Why Is Citrus Sour? Here's What Science Says!

You might be wondering, why does citrus taste sour? Fortunately for you, we've got the answers. Find out what science says about citrus fruit tasting sour below!

It's a good thing humans love the sweet and sour taste of citrus- it has some of the highest concentrations of vitamin C. Human bodies are unable to synthesize vitamin C naturally, unlike most of the animal kingdom, which is why it's needed in our diet to fend off scurvy.

Citrus isn't the only food containing higher concentrations of vitamin C. Why do humans prefer it as a source for this vitamin? Humans have cultivated citrus over thousands of years. We also generally like the sweet and sour taste of citrus fruit.

History of Citrus

Citrus trees of today have a common ancestor that can be traced back 15 million years. The plants are native to tropical and subtropical regions of Asia and made their way across the world through trade until different cultures started to cultivate the fruit on their own.

When citrus reached the Mediterranean, it was coveted by the elite and took on a religious significance in earlier civilizations. Citrus was mostly used for healing, cleaning, and a pleasant smell. Ancient Rome viewed lemons as a sign of privilege and wealth. 

The health benefits of eating citrus fruits were fully realized after their consumption cured scurvy. Symptoms of scurvy took months to develop as vitamin C is depleted from the system. Scurvy is not often seen today but it was a serious condition that plagued sailors and pirates before the 18th century.

Today, citrus is grown all over the world. The U.S. alone produces roughly 8 million tons of citrus a year for this billion-dollar industry.  

How We Interpret Citrus Tasting Sour 

Sourness is the taste our tongue detects from acidity and it is one of the most powerful and least understood flavors.  

A team of researchers from the University of California has found that the chemical element hydrogen is responsible for the difference between sweet and sour in the pulp of citrus. The pulp of sour citrus fruits contains a higher number of hydrogen ions. This lowers the PH, making these fruits more acidic. 

When you consume citric acid, the acids dissolve in your saliva and the hydrogen ions enter the cell through ion channels. This sets off a chain reaction that tells your brain that you are tasting sourness. 

Why do we need to taste sour?

Humans have five basic tastes. Sugary sweetness gives energy, saltiness gives us essential sodium, umami (or savory) are rich in protein, and many bitter compounds have a level of toxicity. Sourness could tell us if foods are acidic and rich in vitamin C. 

Scientists are still researching the taste of sour and it's evolution throughout human history. 

Keep Eating Those Sour Fruits  

The history and science behind citrus tasting sour are not only interesting but one that has baffled scientists for years. Humans have always enjoyed moderately sour (sometimes extreme!) flavors and our human-engineered citrus fruits have kept that taste for that reason.   

Try our seasonal citrus box while its available...the Craft Citrus Club!

Our Rio box is a 15-lb curated box of our fresh-harvested citrus from South Texas. The fruit is NOT gassed, rather it is tree-ripened. Our season runs from Nov-May for oranges, grapefruit and mandarins.

Our Grande box is a 30-lb box of either fresh-harvested Rio Red Grapefruit or Sweet Oranges from South Texas.