What happens if cold soda gets warm?

Quick Answer

When cold soda gets warm, a few key things happen: the dissolved carbon dioxide bubbles out of the liquid, the soda loses its fizz, and the flavor can change slightly. Warm soda often tastes flat or off compared to its chilled state. The optimal temperature to serve soda is around 34-38°F. Once it gets warmer than that, the physical properties and taste can deteriorate. But in most cases, it is still safe to drink soda at room temperature.

What Causes Soda to Go Flat?

Carbonation is the key element that gives soda its bubbly, effervescent texture. Soda gets this fizzy quality from carbon dioxide gas that is dissolved under high pressure into the liquid. When the soda is chilled, the carbon dioxide gas stays dissolved. But when the temperature rises, the solubility of the gas decreases, causing it to be released from the solution in the form of bubbles. This causes the soda to lose its carbonation, or go flat.

Some key facts about soda carbonation:

– Carbon dioxide gas is pumped into soda under high pressure to become dissolved in the liquid. This is called carbonation.

– Colder liquids can hold more dissolved carbon dioxide than warmer liquids.

– As soda warms up, its solubility for carbon dioxide decreases.

– The dissolved CO2 bubbles out of solution as the soda gets warmer, causing it to lose its fizz.

– Flat soda contains less dissolved carbon dioxide and has less pressure than freshly made carbonated soda.

So in summary, temperature has a major impact on soda carbonation. Cooler temperatures help keep the carbon dioxide dissolved, while warmer temperatures cause it to bubble out.

Does Warm Soda Go Bad?

Warm soda does not necessarily go bad, at least not in the way milk or meat would. The main impact of warmer temperatures is a change in taste due to going flat. However, soda that has been left unrefrigerated for an extended period of time may start developing signs of spoilage due to microbial growth.

Some key facts about warm soda:

– At room temperature, soda does not contain conditions that allow rapid microbial growth. Acidity prevents most microbes from growing.

– Diet sodas with artificial sweeteners stay fresher longer than sugary sodas when warm. The sugar in regular soda promotes some microbial growth.

– Over time, warm soda exposed to oxygen can start developing off-flavors due to chemical oxidation. This may impact taste.

– If stored for weeks or months at room temperature, warm soda can start growing mold or yeast, visible as fuzz or floaties. This makes it unappealing.

– Soda cans or bottles may bulge or even explode if left unrefrigerated for too long due to gas pressure buildup from fermentation.

So while warm soda itself does not harbor much microbial growth, over time mold, yeast, or chemical oxidation may start impacting its taste and appearance. But the occasional warm soda you forgot in the car is likely still safe to drink.

How Long Does Soda Last Unrefrigerated?

The exact shelf life of unrefrigerated soda depends on the type and packaging, but general guidelines are:

– Plastic soda bottles: 3-6 months at room temperature before tasting flat or degraded

– Canned soda: 9-12 months before going flat, changing taste

– Diet soda: 12-15 months at room temperature due to lack of sugars

– Glass bottles: Shorter than cans or plastic due to gas permeation through glass

Properly stored canned or bottled soda stays carbonated and enjoyable for at least several months without refrigeration. Over time, the CO2 bubbles will dissipate and the flavors can oxidize, making it taste flat and deteriorated. Keeping sodas sealed helps prolong their shelf life.

Temperature extremes also impact shelf life. Storing sodas at temperatures above 90°F will shorten their lifespan. Freezing cans may cause damage. Optimal storage temperatures are 60-75°F. Refrigerating after opening is recommended.

So while sodas are designed to store at room temperature for months, refrigerator chilling after opening will keep them freshest. Pay attention for any changes in taste, carbonation, or appearance.

Does Shaking a Warm Soda Help?

Shaking a warm soda can help redistribute some of the carbonation temporarily, but it does not prevent the soda from going flat. Here is why shaking helps, but only temporarily:

– Aggressive shaking agitates the soda, causing some of the CO2 bubbles to become re-dissolved.

– This gives the illusion of restored carbonation and fizziness.

– However, the solubility equilibrium has not changed – so the CO2 will rapidly come out of solution again.

– Within minutes, the soda will lose its fizz again as the CO2 continues to escape back into gas form.

So while shaking cold soda is effective at dispersing the carbonation evenly, it does not have a lasting impact once the soda has warmed. The equilibrium between dissolved gas and free bubbles has shifted. Additional CO2 has already left the solution that cannot be replaced just by shaking.

A better option for warm, flat soda is to try chilling it rapidly in an ice bath. This lowers the temperature, helps re-dissolve some of the CO2, and restores some of the lost carbonation, at least temporarily. But the ultimate solution is to prevent soda from warming in the first place by keeping it chilled before serving.

Does Putting Warm Soda in the Fridge Help?

Putting warm soda in the fridge can help improve the taste by bringing it back down to colder, properly chilled temperatures. However, it does not fully restore the lost carbonation. Here is what happens:

– Colder fridge temperatures between 34-38°F allow more CO2 to dissolve back into the soda.

