What Phosphoric Acid Does In Soda

What Phosphoric Acid Does In Soda

Ever cracked open a can of your favorite fizzy drink and decided to give the ingredients list a quick scan? If you have, chances are you’ve come across the mysterious-sounding “phosphoric acid.” What on earth is it, and what’s it doing in your soda? And is it a safe ingredient?

Let’s find out.


Phosphoric acid (H3PO4) is a vital compound in various industries and everyday applications, thanks to its distinctive chemical properties and versatile nature. Its composition, which consists of one phosphorus (P) atom, four oxygen (O) atoms, and three hydrogen (H) atoms, is reflected in its chemical formula.

With a molar mass of approximately 97.99 grams per mole, phosphoric acid exists primarily as a colorless, odorless, and syrupy liquid.

One of the most striking features of phosphoric acid is its acidity with a pH of 1.5 at 0.1 N aqueous solution. It is classified as a weak acid, capable of donating three protons (H+) in a stepwise manner when dissolved in water. This ionization process leads to the formation of dihydrogen phosphate (H2PO4-) and hydrogen phosphate (HPO4^2-) ions, making phosphoric acid a triprotic acid. This property allows it to play a fundamental role in various chemical reactions.

Phosphoric acid is a well-known additive in the food and beverage sector, constituting 25% of all acids employed in this industry. Its primary role is to provide a unique tangy taste and act as an acidulant in soft drinks, enhancing their refreshing flavor. Moreover, it serves as a preservative, extending the shelf life of processed foods. Its notable solubility in water makes it a practical and widely utilized option for these specific applications in the food industry.

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Phosphoric acid also finds applications in various chemical processes. It plays a pivotal role in the synthesis of chemicals, including detergents and pharmaceuticals. Its role in these reactions often involves its acid-catalytic properties, facilitating the formation of desired products.


Phosphoric acid plays a crucial role in sodas as it contributes to both the beverage’s taste profile and its physical characteristics. The primary function of phosphoric acid in sodas is to provide a distinctive and tangy flavor. This acid imparts a sharp and slightly sour taste, enhancing the overall sensory experience of the drink. The acidity balances the sweetness of the sugars present in the soda, creating a more palatable and refreshing beverage. Without it, the flavor profile would be noticeably different. The absence of phosphoric acid might result in a sweeter taste, as the acid helps balance the sweetness of the sugar or high-fructose corn syrup used in the beverage.

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Additionally, phosphoric acid contributes to the effervescence (formation of gas bubbles) of sodas. Phosphoric acid helps dissolve the flavoring agents, and carbon dioxide in the soda. This helps enhance the carbonation process that gives the drink its characteristic fizziness. Its absence might affect the dissolution of the individual components. Moreover, phosphoric acid acts as a chelating agent. Chelating agents bind to metal ions, preventing them from causing undesirable reactions with other ingredients in the beverage. In sodas, this is particularly important to maintain the color stability of certain additives and flavors.

In addition to its contributions to taste and carbonation, phosphoric acid serves as a preservative. Its acidity functions as a preservative by establishing an environment that hinders the proliferation of bacteria, mold, and other microorganisms. The low pH (acidity) of sodas creates conditions unfavorable for the thriving of these contaminants, effectively prolonging the beverage’s shelf life. In the absence of phosphoric acid, sodas might have a shorter shelf life, necessitating the use of additional preservatives.


With an increase in health-conscious consumers and health-related information available online, some people may come across articles or opinions claiming that phosphoric acid is harmful. However, the Food and Drug Administration (FDA) considers it to be generally recognized as safe (GRAS) when consumed in moderation.

It’s important for consumers to be aware of the quantity they consume and maintain a balanced diet. While phosphoric acid in sodas is generally considered safe, excessive consumption of acidic beverages over time could potentially contribute to dental erosion and other health concerns.

While phosphoric acid is considered generally safe by the FDA when consumed in moderation, concerns exist regarding potential health risks of excessive intake. A can of soda typically contains 50-70mg of phosphoric acid, which is within the safe daily limit for most adults. However, maintaining a balanced diet and limiting consumption of acidic beverages is important for optimal oral and overall health.

Excess consumption of acidic beverages, including sodas containing phosphoric acid, can contribute to dental erosion. The acids soften tooth enamel, making it more susceptible to decay. Additionally, preliminary research suggests that high phosphoric acid intake may interfere with calcium absorption, potentially impacting bone health. While these concerns require further investigation, moderation is key to minimizing potential health risks.

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