Increase of the heat stability of white wine by Surface Engineered Silica (SES)
Abstract
Current oenological control of haze forming proteins in white wine is achieved through adsorption of wine proteins onto bentonite which, however, has adverse economic and ecological effects and can negatively affect the quality of the treated wine. In this study Surface Engineered Silica (SES) was used to increase the heat stability of white wine.
Summary
In this study Surface Engineered Silica (SES) developed by the CI Peter Majewski was used to increase the heat stability of white wine. The removal of haze forming proteins was tested using Sauvignon Blanc and Riesling wine vintage 2010 donated by Orlando Wines. The treated wines were analysed with respect to their heat stability and additional characteristics in order to assess the effect of SES on the treated wine.
The tests were performed in batches of 0.75 L and different doses of SES per litre wine. The results clearly show that the heat stability of white wine can be increased up to the required level. The analyses also show that other characteristics of the treated wines were not or only very slightly affected. In most cases a very small decrease of the free sulphur content, total phenolics, and flavonoid extract was observed.
The heat stability tests indicated that SES doses of about 10 to 20 g/L achieve a net turbidity of below 1 NTU after a heat test in static batch treatments.
Riesling wine was also fined in a flow through filter set-up. The filter consisted of a filter cartridge filled with SES which was placed in a filter cartridge holder. The achieved net turbidity was 1.9 NTU after a heat test indicating that lower flow rates at a given dose of SES in the filter would be necessary to achieve NTU levels of below 1 after a heat test.
Riesling and Sauvignon Blanc wines were batch treated with SES and used for the sensory trial against the same wines after bentonite treatment performed at the Australian Wine Research Institute. The heat stability of the wines was analysed to be below 1 NTU after a heat test and the results of the sensory trial was considered as inconclusive showing that SES treatment has no negative affect on the sensory characteristics of the treated wine.
An assessment of the costs of bentonite fining for Australia’s wine industry shows that bentonite fining results in losses of about $ 60 M per year (about $ 0.1 per litre wine) considering export prices for white wine of $ 3/L. In order to have a net gain out of using SES for wine fining, the cost of SES should not exceed about $ 10/kg which is difficult to achieve at the current costs for the chemicals needed for the manufacturing of SES.