Little is known yet about the detentions, which were ordered after food safety officials inspected the Shanghai Husi Foods factory that was at the centre of a Dragon TV probe last weekend into the repackaging of expired meat.
China’s official news service, Xinua, has since reported claims by a Husi quality control manager that the practice was conducted under the “tacit approval of the company's senior managers”.
The Shanghai Food and Drug Administration has confirmed that Husi, which is owned by US-based OSI Group, broke the law after more than 5,000 boxes of their chicken, beef and pork were found to contain meat that had exceeded its expiry date.
The SFDA said in a statement that it had ordered an investigation of OSI’s other factories in China, and had demanded production, quality control and sales records from from the company.
OSI's Shanghai factory, which opened in 1996, has more than 500 workers with five production lines for items including pork, beef and chicken.
McDonald’s and Yum! Brands-owned Pizza Hut, which were each named early on as being among the processor’s customers, provided the regulator with over 4,500 boxes of meat products, while Pizza Hut sealed more than 500 boxes of beef for analysis.
Both chains immediately apologised to consumers following the revelations and pledged to conduct their own investigations.
Now Starbucks, the coffee chain, has added its name to the list of companies using Husi meat, as have Burger King and the Papa John’s pizza chain.
In a statement on the Weibo microblogging service, Starbucks stated emphatically that while it had no direct relationship with Husi, though it admitted that one of its third-party suppliers does sourced meat from the embattled processor. One chicken pastry line has since been taken off its shelves.
And in an international twist, McDonalds has halted the sale of Chicken McNuggets at 500 of its restaurants in Japan after it emerged that Husi had supplied some of the processed chicken for that market.
Some Chinese news outlets have taken a strong view on the multinational companies affected by the scandal.
"Famous international brands have not adopted a dedicated attitude toward Chinese consumers,” wrote the nationalist China Global Times newspaper in an editorial. "Perhaps they believed the Chinese market is a rough place, and that service that is 'just good enough' can work in China.”
Xinhua, China’s official news agency, accused OSI and foreign chains of having double standards towards food safety.
"The out-of-date meat was given firstly to the Chinese market, sparking doubts over double standards on food safety among the supplier, or maybe fast food tycoons," it said.