The beneficial effects of walnuts and walnut products on human health, due primarily to their rich polyphenolic content, have been appreciated as an empirical fact for centuries. The purpose of this study is to determine the polyphenolic contents of liqueurs made from the walnut selections ‘Rasna’ and ‘Sava’ and the walnut cultivar ‘Šampion’ (all harvested at three different times), as well as the polyphenolic contents of their green husks. The walnut liqueurs were prepared according to two traditional recipes using young walnut fruits. The highest antioxidant capacity was recorded in the liqueur made from the ‘Rasna’ walnut selection (89.94%), whereas the highest contents of phenols (83.28 mg GAE/g FW), flavonoids (0.83 mg QE/g FW) and proanthocyanidins were found in the liqueur made from the ‘Šampion’ cultivar (14.75 mg CE/g FW). The youngest ‘Rasna’ walnuts, harvested at the first experimental time point, exhibited the highest phenolic and tannin contents, whereas the highest flavonoid content was observed in the ‘Šampion’ cultivar. The biochemical results obtained indicate a decrease in the polyphenolic content of walnut fruits with their growth and development. Moreover, the polyphenolic profiles of the walnut liqueurs considered were found to be greatly affected by the method of preparation and the cultivar/selection of walnuts.
Sweet cherries (Prunus avium L.) contain various phenolic compounds which contribute to total antioxidant activity. The present study was conducted to assess the antioxidant activity of 15 sweet cherry cultivars from Vojvodina province (north Serbia). The free radical scavenging properties of fruits were evaluated employing two different methodologies, including DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging assay and ferric reducing antioxidant power (FRAP) assay. Strong correlations were found between total phenolics, tannins, flavonoids and anthocyanins and DPPH and FRAP assays. In particular, cultivar Peter showed the highest antioxidant capacity and possesses the highest amount of measured phenolic compounds. This investigation shows large variability among sweet cherry cultivars in measured chemical attributes.
Monilinia laxa Aderh. and Ruhl. is the predominant causal agent of brown rot disease of stone fruit orchards, especially sweet cherries. The objective of this study was to identify reaction in response of nine genotypes cherry, with different pomological properties, against brown rot. These genotypes were harvested at commercial maturity from orchard in the Fruit Research Institute in Rimski Šančevi. The studied genotypes showed significant differences in terms of the occurrence of disease on fruits, both under artificial inoculation and infection in the field. Given the fact that sweet cherry fruits are prone to infection by a number of pathogens in the field, biochemical parameters were analysed on artificially inoculated fruits. Biochemical analysis of fruits determined significant differences in contents of total phenols, flavonoids and anthocyanins, as well as in antioxidant activity. It was genotype specificities and intensity of infection, as well as the interaction of the two that induced differences in the secondary biomolecules content and antioxidant activity. The majority of the genotypes examined showed high polyphenolics content, while under the infection, the content was significantly lower. Based on the results obtained, the secondary metabolites content can be used as one of the parameters for evaluating the resistance of sweet cherry genotypes to brown rot.