Abstract
Pulsed electric field (PEF) is a non-thermal technology able to promote color and polyphenols extraction from grape skins. Most of the publications about PEF in winemaking report data concerning international varieties, poorly considering minor cultivars and the medium/long-term effects of the treatment on wine composition during storage. PEF was applied at different specific energies (2, 10, and 20 kJ kg−1) on grapes of the low-color red cv. Rondinella, after crushing-destemming. Pressing yield, the evolution of color, and total phenolic index (TPI) were measured during skin maceration. Moreover, the wines were characterized for basic compositional parameters, color, anthocyanin profile, phenolic composition (glories indices), metal content (Fe, Cr, and Ni), and sensory characters, two and twelve months after the processing, in comparison with untreated samples and pectolytic enzymes (PE). PEF did not affect fermentation evolution, nor did it modify wine basic composition or metal content. Treatments at 10 and 20 kJ kg−1 led to higher color and TPI in wines, in comparison to PE, because of increased content of anthocyanins and tannins. The sensory evaluation confirmed these findings. Modifications remained stable in wines after twelve months. Glories indices and vitisin A content highlighted greater potential stability of wine color in PEF-treated wines.
Highlights
Color is one of the most important attributes for defining red wine quality
These molecules are located in the vacuoles of grape skin cells, and the red-purple or red-orange hue they confer to the wines is due to their nature and concentration and to their transformation during maceration and fermentation, as well as to the reactions they undergo during wine aging [1,2,3]
Aside from the various forms of mechanical intervention, a common technological tool for improving the extraction of color during skin maceration consists of the use of pectolytic enzymes (PE); this practice is able to increase the extraction of phenolic compounds, allowing to reduce contact time and improve wine color intensity and stability [4,5]
Summary
Its intensity and stability are related to phenolic compounds, in particular, anthocyanins These molecules are located in the vacuoles of grape skin cells, and the red-purple or red-orange hue they confer to the wines is due to their nature and concentration and to their transformation during maceration and fermentation, as well as to the reactions (i.e., polymerization, co-pigmentation, and condensation) they undergo during wine aging [1,2,3]. Aside from the various forms of mechanical intervention, a common technological tool for improving the extraction of color during skin maceration consists of the use of pectolytic enzymes (PE); this practice is able to increase the extraction of phenolic compounds, allowing to reduce contact time and improve wine color intensity and stability [4,5]. Pulsed electric field (PEF) is a promising non-classical method, consisting of the application of short pulses (microto milliseconds) of high-voltage electric current (10–80 kV cm−1 ) to solid or liquid food products [6]
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