Oxalic acid preharvest treatment increases antioxidant systems and improves plum quality at harvest and during postharvest storage.

BACKGROUND: Plums are much appreciated by consumers as fresh fruit but have a limited storage life. Since reactive oxygen species (ROS) are associated with fruit ripening, an increase in ROS scavenging antioxidant systems could lead to a delay in postharvest plum ripening and in maintaining fruit quality after long cold storage. RESULTS: Results showed that crop yield (kg per tree) and fruit weight were enhanced by preharvest oxalic acid (OA) treatment of plum cultivars ('Black Splendor' and 'Royal Rosa'), although the on-tree ripening process was delayed. In addition, the ripening process during cold storage was delayed in plums from OA-treated tress, manifested by lower firmness and acidity losses and reduced ethylene production, as compared with fruits from control trees. Antioxidant compounds (phenolics, anthocyanins and carotenoids) and the activity of antioxidant enzymes were higher in plums from OA-treated trees than in controls, at harvest and during 50 days of cold storage. CONCLUSION: OA preharvest treatment could be a useful tool to maintain plum quality properties during long-term storage, by delaying the postharvest ripening process through a delay in ethylene production, with an additional effect on increasing bioactive compounds with health beneficial effects. © 2018 Society of Chemical Industry.

Preharvest treatments with salicylates enhance nutrient and antioxidant compounds in plum at harvest and after storage.

BACKGROUND: Previous reports have addressed the effectiveness of salicylic acid (SA), acetylsalicylic acid (ASA) and methylsalicylate (MeSA) postharvest treatments on maintaining quality properties during storage in several commodities. However, there is no literature regarding the effect of preharvest treatments with salicylates on plum quality attributes (at harvest or after long-term cold storage), which was evaluated in this research. RESULTS: At harvest, weight, firmness, individual organic acids, sugars, phenolics, anthocyanins and total carotenoids were found at higher levels in plums from SA-, ASA- and MeSA-treated trees than in those from controls. During storage, softening, colour changes and acidity losses were delayed in treated fruits as compared to controls. In addition, organic acids and antioxidant compounds were still found at higher levels in treated than in control plums after 40 days of storage. Results show a delay in the postharvest ripening process due to salicylate treatments, which could be attributed to their effect in delaying and decreasing ethylene production. CONCLUSION: Preharvest treatment with salicylates could be a safety, eco-friendly and new tool to improve (at harvest) and maintain (during storage) plum quality and especially its content of bioactive compounds with antioxidant properties, increasing the health effects of plum consumption. © 2017 Society of Chemical Industry.

Preharvest Application of Methyl Jasmonate as an Elicitor Improves the Yield and Phenolic Content of Artichoke.

The effects of methyl jasmonate (MeJa) treatment as an elicitor of artichoke plants [Cynara cardunculus var. scolymus (L.) Fiori] on the yield and quality attributes of artichokes, especially those related to individual phenolic content and antioxidant activity, at two harvest dates and along storage were analyzed in this research. Plants treated gave a higher yield of artichokes in comparison to control plants, with 0.55 kg more per plant. MeJa treatment also increased artichoke quality and phenolic content in the edible fraction at harvest and during storage at 2 °C for 28 days as a result of the accumulation of hydroxycinnamic acids and luteolin derivatives. In addition, antioxidant activity was enhanced by MeJa treatment and correlated with the total phenolic content. Results suggest that MeJa foliar application could be a simple and practical tool to improve the yield and phytochemical content on artichokes, with elicitation being a cheap and environmentally friendly procedure to improve the health-beneficial effects of artichoke consumption.

Enhancement of Antioxidant Systems and Storability of Two Plum Cultivars by Preharvest Treatments with Salicylates.

In this research the effect of salicylic acid (SA), acetylsalicylic acid (ASA), and methylsalicylate (MeSA) treatments, applied as a foliar spray during on-tree plum development, on fruit quality attributes, bioactive compounds, antioxidant activity, and the activity of the antioxidant enzymes at harvest and after long-term cold storage was evaluated in two plum cultivars ("Black Splendor", BS, and "Royal Rosa", RR). At harvest, plum quality parameters, such as weight, total phenolics (including anthocyanins, in BS), total carotenoids, and antioxidant activity, in both hydrophilic and lipophilic compounds were found at higher levels in plums from SA-, ASA-, and MeSA-treated trees than in those from control trees. During storage, fruit firmness, total acidity, and antioxidant compounds were at higher levels in treated, than in control, plums, which show an effect of salicylate treatments on delaying the plum postharvest ripening process. In addition, the activity of the antioxidant enzymes catalase (CAT), peroxidase (POX), superoxide dismutase (SOD), and ascorbate peroxidase (APX) were also enhanced at the time of harvest in salicylate-treated plums as compared with plums from control trees. The activity of these antioxidant enzymes was also found at higher levels in salicylate-treated plums during storage. Thus, preharvest treatment with salicylates could be a safe, eco-friendly, and new tool to improve and maintain plum quality attributes, and especially their content of antioxidant compounds, with an additional effect on delaying the postharvest ripening process through increasing the levels of antioxidant compounds and the activity of the antioxidant enzymes.

Preharvest application of oxalic acid improves quality and phytochemical content of artichoke (Cynara scolymus L.) at harvest and during storage.

In this study the effect of oxalic acid (OA) treatment of artichoke plants (Cynara scolymus L.) on head artichoke development and on artichokes quality parameters (weight loss, firmness, and color), respiration rate, antioxidant activity and phenolics (measured by Folin Ciocalteu and HPLC-DAD-ESI/MSn) at harvest and during storage for 21days at 2°C was evaluated. OA treatment increased the percentage of the first class artichokes although no significant effect was found in artichoke developmental process. OA-treatment reduced the respiration rate of artichokes and led to higher total hydrosoluble antioxidant activity and total phenolics and hydroxycinnamics and luteolins concentration both at harvest and during cold storage. In addition, luteolin 7-O-glucuronide 3-O-glucoside was identified for the first time in artichoke. Thus, it can be concluded that OA preharvest treatment could be a natural and useful tool to delay the artichoke postharvest senescence and improve the reported health-beneficial properties of artichokes consumption.

Preharvest application of oxalic acid increased fruit size, bioactive compounds, and antioxidant capacity in sweet cherry cultivars (Prunus avium L.).

Trees of 'Sweet Heart' and 'Sweet Late' sweet cherry cultivars (Prunus avium L.) were treated with oxalic acid (OA) at 0.5, 1.0, and 2.0 mM at 98, 112, and 126 days after full blossom. Results showed that all treatments increased fruit size at harvest, manifested by higher fruit volume and weight in cherries from treated trees than from controls, the higher effect being found with 2.0 mM OA (18 and 30% higher weight for 'Sweet Heart' and 'Sweet Late', respectively). Other quality parameters, such as color and firmness, were also increased by OA treatments, although no significant differences were found in total soluble solids or total acidity, showing that OA treatments did not affect the on-tree ripening process of sweet cherry. However, the increases in total anthocyanins, total phenolics, and antioxidant activity associated with the ripening process were higher in treated than in control cherries, leading to fruit with high bioactive compounds and antioxidant potential at commercial harvest (≅45% more anthocyanins and ≅20% more total phenolics). In addition, individual anthocyanins, flavonols, and chlorogenic acid derivatives were also increased by OA treatment. Thus, OA preharvest treatments could be an efficient and natural way to increase the quality and functional properties of sweet cherries.