Packaging
Background
Wines can be placed at risk of oxidative spoilage and premature development through packaging, transport and storage decisions. At present, the wine sector has little in the way of tools to predict shelf life because the factors likely to impact on it are poorly understood or difficult to measure. These research projects aim to develop the tools and collect the data required to assess the relative importance of winemaking practices, packaging choices and transport and storage conditions on oxygen ingress into wines and to link this to wine development in bottles and oxidative spoilage.
Progress
We have undertaken studies to elucidate the relative roles of closure oxygen transfer rate, free SO2 levels at bottling and copper fining before bottling on wine development in the bottle. Two Sauvignon Blanc wines with different levels of volatile thiol compounds were bottled in August 2007. The treatments imposed on the two wines were copper fining (presence or absence), SO2 adjustment (30 and 60 mg/L free SO2) and oxygen transmission rate (OTR) through closures (screw cap, Nomacorc Premium and Nomacorc Light, low to high OTR, respectively). The bottled wines are stored under best practice industry conditions of controlled temperature and humidity.
Several analyses were undertaken after six months of storage. There were only small differences between the treatments. Wine sealed under screw-caps have retained marginally more SO2 and ascorbic acid than those under the Nomacorc closures. There was a trend for the wines sealed with Nomacorc Premiums to contain slightly more SO2 and ascorbate than those under the Nomacorc Lights, as we would expect from knowledge of the OTR, but, data from further time points are needed to confirm this. There were no clear effects of the copper treatment at this stage.
White wine colour was assessed using CIELab. The Sauvignon Blanc wines were very lightly coloured and differences were probably not yet visually detectable. Wines sealed under Nomacorc Light tended to be less green and more yellow than those under Nomacorc Premium; wines under screw-caps were even less yellow than wines under Nomacorc closures. Wines with the higher SO2 addition at bottling were greener and less yellow than those with the lower addition. Again, there were no clear effects of the copper treatment on wine colour at this stage. Informal tasting of the wines after six months of storage confirmed the results of informal tasting after three months; the wines were sound, but differences between the treatments were not clearly evident yet.
Highlights
- Only small differences in wines with different closures six months after bottling
- More SO2 loss under closures with higher oxygen transmission rate
Project leader: Dr Liz Waters
Project team members:
Publications:
731 Skouroumounis, G.K.; Kwiatkowski, M.; Sefton, M.A.; Gawel, R.; Waters, E.J. In situ measurement of white wine absorbance in clear and in coloured bottles using a modified laboratory spectrophotometer. Aust. J. Grape Wine Res. 9(2): 138-148; 2003 (click here to order).
863 Godden, P.; Lattey, K.; Francis, L.; Gishen, M.; Cowey, G.; Holdstock, M.; Robinson, E.; Waters, E.; Skouroumounis, G.; Sefton, M.; Capone, D.; Kwiatkowski, M.; Field, J.; Coulter, A.; D’Costa, N.; Bramley, B. Towards offering wine to the consumer in optimal condition —the wine, the closures and other packaging variables: a review of AWRI research examining the changes that occur in wine after bottling. Aust. N.Z. Wine Ind. J. 20(4): 20–30; 2005 (click here to order).
877 Skouroumounis, G.K.; Kwiatkowski, M.J.; Francis, I.L.; Oakey, H.; Capone, D.L.; Duncan, B.; Sefton, M.A.; Waters, E.J. The impact of closure type and storage conditions on the composition, colour and flavour properties of a Riesling and a wooded Chardonnay wine during five years’ storage. Aust. J. Grape Wine Res. 11: 369–384; 2005 (click here to order).
878 Skouroumounis, G.K.; Kwiatkowski, M.J.; Francis, I.L.; Oakey, H.; Capone, D.L.; Peng, Z.; Duncan, B.; Sefton, M.A.; Waters, E.J. The influence of ascorbic acid on the composition, colour and flavour properties of a Riesling and a wooded Chardonnay wine during five years’ storage. Aust. J. Grape Wine Res. 11: 355–368; 2005 (click here to order).
967 Kwiatkowski, M.; Skoroumounis, G.K.; Lattey, K.A.; Waters, E.J. The impact of closures, including screw cap with three different headspace volumes, on the composition, colour and sensory properties of a Cabernet Sauvignon wine during two years’ storage. Aust. J. Grape Wine Res. 13(2): 81–94; 2007 (click here to order).