Apple Pomace as a Potential Source of Oxidative Stress-Protecting Dihydrochalcones
Ibrahim Rabeeah,
Viktoria Gruber-Schmidt,
Helen Murray,
Negin Afsharzadeh,
Renate Paltram,
Silvija Marinovic,
Hassan Zia,
Olly Sanny Hutabarat,
Mikko Hofsommer,
Ana Slatnar,
Christopher Schlosser,
Karl Stich,
Heidi Halbwirth,
Manfred Gössinger,
Christian Haselmair-Gosch
Affiliations
Ibrahim Rabeeah
Institute of Chemical, Environmental and Bioscience Engineering, Technische Universität Wien, Getreidemarkt 9, 1060 Vienna, Austria
Viktoria Gruber-Schmidt
Institute of Chemical, Environmental and Bioscience Engineering, Technische Universität Wien, Getreidemarkt 9, 1060 Vienna, Austria
Helen Murray
Department of Fruit Processing, Federal College and Institute for Viticulture and Pomology, Wiener Straße 74, 3400 Klosterneuburg, Austria
Negin Afsharzadeh
Institute of Chemical, Environmental and Bioscience Engineering, Technische Universität Wien, Getreidemarkt 9, 1060 Vienna, Austria
Renate Paltram
Institute of Chemical, Environmental and Bioscience Engineering, Technische Universität Wien, Getreidemarkt 9, 1060 Vienna, Austria
Silvija Marinovic
Institute of Chemical, Environmental and Bioscience Engineering, Technische Universität Wien, Getreidemarkt 9, 1060 Vienna, Austria
Hassan Zia
GfL—Gesellschaft für Lebensmittel-Forschung mbH, Landgrafenstraße 16, D-10787 Berlin, Germany
Olly Sanny Hutabarat
Department of Agricultural Technology, Hassanudin University, Makassar 90245, Indonesia
Mikko Hofsommer
GfL—Gesellschaft für Lebensmittel-Forschung mbH, Landgrafenstraße 16, D-10787 Berlin, Germany
Ana Slatnar
Department of Agronomy, Biotechnical Faculty, Chair for Fruit, Viticulture and Vegetable Growing, University of Ljubljana, Jamnikarjeva 101, SI-1000 Ljubljana, Slovenia
Christopher Schlosser
Institute of Chemical, Environmental and Bioscience Engineering, Technische Universität Wien, Getreidemarkt 9, 1060 Vienna, Austria
Karl Stich
Institute of Chemical, Environmental and Bioscience Engineering, Technische Universität Wien, Getreidemarkt 9, 1060 Vienna, Austria
Heidi Halbwirth
Institute of Chemical, Environmental and Bioscience Engineering, Technische Universität Wien, Getreidemarkt 9, 1060 Vienna, Austria
Manfred Gössinger
Department of Fruit Processing, Federal College and Institute for Viticulture and Pomology, Wiener Straße 74, 3400 Klosterneuburg, Austria
Christian Haselmair-Gosch
Institute of Chemical, Environmental and Bioscience Engineering, Technische Universität Wien, Getreidemarkt 9, 1060 Vienna, Austria
Among fruits, the apple is unique for producing large amounts of the dihydrochalcone phloridzin, which, together with phloretin, its aglycone, is valuable to the pharmaceutical and food industries for its antidiabetic, antioxidant, and anticarcinogenic properties, as well as its use as a sweetener. We analysed the phloridzin concentration, total phenolic content, and antioxidant activity in the peel, flesh, seeds, juice, and pomace of 13 international and local apple varieties. In the unprocessed fruit, the seeds had the highest phloridzin content, while the highest total phenolic contents were mostly found in the peel. In processed samples, phloridzin and the total phenolic compounds especially were higher mostly in juice than in pomace. Moreover, the total phenolic content was much higher than the phloridzin content. Juice showed the highest antioxidant activity, followed by the peel and flesh. Across all samples, antioxidant activity did not directly correlate with phloridzin concentrations, suggesting that the antioxidant activity ascribed to phloridzin may need re-evaluation. In the Ferric Reducing Antioxidant Power (FRAP) assay, phloridzin only showed antioxidant activity at high concentrations when compared to its aglycone, phloretin. Considering the large amounts of apple juice produced by the juice industry, residual pomace is a promising source of phloridzin. For technical use, processing this phloridzin to phloretin would be advantageous.
