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Influence of yield and maturation index on polysaccharides and other compounds of grape juice

Riu-Aumatell, M., Lopez-Barajas, M., Lopez-Tamames, E., Buxaderas, S.
Journal of agricultural and food chemistry 2002 v.50 no.16 pp. 4604-4607
grape juice, polysaccharides, grapes, crop yield, Vitis vinifera, plant proteins, winemaking
Wine producers may attempt to increase vine productivity, which usually decreases the quality. The quality of Cava (Spanish sparkling wine; Certified Brand of Origin in Spain) mainly depends on the composition of its colloids, which also determine foam quality. The yield (kg of grape/ha) and maturation index (ratio between soluble solids and titratable acidity) are two external factors that may alter grape characteristics, especially its composition. Twenty white grapes of the same variety (Parellada), but different yields (between 6000 and 17 000 kg/ha) were studied. By PCA, two grape groups were separated according to yield (<10500 and >10500 kg/ha). Yield and maturation index were not significantly correlated. Grapes obtained with yield >10500 kg/ha had significantly higher content of soluble proteins and lower content of total polysaccharides and some polysaccharides fractions (M(r) 62000-48000, M(r) 28 000-24 000, and M(r) 7000-5000) than the grapes of the low-yield group (<10500 kg/ha). Thus, it may be interesting to monitor yield, below 10500 kg/ha, in vines used to produce Cava.