Polyphenolic Compounds Analysis of Old and New Apple Cultivars and Contribution of Polyphenolic Profile to the In Vitro Antioxidant Capacity
Institute of Nutrition, Friedrich Schiller University Jena, Dornburger Straße 25-29, 07743 Jena, Germany
Author to whom correspondence should be addressed.
Antioxidants 2018, 7(1), 20; https://doi.org/10.3390/antiox7010020
Received: 6 December 2017 / Revised: 18 January 2018 / Accepted: 19 January 2018 / Published: 24 January 2018
(This article belongs to the Special Issue Feature Papers in Antioxidants in 2018)
Polyphenols are antioxidant ingredients in apples and are related to human health because of their free radical scavenging activities. The polyphenolic profiles of old and new apple cultivars (n = 15) were analysed using high-performance liquid chromatography (HPLC) with diode array detection (DAD). The in vitro antioxidant capacity was determined by total phenolic content (TPC) assay, hydrophilic trolox equivalent antioxidant capacity (H-TEAC) assay and hydrophilic oxygen radical absorbance (H-ORAC) assay. Twenty polyphenolic compounds were identified in all investigated apples by HPLC analysis. Quercetin glycosides (203 ± 108 mg/100 g) were the main polyphenols in the peel and phenolic acids (10 ± 5 mg/100 g) in the flesh. The calculated relative contribution of single compounds indicated flavonols (peel) and vitamin C (flesh) as the major contributors to the antioxidant capacity, in all cultivars investigated. The polyphenolic content (HPLC data) of the flesh differed significantly between old (29 ± 7 mg/100 g) and new (13 ± 4 mg/100 g) cultivars, and the antioxidant capacity of old apple cultivars was up to 30% stronger compared to new ones.