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GENETIC AND ENVIRONMENTAL INFLUENCES ON THE NUTRITIVE QUALITY OF SPINACH: A NASA ALS CANDIDATE CROP.    C.F. Johnson¹, R.W. Langhans², L.D. Albright¹, R.M. Welch³, G.F. Combs⁴, R.P. Glahn³, and R.M. Wheeler⁵. ¹Dept. Ag. and Bio. Engineering CEA Program, ²Dept. of Flor. and Orn. Horticulture, and ⁴Dept. Nutritional Sciences, Cornell University, Ithaca; ³USDA-ARS, Ithaca; and ⁵NASA, Kennedy Space Center.

Spinach, Spinacia oleracea, is among the candidate crops selected for NASA's Advanced Life Support (ALS) system. NASA has defined three areas of concern regarding spinach: 1) reputed high iron content, 2) high oxalic acid content, and 3) high nitrate content. Studies were performed to assess whether genetic (cultivar selection) and environmental (Controlled Environment Agriculture (CEA)) influences might be used to produce a spinach crop with improved nutritional value for humans.

In vitro digestion methods and human intestinal cell culture (Caco-2 cells) were utilized to assess iron bioavailability.  Spinach digested with ascorbic acid showed increased iron bioavailability, demonstrating the importance of evaluating whole-meals rather than single food items for space flight diets.

Examination of the National Seed Storage Laboratory’s 290 spinach cultivars showed a range in oxalic acid content from 750 to 1750 mmoles/g (dry weight basis) and range in nitrate content from 280 to 1200 mmoles/g (dry weight basis).

Nitrate levels were decreased to undetectable amounts and oxalate levels were decreased by one-half to two-thirds through the development of a new pre-harvest culture technique.  The CEA techniques developed to improve the food-value of spinach were oriented toward large-scale production so the methods are commercially feasible, demonstrating the potential for CEA technology transfer to improve food quality for humans.

(Supported by NASA GSRP #NGT10-52607.)