- Winter 1999 "Update" Newsletter Article -
Grape conveyence tests show little effect on wine
Copyright © 1999. All rights reserved.
A comparison trial of two grape delivery systems has shown no significant differences in the wines made under the two treatments. Details of the experiment, carried out by California State University, Fresno enology professor Carlos Muller, are available in a new CATI publication entitled "Comparison of Two Grape Delivery Systems."
Purpose of the trial was to determine if gentler initial handling of grapes during initial transport at the winery would result in a more pleasing wine, Muller said.
Most large wineries use conventional "V"-shaped stainless steel hoppers to receive incoming grapes. The hoppers have a stainless steel screw at the bottom of the trough that moves the grapes up to a crusher-stemmer or other device. But the screw has the inherent draw-back of extensively juicing and macerating the grapes, Muller said.
In his test, Muller compared two delivery systems at Fresno State's experimental winery. One was a belt conveyor and the other a newly designed hopper with a screw. After in-winery transport by the two methods, the grapes underwent identical processing for wine.
Analysis revealed only one significant difference between the two treatments - in the grapes delivered by belt conveyor the prefermentation volume of lees was 3.2 percent less than in the other treatment, "indicating that the belt delivery system is indeed gentler (not as abrasive) as expected," Muller noted.
Sensory evaluations also indicated no difference in the finished wines. To view Muller's report, visit the Research Publications section of this web site.
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