Distributions of nutrients and avenanthramides within oat grain and effects on pearled kernel composition

Authors: Liu, Keshun; WISE, MITCHELL - Retired ARS Employee

Submitted to: Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/23/2020
Publication Date: 1/30/2021
Publication URL: https://handle.nal.usda.gov/10113/7055761
Citation: Liu, K., Wise, M.L. 2021. Distributions of nutrients and avenanthramides within oat grain and effects on pearled kernel composition. Food Chemistry. 336. https://doi.org/10.1016/j.foodchem.2020.127668.
DOI: https://doi.org/10.1016/j.foodchem.2020.127668

Interpretive Summary: Oat is an important and nutritious cereal. It has relatively higher contents of oil and protein than other cereal grains and is among the very few grains that contain physiologically significant amounts of beta-glucan (BG), a water-soluble dietary fiber. Moreover, unique to oat is the occurrence of phenolic alkaloids known as avenanthramides (AVs). AVs provide beneficial health effects, including anti-oxidation, anti-inflammation, anti-atherosclerosis, and anti-cancer, etc. Among 25 forms, AV 2p, 2f and 2c are most abundantly found in the grain. There is a lack of information on distributions of AVs as well as key nutrients (protein, oil, BG, ash, starch and other carbohydrates (CHO)) within the entire oat grain. There is also a lack of information on concentrations of AVs and nutrients in pearled oat grains with varying degrees of pearling (a process to remove outer layers of grains). Our results from two oat genotypes (one hulless and one hulled) showed that distributions of the six nutrients and four AVs were uneven within grains and varied among them. In general, from surface to inner core endosperm, concentrations of protein, oil, ash, other CHO, and four AVs (2p, 2f, 2c, and 5p) decreased while starch increased. Pearled oat kernels contained lower concentrations of protein, oil, ash, and other CHO and AVs, but higher starch concentration than the whole grain, while oat bran contained more concentrated AVs, protein, oil, ash and other CHO but less concentrated starch and BG than whole or pearled grain. Results from this study are valuable for these who want to reduce loss of important nutritional components and improve nutritional quality and end use of oats for human consumption and health benefits.

Technical Abstract: Hulled Reins and hulless Lamont oats were dehulled and/or sequentially abraded to produce ten pearling fines and corresponding pearled kernels. Contents of nutrients (protein, oil, starch, beta-glucan, ash and other carbohydrates) and avenanthramides (AVA) 2p, 2c, 2f, and 5p in processing fractions and starting grains were measured. Results show that distribution patterns of nutrients varied with individual nutrients, but those of AVAs varied with variety and individual AVAs. In both varieties, from the surface to inner endosperms, protein and oil increased then decreased; ash and other carbohydrates decreased; starch increased; and beta-glucan unchanged except for the surface area. In Lamont oat, the four AVAs decreased but in Reins oat, AVA 2p decreased while 2c, 2f and 5p increased, then decreased. Compared to whole grain, pearled oats not only contained lower AVAs, protein, oil, ash, and other carbohydrates and higher beta-glucan and starch but also had a different AVA composition.