It was the additives that led to infection of the dairy products in Guagdong province, Chinese authorities have said.
More than a hundred kids from three kindergartens in Zhuhai, a coastal city in the province fell ill last Wednesday after consuming high-calcium milk produced by Weiwei Daheng Dairy Company, a local business.
Victims were reported vomiting after drinking the products. The young patients were properly treated and discharged from hospital on Friday.
No serious consequences were reported from the hospitals.
The local food safety enforcement body said subsequently they had found staphylococcus aureus intestinotoxin, which might lead to digestive infection, from samples collected from both the hospitals and the same products in stock.
The government warned consumers in five cities, Zhuhai, Jiangmen, Foshan, Zhongshan and Guangzhou, against the risk of drinking 150-ml high-calcium milk, which was packed on March 26, a local newspaper said.
While making a public apology and promising to compensate for the sick, the dairy company claimed a calcium material imported from the U.S. for producing the dairy products was problematic and blamed it for the infection.
The allegation, however, was not supported by the city health authority.
The staphylococcus aureus infection occurred because the additive adding process was not properly pasteurized, said a source from Zhuhai City Government.
Shortly after the outbreak of the incident, the provincial food safety agency had sealed up 4,167 boxes of the milk suspected of contamination while the manufacturer, Zhuhai Weiwei Daheng Dairy Company, recalled another 2,706 boxes of the same product.
After the incident, sales of Weiwei Daheng Dairy Company plunged by 60 percent, according to the company's marketing manager surnamed Xu.
The incident triggered the Zhuhai city government to start a comprehensive monitoring network which tracks problematic products and survey similar infectious outpatients in hospitals.