I have been playing around with beets sous vide. I have seen a lot of different times for them ranging from 45 mins at185 f or 85 C I have increased the temp to 188 F and held for one hour dropped it to 187 F for another hour and finished it at 185 F for the last hour and still they are a little too al dente for most peoples taste. This is way beyond the 45 mins I have seen posted for most recipes.
I have peeled and cut the beets into 1/2 inch cubes, heated water on top of the stove and plunged the bags into them before submersing them into the bath and started the original temp in the circulator to about 196 F to adjust for the temp loss when dropping the units in. Not overfilling the bags, maybe some more than one layer, liquid in bags at about one third volume and still no great results. I usually braise them in a oven, covered in cold liquid for about 3 hours whole beets and they come out tender. Any suggestions?