How we tested
A grapefruit knife, a small tool with a curved blade that’s serrated on both sides of the metal, is designed to section the pulp by hugging the walls and membranes of the fruit as you cut, separating the sections from the peel without picking up pith. (This gives grapefruit knives a distinct advantage over conventional paring knives.) First, you run the blade around the inner rim of the grapefruit half, hugging the curve to separate the fruit from the peel. Then, you trace the spokes of membrane with the blade tip to make grapefruit triangles, which are easy to scoop up with a spoon. Traditional models look like bent steak knives, but we also found double-ended versions with a traditional blade on one end and a pair of close-set blades on the other that straddle and slice the membrane sections with fewer cuts. We tested five models (priced from $5.66 to $15.39): two traditional, two double-ended, and an innovative design that supposedly digs out the fruit in one shovel-like motion.
The latter failed outright, mangling the fruit, while the double-ended knives made work difficult because their short central handles meant that one blade was always pressed against our palms. Their dual blades also trapped pulp. Of the traditional models, one sported steeply bent blades that punctured fruit and made a juicy mess. Handles affected our agility if they were too long for small hands or too petite for larger ones. The range of handle lengths in our lineup was 2.9 to 4.4 inches. This difference is a little more than an inch, but it’s significant. A 4.4-inch handle was too long for some testers, while 3.9 inches was just right. Our universal favorite sported a moderately long plastic handle, which was comfortable for all testers, and whose gentle 25-degree curved blade made tidy, precise cuts.