From the study's abstract:

"Future long-term human exploration of space will need a supply of resources for astronauts, including fresh food from space farms.

"The food constraints considered were based on the recommendations of the National Aeronautics and Space Administration (NASA), considering up to 36 nutrients and 102 crops.

"As plants contain both edible and inedible parts and require fertilizer input, respective circularity assessments were made determining the waste generation, degree of recyclability, and overall mass processed, using three common metrics of the circular economy.

"The space dish identified as optimal was prepared as a salad."

See more here:

Find out what NASA's optimum daily nutrient intake for an adult male astronaut in his 40s is here: