Abstract
Laboratory procedures were developed to determine the effectiveness of Frostgard (FG). Specific experiments tested its antifreeze, anti-ice nucleation, and cryoprotection properties in grapes. The freezing point of water was related to the amount of impurities in the water and less with FG concentration. FG at 1% (v/v) depressed the ice nucleation temperature (INT) of water solutions by 1°C. Also, FG depressed INT of ice nucleation active (INA) bacterial suspensions in addition to kill the bacteria. The anti-ice nucleation properties were also tested on fluorophlogopite, an inorganic ice nucleator. FG required the presence of ice nucleators to effectively depress INT, possibly by binding to active nucleation sites. FG at 0.25% (v/v) reduced the freezing injury to grape leaf disks by 21% to 25% at -2°C. At lower temperatures there was no protection. Our results suggest that the practical significance of the cryoprotectant nature of FG is very limited.
- Received April 1992.
- Copyright 1993 by the American Society for Enology and Viticulture
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