China's Ministry of Education has warned against schools serving precooked meals to students, after parents complained they may be unhealthy and unsafe for children to eat.

A senior official from the ministry told Xinhua News Agency on Friday that school food safety and nutritional health are important issues that can affect students' well-being.

The official was quoted as saying that due to a lack of unified standards, certification and traceability systems for precooked meals, schools should be extra cautious about serving such meals, and there are no plans from the ministry to introduce them.

Many parents have expressed opposition to their children eating precooked food at school canteens after it was revealed that several schools and kindergartens in Ganzhou, Jiangxi province, had served them.

In the wake of the complaints, many schools across the country have released statements reassuring parents that their canteens do not serve precooked meals.

Wang Liang, principal of a primary school in Changsha, said the canteen there provides lunch to students, and all the ingredients are purchased and cooked in the morning.

"All food at the canteen is fresh, and there is not even one frozen ingredient," he told local media outlet Xiaoxiang Morning News. Many other principals also said their schools do not serve precooked food to students.

A principal of a primary school in Jinan, Shandong province, told Xinhua News Agency that many public schools are not equipped with canteens, so they rely on catering companies to deliver lunch.

However, the principal said the school has made it clear to its caterer that it must not serve precooked food to students.

Many public schools in Haikou, Hainan province, also released statements saying they do not use precooked food in their canteens.

Deng Li, a mother of a third-grade student in Changsha, told China Daily that her daughter eats lunch at her school canteen on weekdays and her school has also promised not to serve precooked food.

The school sometimes sends photos of the food to parent WeChat groups, and Deng makes sure to ask her daughter every day whether she has eaten a good meal at school, she said.

"I think it is very important for children to eat healthy as they are still growing. If I were less busy, I would pick her up during lunch and we'd eat at home," she said.

Deng said she does not allow her daughter to eat meat cooked after being frozen, let alone precooked food, so she is extra cautious about the meals she eats at school.

According to Jimu News, several primary and middle schools and kindergartens in Rongjiang district in Ganzhou began using a central kitchen to serve precooked food to students without gaining approval from parents.

Some parents said the food was cold and didn't taste good, while others said their children had stomachaches after eating it.

According to China National Radio Online, the district stopped offering food to kindergartners through the central kitchen on Sept 7. Meanwhile, primary and middle school students are still offered food cooked by the central kitchen, and parents can decide whether to let their children eat at school or not.

Zhang Chunhui, a researcher at the Institute of Food Sciences and Technology at the Chinese Academy of Agricultural Sciences, said in certain situations precooked food can be convenient. However, some businesses might use substandard materials and production processes, leading to unsafe or even spoiled food being served.

Lei Wanghong, a lecturer at the School of Public Administration at Central South University, said schools should be cautious about allowing precooked food to enter their campuses.

In order to boost profits, some food companies reduce their costs by choosing cheap vegetables or buying a large quantity of one kind and only using that one in the food, she said.

Schools should have more say in deciding which ingredients the companies buy for students and ensure that the companies offer diverse food options to students. Education authorities should also strengthen checks on food and finance management, she added.

Li Hongyang contributed to this story.

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