Frist off, always buy organic kale. Last year, kale was added to the Environmental Working Group’s Dirty Dozen. The Dirty Dozen is produce with the highest amount of pesticide residue on them. For example, last year they found a single grape tested positive for 15 pesticides! So, since kale is on their list…buy it organically. If you cannot find it organically, buy an avocado instead.
Also, only buy kale in the supermarket if it is stored in a refrigerated section. Kale tends to get more bitter the longer it is exposed to room temperature air.
The leaves should be firm and deeply colored with stems that are moist and strong. Make sure that the leaves are not browning or yellowing, and they are free from large holes. If the raw leaves show signs of wilting, it is an indication that the greens have been sitting on the shelf for too long, or they were not properly stored