IVAS 2022 banner
IVES 9 IVES Conference Series 9 IVAS 9 IVAS 2022 9 Influence of Potential Alcohol and pH Adjustment on Polyphenols and Sensory Characteristics of Red Wines Produced at Different Harvest Time Points

Influence of Potential Alcohol and pH Adjustment on Polyphenols and Sensory Characteristics of Red Wines Produced at Different Harvest Time Points


Wine quality is influenced by grape maturity, typically monitored by measuring sugar content and acidity. However, environmental factors such as extreme weather or fungal infections can force winemakers to harvest earlier than desired. This study investigated whether sugar and pH adjustment used to increase potential alcohol and reduce the perception of acidity, can also compensate for immaturity in terms of phenolic extractability, composition, and related sensory attributes. Since anthocyanin and sugar accumulation profiles do not necessarily run parallel during grape ripening, it was important to study several harvest time points.
Wines were made from Pinot noir and Cabernet Sauvignon grapes harvested in 2019 at three different stages of grape maturity, in the range of 18-24 Brix. After bottling, phenolic analysis (HPLC-DAD/FD, LC-QToF-MS and spectrophotometry) and sensory evaluation revealed that adjustment of early-harvest must to pH 3.3 and 24.5 Brix enhanced the extraction of seed-associated phenolics such as monomeric catechins, and resulted in higher ratings of a green, herbaceous and ethereal aroma, rough astringency and a harsh mouthfeel. Adjustment did not significantly increase concentrations of skin-associated phenolics such as anthocyanins and polymeric pigments, and could therefore not compensate for a lack of color intensity. Wines made from the late-harvest grapes had significantly higher concentrations of anthocyanins and polymeric pigments and lower concentrations of monomeric catechins and procyanidins. This resulted in wines with a full body and high ratings in color intensity, dark fruit aroma, and smooth astringency. The data suggests that anthocyanins and polymeric pigments can be used as markers for grape maturity. Potential alcohol and pH adjustment could not change the phenolic composition and sensory perception of an early-harvest wine to mimic those of a late-harvest wine.


Publication date: June 24, 2022

Issue: IVAS 2022

Type: Article


Feifel Sandra1, Weilack Ingrid2, Wegmann-Herr Pascal3, Weber Fabian2 and Durner Dominik1

1Weincampus Neustadt, Institute for Viticulture and Oenology, Dienstleistungszentrum Ländlicher Raum (DLR) Rheinpfalz, Breitenweg 71, 67435 Neustadt an der Weinstraße, Germany
2University of Bonn (Germany)
3Institute for Viticulture and Oenology, Dienstleistungszentrum Ländlicher Raum (DLR) Rheinpfalz, Breitenweg 71, 67435 Neustadt an der Weinstraße, Germany

Contact the author


List of different keywords (keyword1, keyword2, keyword3)


IVAS 2022 | IVES Conference Series


Related articles…

Anthropogenic intervention in shaping Terroir in a California Pinot noir vineyard

In many vineyards optimal parcel size exceeds the geospatial complexity that exists in soils and topographic features that influence hydrological properties, sunlight interception and soil depth and texture (available water capacity).

Enhancing table grape production: addressing challenges and opportunities for sustainability and quality improvement

Table grapes, being consumed as fresh, raisins, and transformed products are among the most appreciated fruits worldwide. Its popularity is increasing also due to its organoleptic and nutritional qualities that meet the consumers’ interest in healthier foods. Recent data from International Organization of Vine and Wine (OIV) revealed that table grape production has doubled in the last twenty years, and varietal availability has increased thanks to the several breeding programs.
To maintain the socio-economic impact of this sector, new challenges need to be addressed.

Agroclimatic characterization of Monreale DOC appellation for vine growing

This paper presents the results of an agroclimatic study of the viticulture area called DOC Monreale (Pa), Italy, which was carried out with the aim to supply a working instrument supporting viticulture planning.

Effect of the commercial inoculum of arbuscular mycorrhiza in the establishment of a commercial vineyard of the cultivar “Manto negro

The favorable effect of symbiosis with arbuscular mycorrhizal fungi (AMF) has been known and studied since the 60s. Nowadays, many companies took the chance to start promoting and selling commercial inoculants of AMF, in order to be used as biofertilizers and encourage sustainable biological agriculture. However, the positive effect of these commercial biofertilizers on plant growth is not always demonstrated, especially under field conditions. In this study, we used a commercial inoculum on newly planted grapevines of a local cultivar grafted on a common rootstock R110. We followed the physiological status of vines, growth and productivity and functional biodiversity of soil bacteria during the first and second years of 20 inoculated with commercial inoculum bases on Rhizophagus irregularis and Funeliformis mosseaeAMF at field planting time and 20 non-inoculated control plants. All the parameters measured showed a neutral to negative effect on plant growth and production. The inoculated plants always presented lower values of photosynthesis, growth and grape production, although in some cases the differences did not reach statistical significance. On the contrary, the inoculation supposed an increase of the bacterial functional diversity, although the differences were not statistically significant either. Several studies show that the effect of inoculation with AMF is context-dependent. The non-favorable effects are probably due to inoculation ineffectiveness under complex field conditions and/or that, under certain conditions, AMF presence may be a parasitic association. This puts into question the effectiveness of its application in the field. Therefore, it is recommended to only resort to this type of biofertilizer when the cultivation conditions require it (e.g., very low previous microbial diversity, foreseeable stress due to drought, salinity, or lack of nutrients) and not as a general fertilization practice.

Can soil water content be used as a predictor of predawn leaf water potential for deficit irrigation scheduling? A case study at Alentejo wine region

Water and heat stress impose new challenges to irrigation management in the Mediterranean areas. This reality has a major impact on the vineyard ecosystem, particularly on the scarce water resources of the Alentejo region (South Portugal). To mitigate this problem, irrigation management should focus on optimizing yield and fruit quality per volume of water applied. This work aims to discuss the use of predawn leaf water potential and soil water status relationships as a decision tool for irrigation management taking as basis data from a field trial where two deficit irrigation strategies were compared.