Every really good drink has a secret ingredient, that single element that brings everything together and adds a spark. In the realm of homemade sodas, the ingredient is acid phosphate and it will transform your soda experience.

First of all, to make any soda you need two things: carbonated water and flavoring. It’s that simple and there are infinite possibilities open to us when we begin experimenting with DIY sodas. Most often the flavoring comes in the form of a sweet syrup that is flavored with anything from fruits to herbs.

When you look at commercial sodas you will notice other ingredients, one of which is citric acid. In the case of DRY Soda, the label clearly states the use of phosphoric acid in the ingredients list (most colas use phosphoric acid as well). In both cases, the acid is what makes the soda so appealing and gives it that snap which tantalizes our taste buds, bringing us back for more.

When we make our own sodas from scratch, we are missing this acid ingredient. That is, unless we add it.

Extinct Chemical Company - Acid Phosphate - SCDrinkStudio.com
Extinct Chemical Company’s Acid Phosphate is an ingredient that no homemade soda should be without. Just a few drops will work miracles on the flavor of your sodas. Photo © S&C Design Studios

Enter the Phosphates

Phosphates were a very popular drink at the earliest soda fountains. The lime, lemon, chocolate, and cherry phosphates were among the best selling sodas at any fountain. The appeal was in the snappy tart that a little acid adds to the drink and something that druggist in the day learned from using the natural acids of citrus fruit.

Being the chemists they were, the druggist/soda fountain operators began experimenting with an acid that could outlast the natural acids and skirt the issue of getting fresh citrus year round in a time when the distribution of goods was not what it is today. Phosphoric acid was already in use at the pharmacy and, according to Darcy O’Neil’s Fix the Pumps, “Phosphoric acid was considered a general tonic, aphrodisiac, and stimulant of the nervous and cardiovascular system.” It was served as a tonic with water and eventually used in the soda to solve the ‘acid issue,’ creating a new style of soda drink for patrons to enjoy.

Acid phosphate was created and sodas that included it became a sensation. At some point in the 1950’s acid phosphate fell out of favor and as commercial soda production increased, citric acid became the acid of choice for the majority of sodas.

Taste the Phosphate Difference

O’Neil’s interest in the history of the soda fountain led him to bring back this key ingredient so we can all get a taste of a true, old-fashioned phosphate. Under the label, Extinct Chemical Company, he sells an old-school formulation for acid phosphate. Any soda lover will find this to be the best money spent.

A few drops of acid phosphate will add, as O’Neil puts it, “tongue tingling sensation and dry tart flavour” to any soda. The difference is truly amazing and I liken it to the flavor enhancement that bitters bring to a cocktail (it can be used in cocktails as well!). It is magic.
Though I’ve long known the impact that seemingly insignificant ingredients can make, I was not a believer until I tried it for myself. I encourage you to get a bottle of  this Horsford’s Acid Phosphate from ECC and do this same test.

  1. Make a fresh lime syrup (1 part sugar, 1/2 part each water and fresh lime juice – prepared like any simple syrup) and have fresh seltzer water at the ready.
  2. In two separate glasses (use the glasses from a set for portion control), pour equal amounts of lime syrup.
  3. Fill both glasses with seltzer.
  4. In one glass, add two to three drops of acid phosphate.
  5. Stir both sodas and taste the difference between the two, going back and forth and noting the change.

What should happen is a subtle, but noticeable, shift in flavor. The non-acid soda will be sweet and tart and otherwise blah. The lime phosphate will be bright, balanced, and have a new life.

I’ve run this test by everyone who enjoys one of my homemade sodas and in every instance, they prefer the phosphate. Why the phosphate ever lost its place in the soda fountain is beyond me, but thanks to O’Neil, it’s back!

Acid Phosphate: The DIY Soda’s Secret Ingredient