Foliar urea and phenylalanine fertilizers (U and P, respectively), and CK were applied three times during veraison. The influences of foliar nitrogen fertilizers on methoxypyrazines and the correlation between methoxypyrazines and amino acids in Cabernet Sauvignon were studied in nitrogen-deficient soil. These findings provide a basis for selecting the most suitable grape varieties to improve wine quality. Furthermore, correlation analysis showed that there was a statistically positive correlation between the expression levels of VvOMT1 and VvOMT3 and MPs content in grape berries, while the lowest association was found in the VvOMT2. However, 3-sec-butyl-2-methoxypyrazine (SBMP) and IBMP were only detected in six wines, and their levels were higher than those in the grape berries. The relative higher 3-isobutyl-2-methoxypyrazine (IBMP) content was observed in Cabernet Sauvignon, Marselan, Merlot, and Malbec berries. Moreover, 2-methoxypyrazine (MOMP), 3-methyl-2-methoxypyrazine (MEMP) and 3-ethyl-2-methoxypyrazine (ETMP) levels were relatively lower, with almost no detectable in berries at maturity. While the anthocyanin content showed the highest in Marselan berries in 2018, in 2019, Petit Verdot berries had the highest anthocyanin content. The results showed that, at maturity, the highest total soluble solid was observed in Petit Verdot grape berries in the two consecutive years. In this study, the quality and MPs levels of grape berries from six representative red wine grape varieties were determined in the two consecutive years. Methoxypyrazines (MPs) are a unique class of volatile compounds containing nitrogenous heterocyclics that impart green bell, vegetal and herbal odors to red grape berries and wines. Copyright © 2007 by the American Society for Enology and Viticulture. 3-Isopropyl-2-methoxypyrazine evolved differently during grape maturation and was less influenced by harvesting year. Climatic conditions, rather than maturity or terroir, had a critical effect upon IBMP concentration in grapes. The genotype dramatically affected the methoxypyrazine content of Carmenere wines, with some clones containing three-fold more than others. Wines from Carmenere grapes had high 3-isobutyl-2-methoxypyrazine (IBMP) concentrations (5.0 to 44.4 ng/L), much higher than most Cabernet Sauvignon wines. Results indicate that methoxypyrazines are present in high concentrations in this variety, probably responsible for the strong vegetative character found in Carmenere wines. The Carmenere variety produces complex wines, marked with herbaceous and 'green' aromas.

Carmenere, a member of the Cabernet family, was recently rediscovered in Chile where it had been misidentified as Merlot.