Search

Plums contain high levels of hydroxycinnamates (neo-chlorogenic acid, Neo-CGA), anthocyanins (ATH) and ascorbic acid. The drying process influences their phytochemical content and plum cultivars are known to have different phytochemical retention after drying, but little data exists regarding to possible differences between conventional (CONV) and organic (ORG) plums. The aim of this study was to evaluate the phytochemical content in three different CONV and ORG plum cultivars (Jubileum, Reeves and Victoria) after freeze drying (FD), conventional oven drying (OD) and solar drying (SD). The three cultivars responded differently to the methods of drying. Notably, Jubileum decreased its ATH mostly when subjected to OD while its Neo-CGA content was mostly reduced after SD. Additionally, ORG Victoria and Reeves stood out for the low decrease of Neo-CGA after drying compared to the same cultivars cultivated with conventional system. The Folin-Ciocalteu index, which was significantly different in OD (6942 mg GAE/kg dw) and SD (5420 mg GAE/kg dw) samples, was positively related with both Neo-CGA and hydroxymethylfurfural. The present findings suggest that for some cultivars, the organic system influences the nutraceutical quality of dried product, thus representing an important factor that regulates the phytochemical content of dried plums.

The aims of this study were to find out if organic apple juice (AJ) contained higher contents of polyphenols or patulin compared to conventional AJ, and if higher storage temperature before processing increases patulin content in juice. AJ was pressed from Estonian, Danish and Norwegian apples. Additionally, three cultivars from Estonian organic and conventional orchards were stored at 3 +/- 2 degrees C and 9 +/- 2 degrees C before processing. Patulin, polyphenol content and antioxidant capacity were determined in pasteurized juices. In 2015, 33% of conventional (n=6) and 46% of organic (n=11) juices contained patulin; two of the organic juices above the legal limit (191 and 64 mu g l(-1)). In 2016, none of the AJs contained patulin. Patulin occurrence was more affected by weather conditions two weeks before harvest than by cultivation system and apple storage temperature. Polyphenol content was higher in organic than in conventional juices and was reduced at higher apple storage temperature.

The present work studied the effect of the year of harvest, the genotype and the cultivation method on the nutritional quality and the allergen content of three plum cultivars. The common quality parameters and the phytochemical content strongly varied with the year and the cultivar, while the system of cultivation had a minor influence. In particular, ascorbic acid greatly decreased in 2016 compared to 2015, while polyphenols were higher in 2016. The health-promoting compounds, and particularly phenolics, were significantly correlated with the antioxidant capacity. Finally, the allergen content was strongly dependent on the content of flavan-3-ols, suggesting that this class of phenolics is determinant in influencing the allergen content in plums. Results showed that the major factor affecting the quality and the concentration of natural metabolites of plum, in addition to the diversity among genotypes, is the year-to-year variation, whereas the system of cultivation plays a marginal role.

Six European plum cultivars ( Prunus domestica L.) grown in Norway have been studied with respect to phenolic composition. Neochlorogenic acid was found to be the most important phenolic acid in all cultivars. Together with other phenolic acids, this compound varied significantly in amount among the cultivars. Cyanidin 3-rutinoside was found to account for60% of the total anthocyanin content. Minor amounts of flavonols (rutin and quercetin 3-glucoside) were detected in all cultivars. Total antioxidant capacity varied from 814 to 290 micromol of Trolox 100 g(-1) of fresh weight. Measurement of total phenolic content in terms of Prussian blue complex formation revealed a method failure of magnitude order compared to results obtained by HPLC. Comparison of the response factors of a range of phenolic compounds obtained upon analysis by the Prussian blue and Folin-Ciocalteu assays revealed that the latter method returned higher yields in terms of gallic acid (GAE).

The threshold values of soluble solids for acceptable quality are 14.2%, 12.5%, 11.3% and 10.8% in sweet cherries, plums, pears and apples respectively. In plums and apples the soluble solids: titratable acidity ratio is an even better criterion. This ratio should be between 12 and 24 in plums and above 16 in apples. Firmness, as recorded by penetrometer, is a good index of textural quality in apples and pears. The threshold values of acceptable texture are 5.75–2.75 kg in apples and 5–2 kg in pears. Size is closely related to quality in sweet cherries and plums. In apples and pears a yellow ground colour indicates a good eating quality. Surface colour is a reliable criterion in partially blushed apples and in sweet cherries and plums at harvest.