Rinaldo Botondi

Temperature and water loss affect ADH activity and gene expression in grape berry during postharvest dehydration

Clusters of Aleatico wine grape were picked at 18°Brix and placed at 10, 20, or 30°C, 45% relative humidity (RH) and 1.5m/s of air flow to dehydrate the berries up to 40% of loss of initial fresh weight. Sampling was done at 0%, 10%, 20%, 30%, and 40% weight loss (wl). ADH (alcohol dehydrogenase) gene expression, enzyme activity, and related metabolites were analysed. At 10°C, acetaldehyde increased rapidly and then declined, while ethanol continued to rise. At 20°C, acetaldehyde and ethanol increased significantly with the same pattern and declined at 40%wl. At 30°C, acetaldehyde did not increase but ethanol increased rapidly already at 10%wl. At the latter temperature, a significant increase in acetic acid and ethyl acetate occurred, while at 10°C their values were low. At 30°C, the ADH activity (ethanol to acetaldehyde direction), increased rapidly but acetaldehyde did not rise because of its oxidation to acetic acid, which increased together with ethyl acetate. At 10°C, the ADH activity increased at 20%wl and continued to rise even at 40%wl, meaning that ethanol oxidation was delayed. At 20°C, the behaviour was intermediate to the other temperatures. The relative expression of the VvAdh2 gene was the highest at 10°C already at 10%wl in a synchrony with the ADH activity, indicating a rapid response likely due to low temperature. The expression subsequently declined. At 20 and 30°C, the expression was lower and increased slightly during dehydration in combination with the ADH activity. This imbalance between gene expression and ADH activity at 10°C, as well as the unexpected expression of the carotenoid cleavage dioxygenase 1 (CCD1) gene, opens the discussion on the stress sensitivity and transcription event during postharvest dehydration, and the importance of carefully monitoring temperature during dehydration.

Temperature affects impact injury on apricot fruit

Abstract Apricot fruit (cv. San Castrese) picked at commercial harvest (14° Brix) were dropped from different heights (5, 10, 20, and 30 cm) onto a flat hard and smooth surface and impact injury was evaluated visually on the skin for 3–4 days at room temperature. The flesh under the impact area turned brown after 3 days in the fruit dropped from 30 cm, but no symptoms were observed on the peel. Ethylene started to rise after 12 h; even sound area on the opposite side produced more ethylene 6 h later. The effect of temperature at the impact time and after the impact was studied. Fruit were impacted at 18 °C and then placed at 4 °C or kept at 18 °C, or dropped at 4 °C and then kept at 4 °C or moved to 18 °C. Ethylene production was greatly affected by low temperature. Ethylene increased more in fruit which were impacted at 4 °C and moved to 18 °C, than in fruit which were kept continuously at 18 °C. Respiration was affected by temperature but not as greatly as ethylene production. L (lightness) and b (yellowness) values decreased significantly in the injured flesh compared to the sound flesh especially in fruit impacted at 4 °C and then moved to 18 °C. Good management of temperature can reduce the physiological response of the tissue to bruising and control the appearance of bruising symptoms.

Ozone fumigation for safety and quality of wine grapes in postharvest dehydration.

This paper proposes postharvest ozone fumigation (as a method) to control microorganisms and evaluate the effect on polyphenols, anthocyanins, carotenoids and cell wall enzymes during the grape dehydration for wine production. Pignola grapes were ozone-treated (1.5 g/h) for 18 h (A=shock treatment), then dehydrated or ozone-treated (1.5 g/h) for 18 h and at 0.5 g/h for 4 h each day (B=long-term treatment) during dehydration. Treatment and dehydration were performed at 10 °C. No significant difference was found for total carotenoid, total phenolic and total anthocyanin contents after 18 h of O3 treatment. A significant decrease in phenolic and anthocyanin contents occurred during treatment B. Also carotenoids were affected by B ozone treatment. Pectin methylesterase (PME) and polygalacturonase (PG) activities were higher in A-treated grapes during dehydration. Finally, ozone reduced fungi and yeasts by 50%. Shock ozone fumigation (A treatment) before dehydration can be used to reduce the microbial count during dehydration without affecting polyphenol and carotenoid contents.

