Apples contain a variety of phenolic compounds. There are five major groups of polyphenolic compounds found in apples: flavanols (catechin, epicatechin and procyanidins), phenolic acids (mainly chlorogenic acid), dihydrochalcones (phloretin glycosides), flavonols (quercetin glycosides) and anthocyanins (cyanidin).
Apple peels have higher levels of polyphenols than flesh or core and also abundant in flavonoids such as quercetin glycosides and cyanidin galactoside. The flesh and core have relatively high concentrations of chlorogenic acid.
Polyphenols originate from the plant aromatic pathway, starting with amino acids of the shikimate pathway and culminating in molecules produced by the phenyl propanoid and flavonoid pathways. The coordinated induction-regulation of these pathways leads to the production of several thousand different molecules.
The nature and content level of polyphenols present in food sources will be influenced by various factors. For apples, the variety, agricultural practices, harvesting, and if supplementing, the extraction process will be among the factors contributing to polyphenol concentration.
Each polyphenol molecule might have specific health benefits. The non-glycosilated form of phlorizin, phloretin, has been shown to influence epigenetic processes, heritable changes not encoded in the DNA sequence itself that play an important role in gene expression regulation in breast cancer cells.
Apple polyphenols also seem to block fat and cholesterol from entering the body and slow the production of fat and cholesterol. This may allow them to lower cholesterol and help with weight loss.
Apple juice may work in cognitive decline of normal aging suppressing over expression of presenilin-1, which is linked to the production of amyloid β-peptide, a marker of Alzheimer’s.
Polyphenols in apples
