China's General Administration of Customs announced on Tuesday that it had seized nearly 100,000 tons of smuggled frozen meat — some of which was more than 40 years old, dating to the time of Mao Zedong — in a nationwide crackdown on the illicit trade earlier this month.

The haul included chicken, beef, and pork items worth some $483 million, according to a report in China Daily, and involved the apprehension of members from 14 criminal gangs that were responsible for bringing contraband meat into the country and selling it. These products typically evade inspection and pose a danger to public health, since the meat in question could be riddled with viruses and bacteria. Because the meat is frozen, customers can't tell that it has already gone bad.

As part of the operation, the Changsha Administration of Customs in Hunan Province alone uncovered 800 tons of frozen smuggled meat at a local wholesale market — the largest such seizure in its history. Officials determined that a third of the meat available at the market had been illegally imported.

Customs of Changsha confiscated from smugglers 800 tons of meat, some frozen for 40 years. — People's Daily,China (@PDChina)June 23, 2015

"The products fully filled an entire compartment," said a local official who was quoted by China Daily. "It was smelly, and I nearly threw up when I opened the door."

Transit channels through Hong Kong for smuggled meat appear to be typical of the trade. According to the authorities, the meat found in Changsha had been acquired abroad, shipped to Hong Kong, and then routed to the port of Haiphong in Vietnam. The meat was sorted into smaller shipments at a border town and subsequently smuggled into China.

After 12 hours on the road in an unrefrigerated truck en route to Changsha — a lack of refrigeration helps keep smuggling costs down — the traffickers refroze the meat after they reached its destination. It had already started to rot when the Chinese customs agents happened upon the Changsha warehouse, which explains why the discovery caused officials to almost retch.

On top of having been defrosted and refrozen repeatedly, several containers of the seized meat were at least 40 years old. The stockpile was set to be distributed across the country for sale in supermarkets and restaurants, and some of it might already have entered the food supply.

In China, meat is also sold over the internet. According to the New York Times, some of the tainted meat was sold online and might have been available for purchase on the retail site Taobao, which is owned by the Chinese e-commerce giant Alibaba and offers a selection of local and imported meats at competitive prices.

Screen capture of the Taobao site. The products seen here have no connection to the meats described in this case.

China has endured a series of food safety scandals over the years, most notably the discovery in 2008 of powdered milk and infant formula that was contaminated with the toxic chemical melamine in order to make it seem as though it had more protein. Six babies died and 300,000 others fell sick.

In September 2011, adulterated oil — produced from waste oil found in gutters — was sold in supermarkets. The government increased inspections, but oil recycling remains a frequent practice in China. The following May, fields of watermelons exploded after farmers used the growth accelerator forchlorfenuron, which increases cell division, to boost production and increase the size of the fruit.

Other stomach-turning revelations around that time included pork that had been steeped in the detergent additive borax and then misrepresented as beef, and rice that was found to be contaminated with the heavy metal cadmium.

In 2012, it was found that Chinese cabbage producers had taken to spraying their produce with formaldehyde to make them more resistant to spoilage during long trips. Among other industrial applications, the carcinogenic chemical is also used to embalm corpses or preserve anatomical organs. Later in the year, it was discovered that fake chicken eggs were being sold at food markets.

Over the last thirty years, per capita meat consumption in China has doubled. There's no word yet on how this discovery will affect the country's appetite.