The Reason Trader Joe's Key Lime Pie Is Yellow, Not Green

When you think of key lime pie, the image that may come up is of a smooth, fluffy, vibrant green dessert. While we associate lemon-based pies like lemon meringue with a yellow hue, lime-centric treats almost always fall in the green camp. In fact, "key lime" is actually the name of a color used in graphic design, and it shows up as — you guessed it — a bright, neon-like shade of green.

But the next time you go to Trader Joe's, take a look at the chain's key lime pie and you'll see the filling is a bright, sunshine-yellow color. This is understandably confusing — after all, key limes themselves are green, similar to regular limes. However, there are a few differences between these two types of limes. Key limes contain more seeds, give off a stronger smell, and are a little tarter than their cousins. And while they may look green at first glance, they have a key characteristic that causes Trader Joe's key lime pie to come out yellow.

Our recipe for sweet and tart key lime pie uses 34 key limes and if they're all true key limes, your pie will likely turn out canary yellow just like the Trader Joe's version because key lime juice is actually light yellow in color. It's true that the juice in a key lime pie is pale yellow, but that's only once it gets mixed into the other ingredients. The juice on its own actually has no color but turns light yellow when it gets mixed with the six egg yolks that are included in the pie filling. 

If you need further proof, check out our vegan key lime pie recipe — eggs are omitted, but we use coconut milk, coconut oil, and cashews, which ends up producing a light, cream-colored pie. To make sure people can identify our vegan key lime pie for what it is, lime slices and zest are added as a garnish. The reason some of these pies turn out green follows a similar course of logic. 

Back in the day, pie makers who didn't have access to key limes would serve lemon pies with green food coloring, so their guests couldn't tell the difference. Eventually, people caught on that they were being duped, and plenty of vendors today, like Trader Joe's, now opt out of green food coloring in favor of a more natural yellow pie.