Does he understand why these kinds of citrus are offering? Not at all. They were something to study for sure - he didn't feel anything odd about them.

But they were what was offered.

Vader doubts any weapon Tech has would protect him or Vader, and he's not certain his own weapon will. Better to learn into the Force. Eyes closed he focused, sensed beyond what humans would see or hear, judging hostility, strength, intent. His stance shifts, as if he was planting feet he didn't have, about a third of his body covering Tech. Braced. Waiting. Ready.

"Come and face me then."