Maria Silvia Pasquariello

Effect of Chitosan Coating on the Postharvest Quality and Antioxidant Enzyme System Response of Strawberry Fruit during Cold Storage

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.

Pomegranate Cultivars: Identification of the New IgE-Binding Protein Pommaclein and Analysis of Antioxidant Variability

The consumption of pomegranate is increasing as it is considered a health-promoting food. Nevertheless, it can trigger allergic reactions, sometimes severe. The LTP Pun g 1 is the only pomegranate allergen so far reported. Based on preliminary clinical observations, the main aim of this study was the investigation of still unknown allergens contained in this fruit. Pommaclein, a homologue of peamaclein, the peach allergen Pru p 7, was isolated, identified by protein sequencing, and characterized as an IgE-binding protein by different test systems. RP-HPLC protein profiles revealed significant variations of LTP and pommaclein content in the red pulp of selected cultivars and accessions. Conversely, the mesocarp appeared free of proteins and much richer in antioxidants. In conclusion, a new allergen has been identified, and it could contribute to improving allergy diagnosis. The study highlights that pomegranate mesocarp could represent a rich and safe source of nutraceuticals also for allergic subjects.

A proteometabolomic study of Actinidia deliciosa fruit development

Abstract Green-fleshed kiwifruit is worldwide appreciated for its flavor and macronutrients that are related to its physiological development. Fruit ripe stage for harvesting does not correspond to an optimal edible condition due to firmness/acidity pome characteristics; this is overcome with postharvest fruit processing. To describe the metabolic pathways/molecular effectors underlying Actinidia deliciosa cv. Hayward pome physiological development, kiwifruits were harvested at four growth stages (from fruit set to physiological maturity), and corresponding outer endocarp samples were analysed for metabolite and protein content. Combined NMR/LC-UV/ESI-IT-MSn procedures quantified 46 metabolites at these developmental stages; similarly, integrated 2D-DIGE/nLC-ESI-LIT-MS/MS analyses described corresponding proteomic changes. Quantitative protein dynamics showed that components related to disease/defense, protein destination/storage, metabolism, energy and cell structure functions were highly affected at specific moments of fruit development, suggesting a rationale to pomological and metabolite content characteristics at those times. Bioinformatic interaction prediction revealed a main network of differentially represented proteins, which may control metabolic changes in developing kiwifruit. Main pome allergens were also quantified, demonstrating their highest levels at the mature stage. By aligning kiwifruit development to a proteometabolomic representation, this investigation integrates previous metabolic observations and provides a reference framework for further physiological/nutritional studies, also allowing cross comparison among crop species. Biological significance Compared with some other fruits, green-fleshed kiwifruit is unique for its nutrient density, health benefits, and consumer appeal; in fact, it is exceptionally rich in vitamins, carotenoids, potassium, fibre and phytochemicals acting in synergy to achieve multiple health advantages. However, kiwifruit is allergenic, and although symptoms in most susceptible individuals are mild, severe reactions have also been described. In the course of their 6-month development, kiwifruit undergoes radical changes in its morphology and chemical composition; these modifications may highly affect fruit nutraceutical and allergenic properties. To gain a better understanding of the molecular processes regulating metabolite concentration during fruit development but also affecting general pomological characteristics, a time-course metabolomic and proteomic analysis of kiwifruit flesh tissues was undertaken. Combined information on modified levels of 46 metabolites and 241 proteins showed that molecular processes underlying central and secondary metabolism, energy, cell structure, protein destination/storage, disease/defense kiwifruit functions were highly affected during fruit development, providing a rationale to the corresponding changes in organic acids, sugars, amino acids, polyphenols, fatty acids, phospholipids and allergens content, but also to the corresponding modifications in pome firmness, pulp colour, protein and total solid content. By providing original information on fruit development, this multiomic study integrates previous metabolomic/transcriptomic observations in describing molecular mechanisms associated with nutritional and agronomic traits of great interest for kiwifruit molecular breeding.