Effect of altitude and berry maturity on chemical composition of Lebanese Grenache grapes and wines

The global warming that affects the chemical composition of wine grapes during ripening would lead to an upward shift of the winegrowing regions worldwide. This study aimed to elucidate the influence of altitude and maturity on the chemical composition of Lebanese Grenache grapes and wines. Grenache berries from three vineyards with different altitudes were sampled at three ripeness levels in 2018 and 2019. Laboratory microvinifications were performed and the quality parameters of the resulting wines were determined. The results showed that the grapes and wines at the high sites had higher acidity due to the lower temperature in 2018. But the lower night temperatures in 2019 resulted in increased acidity at the lowest vineyard. Overall, the altitude had a positive effect on the seed phenolics and a negative effect on the skin proanthocyanins. The most prominent factor was the soil in 2018 and the vintage in 2019. In fact, the highest levels of skin phenolics were found in the vineyard with the poorest soil in 2018 and in the vineyards with the highest increase in the diurnal shift, in 2019. The levels of seed phenolics did not vary much over the ripening period. In 2018, the vineyard with the least fertile soil had the highest content of total individual anthocyanin compounds. For the skin phenolics, the maturity effect was more often dependent on the altitude effect. The skin phenolics decreased mostly at the end of ripening at the lowest vineyard due to the hotter weather, and increased mostly at the end of ripening at the highest vineyards due to the cooler weather. The wine produced from the vineyard with the most infertile soil had the highest amount of total volatiles. Altitude had a positive effect on the wine color intensity as it was greater at the highest sites. The wines from the high altitude vineyards had their aroma compounds more diversified since they had a higher number of volatile compounds with greater levels than those in the lowest vineyard.