The Shanghai Public Security Bureau said in a statement the five included the company officials responsible. It said a quality manager was among them but did not name the five.
Shanghai authorities on Sunday shut an OSI plant for mixing out-of-date meat with fresh product, re-labelling expired goods and other quality problems, following an investigative report by a local television station.
The factory's other customers in China included restaurant operator Yum's Pizza Hut brand, coffee chain Starbucks, Burger King, 7-Eleven convenience stores and Papa John's Pizza, according to separate statements from the companies.
Outside mainland China, McDonald's Japan has confirmed it sourced about 20 percent of its McNuggets from the Shanghai factory.
Police acting "according to the law" detained the five from the Shanghai Husi Food Co., the OSI subsidiary which operated the factory, the statement said.
Media reports had previously said police were questioning "several" employees. Shanghai television has shown a man described as the quality manager and another manager in meetings with government officials in the days after the closure.
OSI said on Monday that it was "appalled" by the allegations and announced it had formed its own team to investigate.
OSI's Shanghai factory, set up in 1996, had more than 500 workers with five production lines for items including pork, beef and chicken, according to the group's website.
The US company is a long-time supplier to McDonald's in China, starting from 1992, it said.
McDonald's chief executive Don Thompson said Tuesday that his company was cooperating with Chinese authorities who are investigating OSI.
"In this case, we do feel we were a bit deceived with respect to one of these plants," he said, as the company announced second-quarter results.
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