Phenolic profile of fungus-resistant varieties (PIWIs) for red wine production

Abstract

Context and Purpose of the Study. PIWI grape varieties (Pilzwiderstandsfähig, fungus-resistant) offer innovative solutions for sustainable viticulture by addressing environmental challenges faced by traditional Vitis vinifera. Resistant or tolerant to fungal diseases such as downy and powdery mildew, growing PIWIs enable the reduction of chemical treatments by ca. 60-80%, lowering costs and labor while promoting eco-friendly vineyard management and economic efficiency. Despite their potential, PIWIs are underexplored regarding their oenological traits, which differ in some characteristics from traditional varieties. This study aimed to evaluate the phenolic profiles of German-bred PIWIs for red wine production, focusing on their potential for sustainable winemaking.

Materials and Methods. Over three vintages (2022–2024), twelve PIWI red varieties (Accent, Baron, Cabertin, Cabernet Cortis, Cabernet Cantor, Levitage, Monarch, Pinotin, Prior, Regent, Rondo, Satin Noir) and four traditional varieties (Bl. Trollinger, Bl Limberger, Pinot noir, Cabernet-Sauvignon) were analysed at the LVWO Weinsberg (Germany). Grapes, harvested at technological ripeness, were analyzed for juice parameters using FTIR spectrophotometry. Micro-scale fermentations enabled the three field replicates to be separately fermented, and wine phenolic composition was determined using the Harbertson-Adams assay.

Results. Significant differences were observed in the phenolic profiles of PIWI wines. Tannin concentrations were up to three times higher in Cabernet Cortis and Rondo wines, with Monarch and Accent showing doubled levels compared to Pinot noir and Bl. Limberger. Conversely, Pinotin, Prior, and Levitage had significant lower tannin concentrations comparable to Bl. Trollinger. Anthocyanin levels in PIWIs wines exceeded those of traditional varieties, ranging from 500 mg/L to 3000 mg/L, with Rondo and Accent showing the highest values. Differences in polymeric pigment content among PIWIs indicated varying color stability abilities. Multivariate analysis of phenolic profiles grouped the varieties into four distinct clusters, reflecting their diversity and oenological potential.

Conclusion. Evaluating the phenolic profiles of PIWIs is essential to understanding their potential for red wine production and optimizing winemaking strategies according to tannin and color extraction potential. These findings provide a foundation for integrating PIWIs into sustainable winemaking practices, supporting both environmental and quality goals.