A Conversation with A Customer

Hi, welcome to Starbucks, how can I help you?

I am outraged. I informed you all that I had a dire allergy to citric acid and your manager assured me that there would be no citric acid anywhere near my coffee.

I’m sorry Sir/Ma’am, what exactly is citric acid? I’m just a barista…

Here, look at this infographic from an article I read:


If you really want the condensed version, citric acid is an organic compound with a formula of C6H8O7. It’s found in fruits and berries and creates the tangy, citrus-y flavor that people tend to associate with fruits like oranges, grapefruit, and pineapple. I want an explanation why, after drinking my coffee, I had to be immediately rushed to the nearby CVS to get an EpiPen shot.

Excuse me, sir/ma’am, but what drink did you order?

I ordered the same thing I always order, a double venti triple mocha americana with four extra shots of expresso…

It’s pronounced espresso

…With non-fat milk and low-calorie whipped cream (because I’m watching my figure).

Well, there shouldn’t be any fruit in that monstrosity, Sir/Ma’am. Have you ever had an allergic reaction outside of this particular coffee?

Well, yes! In fact, every time I order coffee I get this reaction. And it’s entirely your fault! If I don’t have an explanation soon, I’m going to leave and never buy coffee here again!

While I think that is in your best interest, I will do my best to get an explanation for you, Sir/Ma’am.


Excuse me, Mr./Ms./Mrs. Manager, but we have a customer out front complaining that the barista put citric acid in his/her coffee. How should I handle this situation?

Citric acid, you say? Seems like a difficult thing to be allergic to, considering how important Vitamin C is to body function.

Well, sir/ma’am, Vitamin C is also found in broccoli and other vegetables.

Don’t be a smartass. Let’s get this figured out.

(Back at the bar)

Hello Sir/Ma’am, I’m the general manager of this store, and I understand that you have an issue with the coffee you were served?

Finally, someone with some brains. Yes, I was served coffee with Citric Acid, which I am allergic to. Here, look at this graph:

Ah, yes, Citric Acid. What are these other two big acids? Malic and Tartaric?

This isn’t even relevant. Malic acid is also found in fruits like watermelon or apple. It’s also found in wines.

And Tartaric Acid?

Well, I’m not entirely sure, but I know it’s in grapes and avocados.

Sir/Ma’am, did you actually read the article that you got this infographic from? It says right here in the third paragraph that citric acid is found in nearly all organisms. Perhaps you’re allergic to dairy?

Impossible! I ordered just an expresso

It’s espresso

From the coffee shot down the street and it had milk in it and I had no allergic reaction whatsoever!


Mr./Ms./Mrs. Manager, does espresso have dairy in it??

No, employee, espresso doesn’t have any dairy. Clearly this customer is mistaken. Hang on, I know exactly how to resolve this.

(back to Bar)

Excuse me, sir/ma’am, do you have a dishwasher at home?

Of course I do, I’m not a barbarian. I wash my dishes in it all the time. And my dish soap is my favorite scent, tropical breeze! What kind of a question is that? What has that got to do with me not sueing you?

I’m glad you asked. Please, take a look at this chart:


Limescale? Is this what you’ve done to my coffee?? You do realize limes have citric acid in them, don’t you? I knew I was poisoned! I’m calling the police immediately!

Before you do anything rash, can I explain a few things to you first?

You have my attention.

Limescale is a natural buildup of minerals in water on our utensils and dishes. Most often these are calcium, magnesium, sulfate, and bicarbonate ions. We use our utensils with a high frequency and there is probably a large build-up of limescale in our water, which is why we have to clean our work stations so often. While our limescale cleaner is a very strong acid that kills all kinds of bacteria to prevent transmission of pathogens from one coffee cup to another, your dishwasher at home probably uses citric acid to soften the water. Using something called an ion-exchange column, which exchanges the mineral substances that cause limescale with harmless ions, often sodium. This means that every time you’ve used your dishwasher and eaten off a plate, you’ve exposed your body to any residual citric acid left over from your dishwasher.

Oh really, Mr./Ms./Mrs. Smarty-pants manager, then what AM I allergic to?

Well, sir/ma’am, where did you attend undergraduate school?

I went to Transylvania University in Lexington, Kentucky.

AH! That explains it.

What? I don’t get it…

You’re allergic to intelligence!



The Chemistry of Limescale

A Guide to Common Fruit Acids