Updated: Dec 24, 2020
NULL HYPOTHESIS 9 (Limes): Blanching limes for 30 seconds before freeze-drying will not affect taste compared to uncooked
Conclusion: We Rejected this Hypothesis
Abstract: We blanched one batch of limes and left another batch raw. We froze all of them and then freeze-dried them. One of our test subjects tried the raw freeze-dried limes and the blanched freeze-dried limes. All three of our testers could tell a difference in taste between them. Although not relevant, we preferred the non-blanched limes.
Appx. 6 - fresh limes
1 Harvest Right freeze dryer tray with a silicone mat
Pot for steaming
A metal strainer to hold the citrus over the boiling water
1 qt. water
Bowl of ice
Above: The top photo is of frozen limes slices before freeze-drying (left half is blanched, right half is unblanched). The bottom photo is of freeze-dried limes slices (left half is blanched, right half is unblanched).
Boil the water in the pan.
Put half the sliced limes in the boiling water for 30 seconds.
Drain water off lime slices and place them in the ice.
When cold, lay the limes slices out on the tray.
Lay the unblanched slices out on the other tray.
Freeze both trays overnight.
Start freeze drier to the non-liquid, pre-freeze setting (wait 30 mins.)
Once the pre-freeze cycle completes, place the frozen trays in freeze-drier (with 2 other trays of food; we did two trays of lemons, one tray of limes, and one tray of apple pie)
Started the freeze-drying cycle.
Removed limes from freeze-dryer
Taste-tested the slices.
Our actual total starting weight of limes slices on the tray was .354 kg and the finished weight was .148 kg (not including the tray itself).
The freeze-drier completed its ordinary cycle at 21 hours. We added 2 hours for just in case because citrus sometimes takes longer to dry. The temperature scanner showed an approximate average temperature of 98° F. We did not find any cold spots.
When I compare them, the freeze-dried limes look almost indistinguishable, which is interesting since the unblanched frozen limes look so different from the blanched frozen limes.
We only had one blindfolded tester, but she could taste a difference between the blanched limes and the unblanched limes. We rejected our hypothesis with this test. The blanched limes were not as tart.
If you notice in the top picture above, we did make a fun discovery with the round "cake" in the top left corner of the tray. We blended part of one of the limes and froze it in a round ice cube tray. When it freeze-dried, we weren't sure if it would hold together or become a powder. It actually freeze-dried pretty well and held its shape. It tasted pretty good too. We'll experiment with that approach to citrus later.