The impact of different growing techniques on polyphenol contents in sweet cherries and plums

The proposed project intends to study the impact of tree PE covers and organic production on accumulation of polyphenols in two cherry and two plum cultivars commonly grown in Norway. Moreover, plums from different plant experiments will be exposed to dif ferent storage conditions in order to follow polyphenol changes in fruits during cold storage in different packaging materials as well. Results of polyphenol analysis of fruits from different growing conditions will be related to contents of foliar nutrie nts such as K, P, Ca, N to find possible correlations. In addition to antioxidant content analysis, overall fruit quality will be evaluated with standard fruit quality parameters like % SSA, TTA, skin colour and sensoric properties. Fruit from covered tre es of different cultivars will be compared to fruit from uncovered trees of the same cultivars (controls) The quality and polyphenol content of fruits will be determined at commercial maturity, and in the case of storage condition experiments also at the end of storage (prior to consumption). Quantification and identification of individual phenols will be performed with reversed phase high performance liquid chromatography (RP-HPLC) and coupled with diode array detection (UV-Vis DAD). To overcome the lac k of standard phenolic compounds for this kind of work, mass spectrometry (MS) and tandem MSn analysis, coupled to the HPLC-DAD technique will be employed in our project as well. At the end, quantification results of polyphenols in cherries will be compar ed to already obtained data about polyphenols in Slovenian cherries of the same cultivars, but grown in different climate and without PE covers. Such comparisons have never been done before. This project is expected to contribute with original data to the knowledge of stone fruit polyphenols, with special regard to: impact of PE covers and organic production, cold storage and geo-climatical conditions.