According to Tom's Hardware @mryeester has been experimenting with a wide variety of food to see if they can be substituted for off-the-shelf thermal paste and been posting his results -- which have been spectacularly bad.
But when @mryeester added salt to some thermal paste, he saw temperature improvements of 2 to 3C over thermal paste alone.
In another video, he tried replacing thermal paste with powdered sugar, thinking that the fine-grained material would provide enough contact between the IHS and the CPU. Sadly it did not, with temps being about 60 degrees higher than with thermal paste.
Salt apparently has a higher thermal conductivity than most thermal pastes on the market today. At first, @mryeester tried mixing iodized salt with thermal paste, and seeing what would happen. But unfortunately in this first run, he was unsuccessful. But next, he tried grinding down the salt into a fine powder, then mixed it in with his thermal paste, and surprisingly this compound mixture worked. With his normal thermal paste, his CPU was only hitting 49C, but with the powdered salted mixture, temps dropped by 2 to 3 degrees C.
Toms view on this is that some thermal pastes have 1 to 2 degree better thermals than others. So this 2 to 3-degree drop mixing in salt might be matched just by using higher-quality thermal compounds.