The effectiveness of chitosan fruit coating to delay the qualitative and nutraceutical traits of three strawberry cultivars, namely “Candonga”, “Jonica” and “Sabrina”, as well as the effects of chitosan on antioxidant enzymes were evaluated. The fruits were coated with 1% and 2% chitosan solution and stored at 2 °C for nine days. Samples were taken every three days. Physico-chemical (weight loss, soluble solid content and titratable acidity) and nutraceutical (total polyphenol, anthocyanin, flavonoid, ascorbic acid content and antioxidant capacity) properties along with the enzymatic activity (catalase (CAT), ascorbate peroxidase (APX), polyphenol oxidase (PPO), guaiacol peroxidase (GPX) and lipoxygenase (LOX)) were evaluated. Chitosan treatment significantly reduced water loss and delayed the qualitative changes in color, titratable acidity and ascorbic acid content in dose- and cultivar-dependent manners. Additionally, changes in the total polyphenol, anthocyanin and flavonoid contents and the antioxidant capacity of chitosan-coated strawberry fruits were delayed. Chitosan coating enhanced the activity of some antioxidant enzymes, preventing flesh browning and reducing membrane damage. A global view of the responses of the three strawberry cultivars to chitosan coating and storage temperature was obtained using principal component analysis. Chitosan-coated fruit exhibited a slower rate of deterioration, compared to uncoated fruit in all tested cultivars.

Chitosan-based coatings are used as a postharvest treatment to extend the shelf-life of several fruits. In this study, the effectiveness of chitosan-based coating to preserve the physico-chemical (weight loss, soluble solid content, and titratable acidity) and nutraceutical traits (total polyphenol, anthocyanin, flavonoid, ascorbic acid content, antioxidant capacity) in fresh fig “Troiano” has been evaluated. Furthermore, antioxidant enzyme activities, such as catalase (CAT) and ascorbate peroxidase (APX), were evaluated as well as the enzymes activities involved in fruit browning (polyphenol oxidase (PPO), guaiacol peroxidase (GPX)). Fruits were treated with 1% chitosan and 1% ascorbic acid coating, stored at 4 °C for nine days, and sampled every three days. Chitosan-based coating significantly reduced the weight loss and the qualitative changes, improving the total polyphenol, anthocyanin, and flavonoid contents and the antioxidant activity in stored figs. The higher activity of antioxidant enzymes allowed to reduce oxidative stress and prevent the browning reactions in chitosan-coated figs. The principal component analysis allowed to distinguish different behaviors among uncoated and chitosan-coated figs, indicating that the combined effects of chitosan-based treatment and storage time influenced the physico-chemical, nutraceutical and antioxidant system of figs during storage.

Loquat is a non-climacteric fruit consumed fresh for its essential nutrients and phytochemical compounds. In this study, the effects of chitosan coating (1% w/v) on changes in the enzymatic antioxidant and membrane damage in three loquat selections (CREAFRC-S18; CREAFRC-S35 and CREAFRC-S36) and three loquat cultivars (Golden Nugget, Algerie and Nespolone rosso di Trabia) stored at 7 °C over 21 days were evaluated. Chitosan treatment enhanced the activities of superoxide dismutase, catalase and ascorbate peroxidase. Moreover, this treatment inhibited polyphenol oxidase and guaiacol peroxidase activities, extending the storage life of loquat. Chitosan also preserved membrane integrity by inhibiting lipoxygenase activity and malondialdehyde accumulation. Principal component analysis provided a global view of the responses of both loquat selections and cultivars to the postharvest chitosan coating and storage temperature. These findings suggest that chitosan treatment could be a valid tool for improving the activity of antioxidant enzymes, preserving the enzymatic browning of loquat fruits.

Xylella fastidiosa subsp. pauca is a xylem-limited bacterial phytopathogen currently found associated on many hectares with the “olive quick decline syndrome” in the Apulia region (Southern Italy), and the cultivars Ogliarola salentina and Cellina di Nardò result in being particularly sensitive to the disease. In order to find compounds showing the capability of reducing the population cell density of the pathogen within the leaves, we tested, in some olive orchards naturally-infected by the bacterium, a zinc-copper-citric acid biocomplex, namely Dentamet®, by spraying it to the crown, once per month, during spring and summer. The occurrence of the pathogen in the four olive orchards chosen for the trial was molecularly assessed. A ¹H NMR metabolomic approach, in conjunction with a multivariate statistical analysis, was applied to investigate the metabolic pattern of both infected and treated adult olive cultivars, Ogliarola salentina and Cellina di Nardò trees, in two sampling periods, performed during the first year of the trial. For both cultivars and sampling periods, the orthogonal partial least squares discriminant analysis (OPLS-DA) gave good models of separation according to the treatment application. In both cultivars, some metabolites such as quinic acid, the aldehydic form of oleoeuropein, ligstroside and phenolic compounds, were consistently found as discriminative for the untreated olive trees in comparison with the Dentamet®-treated trees. Quinic acid, a precursor of lignin, was confirmed as a disease biomarker for the olive trees infected by X. fastidiosa subsp. pauca. When treated with Dentamet®, the two cultivars showed a distinct response. A consistent increase in malic acid was observed for the Ogliarola salentina trees, whereas in the Cellina di Nardò trees the treatments attenuate the metabolic response to the infection. To note that in Cellina di Nardò trees at the first sampling, an increase in γ-aminobutyric acid (GABA) was observed. This study highlights how the infection incited by X. fastidiosa subsp. pauca strongly modifies the overall metabolism of olive trees, and how a zinc-copper-citric acid biocomplex can induce an early re-programming of the metabolic pathways in the infected trees.