Laura de Palma

Effects of defoliation on quality attributes of Nero di Troia (Vitis vinifera L.) grape and wine

Field studies were conducted in Puglia (Italy) to evaluate the influence of defoliation around cluster zones on grape and wine quality. Nero di Troia grapes were subjected to four different treatments: N: no leaf removal; E: leaf removal in the area of the clusters along the east side (at complete veraison); E/W: leaf removal in the area of the clusters along the east and west side (at complete veraison); and F: almost complete leaf removal along the west side (at complete veraison) and at pre-harvest also along the east side. Grapes of defoliated vines generally showed higher sugar content, lower titratable acidity, total flavonoids, flavonoids different from anthocyanins, and total phenolic content than grapes from non-defoliated vines while their total anthocyanin concentration was not affected by defoliation at a significant level. Concerning wines, alcohol content, residual soluble solids, different forms of anthocyanins but also volatile acidity were generally higher in samples from defoliated vines. Differences were also highlighted among the defoliation treatments: the best results in terms of dry matter, sugar and alcohol content were observed in the samples submitted to the more severe defoliation as a consequence of the higher light availability and berry temperature. Concerning the concentration of the individual phenolics, significant differences were highlighted for: caffeic and caftaric acids, peonidin- and malvidin-3-p-coumaroylglucoside, which were higher in the E wines; quercetin-3-glucoside, galactoside, and rhamnoside, and procyanidins, which were higher in F wines.

Volatile composition and sensory profile of wines obtained from partially defoliated vines: the case of Nero di Troia wine

The effects of defoliation treatments performed in the bunch-zone on volatile composition and sensory attributes of the corresponding wines were evaluated. Nero di Troia grapes were subjected to four different treatments: no leaf removal (N); leaf removal in the fruit-zone along the east side (at complete veraison) (E); leaf removal in the fruit-zone along the east and west side (at complete veraison) (E/W); almost complete leaf removal along the west side (at complete veraison) and at pre-harvest also along the east side (F). For each defoliation thesis, half of the wine was treated with oak chips in order to verify whether the treatments with oak chips can mask the effects of defoliation. Defoliation partially affected the volatile profiles. Data concerning the volatile profiles show that the highest concentrations of total acids were detected in N and E wines, while those of the total ethyl esters were detected in F wines, and the lowest terpenes concentrations were found in E wines. The oak-treated wines show the highest contents of 1-heptanol, 1-octanol, many ethyl esters, and total hydrocarbons. They were the only in which the whisky lactone was detected. From a sensory point of view, the wines from almost completely defoliated grapes exhibited the lowest scores of gustatory-olfactory intensity, persistence, and quality. The wines that were not treated with chips exhibited sensory profiles characterized by floral and fruity notes, while those treated with oak chips showed sensory profiles characterized by spicy and fruity notes.

Effect of hydrolyzed protein-based mulching coatings on the soil properties and productivity in a tunnel greenhouse crop system

Polymeric protein-based biocomposites were used in this work as water dispersions to generate, in situ, biobased mulching coatings by spray technique, as alternative to low density polyethylene films for soil mulching. At the end of their lifetime, these biodegradable coatings degrade in soil thank to the microbial community that mineralizes them. Protein hydrolysates (PH) were derived from waste products of the leather industry, while poly(ethylene glycol) diglycidyl ether (PEG) and epoxidized soybean oil (ESO) were used to make the biodegradable spray coatings. A study under greenhouse condition was carried out using seedling test plots in order to investigate the performance of the spray coatings and their possible influence on some aspects of leaf growth, functionality and nutritional quality of lettuce (Lactuca sativa L., Mortarella selection Romanella variety Duende) and on soil properties. The biodegradable coatings showed the same good agronomic performances comparable with the ones of a commercial low density polyethylene mulching film, maintaining the mulching effect for the requested cultivation period and ensuring at the same time a similar rate of plant growth and dry matter accumulation. The research showed that 2 months after the tillage carried out at the end of the cultivation the amount of coating residues present in the soil was <5% of the initial weight of the biodegradable coatings. At the end of the field test, the soil mulched with the polyethylene film recorded an electrical conductivity value lower with respect to the soil mulched with the sprayed coatings, which release nutrients in the soil during their decomposition.