Controlled release of Pinot noir phenolics by microwave
Carew, ALJ and Godden, P and Close, DC and Connew, S, Controlled release of Pinot noir phenolics by microwave, Australian and New Zealand Grapegrower and Winemaker Magazine, Winetitles, Australia (2013) [Magazine Article]
Controlled release of Pinot noir phenolics by microwave. In a quiet laboratory, in a sleepy suburb, in Australia's smallest State, scientists are working on a hot new idea for red wine making called ‘Controlled Phenolic Release’, which is based on microwaving grape must. Researchers at the Tasmanian Institute of Agriculture (TIA) have been investigating the effect that microwaving Pinot noir must has on wine phenolics. The TIA team found that this unconventional approach produced Pinot noir wines with richer colour and a higher tannin concentration, compared with wines made using a standard submerged cap fermentation process. Dr Anna Carew, principal investigator on the microwave project, says the research is in its early stages but shows promise on a few different fronts ‘early on we were really excited by the difference in tannin concentration between the control and microwave treatment wines. The microwave wines were around three times higher in tannin and had double the anthocyanin concentration of the control. We’re still really pleased about the good phenolic outcomes but there also appear to be some important potential savings in fermentation time and tank space from this approach. Lately, we’ve been adjusting process parameters and we’ve worked out how to ‘dial up’ a desired tannin concentration in Pinot noir grape musts. Obviously tannin concentration is limited by what tannin is available in the fruit, but it would be nice to deliver wine makers just that little bit more control over such an important wine parameter as tannin concentration. There are still plenty of questions that need answers - we need to sort out how our ‘dial up’ must tannin translates into wine tannin concentration, and also to work with wine makers to find out how much tannin they would really like to see in their Pinot noir wines and whether they like the mouth feel qualities of the tannin profile we can create.’ The microwave wine making to-date has been done at a very small scale, with most trials producing around 1.5L of wine. This means that only a select few have tasted the wines. The Australian Wine Research Institute (AWRI) has actively supported TIA's microwave research and AWRI's Group Manager of Industry Applications and experienced wine show judge, Mr Peter Godden was one of the first to put his tastebuds on the line and provide feedback on Pinot noir wines made using the microwave maceration method, ‘this research had always been particularly interesting’, Godden said, ‘but seeing what had previously been numbers on a page relating to the chemical analysis of the wines, translate to the actual wine in the glass was very exciting. The difference between the microwave-treated wine and wine made from the same fruit without microwave treatment was very obvious. The microwaved wine was darker in colour, had a more pronounced varietal fruit nose, and in the mouth it was plush and soft with lovely mouth-coating tannins’. The AWRI’s involvement with TIA’s wine research is funded through the Grape and Wine Research and Development Corporation (GWRDC) and so the research needs to have significance beyond Tasmania and beyond Pinot noir. Mr Godden explained that TIA took the microwave method to the AWRI’s Hunter Valley node during 2013 vintage to examine the effect of microwave maceration on Shiraz. TIA set up a ‘mobile laboratory’ in the corner of De Iuliis Winery at Pokolbin and learned some valuable lessons about the differences between laboratory and ‘real world’ winemaking. Ms Sam Connew, AWRI Hunter Valley Node Manager, said ‘the trial was a great learning experience for all parties involved and a perfect example of the value of doing research outside of the laboratory’. Dr Carew reports that the TIA team worked hard to generate 'proof of concept' that microwave could reliably produce a better quality of wine than standard methods. ‘We really needed to keep our heads down and run lots of trials before sharing what we’ve been up to with industry and other scientists. We are now at the stage of scaling-up the process to semi-commercial. Its taken three years of small-lot wine making just to be sure that we can reliably make good wine and to make all the mistakes we need to so we know where the pitfalls are with this new process. Its also been important to understand how microwaving impacts on the physical structure of the grape. We were lucky to find a terrific histologist who thin sectioned and stained our microwaved grape skin so we could compare it with grape skins that hadn't been microwaved. You could see that microwave had penetrated the grape skin cells and compromised the membranes inside the grape. That seems to be why microwave is releasing colour compounds and tannins so rapidly.' If the TIA group are successful in attracting funding for more microwave maceration research, 2014 will be an exciting vintage for Dr Carew and the wine makers who have volunteered to join semi-commercial trials. ‘We held a tasting in the Yarra Valley and two of the winemakers there volunteered on the spot. I guess they felt the wines we presented had something worth pursuing. We’ve had great interest from Victorian wine makers and so far, five have volunteered to join for next year. The next stage of the research has to be in Victoria because the CSIRO have a commercial-sized microwave unit which they’ve offered us the use of’, said Dr Carew. ‘We have some data that suggests one of our microwave maceration methods may generate intensely fruity, floral aromas in wine. We’d like to investigate that further because if we understand why those wines are so pretty, we might be able to better control that aspect of wines. Switch it up or down a little, depending on the style wine makers and consumers are looking for’. Deputy Director of TIA, Dr Dugald Close, says that prospects are bright for the microwave maceration method and that TIA may deliver more new methods in coming years. ‘One of our researchers, Mrs Angela Sparrow, has taken a new rapid extraction method to semi-commercial trials and early indications are that wine makers are impressed by the tannin structure and mouth feel qualities of wines made using her berry pricking method’. For a small research group, in a small town, the TIA team are working hard to make a big difference to the quality of Pinot noir. It may take a few more years, but new methods like microwave maceration and berry pricking may one day fundamentally alter Australia’s red wine making landscape.