Whole Grains and Phenolic Acids: A Review on Bioactivity, Functionality, Health Benefits and Bioavailability

Abstract

Cereal grains represent one of the major sources of human food and nowadays, their production has increased to fulfill the needs of the world’s population. Among whole grains, wheat is the most popular and contributes significantly to the human diet. Whole grains possess great nutritional and bioactive properties due to their fractions, bran and germ, that comprise unique health-promoting bioactive components. The evidence of health benefits in human intervention studies, as well as a World Health Organization report for 2012–2016, supports the dietary consumption of whole grains and whole-grain foods. The inverse correlation between whole grain consumption and the reduced risk of chronic diseases and metabolic syndromes was underlined by several epidemiological studies. This article focuses on the bioactive components of whole grains and their fractions, namely phenolic acids, starting from their chemical structure, bioactivity and bioavailability. According to the conclusive evaluation of the human intervention studies conducted using cereal bran and whole grains intake, the assumption that the bioactive compounds determine health outcomes is illustrated. In the last part of the work, the functional potential and the health claims related to whole grains and bran intake are discussed, as well as new technologies and strategies to enhance their health potential by an increased bioavailability.

Thermal Processing for the Release of Phenolic Compounds from Wheat and Oat Bran

“…From ancient times, cereals have represented the base nourishment in human nutrition all over the world. Wheat and oat represent staple foods for the worldwide population [1,2]. The European Flour Millers report [3] from 2016 pointed out that in Europe, more than 45 million tons/year of wheat and oat are processed, generating more than 6.5 million tons of bran that are further used for animal feeding.…”

“…The European Flour Millers report [3] from 2016 pointed out that in Europe, more than 45 million tons/year of wheat and oat are processed, generating more than 6.5 million tons of bran that are further used for animal feeding. Byproducts, such as bran, are abundant in valuable compounds [4] (e.g., dietary fibers, minerals, vitamins, polyphenols, or phytosterols), with a positive impact on health [2,5].…”

Bound phenolic compounds of whole cereals grain as a functional food component: part one

“…V manjših koncentracijah so prisotne še spojine železa, cinka, natrija. Med vitamini najdemo največ predstavnikov skupine B (tiamin, riboflavin, niacin) (Călinoiu in Vodnar, 2018;Fraś in sod., 2016;Ragaee in sod., 2006). Strukturni polisaharidi žit kot so rezistentni škrob, β-glukani, arabinoksilani, celuloza in fruktani se v prebavnem traktu ne razgradijo, zaradi česar jih uvrščamo med prehransko vlaknino (Gong in sod., 2018).…”

“…se ne morejo absorbirati, naj bi kazale protimikrobno in antioksidativno delovanje in tako zavirale rast patogenih bakterij. Po drugi strani pa so prisotni mikroorganizmi sposobni pretvoriti nekatere fenolne spojine v aktivnejše spojine, ki se lažje absorbirajo (Călinoiu in Vodnar, 2018;Gong in sod., 2018). Metabolizem fenolnih kislin s strani mlečnokislinskih bakterij je povezan z delovanjem dekarbosilaz in reduktaz.…”

Hydroxycinnamic acids and human health: recent advances

“…Hydroxycinnamic acids (HCAs), although the most widely distributed phenolic acids in plants, are perhaps the least studied polyphenolic class in terms of bioavailability and their potential influence on human health . The main reason for this is the fact that usually HCAs are bound to the plant wall (glycans rich in xylan‐, pectin‐ and arabinose‐containing carbohydrates), and the human genome lacks most enzymes required to degrade these plant polymers with complex structures . However, the anaerobic human gut microbiota can process these glycans (dietary fibers) via fermentation with a consortium of different groups of microorganisms to release HCAs in the human gut, therefore possibly contributing significantly to the health status of the host .…”