Provide your best answer for the following question. Give ONLY the answer, no other words or explanation.
For example:

Answer: <most likely answer, as short as possible; not a complete sentence, just the answer!>.

The question is: In the initial stages of manned space exploration, scientists needed to address adequate nutrition to provide astronauts with energy throughout the mission. Which of these criteria could not be used when considering food and energy for astronauts during manned space flights?
history of space food
Freshness.