Evaluation of the polyphenols potential from grape vinification residues of Rara Neagră and Malbec grapes varieties harvested from Purcari area
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2023-09-08 18:32
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663.26.03 (1)
Vin. Producerea vinului. Oenologie (442)
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SCUTARU, Iury, CODREAN (SCLIFOS), Aliona, DRUŢĂ, Vadim. Evaluation of the polyphenols potential from grape vinification residues of Rara Neagră and Malbec grapes varieties harvested from Purcari area. In: Ecological and environmental chemistry : - 2022, Ed. 7, 3-4 martie 2022, Chișinău. Chisinau: Centrul Editorial-Poligrafic al USM, 2022, Ediția 7, Vol.1, pp. 152-153. ISBN 978-9975-159-07-4.. 10.19261/eec.2022.v1
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Ecological and environmental chemistry
Ediția 7, Vol.1, 2022
Conferința "Ecological and environmental chemistry 2022"
7, Chișinău, Moldova, 3-4 martie 2022

Evaluation of the polyphenols potential from grape vinification residues of Rara Neagră and Malbec grapes varieties harvested from Purcari area

CZU: 663.26.03

Pag. 152-153

Scutaru Iury, Codrean (Sclifos) Aliona, Druţă Vadim
 
Technical University of Moldova
 
 
Disponibil în IBN: 16 martie 2022


Rezumat

Red grape grapes are an important source of phenolic compounds, which possess important physiological properties. As a result of processing, a certain share of polyphenols passes into wine and contributes essentially to the formation of its structure, physico-chemical, microbiological and organoleptic properties. However, a considerable part of them remain in the pomace, and the transfer rate depends on the ripening state of the grapes and the technological processes applied. In this study, different important groups of polyphenols were determined in the wines and pomace resulting from the Rara Neagră and Malbec grapes. The extraction of the active components was performed using two solvents: hydro-acetonic, with the addition of HCl for acidification (S1, acetone-water-HCl conc. 80:20:1, v/v/v), and hydro-ethanolic (S2, 12% ethanol (v/v)), acidified with tartaric acid (5 g/l). The first solvent with lower polarity is preferred for the extraction of less polar organic compounds and is used to determine the quantitative potential of grapes skin and seeds, the second being a benchmark of the qualitative and quantitative composition of the polyphenolic complex, which actually passes into wines under conditions of alcoholic fermentation. For both Rara Neagră and Malbec, the extractable contents of phenolic substances and anthocyanins are influenced by the harvest season, by the drying temperature of the pomace and by the extractant used. Total phenolic substances reach the maximum level for extracts in solvent S2 from Malbec skin dried at 40oC, while pigments predominate in Malbec extracts dried at 105oC. The higher temperature causes an essential degradation of the polyphenolic complex: 2.3 times in Malbec and about 3.3 times in Rara Neagră. The decrease for natural pigments is inhomogeneous: for Malbec the maximum value is reached in the case of grape skins dried at 105oC, and is 1.4 times higher than for 40 oC, while in Rara Neagră the situation is reversed – if drying is done at 40oC their content is 1.6 times higher than at 105oC. In solvent S1, the extraction of polyphenols from the grape skins treated at 105oC is favored for Rara Neagră. The content of similar products extracted from Malbec is slightly higher in samples dried at 40oC. The trend is also observed for Malbec pigments – at 105oC their content is 2.2 times higher than at 40 oC. Although to a lesser extent (just 1.2 times), this order is similar for Rara Neagră. Both the drying temperature and the solvent influence the extraction of polyphenols from seeds. The total content of phenolic compounds extracted in both S1 and S2 is maximal in the case of Rara Neagră seeds, harvested late and dried at 40 oC. On the contrary, for Malbec the high drying temperature of the seeds contributes to the higher extraction of polyphenols in both S1 and S2, the effect being considerable (1.6-2.3 times). It has been shown that actual industrial technologies of wines production from Rara Neagră and Malbec grapes have contributed to the extraction of only about 10-18% of the polyphenols. The predominant amount of phenolic compounds with important biological and nutritional value is still concentrated in pomace, which should be treated accordingly for the extraction of the desired bioactive substances.