Giovanna Giacalone

Anthocyanins, phenolics and antioxidant capacity after fresh storage of blueberry treated with edible coatings

Abstract The influence of different edible coatings on total phenolic content, total anthocyanin and antioxidant capacity in highbush blueberry (Vaccinium corymbosum L. cv Berkeley and O’Neal) was investigated, mainly for industrial applications. Also titratable acidity, soluble solids content, firmness and weight loss of berries were determined at harvest and at 15-day intervals during 45 storage days at 0 °C, in order to optimize coating composition. Application of chitosan coating delayed the decrease in anthocyanin content, phenolic content and antioxidant capacity. Coating samples showed no significant reduction in the weight loss during storage period. In cv Berkeley, the use of alginate coating showed a positive effect on firmness, titratable acidity and maintained surface lightness of treated berries. In cv O’Neal, no significant differences in total soluble solids content were found, and the chitosan-coated berries showed the minimum firmness losses. In both cultivars, the addition of chitosan to coatings decreases the microbial growth rate.

Effect of different coatings in preventing deterioration and preserving the quality of fresh-cut nectarines (cv Big Top)

Fresh-cut nectarines are very perishable product, and thus have a short shelf-life. In this study, minimally processed nectarines (cv Big Top) were treated with chitosan (20 g/L), sodium alginate (20 g/L) and Chitoplant® (20g/L), sealed in polypropylene plastic bags, and stored at 4°C for 5 days. Effects of the coatings on nectarine slices shelf-life and qualitative attributes were evaluated by investigating changes in colors, browning potential, total soluble solids content, and titratable acidity. Changes in quality parameters were lower in coated samples as compared with the control. The alginate coatings were effective on delaying the evolution of the parameters related to postharvest ripening, such as color (Hue, L*) and loss of acidity. The application of sodium alginate coating could be used to reduce deteriorative processes, maintain quality and improve the shelf-life of fresh-cut nectarine stored at 4°C.

Studies on shelf life of "lateblue" highbush blueberries

There is a considerable scope to mantain the quality and extend shelf-life of perishable and soft fruits such as strawberries, raspberries, and blueberries by developing and evolving packaging strategies. In this work a study on the packaging of blueberries in plastic film for short-to-medium term storage was carried out. Blueberries cv Lateblue were hand-picked from a commercial plantation and packaged in different barrier films. Four commercially available films were used as packaging materials: two micro-perforated (0.3 mm and 1 mm in diameter), a non-perforated and a macro-perforated (6 mm in diameter). All the samples were stored at 4 °C for 15 days. The benefits of small packages (consumer packs), were evaluated through chemical (total soluble solid content (TSS), titratable acidity and pH), visual (color intensity, surface shine, firmness by touch, intensity of odor, and overall appearance) and sensory (crispness, sweet taste, acidic taste, total flavor, and overall appreciation) evaluation. The berries packaged in micro-perforated (1 mm in diameter) and non-perforated film maintained better quality attributes (high TSS content and titratble acidity) throughout the cold storage. The non-perforated film maintained also berry crispness and a good intensity of flavor. Non and micro-perforated packaging films gave the best results and appeared to be a feasible practice in order to ensure good quality during medium-term storage of blueberries. Moreover nonperforated film treatment was the only treatment that reduced in little or no significant pathogen-induced decay during cold storage.

Thyme and Savory Essential Oil Vapor Treatments Control Brown Rot and Improve the Storage Quality of Peaches and Nectarines, but Could Favor Gray Mold

The effect of biofumigation, through slow-release diffusors, of thyme and savory essential oils (EO), was evaluated on the control of postharvest diseases and quality of peaches and nectarines. EO fumigation was effective in controlling postharvest rots. Naturally contaminated peaches and nectarines were exposed to EO vapors for 28 days at 0 °C in sealed storage cabinets and then exposed at 20 °C for five days during shelf-life in normal atmosphere, simulating retail conditions. Under low disease pressure, most treatments significantly reduced fruit rot incidence during shelf-life, while, under high disease pressure, only vapors of thyme essential oil at the highest concentration tested (10% v/v in the diffusor) significantly reduced the rots. The application of thyme or savory EO favored a reduction of brown rot incidence, caused by Monilinia fructicola, but increased gray mold, caused by Botrytis cinerea. In vitro tests confirmed that M. fructicola was more sensitive to EO vapors than B. cinerea. Essential oil volatile components were characterized in storage cabinets during postharvest. The antifungal components of the essential oils increased during storage, but they were a low fraction of the volatile organic compounds in storage chambers. EO vapors did not influence the overall quality of the fruit, but showed a positive effect in reducing weight loss and in maintaining ascorbic acid and carotenoid content. The application of thyme and savory essential oil vapors represents a promising tool for reducing postharvest losses and preserving the quality of peaches and nectarines.

Improving Storability of Strawberries with Gaseous Chlorine Dioxide in Perforated Clamshell Packaging

Abstract A chlorine dioxide generating pad has been used as postharvest treatment to maintain the quality and safety of strawberries in two different storage conditions. During the short storage time (3 days at 4°C + 2 days at 20°C) fruit treated with ClO2 maintained better quality parameters, as color, titratable acidity, total soluble solids, anthocyanins, antioxidant capacity and lower values of weight loss. During the long storage time (12 days at 2°C), the parameters related to postharvest quality were generally preserved and the effect of ClO2 was positive to reduce the total yeast and mold, except the last period of the experiment when the ClO2 gas-generating pad was probably exhausted. The sensory evaluation revealed that the sanitization with ClO2 maintained a global positive acceptance in particular during the short storage time. The results suggest that this treatment may be suitable to maintain the quality during short storage and long storage until 8 days and it may be an important alternative sanitizer thanks to the positive action against the yeast and mold without modifying the quality of the strawberries.