It follows a report by local television channel Dragon TV, where undercover filming had allegedly showed workers using meat that had been on the floor, as well as out-of-date beef and chicken.
OSI Group said it had been "appalled" by the report. For Shanghai Municipal Food and Drug Administration, alongside The State Administration for Industry & Commerce of the People’s Republic of China (Shanghai AIC), began a joint investigation last month.
Sheldon Lavin, chairman, chief executive officer and owner of OSI Group, said at the time: "What happened at Husi Shanghai is completely unacceptable. I will not try and defend it or explain it. It was terribly wrong, and I am appalled that it ever happened in the company that I own."
Following the revelations, the group withdrew all products manufactured by Shanghai Husi from the marketplace.
The six employees detained earlier this month by the Shanghai branch of the Public Security Bureau have now been arrested. OSI Group, which has also been conducting its own internal investigations, said it would continue to operate fully with the authorities.
In July, president and chief operating officer of OSI Group, David McDonald announced a restructure of its management structure in order to ensure corporate compliance and the integrity of its operations in China. These now come under the OSI International umbrella, rather than operating as a separate decentralised entity, with the new organisation called OSI International China.