Does Refrigerating Coffee Reduce Acidity? The Science Explained

December 2, 2025 •

3 min read

A study in Scientific Reports indicated cold brew has lower titratable acidity than hot brew, yet the impact of refrigerating brewed coffee requires deeper examination. The effect of chilling hot coffee differs from the cold brewing process.

Quick Summary

Refrigerating hot-brewed coffee does not diminish acidity, but keeps its current acidic level while potentially making it stale. The lower acidity of cold coffee comes from cold brewing, which extracts fewer acidic compounds during extended steeping.

Key Points

Refrigeration Doesn't Reduce Acidity: Chilling hot-brewed coffee does not lower its acidic compounds; it simply preserves the existing chemical profile at a cold temperature.
Cold Brewing Reduces Acidity: The cold brewing process extracts fewer acidic compounds and more natural sugars, resulting in a naturally smoother and less acidic coffee.
Acidity Can Increase with Time: Chemical changes can occur as hot coffee cools, potentially increasing bitterness.
Flavor Deteriorates in the Fridge: Refrigerating hot coffee exposes it to oxidation and allows it to absorb other food odors, leading to a stale and unpleasant flavor.
Use Cold Brew for a Low-Acid Option: Making cold brew from the start is the most effective method for truly low-acid coffee, as the brewing temperature is the key variable.
Other Acidity-Lowering Methods: Darker roasts, coarser grinds, and adjusting brewing time can also help reduce acidity.

The Core Difference: Brewing vs. Chilling

Understanding the lack of acidity reduction from refrigerating coffee hinges on distinguishing between brewing and chilling.

How Hot Coffee Changes as it Cools

Hot water brewing quickly extracts various compounds from ground beans. This includes chlorogenic acids, responsible for coffee's perceived acidity. These acids don't disappear as the coffee cools; some chemical changes might intensify acidic notes or introduce bitter compounds. Specifically, roasted chlorogenic acids can transform into bitter-tasting lactones and phenylindanes, causing the coffee's pH to drop, resulting in increased bitterness and acidity. Simply refrigerating hot coffee doesn't reverse this; it only slows degradation and chills the brew at its existing acidity.

The Cold Brew Method: Extraction at Low Temperatures

Cold brew is a brewing technique, not just a temperature. It involves steeping coarse coffee grounds in cold or room-temperature water for 12 to 24 hours. The low temperature slows extraction, resulting in a different chemical profile. Fewer chlorogenic acids and acidic compounds are extracted, while more natural sugars are pulled from the grounds. This creates smoother, sweeter, and less acidic coffee. Cold brew can have up to 70% lower acid levels than hot-brewed coffee using the same beans. This reduced acidity results from the brewing process, not the chilling.

Does Refrigerating Brewed Coffee Affect Its Flavor?

Yes, refrigerating brewed coffee significantly affects its flavor. Although it preserves the coffee from spoiling, it does not lock in the freshly brewed taste.

Common Flavor Changes in Refrigerated Brewed Coffee:

Oxidation: Coffee oils and acids start to break down through oxidation once brewed. Refrigeration slows this but doesn't stop it, causing a stale and flat flavor.
Odor Absorption: Coffee is porous and absorbs odors. Storing it in a non-airtight container in the fridge leads to off-putting tastes.
Bitterness Increase: The development of quinic acid as hot coffee cools contributes to a harsher, more bitter flavor profile that is locked in when refrigerated.
Muted Aromatics: The cold temperature suppresses many volatile aromatic compounds, which give coffee its fresh smell.

Comparison: Refrigerated Hot Coffee vs. Cold Brew


Feature	Refrigerated Hot Coffee	True Cold Brew Coffee
Acidity Level	Maintains the initial, higher acidity of hot brewing. May become more bitter as it sits.	Significantly lower acidity due to the cold brewing process.
Flavor Profile	Becomes stale, flat, and potentially bitter over time. Prone to absorbing other fridge odors.	Smooth, sweet, and mellow taste profile. Flavors are locked in by the low temperature.
Brewing Time	Minutes to brew, then a few hours to chill.	Requires a long steeping period, typically 12–24 hours.
Shelf Life	Best consumed within 2–3 days for optimal flavor, though safe for longer.	Concentrate can last for up to two weeks in the fridge.
Best For	Quickly chilling leftovers for immediate iced coffee.	A consistently smooth, low-acid coffee experience over an extended period.

The Verdict: How to Get Lower Acidity

Refrigerating hot-brewed coffee won't reduce its acidity. The only way to lower coffee acidity is to influence the initial brewing process. Cold brew is the most effective technique. Darker roasted beans, coarser grinds, and longer steep times can also be used. For those with sensitive stomachs, exploring alternative brewing methods and specific bean varieties can lead to a more pleasant coffee experience.

Conclusion: Brewing for a Smoother Cup

The question "does refrigerating coffee reduce acidity?" highlights a misunderstanding of how temperature affects coffee. While chilling pre-brewed coffee provides a quick iced drink, it won't decrease inherent acidity and can worsen the flavor. For low-acid coffee, the brewing method is key. Embracing cold brew, or adjusting hot brewing with darker roasts and coarser grounds, is the most effective approach. The focus on the brewing process—not a post-brewing fix—is the secret to a smoother cup. Learn more about coffee acidity from the Specialty Coffee Association's sensory analysis findings.

Frequently Asked Questions

Yes, cold brew coffee is scientifically proven to be less acidic than hot-brewed coffee. The lower brewing temperature extracts fewer of the acidic compounds from the coffee grounds, resulting in a smoother flavor profile.

As hot-brewed coffee cools, chlorogenic acids can break down into bitter compounds like quinic and caffeic acid, which increase the perception of acidity. This chemical process is why day-old hot coffee often tastes harsher.

Brewed hot coffee should be consumed within 2–3 days for the best flavor. Cold brew concentrate can last up to two weeks.

Adding milk, cream, or other alkaline ingredients can neutralize some of the acids, affecting the overall pH and taste, making it feel smoother on the palate.

Yes, darker roasts tend to have lower acidity because the longer roasting process breaks down more of the acid compounds. Lighter roasts retain more of the bean's natural acidity.

Reheating refrigerated coffee isn't recommended. Reheating can cause further breakdown of aromatic compounds, leading to a flatter, more bitter flavor.

No, iced coffee is brewed hot and poured over ice, while cold brew is steeped in cold water. This difference in brewing temperature is why cold brew is less acidic.