Of the preservation methods currently being used for NASA flight food, the thermostabilized items have the longest shelf life and could be used on longer duration space missions. Currently four approved International Space Station thermostabilized packaged foods are undergoing accelerated shelf life testing at NASA/Johnson Space Center. Bread pudding was produced in the summer of 2001 and carrot coins, tuna noodle casserole, and apricot cobbler were produced for shelf life testing in the summer of 2002.
The foods are being stored in controlled temperature chambers at 4°C (40°F), 22°C (72°F), and 35°C (95°F) for up to 3 years. Analytical tests to measure color, texture, pH, and water activity will be correlated with the sensory tests to determine the changes occurring in the foods. The sensory tests will measure the difference from control (4°C) as well as overall acceptability.
The results for bread pudding, after 16 months of storage at 4°C, 22°C, and 35°C, indicate that there is very little difference in the sensory scores and analytical values between the 4°C and 22°C. Between the lower temperatures and 35°C, there was some increased browning and increase in the red color as noted in the colorimeter data. The sensory scores indicated a loss of sweetness and the aftertaste was less acceptable for the 35°C sample. The bread texture is getting firmer, especially in the 35°C samples. Even with these changes the bread pudding, including the 35°C samples, are acceptable after 16 months.