It is my experience that thawed frozen (and vacuumed) fresh fruit and veggies are mushy to some degree. In my mind it is due to the following. Please tell me where I go wrong re ice crystal formation and it's relation to freezing time and defrosting.
- The faster the food freezes, the smaller the ice crystals will be.
- This means less damage to the food cell walls.
- This means less mushy food when defrosted.
- And now I'm guessing here, on how this might apply to freeze dried foods.... the food will be less mushy when rehydrated, assuming one reintroduces the same (or less) amount of water as was lost, as long as it was frozen quickly as per above.
Question: is freezing with the freeze dryer faster, and does it do less damage to the cell walls than pre-freezing in a regular freezer (set to 0F/-17C? Note: I am not talking about sauces or liquids here - pretty sure the blender took care of those cell walls.
And if the freeze dryer does freeze faster thereby creating smaller ice crystals, then maybe I should be using IT to pre-freeze the food that I want to stick in the chest freezer for long term storage because it would do less harm to the food?
And one theoretical question that will help me understand the process.... if I managed to flash freeze a bunch of strawberries using dry ice, could I still freeze-dry them? I ask because the temp is way colder than what the freeze dryer gets to. Of course the only reason one would need to freeze dry in this case is to save room in the freezer...
I've seen found this video that is all about my question, but with regards to a competitor's freeze dryer. There may be enough differences between the HR and Blue Alpine to still make some of my question relevant?
"https://www.youtube.com/watch?v=6x8Dmu2Bs-s"
Lise, I'm just another average user. Dry ice would definitley preserve cellular integrity over a typical non commercial freezer. There are even better methods to 'flash freeze', but out of the typical freeze drying enthusiast budget (subjective). Here's a pretty good link you may have already found. https://agriculture.institute/post-harvest-mgt-principles/differences-between-quick-and-slow-freezing/
I prefreeze with a chest freezer, placing the trays at the very bottom of the freezer. Standup freezers are seriously more convenient, but dump all the cold air when opening and takes time to replenish the cold air, the chest freezer tends to keep the cold in allowing less time spent freezing. delicate fruits like raspberries and strawberries tend to fall apart with freezing within my budget. Please let us know your results with dry ice, I just can't justify the time to find out.
@Jim Dunbar,
Now you've got me looking at shock freezers!
I will have plenty of time come the spring, so I think I'm going to give this 'dry-ice-in-a-cooler' idea a shot. I'll let you know how it goes. And thanks for that link.