The National Aeronautics and Space Administration (NASA) is working towards future long duration manned space flights beyond low earth orbit. During these missions, vegetable crops may be grown on the transit vehicle as well as the lunar or planetary surface. The vegetable crops will provide the crew with added nutrition and variety. The vegetable crops, unlike the prepackaged foods, will add bright colors, fresh textures (e.g., crispiness), and fresh aromas to the crew’s menu. Ten vegetable crops have been identified for possible use in long duration missions. They are lettuce, spinach, carrot, tomato, green onion, radish, bell pepper, strawberries, fresh herbs, and cabbage. Since these crops do not require any cooking or food processing prior to consumption, careful sanitation procedures need to be performed.
Whether these crops are grown on a transit vehicle (e.g., International Space Station) or on the lunar or planetary surface, it will be necessary to determine how to safely handle the vegetables while maintaining acceptability. Since hydrogen peroxide degrades into water and oxygen and is generally recognized as safe (GRAS), hydrogen peroxide has been recommended as the sanitizer.
The objective of this research was to determine the required effective concentration of hydrogen peroxide without adversely affecting the quality of the vegetables. Store bought vegetables were dipped in deionized distilled water, 1% hydrogen peroxide, 3% hydrogen peroxide, or 5% hydrogen peroxide. Treated produce and controls were stored in plastic bags at 5°C for up to 14 days. Sensory, color, texture, and total plate count were measured.
Although each vegetable reacts to hydrogen peroxide differently, the data suggest that with the exception of green onions, which may require a 5% dip, the other vegetables will only require a 0% or 1% hydrogen peroxide dip to reduce the microbial total count while not adversely affecting the quality of the vegetable. More testing still needs to be done on actual chamber grown vegetables. It is expected that chamber grown vegetables will have a lower microbial count and may not need as strong a treatment of hydrogen peroxide.