F. W. Collins, Eastern Cereals and Oilseed Research Centre, Agriculture and Agri-Food Canada, Ottawa, Ontario, Canada. The author is an employee of the Department of Agriculture and Agri-Food, Government of Canada. ©Her Majesty the Queen in Right of Canada, as represented by the Minister of Agriculture and Agri-Food Canada.
OATS: Chemistry and Technology, Second Edition
Pages 157-217
DOI: https://doi.org/10.1094/9781891127649.010
ISBN: 978-1-891127-64-9
Abstract
Since the review of oat phenolics in the first edition of this monograph on oats (Collins 1986), significant advances have been made in both the separation sciences and mass spectrometry, allowing more rapid identification of and ever-increasing sensitivity in the quantitative analysis of cereal phenolics. Advances have also been made in the assessment of the potential health benefits associated with consumption of oat and cereal phenolics, using both in vitro and in vivo systems.
This review has been written from the standpoint of a phytochemist and biochemist interested in a broader knowledge of the phenolic natural products of cereals in general and oats in particular. To facilitate comparison of quantitative data, levels of most of the phenolics have been converted to parts per million (ppm) values, based on a dry-weight basis unless otherwise stated. The review draws attention to phenolic constituents known to be present in cereals other than oats in order to show the types, diversity, and comparative functionality of phenolics in systematically related genera and to offer a broader perspective on oat phenolics as a possible guide for future research efforts. In recent years, numerous articles have appeared in the literature concerning the antioxidant capacity of largely uncharacterized cereal extracts and slurries as measured in vitro using several redox-linked assays. While conclusions reached in such experiments may seem helpful in some instances, they invariably generate more discussion and confusion than answers. For instance, the opiate drugs morphine and codeine are phenolics that exhibit antioxidant capacity in vitro, but their physiological significance resides elsewhere. Without a clear picture of the chemical identities of components in complex mixtures and their bioavailabilities, the antioxidant capacity as a predictor of functionality is of diminished use (e.g., Arts et al 2004). Thus, literature dealing with total antioxidant capacity of oat and other cereal extracts is generally not discussed.
The increasing use of oats as a fodder crop in Western Canada and the United States and the appearance of several sprouted or malted oat products have generated interest in the phenolics of more than just the kernel, and the major flavonoids of the whole plant are included in this review. Lignans, although they constitute rather minor components in cereals (compared to, for instance, flax), are also included.
