Douglas P. Lee, Danny Alexander and Satya S. Jonnalgadda
Grains are a major food source providing many essential nutrients. The objective of this work was to determine the biochemical (<1,500 Da) composition of selected grains and grain fractions. We hypothesized that the nutrient composition of grains is not only dependent on the grain type, but also influenced by the milling process to generate individual fractions. Whole grain corn, oat, and wheat were milled and separated into bran and flour/meal fractions. The biochemical composition of the whole grains and their subcomponents were determined by untargeted metabolomic profiling on methanol extracts. This global analysis identified 325 biochemicals, belonging to diverse nutrient categories including carbohydrates, antioxidant, vitamins and amino acids. Many of the metabolites were significantly different between the grain types and grain fractions; statistical analysis showed clear differences in the biochemical composition of corn, oat, and wheat grains. Principle component analysis showed that whole wheat flour and whole oat flour were not distinguishable from their respective grains, while corn meal could be distinguished from the corn grain kernel. Many of these nutrients were decreased in the bran fractions upon processing. This
preliminary study provides a glimpse into distinct profiles of different grains and their fractions, which can potentially have an impact on nutrition, health and other parameters. Further research is needed to better understand the health benefits of these compounds in individual grains and grain fractions. The use of metabolomics techniques to better understand the profiles of foods not only can help understand their role in improving their health, but also their impact on food product quality, food safety and other parameters.