Fabio Mencarelli

Chemical and biochemical change of healthy phenolic fractions in winegrape by means of postharvest dehydration.

Clusters of Aleatico winegrape were picked at 18 degrees Brix and placed at 10, 20, or 30 degrees C, 45% relative humidity (RH) and 1.5 m/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). Selected polyphenols and sugar content (expressed as SSC = soluble solids content) both measured on dry weight basis, polyphenol oxidase (PPO), and phenylpropanoid pathway gene expression were analyzed. Phenolic acids increased significantly at 20% wl at 20 degrees C, while at 10 degrees C the increase was lower. Stilbenes (trans-resveratrol and trans-piceid) and catechins rose more than double to 100 mg/kg and more than 3-fold to 135 mg/kg at 20 degrees C and 10% wl. At 10 degrees C the increase of these compounds was less, but higher than initial values. At 30 degrees C, except for a significant rise at 10% wl for catechins and stilbenes, all the rest of the compounds diminished. Anthocyanins increased at 10 and 20 degrees C, but decreased at 30 degrees C. PPO rapidly increased at 20 and 30 degrees C at 10% wl and then declined, while at 10 degrees C the activity lasted longer. Relative gene expression of phenylalanine ammonia lyase (PAL), stilbene synthase (STS), chalcone isomerase (CHI), dihydroflavonol reductase (DFR) were upregulated at 10 degrees C more than at 20 degrees C, at 20% wl, while at 30 degrees C the gene expression was downregulated.

Feasible Application of a Portable NIR-AOTF Tool for On-Field Prediction of Phenolic Compounds during the Ripening of Olives for Oil Production

Olive fruits of three different cultivars (Moraiolo, Dolce di Andria, and Nocellara Etnea) were monitored during ripening up to harvest, and specific and total phenols were measured by HPLC (High Pressure Liquid Chromatography). On the same olive samples (n = 450), spectral detections were performed using a portable NIR (Near Infrared)-AOTF (Acousto Optically Tunable Filter) device in diffuse reflectance mode (1100-2300 nm). Prediction models were developed for the main phenolic compounds (e.g., oleuropein, verbascoside, and 3,4-DHPEA-EDA) and total phenols using Partial Least Squares (PLS). Internal cross-validation (leave-one-out method) was applied for calibration and prediction models developed on the data sets relative to each single cultivar. Validation of the models obtained as the sum of the three sample sets (total phenols, n = 162; verbascoside, n = 162; oleuropein, n = 148; 3,4-DHPEA-EDA, n = 162) were performed by external sets of data. Obtained results in term of R(2) (in calibration, prediction and cross-validation) ranged between 0.930 and 0.998, 0.874-0.942, and 0.837-0.992, respectively. Standard errors in calibration (RMSEC), cross-validation (RMSECV), and prediction (RMSEP) were calculated obtaining minimum error in prediction of 0.68 and maximum of 6.33 mg/g. RPD ratios (SD/SECV) were also calculated as references of the model effectiveness. This work shows how NIR-AOTF can be considered a feasible tool for the on-field and nondestructive measurement of specific and total phenols in olives for oil production.

Discrimination of sweet wines partially fermented by two osmo-ethanol-tolerant yeasts by gas chromatographic analysis and electronic nose.

Some special sweet wines are obtained by partial fermentation of musts from off-vine dried grapes containing large amounts of sugars. This process is very slow and subject to serious stop problems that can be avoided by using osmo-ethanol-tolerant yeasts. Musts containing 371g/l of sugars were partially fermented with selected Saccharomyces cerevisiae strains, X4 and X5, to 12% (v/v) and the wines obtained with X5 exhibited a higher volatile acidity but lower concentrations of higher alcohols, carbonyl compounds and polyols than those obtained with X4. A principal component analysis (PCA) of the data provided by an electronic nose (E-nose) afforded discrimination between fermented and unfermented musts, but not between wines obtained with X4 or X5. The PCA applied to the major volatile compounds and polyols shows similar results, but a clear discrimination between wines is obtained by removing the polyols glycerol and 2,3-butanediol from the PCA.

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.

Bacterial Populations Related to Gerbera ("Gerbera jamesonii" L.) Stem Break

Bacterial distribution, both external (epiphytic) and internal (endophytic), on Gerbera jamesonii L. cv. Provence and its relationship to gerbera stem break and ethylene production were investigated. The greatest number of epiphytic bacteria was found at capitulum level and 20 cm below. Three genera of bacteria were identified: Acinetobacter, Bacillus and Pantoea. A silver-nitrate solution greatly reduced ethylene production in cut flowers. The use of acid fuchsin solution revealed an occlusion of the xylem vessels, probably due to bacterial cells. The bacteria Acinetobacter, Pantoea and Bacillus appeared to be involved in stem break once their populations reached 105 cfu g-1 of stem tissue.

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.

Influence of Bunch Position in the Canopy on Berry Epicuticular Wax during Ripening and on Weight Loss during Postharvest Dehydration

Passito wine, made with dehydrated grapes, is widespread in Italy. The quality of the grapes to be withered is strongly influenced by qualitative factors and the anatomy and morphology of the berry, which in turn, are affected by vineyard management and microclimate. In Trebbiano toscano and Rossetto vines grown in the Latium region, the epicuticular wax of berries from bunches developed in intracanopy and extracanopy positions was analyzed from preveraison to preharvest during the 2007 and 2008 growing seasons. At harvest, the characteristics of cuticle and epidermis of each sample were examined using light and electron microscopy. The berries were then dehydrated at 20°C to 45% moisture to evaluate differences in water loss rate and the mechanical characteristics of the skin. The amount of epicuticular wax decreased during berry development. SEM observations of the berry skin at harvest showed differences in the structure of the epicuticular wax layers, with a wider berry surface covered with plate-like wax in extracanopy berries. The number of cell layers and the thickness of the berry skin were significantly different between cultivars and canopy positions, but these factors did not affect cuticle thickness. Shaded berries of both varieties dehydrated more slowly, particularly in vigorous Trebbiano toscano vines, in which intracanopy berries reached 40% weight loss later than the extracanopy berries. During dehydration, the berry skin color (hue angle) decreased and berries of both varieties increased skin resistance to puncturing; this was not affected by the position of the berry in the canopy.

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.