1. Monitoring the impact of pectolytic enzymes on autolysis characters in sparkling wine during bottle ageing
Neil Scrimgeour 1, Alana Seabrook 2, Eric Wilkes 1, Wies Cynkar 1, Peter Godden 1, Bob Dambergs 1
1 The Australian Wine Research Institute, PO Box 197, Glen Osmond (Adelaide) SA 5064, Australia
2 The Yalumba Wine Company, PO Box 10, Angaston SA 5353, Australia
Corresponding author’s
Introduction
Sparkling wine is an important, growing, and highly-profitable sector of the Australian wine industry. However, limited research has been conducted into the production of this wine type and the mechanisms by which secondary fermentation and ageing on lees contribute to the final sensory characteristics of the wine.
Commercial enzyme preparations have β-glucanase and pectinase activity and are purported to increase the speed of the ageing process and generate desirable autolysis characters in a shorter timeframe, allowing quicker market access and reducing storage and management resources.
In conjunction with the Yalumba Wine Company, the impact of two commercial pectolytic enzymes on the development of autolysis characters was investigated at different dose levels in a commercial sparkling wine using UV-Vis and mid-IR spectroscopy. The purpose of the trial was to assess whether the addition of commercial enzyme preparations is appropriate and effective for lower-end sparkling products which may not have as much time on lees in bottle as a premium product.
Method
A commercial Pinot Noir/Chardonnay sparkling wine from the Riverland (South Australia) was treated with the two enzymes at 0.5, 1 and 2 g/hL (grams per hectolitre) of Lallazyme MMX (Lallemand) and 1, 2, 4 and 10 g/hL of Levulyse (Institut Oenologique de Champagne (IoC)). A control treatment (no enzyme addition) was also included for comparison. The bottles were capped with crown seals and stored at standard tirage conditions (approximately 20°C).
Chemical analysis was conducted at 0, 2, 3, 6 and 9 month time points by the Yalumba Wine Company, including % alcohol, pH, TA, malic acid, acetic acid, sugar level (glu/fru) and SG. Spectroscopic analysis was also carried out at these time points. Prior to UV/Vis measurements, samples were centrifuged and degassed. Haemocytometer yeast counts were performed to measure yeast cell numbers where applicable.
Informal sensory analysis was carried out by a small panel of Yalumba winemakers at the 3 and 9-month time points. Tasters were asked to rate each wine against a series of aroma and palate attributes on a 0-9 scale.
Results & Conclusions
UV spectra proved to be the most valuable in monitoring the development of the sparkling wines over the nine-month period, with differences due to the two enzyme types and dose level applied being apparent . Key wavelength regions appear to be nm and nm, which likely correspond to the combination of phenolics, peptides and nucleotides found in sparkling wines, along with hydroxycinnamates, which most likely exist as tartrate esters. UV spectra were successfully used to track the development of the wines. The principal component analysis (PCA) plot in Figure 1 shows the relative differences that develop during the first 6-months and the impact of enzyme type and dose level.
Figure 2: Radar plot showing comparison of key sensory attributes against enzyme type and dose level after 9 months in bottle
Sensory assessment of the wines and subsequent chemometric analysis has revealed that the perceived aroma and flavour attributes of the wines are impacted by enzyme type and dose level, with fresh fruit, citrus, honey, aldehyde, creamy, viscosity, fruit length and acidity attributes being the most important (Figure 2). Levulyse treatments were associated with stronger aldehyde, viscosity and creaminess.  The MMX treatments (spectrally) were more similar to the control wine, although the 2g/L dose level was associated with higher biscuit and floral characters (Figure 3).
This study shows the value of using spectral analysis techniques (particularly UV) in monitoring development of autolysis characters in sparkling wine and obtaining a better understanding of influential factors such as pectolytic enzymes.
Figure 1: PCA plot showing development of sparkling wines over first six months’ storage
Figure 3: PCA plot showing correlation of aroma and flavour attributes with enzyme type and dose level