P. 267 in the commentary (7th perek). Most of our work in this world happens in the field of the klipah nogah. Our first job in dealing with the klipah nogah is birur (clarification), to sort the good out from the mixture of tov and ra. Even eating Kosher can be an opportunity to get lost in the desire to eat. Our second job is to lift up the good for the purpose of kedusha (holiness). The highest level of lifting up is to reveal Elokus (holiness) through eating. Another high level is for men to have the intention to fulfill the mitzvah of oneg Shabbos or Yom Tov though eating high quality food.