Metabolomic Profiling and Antioxidant Activity of Fruits Representing Diverse Apple and Pear Cultivars

SIMPLE SUMMARY: Apples and pears are popular with consumers because of their pleasant taste and high content of bioactive, health-promoting phytochemicals. However, the metabolic profiles of apples and pears are affected by genetic and environmental factors and, therefore, differ even between cultivars of the same species. Biochemical characterization and testing of antioxidant activity are useful tools to identify cultivars with superior organoleptic properties and potential health benefits. We, therefore, used these complementary approaches to analyze the metabolic profiles of six apple and five pear cultivars during two growing seasons, revealing variations in the content of primary and specialized metabolites. We found one ancient Italian apple cultivar rich in polyphenols and one pear cultivar low in sucrose that may be particularly attractive to consumers. ABSTRACT: The false fruits of apple (Malus domestica) and pear (Pyrus communis) are consumed all over the world, contributing to the dietary intake of health-promoting antioxidant phytochemicals. For example, polyphenols confer many beneficial effects (according to their chemical structure, bioavailability, and absorption efficiency in the gut) and the consumption of polyphenol-rich apple and pear fruits may therefore reduce the risk of some diseases. However, the content of such molecules is highly dependent on the specific fruit cultivar. To examine this metabolic diversity in detail, we used metabolomic analysis (NMR and HPLC-DAD/MS) to profile the metabolome of six apple and five pear cultivars. We also determined the antioxidant capacity of the extracts (FRAP assay) and correlated this with the metabolomic composition and abundance of specific metabolites. We observed the cultivar-specific accumulation of sugars, amino acids, malic acid, and various polyphenols, which was also related to the growing season for some cultivars. We found that the ancient Italian apple Pom Prussian was enriched for chlorogenic acid as well as more characteristic polyphenols (phloretin derivatives), the pear cultivar Abate Fetel was low in sucrose, and both cultivars displayed high in vitro antioxidant activity. These cultivars may, therefore, be particularly attractive to health-conscious consumers.