Currently, Delta uses LSG Sky Chefs as their caterer at JFK. From what I heard, DL used to use Gate Gourmet at JFK.

It seems that historically, Delta has a preference for Gate Gourmet. So, when did Delta switch to LSG Sky Chefs at JFK, and why?

Currently, the following hubs use Gate Gourmet:
ATL
LGA
MEM
CVG

The following hubs use LSG Sky Chefs:
DTW
MSP
SLC
JFK

Out of the hubs, only ATL, DTW, and JFK have both Gate Gourmet and LSG Sky Chefs ops. DL once used Gate Gourmet at DTW prior to merging with NW, but since the merger DL has used LSG Sky Chefs due to Gate Gourmet's facility being too small to handle the combined ops, and LSG Sky Chefs was already catering NW flights.

But why did Delta switch to LSG Sky Chefs at JFK?