A Wine Australia-funded study that found that carrageenan derived from red edible seaweed is a viable alternative to bentonite to heat stabilise white wine has won its lead author the prestigious ASVO award for Oenology Paper of the Year 2020.
Dr Vanessa Stockdale’s study is a potential gamechanger for two reasons: firstly, unlike bentonite, carrageenans don’t strip flavours from wine – even when added in large doses. In fact, sensory analysis indicated that wines heat-stabilised with carrageenans had more intense flavour and aroma profile than those heat-stabilised with bentonite.
Secondly, carrageenan is derived from red edible seaweed, is renewable and can be farmed as a carbon negative crop. In contrast, bentonite is a clay that is generally mined from aged volcanic ash deposits.
Vanessa’s study looked at a wide range of wine processing parameters to determine if carrageenan – a polysaccharide, was a possible alternative to bentonite to heat stabilise white wine.
‘There are different types of commercially available carrageenan and our study found that those most effective for heat stabilising white wines were kappa carrageenan’s with K+ ions. This is because of their ability to heat stabilise wines with a minimal impact on sensory profiles, wine lees, turbidity, filtration and concentration of metal cations’, said Vanessa, a Wine Technical Improvement Specialist with Accolade Wines.
Importantly, the study also found that carrageenan could be added at different stages of the winemaking process – including to juice, ferment or wine – and still resulted in a stable wine.
‘This provides the ability to add carrageenan prior to innate clarification steps, thereby streamlining the winemaking process’, Vanessa said.
However, to avoid wine filtration problems, she said juice needed to be pectin-negative when using carrageenan.
Vanessa said proof of concept trials had now been performed on a commercial scale, with success in efficacy and sensory. However, larger commercial scale trials were required to focus on how best to mix and add carrageenan to the tank.
‘It’s a little hard to mix carrageenan in standard winery mixing tubs, however, many wineries are moving towards powder blending pumps which I think would be more suitable’, she said.
Vanessa said the ASVO award meant a lot to her.
‘I’ve been a big fan of this award and also an enthusiast of both basic research as well as practitioner-type wine research. It makes our sector diverse and rich. My role in wineries has always been to implement new technologies. I love the challenge to take a new idea from concept right through to something that ticks all of the boxes and is accepted at the coal face.
‘With this project, I’m proud of the opportunity to be able to do this to the standard of peer reviewed research and publication in an esteemed scientific journal. I’ve hung my award above my desk in the winery so that I’m regularly reminded of this achievement! It’s very motivating.’
The study is entitled:Ratnayake, S., Stockdale, V., Grafton, S., Munro, P., Robinson, A., Pearson, W., McRae, J. and Bacic, A. (2019), Carrageenans as heat stabilisers of white wine. Australian Journal of Grape and Wine Research, 25: 439-450. https://onlinelibrary.wiley.com/doi/full/10.1111/ajgw.12411