The size and shape of ice crystals is directly related to the amount of damage they cause, particularly in disrupting cellular organelles like membranes. Their size/shape is affected by the rate of freezing, among other parameters. Rapid and multiple freeze-thaw cycles are very bad for all living cells. Minimizing the number of freeze-thaw cycles and allowing controlled thawing make a big difference - cells can repair a certain amount of damage, but not rapidly and constantly. I think of frost as the white stuff that coats things but isn't ice or snow. Freezing is a descriptor of temperature - i.e. a temperature below the freezing point of whatever the material is. You can freeze without encountering frost. Best, J. John T Lonsdale PhD 407 Edgewood Drive, Exton, Pennsylvania 19341, USA Home: 610 594 9232 Cell: 484 678 9856 Fax: 801 327 1266 Visit "Edgewood" - The Lonsdale Garden at http://www.edgewoodgardens.net/ USDA Zone 6b