157 Towards a Healthier Apple - Chemical Characterization of an Apple Gene Bank Hilde Nybom 1 , Kimmo Rumpunen 1 , Helena Persson Hovmalm 1,2 , Salla Marttila 2 Mira Rur 2 , Larisa Garkava-Gustavsson 1 and Marie E. Olsson 2 1 Balsgård-Dept Crop Science, Swedish University of Agricultural Sciences, SE-29194 Kristianstad, Sweden 2 Dept Crop Science, Swedish University of Agricultural Sciences, SE-23053 Alnarp, Sweden Keywords: allergy, antioxidant, flavonoid, Mal d 1, microsatellite DNA, phenol, RAPD Abstract Apple cultivars in a Swedish gene bank were evaluated for phenolic com- pounds and for the Mal d 1 allergen. The analysed cultivars differed considerably in content of total polyphenols determined in fruit skin ranging from 5710 to 26,180 µg GAE/g dm (GAE=gallic acid equivalents) with an average of 13,950 µg GAE/g dm. They also varied in content of the major phenolic compounds (range in µg/g dm): quercetin-3-rutinoside, 0–720; quercetin-3-galactoside, 60–2290; quercetin-3-gluco- side, 20–1770; quercetin-3-xyloside, 80–970; quercetin-3-arabinoside, 180–2160; quercetin-3-rhamnoside, 30–3440; catechin, 0–1630; procyanidin B2, 100–4380; epicatechin, 60–3700; phloridzin, 30–2840; and chlorogenic acid, 15–3590. The average content of phenols, the range in content of each phenolic compound, and the coefficient of variation was consistent between years in 99 cultivars analysed in two successive years. The correlation coefficient was also high between years for each of the phenolic compounds studied. The amount of Mal d 1 was determined by Western analysis in freshly harvested fruits and in fruits stored for 2–8 weeks. Apple skin had a higher concentration than the fruit flesh in freshly harvested fruits. During storage, the amount of allergens increased both in the skin and in the fruit flesh. Considerable differences were found between cultivars in the initial amount of Mal d 1 and in the development during storage. Preliminary results also suggest an influence from time of harvest and storage conditions. Establishment of DNA marker profiles for the chemically investigated cultivars with RAPD and SSR loci enabled unambiguous iden- tification of the plant material as well as estimation of genetic relatedness among genotypes. INTRODUCTION Apple production costs are very high in Sweden due mainly to adverse climatic conditions (cold winters, short and relatively cool summers) and high labour costs. Commercial orchards in Sweden rely on Northern regional cultivars like Ingrid Marie, Gravensteiner and Discovery, and some Swedish-bred cultivars like Aroma and Katja. In order to remain (or, preferably, become more) competitive, we believe that Swedish apple growers need to provide a value-added niche product. Since apples are often regarded as a symbol of health ('an apple a day keeps the doctor away'), we have investigated the possibilities of raising the image of healthiness in apples. Our short-term goal is to screen existing apple cultivars for health-related traits, while our long-term goal is to breed new apple cultivars with optimal combinations of these traits together with the standard requirements for productivity, fruit quality, and disease resistance. Polyphenols Phenols constitute an important class of secondary metabolites that are widely found in apples (Treutter, 2001; Tsao et al., 2003). The major classes of phenols in apples include phenolic acids, e.g., hydroxybenzoic acids and hydroxycinnamic acids, and the flavonoids, e.g., flavan-3-ols, procyanidins, flavonols, chalcones and anthocyanins. These compounds have numerous important roles in the human diet (Parr and Bolwell, 2000) Proc. XXVII IHC - Plants as Food and Medicine Eds.-in-Chief: G. Gardner and L.E. Craker Acta Hort. 765, ISHS 2008