An inexpensive and simple process for producing sparkling wine using a magnetic separation method reduces the time and energy traditionally required to make champagne and other sparking white wines using the méthode champenoise, according to the research team that invented the new method in Ljubljana, Slovenia.
Magnetic separation is enabled by using magnetically responsive yeast cells obtained by adsorption of superparamagnetic, iron-oxide maghemite nanoparticles onto the surfaces of the yeast cells. Those absorbed magnetic nanoparticles speed up the metabolic activity of the wine yeast by “fastening the fermentation process kinetics but not changing the final wine composition,” the researchers say.
This new separation method uses magnets and reduces the waste yeast separation remuage—or riddling—time to 15 to 20 minutes, much faster than the classic method that requires about 60 days of manual rotation and elevation of each bottle, the researchers say. The method results in a product with iron concentration of 8.30 ±0.16 mg/L Fe3+, which falls within the 10.00 mg/L Fe3+ range permitted by the European Union for white wine. That contrasts with the iron content in the control sparkling wine used in the research, which was 0.35 ±0.04 mg/L Fe3+.
The iron-oxide nanoparticles “are inexpensive and their synthesis is relatively simple. … They are considered to be non-toxic and were even approved for in vivo medical applications by the [FDA],” according to the research published recently in Biochemical Engineering Journal.
Professors Marin Berovic, University of Ljubljana Department of Chemical, Biochemical and Environmental Engineering, and Darko Makovec, Department for Materials Synthesis at Jožef Stefan Institute, and their teams invented the method. Dr. Berovic says that no potential problems related to food safety have been identified with this new method and that “chemical and sensorial analysis have shown no practical differences in the taste of the final product.” According to Dr. Berovic, “the great advantage of the magnetized yeast is that it is possible…to magnetize any wine yeast inoculums used in sparkling wine production.”
Chemical analysis found that, in addition to faster microbial kinetics, there were no negative influences on the cell metabolism. The color intensity and color depth in visual tests were identical in the wine produced by both the new and traditional methods, with the some flavors “slightly more expressed” with the new technique. Dr. Berovic says that the method could also be used by the fruit juice and milk industry, as well as in beer production.
Looking for more info on wine production? Take a read about Wine Quality and Safety 101 in our August/September Food Quality & Safety issue.