Air Carrier Captain reported a ground conflict with a catering vehicle during taxi-in requiring abrupt braking by the crew to avoid a possible collision.

Narrative

During taxi in to Gate on (date); Flight XXX daytime clear weather; as we were turning on to the j-line a commercial delivery truck drove in front of our aircraft. We stopped abruptly to avoid a collision. Also Ground Marshallers and Wing Walkers signaled a stop. All the Company Personnel did their job properly. The truck was rather large and was not a Company truck. The solid color made it blend in which the white walls of the international terminal at HOU. It was a close call since I was scanning left and looking at the j-line while turning. The truck came from right to left and did not yield while it was on the access road. I had just turned off my taxi light per procedure when joining j-line. A good scan by my First Officer saved the day. If it were night or low visibility it could have been damaging especially since the ramp area is congested and uncontrolled by Ground.Ensure commercial delivery Drivers are qualified to drive on ramp access roads. Truck lights should be on; hazard lights flashing would help and drivers yield to aircraft. Emphasize heads out of the cockpit when taxiing as this will avert any collisions.