– This helps provide some renewed fizz and pop.

– But the equilibrium has shifted – much of the CO2 has already come out of solution.

– Fridge chilling cannot fully restore this lost carbonation.

– The soda may taste improved but still flatter than originally.

– Storing open sodas in the fridge will help prevent further CO2 loss.

So while chilling warm soda in the refrigerator helps, it is not magic. The soda may regain a small amount of its fizz, but it will not be restored to its originally carbonated state. The key is keeping sodas chilled before opening, not trying to save them after.

Does Soda Go Flat Faster in a Glass or Can?

Exposed to air in a glass, soda will go flat faster than if left sealed in its original can or bottle. Here is why:

In a Glass:

– More surface area exposed to air

– Bubbles escape easily from large opening

– No air-tight seal to contain carbonation

– CO2 dissipates within minutes of pouring into an open cup

In Cans/Bottles:

– Tight seal helps contain CO2 gas

– Small opening limits CO2 escape

– Rigid containers prevent pressure loss

– Aluminum cans are especially good at maintaining carbonation

So soda poured into an open glass will lose its fizz noticeably faster than soda left in a sealed metal can or even plastic bottle. The more airtight the container, the better job maintaining carbonation. For maximum carbonation retention, drink right from the can or bottle and minimize pouring over ice.

Does Shaking a Soda Bottle Make it Lose Carbonation?

Shaking up a sealed soda bottle generally does not cause it to lose significant carbonation or go flat. In fact, it helps evenly distribute the CO2. Here’s why:

– Agitation helps disperse CO2 bubbles stuck to the container sides.

– This evens out the carbonation profile throughout the liquid.

– The seal keeps the CO2 safely contained in the closed bottle.

– Pressurized CO2 has nowhere to escape to, so remains dissolved.

– Bottles are designed to handle pressure from shaking or agitation.

– As long as the bottle stays properly sealed, carbonation remains intact.

So go ahead and shake up that soda bottle before opening! This insures you will get properly mixed, evenly carbonated soda once poured over ice or into a glass. It does not accelerate the soda going flat. The true risk to carbonation is from opening the seal and exposing the soda to air.

Does Adding Extra CO2 Prevent Soda Going Flat?

While home carbonation systems let you add extra CO2 to soda, this does not prevent it from going flat. The key reasons are:

– Added CO2 quickly escapes open containers as new bubbles.

– Equilibrium between dissolved & free CO2 depends on temperature.

– Open sodas will release CO2 until reaching equilibrium again.

– Extra CO2 may provide very temporary fizz, but soon escapes.

– Cannot change physics of CO2 solubility in warmer liquids.

So while you can inject more bubbles into flat soda from devices like Sodastream, it is a temporary effect. Without chilling it or sealing the container, the CO2 will rapidly dissipate again. To maintain carbonation, the soda needs kept cold and sealed.

Does Soda Lose Carbonation as it Ages?

Even stored properly in sealed containers, soda very gradually loses small amounts of carbonation over time as it ages:

– Metal cans begin slowly losing pressure after being manufactured.

– Tiny amount of CO2 permeates through plastic bottles over months/years.

– Glass bottles allow more gas diffusion than cans or plastic.

– Soda fountains also lose small CO2 amounts over time.

But if kept sealed at cool temperatures, sodas hold carbonation extremely well for 9-12+ months. Gradual CO2 loss only becomes noticeable over years. Aging impacts flavors more than carbonation. So while not impervious, modern soda packaging does a great job preserving carbonation.

Can Flat Soda Make You Sick?

Flat soda does not inherently contain anything harmful or dangerous. The main risks of getting sick would come from contamination or adulteration:

– Flat soda alone cannot directly cause food poisoning or illness.

– Its lower acidity when flat could allow more microbial growth over time.

– Rare risk if left unsealed & became contaminated with pathogens.

– Main symptoms would be GI upset – nausea, vomiting, diarrhea.

– Off-flavors or smells can signal microbial spoilage.

– Rancid/rotten soda from mold is unappetizing but not toxic if consumed.

So while undesirable, flat soda itself poses little health risk. As with any beverage, proper handling, storage, and avoidance of contamination provides maximum safety. Fresh, chilled, and sealed sodas have minimal risks.


To summarize, when soda gets warm it loses the carbonation that provides its characteristic fizziness due to the CO2 bubbles escaping from the liquid. Shaking or adding more CO2 can temporarily restore some bubbles, but the ultimate solution is preventing soda from warming in the first place. Keeping sodas chilled before serving will maintain optimal carbonation, crisp taste, and enjoyment. And while warm, flat soda may not taste great, it is generally safe to drink as long as proper care has been taken against contamination. Following sound storage and handling practices keeps soda refreshing right to the finish.

Soda Carbonation Data

Beverage Carbonation Level (volumes of CO2)
Cola 2.0–2.5
Root Beer 3.0–4.0
Ginger Ale 3.0–4.0
Sparkling Water 4.0–6.0

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