Senior Research Scientist

Agnieszka will be speaking in Session 5. Fresh Science A. Click here to see more. 

Abstract

Tartrate stabilisation of wines continues to be a necessary step in commercial wine production. The conventional refrigeration method for preventing potassium bitartrate (KHT) crystallisation is time-consuming and energy-intensive and involves a filtration step to remove the sediment. However, it is still the most economical stabilisation option compared to other technical solutions such as reverse osmosis, electrodialysis, or ion exchange.

The objective of this study was to develop alternative cold stabilisation strategies. For this purpose, natural zeolites and plasma polymerized surfaces were used for the first time.

It was found that natural zeolites brought cold-unstable white wines to, or very close to, cold stability, as measured using the mini-contact test. Zeolite addition achieved this effect by reducing potassium content and initiating crystallization. Since zeolite also removes protein, the results demonstrated the potential for zeolites to induce both heat- and cold-stability in a single treatment.

Another novel approach was developed using plasma-modified surfaces with different surface functional groups. To test the efficiency of different functional groups for KHT crystal adsorption, surfaces were placed into cold-unstable wines at 15oC for different time periods, and cold stability was measured. These experiments revealed that the surface functional groups of plasma polymers induced significant differences in KHT adsorption. Some modified surfaces were effective, while others were less successful in their KHT binding capacity. The results indicate the potential for cold stabilisation to be induced at higher temperatures, reducing the need for cooling facilities.

Biography

Dr Agnieszka Mierczynska-Vasilev is a physical chemist specialising in colloid and interface science which she now applies to solve problems associated with improving wine quality. She has 15 years of experience working on industry-sponsored research projects. At the AWRI, her work is dedicated to understanding the complex interactions between colloids in wine, how this knowledge can be applied to improve the quality of wines, and how to use novel science to solve problems in the wine industry (e.g., protein and tartrate instability, fouling phenomena and taint/off-odour removal). She is expanding knowledge and generating innovative technologies capable of paradigm shift and innovation in the wine industry and research. As an example, she has developed a novel magnetic separation technology that allows to selectively remove pathogenesis-related proteins from white wines.