POST-HARVEST AS A TOOL TO IMPROVE BERRY FRUIT QUALITY

The purpose of this thesis was to research some innovative post-harvest techniques with potential to extend the shelf-life of berry fruit during storage and enhance their overall quality. Emphasis was given to different packaging system, in particular microperforated film, edible film, and electrostatic spraying of antimicrobial coating. The berry fruits studied were blueberry and strawberry. These fruits were selected because of their increasing worldwide consumption, among the many different types of berries. The application of microperforated polypropylene film to store freshly harvested blueberries, demonstrated the importance of selecting a proper packaging to increase the storage period and maintain the quality attributes of the fruit. The number of microperforations made to the film (1, 10, and 30) created a passive modified atmosphere within the package that led to improvement of firmness and antioxidant activity of the fruit, throughout their storage period. Equilibrium atmosphere within the packaging was achieved after two days of storage and the concentration of gases remained constant for the rest of the storage period. This stable atmospheric condition resulted in an extension of the shelf-life of blueberry for up to 16 days, at 4°C. Strawberry shelf-life extension and quality improvements were obtained by storing the fruit in clamshells that contained strawberry puree edible films infused with carvacrol and methyl cinnamate. The strawberry puree edible films served as matrix for the controlled release of natural antimicrobial’s (Carvacrol and methyl cinnamate) vapors, over time. Fresh strawberries packed in clamshells had an extended shelf life of 10 days, at 10◦C and 90% RH. The released vapors from the strawberry puree edible film extended the strawberry shelf-life by delaying spoilage of the fruit and improved main quality-related attributes, such as firmness and brightness. The natural antimicrobial vapors also increased the total soluble phenolic content and antioxidant activity of the stored strawberry. Besides microbial spoilage, that limits strawberry shelf-life, the presence of foodborne pathogens bacteria that can be carried by the fruit as result of contamination, is another important issue that can lead to serious outbreaks. Antimicrobial edible coatings can be an effective post-harvest technique to assure microbial safety and, at the same time, retain overall quality of the fruit. Antimicrobial alginate coating was developed and optimized using response surface methodology. Antimicrobial activity against Escherichia coli O157:H7 and Botrytis cinerea, as well as physical properties such as viscosity, turbidity and whitish index of the coating were also optimized based on carvacrol and methyl cinnamate concentration. After the optimization, the resulted antimicrobial coating solution was applied on the surface of freshly harvested strawberry fruit using an electrostatic spraying technology. This technology presented unique advantage with regard to transfer efficiency and evenness application of the antimicrobial coating solution. The antimicrobial coating application led to a significant increase on strawberry shelf-life. Additionally, the strawberry coated using the electrostatic spraying technology presented a significant reduction of visible decay of four days compared to not-coated fruit, and of one day compared to fruit coated with conventional spray method. Moreover, the firmness and color of the strawberries were improved by coating the fruit using the electrostatic spraying technology. Therefore, electrostatic spraying could be considered a potential technology for the commercial application of liquid coating to extend the shelf-life and improve the post-harvest quality of strawberry and other perishable fruits

Changes in Qualitative Traits of Blueberry and Blackberry in Relation to Storage Temperature and Film Type

The use of alternative fertilizers plays nowadays an increasing importance because of increase of price of mineral fertilizers and organic matter decrease in cultivated soils. Veneto Region plays an active role in waste recycling and composting activities that allows to use new organic matter sources in order to improve soil properties. In this study we evaluated the effect of compost use on the agronomic and nutritional qualitative traits of cabbage. The experiment was conducted at the University of Padova considering the following theses: control unfertilized (F0), treatment with mineral fertilizers (FMIN) in which the 100% of the nitrogen requirement was supplied in mineral form, treatment where 50% of the nitrogen requirement was made in mineral form and the remaining demand with compost (F50), 100% of nitrogen requirements necessary for the culture was made from compost (F100) and 200% of demand in nitrogen was supplied through compost (F200). Dry matter content, antioxidant capacity (AOA), total phenols (TP), ascorbic acid (AA), phenolic acids, organic nitrogen and nitrate (NO3) were evaluated as qualitative traits. It was also determined the quantity of Al, Ca, Cu, K, Mg, P, Zn and heavy metals (Cd, Cr, Hg, Ni, Pb). Results showed that AOA and TP were higher in plants grown with F0 and F200. About AA values the most interesting result was observed in F200 too. The main phenolic acids detected were chlorogenic and p-coumaric acid on which fertilizer treatment did not significantly influenced. However, for both acids, the highest values were measured by plants cultivated with F200. In assessing the content of NO3, plants of the thesis that during the crop cycle were held to a higher proportion of available nitrogen (F50 and FMIN), showed the highest concentrations of nitrogen compounds. Concerning heavy metals Cd, Hg, Pb were below the detectable limit

Influence of planting date and mulching on some qualitative traits of processed tomato

Tomato is one of the most important vegetables in the world. This crop can be used as a fresh vegetable and, since the last century, for processing (sauce, paste etc.). For this reason, breeders have been selecting and improving many cultivars in order to satisfy industry requirements like high yield, handling resistance of fruits, maturation time, uniformity of shape, and resistance to pests and diseases. Recently attention has focused on qualitative aspects because of consumers’ increased health awareness. Some of the most recent studies have been on improving aspects like contents of antioxidants, ascorbic acid, dry matter, sugar, and pH. The aim of this experiment was to study if mulching and planting date could affect fruit qualitative properties of different cultivars of processing tomatoes. Four cultivars ‘Augusto’ F1 (AUG), ‘NPT 63’ (NPT), ‘Safaix’ (SAF) and ‘Tiziano’ F1 (TIZ), four planting dates 14/4, 4/5, 14/5 and 25/5 called P1, P2, P3 and P4 and two mulching treatments named mulched (M) and not mulched (NM) were compared. Samples were analyzed to determine peel resistance and flesh consistency, pH, titratable acidity, phenols, total antioxidant activity and soluble solids content (SSC). From a quality point of view results showed that TIZ was the best cultivar with suitable properties for processing. Mulching seemed to decrease the content of total phenols and the consistence of tomato fruits, stimulating yield. Planting date also affected organoleptic tomato quality. P4 fruits had the highest phenol content, antioxidant activity, dry matter and flesh color. Structural properties of P4 fruits were good for processing but slightly lower than P1 fruits

Increasing strawberry shelf-life with carvacrol and methyl cinnamate antimicrobial vapors released from edible films

The effect of carvacrol and methyl cinnamate vapors incorporated into strawberry puree edible films on the postharvest quality of strawberry fruit (Fragaria x ananassa) was investigated. Fresh strawberries were packed in clamshells and kept at 10 degrees C for 10 days with 90% RH. Strawberry puree edible films, applied in the clamshell, served as carriers for the controlled release of natural antimicrobial compounds without direct contact with the fruit. Changes in weight loss, visible decay, firmness, surface color, total soluble solids content, total soluble phenolics content and antioxidant capacity of strawberries during storage were evaluated. A significant delay and reduction in the severity of visible decay was observed in fruit exposed to antimicrobial vapors. Carvacrol and methyl cinnamate vapors released from the films helped to maintain firmness and brightness of strawberries as compare to the untreated strawberries. The natural antimicrobial vapors also increased the total soluble phenolics content and antioxidant activity of fruit at the end of the storage period. (C) 2013 Elsevier B.V. All rights reserved