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Tesi etd-06192014-141241

Thesis type
Tesi di dottorato di ricerca
A biochemical and molecular dissection of the response induced by postharvest UV-B radiation on quality traits of peach fruits
Settore scientifico disciplinare
Corso di studi
tutor Tonutti, Pietro
tutor Prof.ssa Ranieri, Annamaria
Parole chiave
  • postharvest
  • peaches
  • UVB
Data inizio appello
Riassunto analitico
In the present study the possibility of enhancing the content of health-promoting<br>compounds of peaches and nectarines (Prunus persica L. Batsch) by post-harvest irradiation with<br>UV-B was assessed. Moreover, the impact of UV-B on the cell wall metabolism of peach fruits was<br>also investigated.<br>Fruits of ‘Suncrest’ (Melting flesh-type, MF) and ‘Babygold 7’ (Non-Melting flesh-type, NMF)<br>peach and ‘Big Top’ nectarine (Slow Melting flesh-type, SM) cultivars were firstly irradiated with<br>UV-B (1.69 W/m2) for 12 h, 24 h and 36 h. A photosynthetic photon flux density of 500 μmol m-2<br>s-1 was provided. Control fruits underwent the same conditions but UV-B lamps were screened by<br>benzophenone-treated polyethylene film. Subsequently, fruits of ‘Suncrest’ and ‘Big Top’ cultivars,<br>which showed a positive response to the UV-B radiation, were subjected to a second different<br>experiment providing 24 h of irradiation after which treated and control fruits were stored up to 36<br>hours at 10 °C.<br>The effectiveness of the UV-B treatment in modulating the concentration of phenolic compounds<br>and ascorbic acid was cultivar-dependent. ‘Big Top’ and ‘Suncrest’ fruits were generally affected<br>by increasing health-promoting compounds whereas in ‘Babygold 7’levels of secondary metabolites<br>decreased after UV-B irradiation. A corresponding trend was exhibited by most of phenylpropanoid<br>biosynthetic genes which were tested by qRT-PCR. In MF-type fruits, UV-B radiation slowed down<br>the softening process and reduced the flesh firmness loss. This evidence was attributed to the<br>inhibition of expansin synthesis, regulated at gene level by UV-B. The UV-B treatment did not<br>induce differences in flesh firmness between control and treated fruits of NMF and SM fruits.<br>After 36 h of storage at 10°C, fruits treated with UV-B exhibited generally higher contents of<br>antioxidant compounds. In both experiments, the concentration of phenolic compounds and<br>ascorbic acid were correlated with the accumulation of radicals measured by EPR analysis.<br>Based on these results UV-B irradiation can be considered a promising technique to increase the<br>health-promoting potential of peach fruits at the same time improving shelf-life and quality.