Task Progress:
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NASA, in planning for long duration missions, has an imperative to predict and plan for the shifting nutritional quality of space food provisions to ensure sustainment of crew health and performance. No cumulative source of nutrient kinetic information is available -- not on a broad spectrum of vitamins nor on processed foods. This review encompasses both the current scientific knowledge of intrinsic nutrient degradation kinetics under various processing conditions, storage conditions, and within the context of different ingredients and product structural matrices.
The evidence from this review indicates that nutrient degradation in food is determined by a number of factors related to the food system. The degradation rates of vitamin C in food were affected by the food matrix, pH, processing conditions, and potentially frozen state storage conditions. Thiamin degradation was influenced by the food matrix, moisture, pH, and temperature. Beta-carotene degradation rates were influenced by the product moisture, processing conditions, and frozen state storage temperatures. Riboflavin concentrations in food were affected by available light but not by the water activity of the food in the low to intermediate moisture range. The complexity of food systems and the limited data available on nutrient degradation kinetics in actual food materials make nutrient degradation predictions difficult.
The general kinetic theory and the application to food systems are available in published literature upon which to build nutrient kinetic models if the correct initial data is gathered. In order to inform space food shelf life requirements, kinetic data is needed for specific combinations of food moisture, formulation, processing, and controlled-temperature storage conditions. There is significant kinetics data on thiamin, riboflavin, vitamin C, vitamin A, vitamin B6, and folic acid but the potential application for flight foods is limited due to differences in processing, packaging, and potential long duration mission storage temperature range. Freeze-dried products remain viable options for long duration missions so data is needed for a wide variety of low moisture products. Reduced temperature food storage, or even abusive food temperature storage conditions, are yet undefined for the mission scenario; kinetics applicable to a wide temperature range are also required. The conditions of experimental data would need to be similar to actual flight food conditions to facilitate accuracy in extrapolation. Other vitamins, which lack degradation kinetics data in actual food, must be considered as candidates for more detailed studies based on the expected value of such studies given the results of space food-specific nutritional snapshot studies, comparison of the anticipated concentrations to the level of quantitation necessary for analytical detection of the vitamins, and the available financial resources to support further studies.
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