A kitchen calamity

A kitchen calamity

Following the recent controversy over two disastrous dishes on MasterChef Thailand, a nutrition expert shares guidelines on food safety and how to avoid natural toxins in raw ingredients

As a self-protective means, potatoes naturally release a toxin called solanine which accumulates on the outer and inner skin and therefore must never be eaten raw.
As a self-protective means, potatoes naturally release a toxin called solanine which accumulates on the outer and inner skin and therefore must never be eaten raw.

Nathinee Jiamprasert approached the MasterChef Thailand judging table with full confidence as she served a menu called Shanghai frog, which basically is a breadcrumb frog dish topped with spring onions.

"It's probably the first time I am totally happy with my dish," said the 38-year-old contestant from Phuket in the TV cooking contest which aired last month.

Unfortunately, the judges were not as exhilarated. Nathinee's spring onions came with dirty roots -- a culinary malpractice which, according to the appraisers, was extremely unacceptable.

"You must be responsible for the people who eat your dish," said one of the judges, furiously.

In the same episode, another contestant, Jitsak Lim-Pakornkul, 42, also from Phuket, served raw potatoes -- also a cooking no-no. At the end of the episode, Jitsak was in the bottom three while Nathinee was asked to leave the programme.

Setting aside the heated drama in MasterChef Thailand that aims to make the programme all the more entertaining, it is in fact a universally known cooking mantra that serving raw potatoes and vegetables contaminated with dirt is an absolute must-not. Not only did the episode provide contestants with a memorable lesson; it also stirred up public discussion as to whether the judges had overreacted, and if the incident was due to a lack of knowledge among Thais with regard to food safety.

Monruedee Sukprasansap, lecturer from the Institute of Nutrition under Mahidol University, explained that certain kinds of vegetables release natural toxins to shield themselves against enemies, and there are chances that those toxins are still there even after harvest. Knowledge on food safety and hygiene is therefore paramount for chefs and consumers alike.

"The best prevention is to opt for food that is clean and healthy. But that's easier said than done," commented Monruedee.

Potatoes, she added, must never be eaten raw. To protect themselves against foes such as earthworms as well as germs like bacteria, mould and microorganisms, potatoes naturally release a toxin called solanine, which accumulates on the outer and inner skin, with a slight amount in the flesh. Such a natural poison is released by other plants, including green tomatoes and eggplants.

"How much solanine will be released by plants depends on various environmental factors," she explained. "Heat and sunlight trigger the release of the chemical; so does stress that is caused by, say, wounds. Parts of the potato that turn green contain a high level of solanine, which is detrimental. People should slice that part off before consumption."

It's also usually advisable that potatoes be kept in dry storage, away from sunlight. Failure to do so could also potentially stimulate the release of solanine, even though the potatoes are no longer under the soil. According to the US Food and Drug Administration (FDA), a dangerous dose of solanine in potatoes is 20-25mg per gramme.

Reactions to the toxin can be acute, said Monruedee. "Symptoms in the gastrointestinal tracts can hit only half-an-hour after consumption up to 12 hours. People might develop conditions like stomach pain, nausea, vomiting and a sharp pain down the food pipe."

The nervous system can also be severely impacted by the consumption of solanine, but mostly following toxic accumulation over an extensive period and high-dose consumption. In such cases, the poison will wreak havoc on the nerve cells, interrupting certain neurotransmitters. People are likely to suffer blurry vision, hallucinations, numbness, paralysis, lowered body temperature and sensory loss.

"Such reactions are not very common in Thailand, because potatoes are not a staple food [here]," she added. "Though solanine intake can be deadly, it is very rare."

Vegetable roots contaminated with soil -- another problematic issue -- have nothing to do with natural toxins. But soil, according to Monruedee, is full of E. coli and salmonella. These bacteria can cause stomach pain and discomfort, diarrhoea and other symptoms.

Vegetable roots contaminated with soil can be full of E. coli and salmonella which can cause stomach pain and diarrhoea, among other symptoms.

"Soil abounds with microorganisms that can be detrimental to health. Excessive intake of those microorganisms is likely to lead to blood poisoning, which can result in death if left unattended."

There is a piece of good news, though. Solanine from potatoes is not invincible. According to Monruedee, the toxin can be destroyed at temperatures above 170C.

At such high temperatures, the amount of solanine will be reduced by 20-80%. Boiling or steaming potatoes must therefore be done long enough to ensure that it reaches a temperature where the toxin can be broken away.

"[Given the temperature], roasting does not really help. But it can certainly help reduce the amount of poison in the vegetable," she added.

As for vegetable roots, it is best not to serve them. But for certain types of roots that are widely used as an ingredient or seasoning, such as coriander roots, it is crucial to wash away all the soil and dirt. That can help reduce contamination by over 50%.

"Boiling or steaming those roots can further reduce the microorganisms, because most of them can be destroyed at the temperatures of over 100C," she advised.

But in the worst cases, wherein symptoms develop as a result of toxin intake, patients are strongly recommended to be treated by medical specialists rather than self-medication.

"When symptoms hit, many do not even realise it is a result of them having eaten a toxic chemical. They then take paracetamol, in the hope that it can be alleviated. Those toxin-related conditions won't be healed by pain-relief tablets. It is best that they visit a hospital so that doctors can prescribe the right antidote."

When it comes to food safety, the basic is still the best practice -- eating freshly cooked food, using serving spoons, and frequent hand-washing. Half-cooked and raw meat should be avoided, especially during summer, when hazardous microorganisms can quickly proliferate.

"Microorganisms can grow surprisingly fast," Monruedee said. "In a matter of seconds or minutes, they can proliferate 10 times or even 100 times. So if you, say, buy some food for lunch and cannot finish it, storing it for dinner in air-conditioned temperatures is not enough. You have to put it in the fridge to stop bacterial proliferation.

"And don't be overly anxious. If you know how to deal with your ingredients and your food correctly, you should be safe to a certain extent."

Cabbage naturally releases goitrogens, a chemical that reacts with iodine. In other words, the goitrogenic substances interfere with iodine uptake in the thyroid. However, goitrogens can be purged by high temperature. People suffering goitre — an abnormal enlargement of the thyroid gland — and those suffering hypothyroid should avoid eating raw cabbage.

Mung bean sprouts that look really white could mean they are bleached. The best prevention is to buy them from a reliable source.

Blood is bacteria and microorganisms' favourite food source. Uncooked meat can also be full of worms, worm eggs and other life-threatening disease-causing agents which can release toxins that can enter the bloodstream. These agents can mostly be destroyed by temperatures above 100C only. So food with raw ingredients, like animal blood or meat, should be avoided.

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