- Winter 1996 "Update" Newsletter Article -
MIVAC study yields new data on grapes
From CATI Publication #960101
Copyright © 1996. All rights reserved.
A researcher studying temperature curves of grapes heated in a microwave vacuum (MIVAC) dehydration system hopes the study results will lead to more effective use of the patented system.
Industrial technology professor Matthew Yen has concluded a first phase of research on dehydration and heating rates in the MIVAC system developed at Fresno State's Viticulture and Enology Research Center (VERC). Yen's primary focus was on the rate of dehydration of grapes and how they become puffy when run through the system.
The temperature of the grapes heated by microwave energy rises in three stages, in conjunction with the temperature of the water in the pulp and skin of the grape, Yen found. As the trapped water grows hotter, it expands, finally rupturing cell walls and vaporizing. This is what leaves the Grape Puffª puffy.
"By analyzing temperature profiles at the three stages of the heating process, it leads to insights about the actual formation of the structure of the Grape Puff and can be used to predict results prior to the MIVAC treatment," Yen concludes. "It could also serve as a useful tool for the design of future MIVAC units," he added.
Theoretical discussion of the MIVAC temperature curves, along with calculations used to determine them, are all contained in a Research Bulletin now available from CATI. It is entitled Why Is the Grape Puffª Puffy? An Analysis of the MIVAC Temperature Curves. Co-author along with Yen is VERC research scientist Carter Clary, who helped to develop the MIVAC system.
To obtain a copy of the publication, see the request form at the bottom of Page 7. Yen may be contacted through his department office at (559) 278-2145.{ page top }