Issue link: http://read.dmtmag.com/i/369547
w w w. v w m m e d i a . c o m S e p t - O c t 2 014 | V I N E YA R D & W I N E RY M A N A G E M E N T 4 9 further reducing the time required for riddling – specifically, by modi- fying the forms of yeast inoculum used in secondary fermentation. Researchers began experimenting with modifying wine yeast in the 1980s, and current research has produced several forms of yeast that have reduced the mechanized riddling process from days to hours to minutes. YEAST NANOTECHNOLOGY A team of biochemists at the University of Ljubljana in Slovenia, working in conjunction with a nano- technology researcher at the Jožef Stefan Institute, have introduced a riddling technique that uses mag- netic nanoparticles and a mag- net to riddle a bottle of sparkling wine in approximately 15 minutes. The process was first introduced in 2011 by Ljubljana professors Dr. Marin Berovic, who is also a biochemical engineer, and nano- technology researcher Dr. Darko Makovec. Their technique won an award in 2011 at the International Technology Transfer Conference in Ljubljana and has since been pub- lished in the March 2014 edition of the Biochemical Engineering Journal. ronmental Engineering at the Uni- versity of Ljubljana, along with Makovec, who heads the Depart- ment for Materials Synthesis at the Jožef Stefan Institute. Togeth- er they developed an elegant and inexpensive method of bonding silica-coated nanoparticles of iron oxide to yeast cells (a mass ratio of 1:10), then using a strong per- m a n e n t m a g n e t t o d e p o s i t a s sediment the spent magnetized yeast cells. "The method itself is 4,000 times faster than classical hand remuage," explained Berovic, who is currently a visiting professor at the Univer- sity of Santiago in Chile. "Given the investment and energy require- ments of gyropalettes, sparkling wine producers in Spain, Chile and Argentina are expressing a great deal of interest in the technology." Potential uses for magnetized yeast nanotechnology extend well beyond sparkling wine produc - Berovic's team includes Mat- jaz Berlot and Slavko Kralj, faculty members of the Department of Chemical, Biochemical and Envi- Nanotechnology researcher Dr. Darko Makovec heads the Department for Materials Synthesis at the Jožef Stefan Institute in Ljubljana, Slovenia. + Different forms of yeast inoculum have reduced riddling time for sparkling wines from days to hours to minutes. + Magnetic riddling technol- ogy would eliminate the need for gyropalettes. + In a blind trial, magne- tized-yeast fermentation increased the intensity of aromatic compounds and mouthfeel. + It also resulted in higher- than-average levels of iron in finished wines. AT A GLANCE