Phenolic composition of 91 Australian apple varieties: towards understanding their health attributes

Introduction: Apples, an important contributor to total dietary phenolic intake, are associated with cardiovascular health benefits. Determining the phenolic composition of apples, their individual variation across varieties, and the phenolic compounds present in plasma after apple consumption is integral to understanding the effects of apple phenolics on cardiovascular health. Methods: Using liquid chromatography we quantified five important polyphenols and one phenolic acid with potential health benefits: quercetin glycosides, (-)-epicatechin, procyanidin B2, phloridzin, anthocyanins, and chlorogenic acid, in the skin and flesh of 19 apple varieties and 72 breeding selections from the Australian National Apple Breeding program. Furthermore, we determined the phenolic compounds in plasma of 30 individuals post consumption of an identified phenolic-rich apple, Cripp’s Pink. Results: Considerable variation in concentration of phenolic compounds was found between genotypes: quercetin (mean ± SD: 16.1 ± 5.9, range: 5.8-30.1 mg/100 g); (-)-epicatechin (mean ± SD: 8.6 ± 5.8, range: 0.2-19.8 mg/100 g); procyanidin B2 (mean ± SD: 11.5 ± 6.6, range: 0.5-26.5 mg/100 g); phloridzin (mean ± SD: 1.1 ± 0.6, range: 0.3-4.3 mg/100 g); anthocyanins (mean ± SD: 1.8 ± 4.4, range: 0-40.8 mg/100 g); and chlorogenic acid (mean ± SD: 11.3 ± 9.9, range: 0.4-56.0 mg/100 g). All phenolic compounds except chlorogenic acid were more concentrated in the skin compared with flesh. We observed a significant increase, with wide variation, in 14 phenolic compounds in plasma post-consumption of a phenolic-rich apple. Conclusion: This information makes an important contribution to understanding the potential health benefits of apples.