Experts warn over rising sale of ‘toxic’ cooking oil

The selling and consumption of deliberately-adulterated foods, experts warn, has reached alarming levels.

In Nairobi, most of the food sold at low-end outlets, a new survey shows, is being fried with highly-poisonous oils, risking the health of consumers.

The foods which include fried fish, potato chips, crisps, mandazi and samosas fed on by millions of the city poor, food experts say, are a public health hazard.

The frying oils, the study shows, are deliberately overused and adulterated for more profits with no concern for consumer health.

Researchers from Jomo Kenyatta University of Agriculture and Technology (Jkuat) collected and tested food frying oils from low-end outlets in parts of Nairobi and found most of it unfit to prepare food for human consumption.

“Our results show that most of the fresh, in-use and discarded oil samples were unfit for consumption,” said Michael Wawire, a lecturer at the Department of Food Science and Technology and study co-author.

Degradation in all discarded oil samples, the study shows, was way above the maximum level recommended by regulatory bodies but with evidence these were being resold for further use.

Over-cooked or adulterated frying oil, Dr Wawire explained, changes its chemical composition to a possible human poison.

“Degraded oils are actually toxins in nature, which means that their build-up in the human body can lead to health complications,” Wawire told The Standard in an email.

Street kitchens

In the study appearing in July issue of the Journal of Food Composition and Analysis  Wawire and colleagues, Solomon Karimi and Francis Mathooko, the latter from Machakos University, tested food frying oils from street kitchens, and lower end restaurants in Nairobi City, Juja and Githurai areas.

All in-use and discarded oil samples, the study says, showed extremely high levels of degradation putting into question the safety of foods prepared with such oils.

But even this highly-degraded oil, the research shows, is resold for further food preparation or remixing with fresh oil.

The team also found much of the fresh oils to be highly degraded indicating a widespread network of trading in used frying oils in Nairobi and its environs.

Dr Wawire alluded to the possibility of traders using transformer oil - used for cooling electricity transmission transformers - to fry food in Nairobi.

“Generally traders could add transformer oil to lower the smoking point of the cooking oil, and get more frying cycles. We plan to study this further,” said Wawire.

But the adulteration of food is not just a Nairobi problem alone with a second report involving the ministries of Agriculture and Health showing the vice has been devolved even to the most unlikely counties.

For example, the report shows up to a quarter of the raw milk sold in Lamu is contaminated with either antibiotics, water, herbs or other dangerous additives.

[www.rocketscience.co.ke]