Influence of summer management practices and date of harvesting on organic acids concentration and sugar concentration in grapes of Vitis vinifera L., cv. Riesling

Abstract

The impact of summer canopy management was investigated in Vitis vinifera L., cv. Riesling. Sugar and organic acid concentrations were measured for the six defoliation treatments. Titratable acidity (TA) was measured twice before harvest and once at the date of harvest. The same measurements were done twice during wine ageing. The young wine was measured for concentrations of malic, tartaric and volatile acids. Treatments with appropriate defoliation, where shortened lateral shoots (up to two leaves) were retained, supported the process of wine grape ripening to the greatest extend in the cool climate of the Czech Republic, while treatments with almost no defoliation yielded the worst results. The TA decreased during fruit ripening after veraison and continued to decrease during wine maturation. The tendency of decreasing with time was shown for the malic to tartaric acid ratio as well. Concentrations of volatile acids were sufficiently low in each of the treatments.

The effect of rootstocks on the growth, yield and fruit quality of hybrid grape varieties in cold climate condition

“…The total soluble solid (TSS), organic titratable acid (TA) contents and the pH value of the grape must are the most important indicators of the grapevine fruit maturity and harvest date. The values depend primarily on two variables: the climatic conditions between the flowering and harvest and also on the fruit to leaf ratio of the plants (Duchêne 2016;Lampíř, Žaloudek 2018).…”

Дестабилизация Вин. Кристаллообразование Калиевых Солей

“…снижение концентрации винной кислоты в молодых необработанных виноматериалах происходит за счет процессов образования и выпадения в осадок ее нерастворимых солей. такая кристаллическая самостабилизация приводит к изменению концентрации тартратионов -за два месяца отмечается снижение значений с 4,0-5,3 г/л до 3,5-4,0 г/л [14].…”

“…согласно закону действия масс, чем выше концентрация участников химического процесса или одного из них, тем выше скорость реакции [29] и тем активнее происходит образование нерастворимых соединений и выпадение осадка. Это касается как чистых растворов [29], так и вин [14], которые можно рассматривать как растворы, пересыщенные битартратом калия. теоретически 1 г винной кислоты может взаимодействовать с 0,26 г калия с образованием 1,26 г битартрата калия [30], который обладает растворимостью в водном растворе 5,4 г/л (при 20 ºс) [8].…”