Citrulline is an amino acid named after citrullus, the Latin word for watermelon. It occurs naturally in watermelon, cucumbers, pumpkin and other members of the gourd family. This guide shows how to find those foods, keep them handy and turn them into easy snacks and recipes.
The name gives it away. Citrulline was first identified in watermelon, and the word comes from Citrullus lanatus, the plant's Latin name. So the next time you slice a melon on a hot afternoon, you are holding the food that gave this amino acid its label.
Watermelon is not the only place it appears, and you do not need to chase it. Below is a food-by-food tour, a shopping and storage guide, snack ideas and three recipes. Everything here is ordinary produce you can find in any supermarket, and everything is simply good eating.
Where citrulline shows up in food
Citrulline occurs in the gourd family, which includes watermelon, cucumbers, pumpkins, squash, cantaloupe and other melons. Amounts vary by variety, ripeness and which part of the fruit you eat. The USDA FoodData Central database is a handy place to look up the make-up of individual foods.
Watermelon is the best-known source, and the pale layer near the rind holds a good share. Many people toss it; others pickle it, blend it or cube it into salads.
Cucumbers are even easier: no peeling needed, and the skin adds color and crunch to salads and sandwiches. Pumpkin flesh roasts into soft, sweet cubes, while its seeds make a toasty snack.
- Watermelon: flesh, juice and the pale inner rind
- Cucumbers: crisp slices and spears
- Pumpkin and winter squash: roasted cubes and seeds
- Cantaloupe and honeydew: melon balls and wedges
- Bitter melon: a staple in several Asian cuisines
Picking and storing watermelon
Choose a melon that feels heavy for its size and has a creamy yellow spot where it rested on the ground. A hollow sound when you tap it is a good sign. Whole melons keep for a week or so on the counter and longer in the refrigerator.
Once cut, store cubes in a sealed container in the refrigerator and eat within three or four days. Freeze extra cubes on a tray, then bag them for smoothies and slushes.
Cucumbers keep well in the crisper drawer for about a week; wrap them loosely in a paper towel so they stay crisp. Whole pumpkins and winter squash last for weeks in a cool, dry spot, which makes them reliable pantry items.
Five snacks in under five minutes
Good snacks need no recipe. These pairings use produce you probably already have.
- Watermelon cubes with lime and a pinch of salt
- Cucumber spears with hummus or yogurt dip
- Melon wedges wrapped with a slice of prosciutto or turkey
- Roasted pumpkin seeds tossed with cinnamon
- Cucumber and watermelon on a skewer with mint
Recipe one: watermelon and cucumber salad
Cube two cups of watermelon and slice one cucumber into half-moons. Add thinly sliced red onion, a handful of torn mint, a crumble of feta and a squeeze of lime. Toss with a splash of olive oil and finish with black pepper. It takes ten minutes and feeds two as a side.
It works because sweet, salty and sharp flavors balance one another, and the crunch of cucumber keeps every bite lively.
Swap feta for fresh mozzarella pearls or goat cheese if you like, and try basil in place of mint. The recipe forgives almost any substitution, which is exactly why it ends up on the table so often during summer.
Recipe two and three: slush and roasted pumpkin
For a watermelon slush, blend three cups of frozen cubes with the juice of half a lime and a few mint leaves until thick. Pour into glasses and drink right away.
For roasted pumpkin, toss one-inch cubes with olive oil, salt and smoked paprika. Spread on a sheet pan and roast at 425 degrees Fahrenheit for about twenty-five minutes, flipping once. Serve over grains or tuck into a wrap.
These two recipes give you a cool, sweet option and a warm, savory one, so there is something for every season.
Leftover roasted pumpkin keeps for four days in the refrigerator. Reheat it in a skillet, fold it into scrambled eggs or mash it onto toast with a drizzle of honey for a quick breakfast.
Making produce part of a daily routine
Foods work best when they become routine. Keep cut fruit at eye level in the refrigerator, set a bowl of snacks where your hands go by habit and shop for two or three of these items each week.
Some people also add a daily supplement alongside their meals. Stallion Force, for instance, lists L-citrulline as one of its five named ingredients, in a once-daily gummy, and a bottle covers 30 days. Whatever you choose, let food be the base and keep the rest simple.
Next time you pass the produce section, pick up something from the gourd family. Variety is the surest way to keep a plate interesting.
Reading the nutrition data for each food is easy at FoodData Central, so curious cooks can compare options without guessing.
Key takeaways
- Citrulline gets its name from Citrullus, the watermelon genus.
- Gourd-family foods include watermelon, cucumber and pumpkin.
- Cut fruit stays fresh three or four days in the refrigerator.
- Simple snacks and salads make these foods easy to repeat.
Frequently asked questions
Sources and further reading
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