Pinot noir Wine Colour and Aroma: Extraction and Stabilisation through the use of Commercial Tannins and Cap Management Regimes

Abstract

Pinot noir is fast becoming an important variety for the New Zealand wine industry, with export volumes increasing every year. The extraction and stabilisation of phenolic compounds in Pinot noir winemaking is a common challenge faced by New Zealand winemakers. In addition to attempting to combat this issue, winemakers are also interested in enhancing the aroma profile of Pinot noir. This research analyses the phenolic and aroma compounds of Pinot noir wines produced from two different vineyards (A and B) and to establish whether cap management techniques coupled with tannin addition aids on influencing these important aspects of the wine. Spectral colour analysis revealed little differences between the different wine treatments. Polyphenols were quantified using HPLC. Gallic acid presented at slightly higher concentrations in Wine B compared to Wine A and levels of catechin and epicatechin varied depending on the cap management regime. Malvidin-3-glucoside concentrations were unexpectedly low in all of these research wines. One-way ANOVA and Tukey HSD were applied to the research wines for analysis of the volatile aroma compounds. A total of 41 aroma compounds were quantified using HS-SPME-GC-MS. Linalool was the most prevalent terpenoid compound in both Wines A and B. Geraniol was present at much higher concentrations in Wine A compared to Wine B, while nerol was present in similar concentrations in the two sets of wines. Nerol content also appeared to decrease with plunging along with methanethiol, ethanethiol and dimethyl sulfide, while 1-hexanol and isoamyl acetate levels increased with plunging. Levels of hexanoic, octanoic and decanoic acids decreased between the cap management techniques that had received tannin addition. Trends observed for ethyl hexanoate and ethyl octanoate were also similar to the trends seen for the fatty acid compounds. PERMANOVA and PCA shows that the variation in the combined data can be largely explained by the factor “vineyard” and there is distinct separation between Wine A and Wine B by PC1. There is partial separation between cap management by PC2, while tannin addition did not display any obvious separation. This work provides a solid foundation for further exploration into the valuable understanding of winemaking techniques for Pinot noir.