your 50/1.8 should be a good start for portrait photography.
The term 'portrait photography' is a bit vague though. You need to think about what kind of shots you're after most of the time. Full-body, half-body, head and shoulders, etc...?
There isn't a "food photography" lens or a "portrait photography" lens per se. You think about what kind of shot you want and get the appropriate lens for the job.