactive with your stomach.

So, choosing low acid coffee or coffee with lower measured acidity may not provide relief for coffee drinkers with stomach sensitivities.

If low acid coffee may not be the answer, what should you look for in a coffee that won’t upset your stomach?

Most coffee packaging won’t outline levels of NMP or chlorogenic acids present in the beans. So, you have to consider other factors to determine NMP and chlorogenic acid levels. 

Coffee plant

Studies have shown that the origin of coffee beans can affect the amount of chlorogenic acid present in coffee. Coffee beans grown at higher altitudes and in the shade tend to have the highest chlorogenic acid levels. Also, coffee beans that underwent the wash processing method had higher levels of chlorogenic acid

Robusta coffee beans will have more chlorogenic acid relative to Arabica. Several other aspects of the coffee plant variety and species will affect acid levels in the beans.

If you are a coffee drinker dealing with stomach sensitivities, the first thing to do is research coffee origins. Your research will hopefully reveal where the beans were grown, how they were processed, and the variety and species of the coffee plant.

Roasting levels can also determine chlorogenic acid levels but do not affect caffeine content as much.

If you are a home roaster, take the time to roast the green coffee beans for a more extended period. Increased roasting times give the organic acids in the beans the opportunity to break down. So the chlorogenic acid decreases in addition to others, including citric and malic acids

Dark roasted low acid coffee beans.

While the stomach-irritating acids decrease (and therefore the pH acidity), so do those acids that contribute to the perceived acidity of the coffee. Striving for a darker roast will make the coffee more stomach-friendly, but the taste will be flatter (duller, less crisp) and the body fuller (heavier mouthfeel). So, taking the time to slow roast your coffee beans to a dark roast, will increase the pH acidity, but reduce the coffee’s perceived acidity. However, keep in mind, that roasting the beans too dark may cause stomach issues as well.

N-methylpyridinium (NMP) is formed during the roasting process. It continues to develop as the beans roast, so darker roast coffees have higher concentrations of it.

Roasting time does not significantly affect the caffeine content per bean. However, it does affect the beans’ density. If you compare the caffeine content of the same measured weight of light roast and dark roast, you will find the dark roast coffee has more caffeine. Still a little confused? Learn more by reading our post on the caffeine content of coffee.

Bottom line – low acid coffee may not be as effective in protecting stomach sensitivities as many people think.

If you are an avid coffee drinker looking for something easier on your stomach, low acid coffee may or may not be the solution. It’s not a lower measurable acidity (pH) that will save you from stomach irritations or heartburn; it’s specifically the combination of chlorogenic acids and caffeine that may make the difference for you—that, along with the presence of NMP. 

Each person’s stomach may react differently to various coffees. Finding the right coffee for you may take some trial and error. You may want to start with darker roast coffees since they will contain some level of NMP. Adjust your roast level depending on what your stomach can handle and the flavor profile because you still want the coffee to be enjoyable.

It is also possible that what is labeled a “low acid coffee” may give you what you need in terms of chlorogenic acid and caffeine levels. You will just need to do a little more research to find out.

As a final note, although chlorogenic acid can do a number on your stomach, it does have some positive attributes.

Studies have shown some benefits of chlorogenic acid include lowering blood sugar levels, boosting fat metabolism, and reducing cholesterol. There have also been continuing studies on the positive effects it may have on cognition over the longterm, specifically with dementia and Alzheimers. Take these things into consideration as you determine the coffee that is right for you.

Here are some green coffee beans to consider if you are home roasting:


If you have questions about these coffees or any others, connect with the coffee experts at Burman Coffee Traders. They can help you evaluate green coffee beans originating from a variety of regions. Contact them with any questions, and they would be more than happy to share their coffee knowledge.

FreshRoast SR540: Perfect for Beginners

home coffee roasting primers from BCT


We carry several types of home coffee roasters, with different batch sizes and mechanisms to suit different needs.

Our Favorite Home Coffee Roaster

For new home roasters, we have long recommended the FreshRoast SR540, a “fluid bed” roaster which is super easy to use. Fluid bed roasters are very similar in design to the familiar hot-air popcorn poppers – minimal mechanical parts, simply a fan and a heating element – the only significant difference is a smaller (and therefore hotter) roasting chamber. See video of FreshRoast SR540 in action.

The SR540’s glass roasting chamber makes it easy to watch as the roast develops, and then stop the roast at exactly the right moment. These popular roasters are economically priced, will roast a modest amount of beans in a speedy 7-20 minutes (including cool time), and are very easy to clean and maintain. Simple, safe, and accessible, the SR540 is ideal for new home coffee roasting enthusiasts.

