- Winter 1994 "Update" Newsletter Article -
Video cameras aid in MIVAC fine-tuning
From CATI Publication #940101
Copyright © 1994. All rights reserved.
The everyday operation of a $2 million commercial-size microwave oven seems almost commonplace nowadays at CSU, Fresno, where the prototype vacuum drying unit for fruits and vegetables churns out dried products on a regular basis.
The one-of-a-kind MIVAC unit stationed at the university's Viticulture and Enology Research Center has been operating for more than two years now, producing everything from the patented Grape Puff¨ to dried tomato slices. But initial construction and operation of the experimental system has not signaled completion of the MIVAC project, noted VERC research associate Carter Clary, who has overseen development of the patented technology along with VERC director emeritus Vincent Petrucci.
Because there are are several phases of the MIVAC drying process that require different applications of technology and differing amounts of energy, researchers are now focusing on fine-tuning the system so it produces a high- quality product in a minimum amount of time, with a minimum level of power usage.
"The original design of the MIVAC was for handling grapes," said Carter. "But we want to try as many applications as we can. And different products have different characteristics."
The MIVAC drying unit is not simply a giant microwave oven that dries one batch of grapes at a time, he explained. The process is one of continuous flow - where fruits, vegetables or other products are fed into the unit on a conveyer belt, go through several processes inside the unit, then are released in their final form. Since the system operates in a vacuum, two air locks operate where the product enters and exits the unit. And within the unit, which is 20 feet long and six feet in diameter, there are four separate compartments through which the product passes on the conveyor system.
The first two "zones" use microwave technology to dry the fruit; the last two use air pressure and temperature to help the product "set" with the proper texture and consistency.
Many variables in the system can affect the quality of the end product, and sometimes it's difficult to determine where in the system the problem has occurred, if there are problems, Clary said. "Questions we ask are, 'Is there burning or overheating of the product in zone one or two?' or 'Is the product transferring successfully from one zone to another?'"
To help answer those questions, researchers will mount four video cameras that can peer through strategically- placed portholes in the MIVAC unit and track the product as it travels through the various zones. The advantage of the cameras is their ability to zoom in for close-ups of the belts. The images will be transferred to a high-resolution video screen for monitoring by technicians.
"We will be able to examine four critical process points in the system," Clary said. "This will enhance our ability to hone in on and solve problems."
Researchers continue to test the MIVAC system for drying various food and non-food products Clary said. VERC is currently conducting custom trials for two food processing companies from private industry, and another production firm is negotiating terms for production of larger commercial MIVAC units.
The greatest industry interest in MIVAC technology is for the production of dried ingredients for packaged food such as snacks and cereals.
Funding for the video monitoring equipment was provided by the California Agricultural Technology Institute.{ page top }