Pesnica pri Mariboru, Slovenia
Pesnica pri Mariboru, Slovenia

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Bizjak J.,University of Ljubljana | Jakopic J.,University of Ljubljana | Slatnar A.,University of Ljubljana | Stampar F.,University of Ljubljana | And 4 more authors.
European Journal of Horticultural Science | Year: 2012

In this study the influence of prohexadione-Calcium (Pro-Ca) treatment on peel colour development and polyphenol metabolism of apples during advanced maturity was investigated. Apple trees were treated 3 weeks before technological maturity. Changes in the content of hydroxycinnamic acids, dihydrochalcones, flavonols, flavanols and anthocyanins were monitored six times during the advanced maturation until technological maturity of the fruits. To evaluate the effect of Pro-Ca on the coloration of apples, the changes in the chromaticy values a*, h° and the lightness coefficient L* were monitored. The parameters showed a significant difference in the intensity of red coloration between the treated and untreated apples. The application of Pro-Ca led to a decrease in the enzyme activities of the 2-oxo-glutarate dependent dioxygenases flavanone-3-hydro- xylase (FHT) and flavonol synthase (FLS), and the fla-vonoid pathway was negatively affected in general. Concomitantly, the concentrations of flavonols, antho-cyanins and dihydrochalcones in the peel of treated apples decreased, whereas the contents of total phenolic compounds and hydroxycinnamic acids increased. Flavanol contents, however, remained unchanged. In apple pulp, slightly higher concentrations of all phenolic compounds were measured in the treated apples compared to the control on the majority of sampling dates. The results indicate that Pro-Ca modulates the polyphenol spectrum resulting in a pronounced decrease of red coloration during advanced maturation of apples. Pro-Ca therefore to some extent exhibits the potential to avoid undesired red coloration of apple fruit. © Verlag Eugen Ulmer KG, Stuttgart.

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