The bioavailability, health advantages, extraction method, and distribution of free and bound phenolics of rice, wheat, and maize: A review

Abstract

One of the primary sources of human sustenance is cereal grains, and the production of these grains has expanded recently to meet the demands of the growing global population as a primary source of human food and health. Rice, wheat, and maize are the most popular whole grains and contribute significantly to the human diet. Whole grain contains bioactive phytochemicals, mainly phenolic compounds, which comprise health-beneficial properties. Different studies emphasized the inverse correlation between whole-grain phenolic consumption and the reduced risk of chronic diseases and metabolic syndromes. Phenolic compounds are mostly available in two forms: free and bound phenolics. As the extraction or isolation of free phenolics is easy, bound phenolics are extracted or isolated with various chemical, physical, and biological methods. These free and bound phenolics have various pharmacological activities. Some cereal polyphenols are absorbed in the small intestine, whereas the bulk is accumulated and metabolized by the colonic microbiota within the digestive system. The bioactivity and bioaccessibility of phenolic compounds are controlled by chemical and enzymatic reactions during gastrointestinal digestion. This review provides valuable information on the bioavailability, health benefits, extraction, and separation process of rice, wheat, and maize.