Abstract
Wine research in the past years has mainly been focused on laboratory scale due to the possibility of controlling winemaking variables. Conversely, studies on wine quality in relation to the winemaking variables at the winery scale may be able to better account for the actual challenges encountered during wine production. Winemaking problems are recently arising from progressive changes in environmental conditions in relation to the terroir. It is important to realize that each wine region may have specific winemaking protocols and that winemakers often base their decisions on subjective, emotional, and empirical opinions. Due to all the above-mentioned issues, taking the correct decision in winemaking to achieve the desired goals may become even more challenging. Hence, comprehensive analytical and sensory tools could provide substantial support for winemakers to base their decisions on data obtained from validated methodologies throughout the winemaking process.
This report presents an example of a collaboration study on a winery-scale production of Pinot Blanc which has become an important production in South Tyrol (Italy) over the last decades, with its cultivation covering 10.3% of the total vineyards (www.altoadigewines.com). The main objective of the present project is to build a fingerprint database for wine identity (chemical and sensory data of Pinot Blanc in that area) to understand how terroir and winemaking practices are influencing the analytical and sensory/hedonic qualities of this wine, and to provide guidelines to winemakers accordingly to aid their decisions.
The experimental plan for this study included factors such as (I) vineyard location, (II) pre-fermentation freezing of the grapes, and (III) simultaneous alcoholic and malolactic fermentations The samples were analyzed by HPLC-DAD for the determination of the phenolic compounds and by HS-SPME-GCxGC-ToF/MS for determining the volatile profiles. The sensory analysis was performed using Quantitative Descriptive Analysis (QDA ®) (Poggesi et al., 2021). The application of whole grape freezing in pre-processing turned out to be the main differentiating factor of the wines. The results also showed a strong dependence of the measured parameters on the vineyard which could be classified according to significantly different relative abundances of phenolic and volatile compounds. No difference was observed in the phenolic profile as a function of co-inoculation with malolactic bacteria. On the other hand, specific volatile compounds could differentiate samples undergoing simultaneous alcoholic and malolactic fermentation. The chemical results were then integrated with sensory data to create multivariate models, to show how the factors played out on the final quality of the wine obtained. Prospectively, fingerprint databases can be built on these models for authenticity purposes and to assist the winemaker during production.