P. 272 in the commentary (7th perek). The aspect of taiva (lust) needs to be separated out from the eating experience in order to access the Elokus (G-dliness) in the food. Afterwards, the food can then be elevated to Hashem like a korban (sacrifice). Words of this world, including jokes are from the klipah nogah. Torah learning needs to be pleasurable these days in order to open the mind and heart. The path of Chassidus is to harness the taivos to bring us close to Hashem, to true joy.