RIO DE JANEIRO — Federal agents raided the operations of Brazil’s largest food companies on Friday over accusations that their employees oversaw a scheme that included bribing inspectors to allow rotten meals to be served in public schools and salmonella-contaminated meat to be exported to Europe.

The investigation by Brazil’s Federal Police, an agency similar to the F.B.I., deals yet another blow to the country’s business establishment, which is struggling to recover from colossal graft scandals around Petrobras, the national oil company, and Odebrecht, a huge construction company.

In the newest corporate scandal, investigators said that employees at two food-processing giants, JBS and BRF, paid federal inspectors to ignore the adulteration or expiration of processed foods. Inspectors also falsified sanitary permits, and bribes were channeled to the Brazilian Democratic Movement Party of President Michel Temer, according to the authorities.

Rafael Cortez, a political scientist at Tendências, a consultancy in São Paulo, called the meatpacking inquiry “one more element that will add to the picture of political instability.” Brazil’s political establishment was already reeling from an array of other graft cases.