Do you have any lab-based research experience? If not, that might hold you back from anything with research in the title unless it is public-health specific related research in which case your MPH would do just fine.
Try browsing around on
www.usajobs.gov as well. I got quite a few hits just searching for "public health" and "food safety". A lot of them are more regulatory in nature and maybe not quite as down-and-dirty food technology based, but there seems to be a variety.
It sounds like some flavors of Veterinary Medical Officer or something else within APHIS (Animal and Plant Health Inspection Service), FSIS (Food Safety Inspection Service), or the USDA as a whole would be an ideal career for you if you like public health and food stuff along with animal health. However, to be a full VMO you'd need to either have a DVM from a US vet school or fulfill one of these requirements - or, as per govt website:
Graduates of foreign veterinary medical schools that are not accredited by the AVMA Council on Education must meet one of the following requirements: (Refer to AVMA website for schools in this category.) a) Proof of certification of their final transcript by the Educational Commission for Foreign Veterinary Graduates (ECFVG); b) Possession of a permanent, full, and unrestricted license to practice veterinary medicine in a State, District of Columbia, the Commonwealth of Puerto Rico, or a territory of the United States that includes successful completion of the North American Veterinary Licensing Examination (NAVLE) or its predecessors, the National Board Examination (NBE) and the Clinical Competency Test (CCT); OR c) Proof that the education obtained in a foreign veterinary medical program is equivalent to that gained in a veterinary medical program that is accredited by the American Veterinary Medical Association Council on Education. An AVMA-accredited veterinary medical school or college must have accepted the final transcript from the foreign veterinary medical school at full value for placement into an advanced degree, postgraduate educational program, or training program (e.g., residency or graduate program).