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Oat Tocols: Saponification vs. Direct Extraction and Analysis in High-Oil Genotypes¹

¹Cooperative investigation of the U.S. Department of Agriculture, Agricultural Research Service, and the University of Wisconsin Agricultural Experiment Station. Names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by USDA implies no approval of the product to the exclusion of others that may also be suitable. ²USDA, ARS, Cereal Crops Research Unit, 502 Walnut St., Madison WI 53726. ³Corresponding author. E-mail: dmpeter4@wisc.edu ⁴USDA, ARS, Small Grains and Potato Germplasm Research Unit, 1691 S 2700 W, Aberdeen ID 83210, deceased. ⁵Department of Crop Production Ecology, Swedish University of Agricultural Sciences, Box 7043, S-75007, Uppsala, Sweden.

Tocols are natural antioxidants that occur in grains that may benefit human and animal health. Therefore, it is important to accurately measure their concentrations in foods and feeds and to determine how genetics and growing environment can influence their levels. The first objective was to evaluate saponification versus direct extraction for the analysis of tocols in oat (Avena sativa L.). The second was to determine the effects of growing environment, hulled versus hulless phenotype, and genetic background on tocol concentration, and to see whether tocol and lipid concentrations were associated. For the first objective, oat grain samples from two locations were either extracted by saponification or directly with methanol, and extracts were analyzed by HPLC. The saponification method increased yield by ≈25% and was less time-consuming, so it was adopted for the second objective. For the second objective, oat genotypes were developed by crossing high-oil parents from Iowa State University with hulled and hulless cultivars adapted to arid Western environments. These were grown at Aberdeen and Tetonia, ID, and the tocols and lipid concentrations were analyzed at Madison, WI. There were significant effects of growing environment, genotype, and the presence or absence of hulls on tocol concentrations. Tocol and lipid concentrations were not correlated. Progeny of crosses involving the genotype IA91098-2 had tocol concentrations that exceeded both parents.