CHINA - Characters in Chinese martial arts fiction use silver needles to test the dishes served to them when they are afraid of being poisoned.
It is said that the needles will turn black if the food has been tainted.
In real life, there are consumers in China who rely on test kits to ensure that the food products they consume are safe.
Their paranoia is fuelled by the food safety problems that have emerged, including fake meat, tainted milk or "gutter oil", which refers to reproduced waste oil collected from the drains, oil refined from low-quality pork or overused oil.
Companies have been quick to identify business opportunities in the crisis. Banking on the fact that people have lost confidence in the locally produced food products, they have introduced simple-to-use test kits to detect the harmful substances.
Beijing-based Zhiyunda Science and Technology Company, which was set up in 2003, claimed to be the first to modify its industrial and commercial food safety machines to suit the needs of individual customers in June last year.
It now offers up to 160 commercial and personal tests through its online store on Tmall.com, dedicated to a long list of food concerns.
To name a few, there are products to determine the freshness of eggs, verify the authenticity of red wine and detect clenbuterol in meat and poppy seed pods in steamboat soup.
The instant food safety tests allow users to play scientist at home, sans lab coats and a degree in chemistry. Packed in small plastic boxes, the kits contain a one-page instruction along with simple devices and tools unique to each test.
To detect the presence of melamine in milk powder, for instance, users have to first dissolve a portion of the milk powder in 10 portions of distilled water.
Next, drip three or four drops of the solution onto a device that resembles a pregnancy test kit, and wait for three to five minutes.
If two lines appear on the device, congratulations - the milk is not contaminated.
Another common concern among consumers is the residual chlorine in water supplied to houses.
For this test, simply soak the filter paper in the water and then note the colour changes.
The personal test kits are mostly priced below 150 yuan (RM80).
Zhiyunda's web manager Zhang Likui said the sales derived from its online store had increased from just a few hundred yuan in the beginning to nearly 200,000 yuan (RM106,178) a month.
"Sales of up to 150,000 yuan (S$30,918) were recorded in October," she said.
The top sellers are the kits to detect melamine in milk, residual pesticides in farm produce, nitrate in canned food and gutter oil.
Its gutter oil test kit was chosen by the Health Ministry in 2012 as one of the three instant methods to detect gutter oil.
Zhiyunda marketing manager Cheng Chao said the company advised customers to lodge reports with the relevant authorities should they get positive results on the test kits.
Another company sharing a piece of the pie is Sinomedisite.
A company spokesman said the first product rolled out into the market was the kit to detect melamine in milk.
This product, which remains the company's bestseller, is called "kang nai xin".
While "kang nai xin" literally means carnation, "nai" is milk in Chinese.
The company offers three package deals online on jd.com, combining a few essential test kits in a box.
A customer, who purchased a combo with test kits to discover formaldehyde, iodised salt, residual pesticide and residual chlorine, said he could now determine the safety of the respective food products.
"This box looks like a first-aid kit. I am particularly interested in the test to detect residual chlorine in water. Now I can tell whether the bottled drinking water is safe for consumption. Thumbs-up for the manufacturer's creativity," the customer commented on the online store.
Another user commented on the package deal containing the melamine test.
"With this kit, I can safely feed the tested milk to my baby. This product is a godsend to moms."
The marketability of the test kits depends on food safety problems that are unearthed and widely publicised in the media.
Do the companies worry about the sale of their products should the crisis cease to exist in China one day?
A Sinomedisite spokesman said the company's ultimate goal of manufacturing the test kits was to see an end to the food safety problems.
"If one day the market is free of dangerous food items that pose a threat to consumers, the test kits have proven their value of existence," he said.
Cheng, meanwhile, has a different take on the question.
She said the test kits would always have a role to play in food production industry, serving inspection and monitoring functions.
"Look at the recent Fonterra milk scare," she said.
"A zero-risk environment is impossible. There should always be preventive measures in place."
New Zealand dairy company Fonterra was thrown into the limelight in August this year when its whey protein products were found to be contaminated with bacteria that could cause botulism, a type of serious food poisoning. Moving forward, Sinomedisite will be focusing on developing test kits that can yield better and faster results.
Zhiyunda, meanwhile, will soon roll out tests to detect harmful ingredients in slimming products, health supplements and make-up products.
The views expressed are entirely the writer's own.