Effects of Exogenous Propylene on Softening, Glycosidase, and Pectinmethylesterase Activity during Postharvest Ripening of Apricots

Apricots (Prunus armeniaca L. cv. Boccuccia spinosa) picked at the commercial ripening stage [soluble solids content (SSC) 12.6%] were left to reach full ripening in continuously humidified air at 20 degrees C. Changes in the rate of ethylene production, firmness, soluble solids concentration, and titratable acidity were measured. The alpha-D- and beta-D-glucosidases, alpha-L-arabinofuranosidase, alpha-D- and beta-D-galactosidases, beta-D-xylosidase, and alpha-D-mannosidase activities were assayed. To evaluate the influence of ethylene on glycosidase activity, propylene (500 microL x L(-1)) was applied to apricots for 24 and 48 h. In apricots ripened in air, ethylene production increased on the first day and exhibited a typical climacteric pattern. Good edible quality was reached in 5 days when SSC was at least 14% and acidity was between 1.1 and 1.2% (% malic acid). During postharvest ripening, alpha-L-arabinofuranosidase activity increased from 1.9 to 11.6 nkat until day 7. alpha-D-Galactosidase, alpha-D-mannosidase, and beta-D-galactosidase activity increased continuously but at a lower rate. beta-D-Xylosidase activity also increased, but the level of activity was lower than the other glycosidases assayed. Pectinmethylesterase (PME) decreased during the postharvest ripening, and propylene enhanced this pattern, by stimulating ethylene production. Even the activities of alpha-L-arabinofuranosidase, beta-D-xylosidase, alpha-D-mannosidase, and beta-D-galactosidase were greatly stimulated by the propylene treatment, which consequently induced rapid softening of the fruits.

Influence of impact surface and temperature on the ripening response of kiwifruit

Abstract Kiwifruit ( Actinidia deliciosa ) at a typical harvesting stage were subjected to a drop height of 30 cm onto a steel plate (impact injury), and to abrasion injury by being drawn under pressure across a piece of packing-case wood. Reactions in terms of soluble solids content (SSC) and deformation measurements of flesh and core tissue, were assessed. Impact caused greater increases in SSC and deformation than abrasion, but both were greater than controls. More detailed impact tests involved comparisons of smooth steel plate with fine (280 mesh) and coarse (100 mesh) sandpaper surfaces, again measuring SSC, deformation and ethylene production. Fine sandpaper generally produced greater increases compared with steel than did coarse paper. Chilling to 4 °C either on impact or during storage reduced increases in SSC and deformation responses. It is concluded that careless handling and rough surfaces in packing materials should be avoided, but prompt cooling will delay the onset of deterioration resulting from mechanical damage.

Postharvest Gaseous Ozone Treatment Enhances Quality Parameters and Delays Softening in Cantaloupe Melon during Storage At 6 °C

BACKGROUND A trial was conducted to evaluate the effect of postharvest gaseous ozone (O3 ) treatment on quality parameters and cell wall enzymes of cantaloupe melon cv. Caldeo during storage at 6 °C for 13 days. Fruits were kept in cold storage and treated with 0.15 ppm gaseous O3 during the day and 0.3 ppm overnight; control fruits (CK) were stored in normal atmosphere. RESULTS Firmness was higher and ethylene concentration significantly lower in O3 fruits compared with CK fruits. During storage, microbial counts were lower in both O3 and CK fruits; from day 9, O3 fruits showed a significant decrease in mesophilic aerobes. Additionally, total carotenoids had a tendency to be higher, with no significant differences between CK and O3 fruits. The same trend was observed for ascorbic acid, colour, total soluble solids content and acidity. Finally, O3 treatment reduced the activities of cell wall enzymes α-arabinopyranosidase, β-galactopyranosidase and polygalacturonase starting from day 3 of storage. Pectin methyl esterase activity did not seem to be affected by O3 treatment. CONCLUSION Gaseous O3 treatment during cold storage was effective in decreasing ethylene production and delaying fruit softening in cantaloupe melon by extending quality maintenance.