- Spring 1997 "Update" Newsletter Article -
Resin research to continue at VERC
Processed juice shows protein stability after initial treatments with adsorbent resins
From CATI Publication #970401
Copyright © 1997. All rights reserved.
Successes in initial tests have prompted researchers at California State University, Fresno to step up efforts in evaluating new fining materials for use in wine-making.
Traditional fining methods - which help to prevent clouding of wine and grape juice products - have become increasingly costly because of the expense of land-filling the leftover materials, noted chemistry professor Barry Gump, who is directing the study with the support of the university's Viticulture and Enology Research Center (VERC).
The most common fining agent still used by most wineries and juice processors is bentonite, a natural clay that absorbs proteins and other molecules that cause wine and juice to become cloudy after time. But the bentonite lees left over from processing can no longer be legally used as a fertilizer because of their alcohol content. And land-filling costs continue to rise for such materials.
"The wine industry has recognized that it needs alternative technology for fining," Gump said. That's one reason his project has received financial support from the American Vineyard Foundation as well as Fresno State's California Agricultural Technology Institute (CATI).
The resins Gump is testing are commercial products already in use by the food processing industry for adsorbing color. Unlike bentonite, commercial resins are synthetic, made of co-polymeric beads that have the texture of fine sand. The resins serve as a molecular filter in a low-pressure, flow-through system through which the wine or juice is slowly pumped.
Initial tests with small quantities showed positive results. "We do know that the processed juice is protein stable," Gump said. However, he considers the success to be a "small step" in the overall process of developing resins for fining. For example, because resins can be used in a flow-through system rather than in a batch system like bentonite, the potential exists to treat larger quantities of wine or juice. But no one knows how much can be treated.
And because of the way resins work in the filtering process, they also should be reusable following a clean-up process, Gump explained. But that brings new costs into the picture.
"Proving a technology works is not the same as proving it's economical," Gump said. But that's all part of the research process. The next step will be to increase the test batches from five liters to 45 liters.
Gump also will examine sugar content, acidity, pH, flavor, and other components of the test juices during upcoming months. More results will be published through CATI as they become available. For details on this project, contact VERC at (559) 278-2089.
Additional information about VERC activities and research is now available on VERC's Internet home page, at (http://cati.csufresno.edu/verc).{ page top }