We offer a wide variety of home roasters – different styles for different preferences. For new coffee roasting hobbyists, we frequently recommend the FreshRoast SR540 because it is easy and very popular

How to use your FRESHROAST SR540 coffee roaster

filling FreshRoast SR540

Here are the basic steps:

  1. Start with four level scoops of green coffee (about 4.5 ounces by weight).
  2. Remove the chaff collector, add the coffee to the roasting chamber and put the chaff collector back on.
  3. The new improved control panel is very easy to use. Simply press the knob on the right, and one of the numbers – FAN, POWER, TIMER – will begin to flash. Turn the knob to increase or decrease that setting, or press the knob again to switch to the next setting. Turning the knob while none of the numbers are flashing will display the Temperature in the chamber (NOTE that this is air temp, not internal bean temp, but it still gives an approximate idea of how far along the roast has come). The same RUN/COOL button begins and ends the roast cycle.
  4. Begin with Fan Speed set to 9 and Power set to 5.  Set the Timer for about 15 minutes. Total roast time should come in between 6 and 15 minutes dependent on settings. You may add time at any point by clicking the knob until Timer is flashing and then turning it clockwise; Fan and Power settings also may be adjusted at any time.
  5. Press the RUN button. Starting the roast with low temperature and high fan speed lowers moisture content and gets the beans moving; this will ensure an even roast. After approximately two minutes turn Power up to 9. As the roast progresses, coffee beans will begin turning over vigorously, especially after first crack. Turn the Fan speed down as needed; slower-moving beans will build heat to roast faster and more evenly.
  6. As coffee beans roast they will begin to brown, double in size and shed chaff, emitting a light audible “first crack.” Begin to pay close attention, watching for your desired roast level. For many coffees, we recommend a roast that ends shortly before second crack – beans will appear medium to medium-dark brown and the surface of the beans will begin to turn from dull/flat to a velvety sheen. This is within the range of “City Roast” to “Full City Plus Roast,” and is a good place to start for most coffees. When you are happy with the roast level, simply hit the COOL button to complete the cycle.
  7. Be aware that roasting goes much faster as you move into the dark end of the spectrum. “Second crack” occurs when internal bean oils and moisture expand from an exothermic reaction, producing a small hole in the bean and emitting a subtle crackling sound; this is the start of a dark roast. Sometimes second crack is very quiet, but if you see shiny oils on the surface of the beans, you are into the second crack – consider turning off the heat at this time, as beans will very rapidly darken beyond this point. If you see smoke coming from the roaster, you are well into the second crack and at a dark roast; definitely hit the COOL button now.
  8. DO NOT SKIP THE COOL CYCLE! This function not only stops the roast from continuing and cools beans enough that they may be handled, but also it is very important to allow the equipment to cool before beginning the next batch.
  9. After the cool cycle shuts off, remove the chaff collector (be careful – it may be still pretty warm), lift out the roast chamber by its handle and dump out the beans.  Let freshly roasted beans sit in a glass or ceramic bowl to allow “set-up” for a day or two, then put them in an air tight container. We like to store the set-up roasted beans in a small canning jar.
  10. The only cleaning necessary is to dump out the chaff from the chaff collector and wipe it out; a small basting brush works perfectly. This model yields about 28 cups per batch.

Follow roasting with a “set-up” rest period

Freshly roasted beans will be at their peak of flavor only after they have “set-up” for about 12-24 hours. This is due to necessary off-gassing of carbon dioxide that balances the acidic tones in the beans. Read our primer about roast styles to learn more.

different coffee roasting styles coffee beans set up

What if roasts are too dark or too light?

Batch size is critical to the roasting process. In all air roasters, smaller batches roast slower and larger batches roast faster. It may seem counter-intuitive, but hot air flows more freely with fewer beans, meaning that less heat builds up in the chamber. If your roasts are too dark decrease your batch size to increase air flow or hit the COOL button earlier. If your roasts are too light increase your batch size to increase trapped hot air, or increase time and heat settings.

We recommend taking notes in a Roasting Journal, so that you can remember exactly what settings work best for each unique bean.

Not sure if you want it lighter or darker? Read our primer about roast styles if you would like to experiment with different roast levels.

More Coffee Roaster Tips:

All roasters are sensitive to your home voltage, so it helps to identify a circuit that will not be used by any other appliances while you are roasting. This also means that roasting times may vary slightly from one batch to the next, so be sure to watch carefully, especially with a new roaster.

Keep in mind that these are home roasters not intended for commercial-scale use. It is very important to let them cool down between batches or you may trigger the thermal protection safety features, which require the roaster to be reset by the manufacturer and may void the warranty.

If you want to stop the roast at any time, just hit the COOL button. It is inadvisable to switch the roaster off, as it will be very hot and it will require a cool cycle before handling. We cannot emphasize it enough – the cool cycle is very important to maintaining the longevity and effectiveness of your FreshRoast SR540.

Never leave any roaster unattended. Think of home coffee roasting as similar to frying bacon – it can and will burn if you walk away from it!

Details & NEW Video Guide to FreshRoast SR540

Want to learn more about Green Coffee before diving in? Follow these links:

Ready to get started with Roasting Coffee?