Keeping Basil Green in Pesto

By Cook's Illustrated Published May 2013

We found two proven methods on how to keep the basil from discoloring over time.

There’s no getting around it: Pesto looks the best right after you make it. With time, it can oxidize into a drab army green. But there seem to be as many suggested techniques for keeping pesto bright green as there are cooks who make it. We tried four methods, including using vitamin C powder, which left our pesto with an odd sour taste, as well as parsley, which does contain the antioxidant ascorbic acid—just not enough to make a big difference. Here are two methods that work.


How It Works: Blanching deactivates the enzyme that causes browning when cut basil leaves interact with oxygen.

How to Use It: Blanch basil for 30 seconds in boiling water and then shock it in ice water before drying it and proceeding with the recipe. This brief dunk causes minimal flavor loss.



How It Works: Lemon juice contains the antioxidants citric and ascorbic acids.

How to Use It: Add 4 teaspoons of lemon juice per 2 cups of packed basil. Lemon juice lends a pleasant acidity to pesto.