Color is one of the chief attributes Chinese consumers look for when buying meat and fish. But an article on the China animal husbandry bureau web site, "What kind of Meat is unwanted by 10 million buyers?" warns that buying meat based on its color could be a losing proposition.
The reporter frequently hears shoppers in the market uttering phrases like, “This chicken foot is very yellow; I’ll buy this one,” or “The pork here is very red; this kind is good.” Some consumers will not buy chicken feet unless they are a yellow color. They also prefer red pork. A bright color connotes the all-important "freshness" or a new unusual food item--both popular attributes with Chinese shoppers. The reporter notes that not long ago there was a type of fish with yellow bones called a “strange banana fish” in a market in Shunde.
An individual with a Chinese feed company told the reporter that this is a mistake. If you eat very yellow chicken feet or red pork, they were mostly likely made that way by adding dye to feed. According to another industry insider, the "banana fish's" color was produced by adding a yellow pigment to feed.
The additives are of two types. One is natural additives--for example, adding corn can produce a yellow color in meat. Another is through synthetic chemical dyes which are often used because of their low cost. Generally, large reputable companies use only natural additives, but a few illegal small enterprises and farmers use chemical dyes to cut costs. The resulting meat looks good and sells well; it’s hard for ordinary consumers to detect the dyes. But the ingestion of dyes could have harmful effects on people who consume it.
Of course, this is also an issue for fruits and vegetables. If they look shiny and free of blemishes, there's a good chance that is because they were bathed in pesticides.
Toxic dyes, preservatives, and other additives are probably the biggest single food safety problem in China. These problems are among the most commonly cited violations by FDA officials in their refusals of Chinese food shipments.