The familiar pop that comes from opening a bottle of Yoo-hoo is one of deep nostalgia. The drink is refreshing and satisfying, but one thing is for sure: It’s not chocolate milk. So, what exactly is in a bottle of Yoo-hoo?

Yoo-hoo was launched in the 1920s by Natale Olivieri, a New Jersey grocery store owner. Olivieri had already created a line of fruit juices called Tru-Fruit and felt a chocolate drink would also be appealing to his customers. Knowing that chocolate milk was a popular drink at the time, Olivieri wanted to create an alternative that would, unlike milk, stay fresh for longer periods of time and not spoil in warm environments if stored in a sealed bottle. 

Technically, there’s no liquid milk in Yoo-hoo. Both the original chocolate and strawberry flavors of Yoo-hoo may taste like chocolate and strawberry milk, but Yoo-hoo must be labeled as a “drink,” not a flavored milk. 

Although the official formula for Yoo-hoo is kept secret—the top flavor scientist known as Dr. Yoo-hoo was rumored to actually keep it locked in a safe in his office—there is a publicly available list of ingredients. So, what’s in Yoo-hoo? Their website states that a bottle of chocolate Yoo-hoo contains water, high fructose corn syrup, and whey (a liquid that naturally surfaces after milk has been curdled via processing—it may look weird by itself, but it’s full of nutrients like calcium, protein, and good-for-you fats).

Yoo-hoo also contains “less than 2 percent” of cocoa, nonfat dry milk, natural and artificial flavors, sodium caseinate (a type of protein found in milk), corn syrup solids and sucralose for additional sweetening, “salt” and “spice” for flavor, as well as palm oil, guar gum, xanthan gum, soy lecithin, and mono- and diglycerides for thickening and emulsifying.

To keep bottle of Yoo-hoo shelf-stable when sealed, the drink also contains a stabilizers like calcium phosphate and a nutritional enhancer known as dipotassium phosphate, in addition to niacinamide (vitamin b3), vitamin a palmitate, riboflavin (vitamin b2), and vitamin d3.