On Chadzilla's blog I first read about the idea of cooking vegetables (potatoes, in that case) at 182F/83C in order to dissolve the starch but not the pectin. I checked Keller and he is in the same range for potatoes - 185F/85C.
I decided to mess around with beets and radishes to see how they behave at and near these temperatures. I prepared three bags, and filled each with large diced beets & halved radishes, along with canola oil and salt. (I've found that water (and water based liquids like stock) tend to waterlog firm starchy vegetables when cooked sous-vide.) I labeled the bags 170F, 182F and 192F:
(There's also some diced daikon in there but I can't remember what happened to it). I cooked them for 2 hours each (in my Auberins/Sanyo rice cooker rig) at their labeled temperatures. The oil stayed clear, but enough water leaked out of the vegetables to transfer lots of beet dye to the radishes:
(This is a different bag than the 192F bag shown above - the vegetables didn't fight and rearrange themselves during cooking). So obviously don't cook beets with anything else unless you want them dyed red . . . (I didn't mind for this project).
On to the results:
BEETS - Despite all the beet color in the bag, the beets didn't appear "cooked". There was a nice progression of textures and the different temps, and none were unpleasant. 170F beets are very firm with a hit of crunch, like an al-dente (underdone) potato. 182F beets were firm but yielding - definitely my favorite. 192F beets were noticeably softer but not mushy or overdone. However, something fundamental changed in the structure because the beets were very salty -- the salt had penetrated throughout the beet. Maybe this was from pectin breakdown? The 170F and 182F beets were nicely seasoned. 182F = the winner.
RADISHES - It was clear that the radishes had been cooked, as most of the color leeched out of the skin (and was replaced by deep red beet color in some cases). 170F radishes were the best, firm but no raw crunch, and nicely seasoned. 182F radishes were okay, but some are too soft. 192F radishes were too soft (mushy) and VERY salty similar to the 192F beets. 170F = the winner, but I would like to play around some more in the 170-180F range (although I'm not sure my rig is precise enough to break that down too finely).
