Your setup looks pretty good, You should get a one way valve for your vacuum to the cold trap so no negative pressure issues, also some timers so you don’t need to have the vacuum on all the time. The boiling issue might just be that your fruits weren’t fully frozen before pulling a vacuum, maybe leave them in the freezer longer or sticking it in the cryofluid longer before hand.
Very interesting experiment & I commend ur efforts. As an old fridgee this had me intrigued & I have wondered how they made these freeze dried fruits. Dried mango & pineapple is the best ever. IDK if u can 3D print a rack to raise the sample up higher in the chamber maybe even telescopic legs for height adjustment & incorporate a thin heating element into it so you can use ur lab PSU to control its heat range while dehydrating ur fruit pieces & have that heat almost in contact with ur product, that way you probably would not need so much heat to do the same job. Definitely weigh ur products before & after, and ideally the cold vessel liquid as well to get an idea of how it is all coming out. Have you tried to see if any flavour was in the cold vessel ice/liquid after the process? I guess moving forward you could gut a small 12v fridge system & wrap an evaporator around ur cold vessel & recycle the heat back through ur vacuum drying vessel, but this might require a bypass valve line for a bit of extra temp control, but would forego ur need for dry ice. Nice setup. Cheers
Thanks for the ideas! I do want to set this system up again sometime and try a few more things. Check out this newer video in the series for a heating rack I built: th-cam.com/video/RvJgVv9kXG4/w-d-xo.html
You have the patience of a saint. I don't have the brain power or patience to go much beyond using my dehydrator. Perhaps placing the fruit on a grill to keep it off the bottom may help.
You can monitor the dryness (sort of) by monitoring the temperature and pressure (using an absolute pressure sensor capable of low pressure readings) the system will not cross the sublimation line until all available water is removed. Heating will speed that process up, but you cannot be sure all moisture is removed otherwise.
One more thing if u wanna keep upgrading is microwave radiation to sublimate the water faster supposedly it’s the best way to heat the water particles, it penetrates much more than conduction
I'd argue kiwi fruit isn't that great at the best of times. Usually on commercial fruit platters its left behind or the last to go most of the time. The melons, strawberries/grapes and pineapple would go before the kiwi...
Your setup looks pretty good, You should get a one way valve for your vacuum to the cold trap so no negative pressure issues, also some timers so you don’t need to have the vacuum on all the time. The boiling issue might just be that your fruits weren’t fully frozen before pulling a vacuum, maybe leave them in the freezer longer or sticking it in the cryofluid longer before hand.
Very interesting experiment & I commend ur efforts. As an old fridgee this had me intrigued & I have wondered how they made these freeze dried fruits. Dried mango & pineapple is the best ever.
IDK if u can 3D print a rack to raise the sample up higher in the chamber maybe even telescopic legs for height adjustment & incorporate a thin heating element into it so you can use ur lab PSU to control its heat range while dehydrating ur fruit pieces & have that heat almost in contact with ur product, that way you probably would not need so much heat to do the same job.
Definitely weigh ur products before & after, and ideally the cold vessel liquid as well to get an idea of how it is all coming out. Have you tried to see if any flavour was in the cold vessel ice/liquid after the process?
I guess moving forward you could gut a small 12v fridge system & wrap an evaporator around ur cold vessel & recycle the heat back through ur vacuum drying vessel, but this might require a bypass valve line for a bit of extra temp control, but would forego ur need for dry ice. Nice setup. Cheers
Thanks for the ideas! I do want to set this system up again sometime and try a few more things. Check out this newer video in the series for a heating rack I built: th-cam.com/video/RvJgVv9kXG4/w-d-xo.html
You have the patience of a saint. I don't have the brain power or patience to go much beyond using my dehydrator. Perhaps placing the fruit on a grill to keep it off the bottom may help.
You can monitor the dryness (sort of) by monitoring the temperature and pressure (using an absolute pressure sensor capable of low pressure readings) the system will not cross the sublimation line until all available water is removed. Heating will speed that process up, but you cannot be sure all moisture is removed otherwise.
Wait, a Dryer? Why would your Hills Hoist have to be plugged in?
Huzzah! Crispy!
One more thing if u wanna keep upgrading is microwave radiation to sublimate the water faster supposedly it’s the best way to heat the water particles, it penetrates much more than conduction
nice
I'd argue kiwi fruit isn't that great at the best of times. Usually on commercial fruit platters its left behind or the last to go most of the time. The melons, strawberries/grapes and pineapple would go before the kiwi...
Yeah, I'm not a huge fan either. Kids love 'em for some reason though!
I like your videos. I hope to see you on Linkedin.
Thanks very much Shreyas! I don't do much social networking. I do post on mastodon though: howse.social/@tj