Prediction of Acid Concentration in Wine and Table Grape Berries from Air Temperature

Abstract

To develop equations to predict the titratable acidity of grape berries at harvest from air temperature, we analyzed several years of datasets on wine grapes grown in experimental vineyards in seven prefectures and of table grapes grown in 37 prefectures in Japan. Although the number of days from the full-flowering date to harvest date varied with the cultivar, the temperature throughout the period of 40 to 50 days before the harvest date was the most strongly correlated with the titratable acidity of all tested cultivars. The titratable acidity at the harvest date of the wine grape cultivars decreased as the mean temperature of the period increased as did that of the table grape cultivars, although the latter did not decrease much above 24°C. The titratable acidity of the wine grape cultivars showed good linear regression with the mean temperature from 60 to 99 DAF (days after full-flowering) in 'Chardonnay', from 65 to 109 DAF in 'Monde Briller', and from 35 to 84 DAF in 'Colline Verte'. That of table grape cultivars grown in cold regions showed good quadratic regression with the mean temperature from 50 to 92 DAF in 'Kyoho', from 46 to 91 DAF in 'Pione', and from 52 to 93 DAF in 'Suzuka'. The titratable acidity of table grape cultivars grown in warm regions was estimated to be about 0.5 g/100 mL. These regression equations can be used to select cultivars to plant and to identify suitable regions for each cultivar, as well as to estimate changes in acid concentration under global warming. We also determined the relationship between the rate of acid reduction of the wine grape cultivars and temperature from serial measurements of titratable acidity to allow growers to predict the change in titratable acidity.

Projected effects of climate change on Tempranillo and Chardonnay varieties in La Mancha Designation of Origin

“…For Chardonnay, the decrease in titratable acidity was also related to Tmax in the same period and it could decrease 0.17 gL −1 for an increase of 1°C of Tmax, while malic acid could decrease 0.16 gL −1 , for an increase of 1°C of Tmax in the BL-V period. The results agree with those of Sugiura et al (2020), who related acidity to temperatures in sensitive periods after flowering, and in particular with the increase that malic acid usually takes place just…”

Macabeo (Viura) grape response to climate variability in areas located at different elevations in the Rioja Designation of Origin

“…2009, 2011, 2012 or 2017). The results are in accordance with that observed in recent decades in other areas and for other varieties, 14,39‐41 which has been associated with an increase in temperature and with differing water stress. In addition, the time at which this increase in temperature occurs may be relevant.…”

“…6). Sugiura et al 41 suggested that the temperature recorded in the 40–50 days before harvest date had a great influence on titratable acidity, and they found that for Chardonnay the mean temperature from 60 to 99 days after full flowering had the strongest influence. However, for the analysed variety the effect of temperature seemed to be more relevant during ripening and higher for the warmest area, where the effect of variations in maximum and minimum temperatures could also affect the final acidity values.…”

Spatial and temporal variability of cv. Tempranillo response within the Toro DO (Spain) and projected changes under climate change

“…It is known that grapes grown in warmer climates have lower acidity than grapes grown in cooler climates and that grape acidity decreases with increasing temperatures. In this respect, Sugiura et al (2020) found that titratable acidity at harvest decreased when the temperatures of the previous period (40-50 days before to harvest) increased. Vršič et al (2014) also found strong correlations between changes in temperature and fruit composition indicating trends toward higher sugar levels and lower titratable acidity with the increasing temperatures.…”