As a person organizing a conference, one issue you have to deal with is that of catering. This is because the people who will be attending the conference are expected to eat. Thus, while the issue of catering is not a core business for you, it is still something you have to care about.
One approach to dealing with matters to do with catering in a conference is that of partnering with an outside catering company.
Another approach to dealing with matters to do with catering in a conference is that of doing it yourself (by employing your own people to do the catering).
Yet another approach to dealing with matters to do with catering in a conference is that of having the owners of the facility where the conference is being held do the catering. If, for instance, the conference is being held in a hotel, you can have the operators do the catering.
The model you ultimately decide to use depends on things like the financial ability of the attendees, the nature of the conference and the venue of the conference. There are conferences whose attendees expect to be given extended benefits, in terms of things like meals – and there are others where the attendees are the sorts of people who take pride in self reliance especially for simple things like catering.