Smoked and Roasted Foods: A Call for Proper Monitoring and Regulation

Abdulrahman Olagunju, FASLN

Sunday, 18 July 2021

An average Nigerian, while growing up, was such a picky child. Although they are not too crazy about junk foods or sweets, they are just enthused with the idea of tasting different spices which can easily be traced to their origin - as practised by early African men.


These ancient culinary practices are evidently not backed up by any scientific knowledge, and the science of how it works is not too clear to them either. They are often based on self-discovered methods and are continuously upheld till today with relatively little changes.


Smoking, roasting, grilling and barbecuing foods such as fish, meat, maise, plantain, yam etc., have been some of the various processes of curing food commonly seen in Nigeria.


The Unintended dark side: Science behind Smoked Foods

Food smoking belongs to one of the oldest technologies of food preservation which mankind has used in meat and fish processing. Although it is a common source of protein in most diets, smoking not only gives them unique taste, texture and aroma, it also improves preservation due to its dehydrating and bactericidal properties.


However, smoking has serious unintended effects that are potential health hazards. "Smoked foods may be contaminated by cancer-causing components of wood smoke – mainly polycyclic aromatic hydrocarbons (PAHs) and other derivatives of PAHs, which break down in human bodies to more toxic and dangerous PAHs," says Dr Temilola Oluseyi, a Senior Lecturer and Group Leader of Analytical and Environmental Chemistry Research Group, Department of Chemistry, University of Lagos, Nigeria.


Dr Oluseyi, who had previously conducted a study on these poisonous components in some locally consumed fishes in Nigeria, further explained that foods become contaminated during thermal processing (such as smoking, roasting, baking, and grilling) as a result of the incomplete combustion of carbon. "My research group carried out this study in 2011, the oil content of the different types of fish were analysed, and the temperature of the smoking process was found to affect the concentration of the PAHs in the food," she added.


Not only in fishes, roasted plantain known as 'Boli' or 'Bole', corn and yam are another popular West African food and one of the favourite street foods in Nigeria, which are done through direct contact with heat sources also has the potential to produce the toxic chemicals.So, "due to their carcinogenic activity, PAHs have been included in the European Union (EU) and the United States Environmental Protection Agency (USEPA) priority pollutant lists which make processing of food at high temperatures (grilling, roasting, frying and smoking) major sources generating PAHs," says Dr Oluseyi.

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Health Implications of Smoked Foods

Community-wide studies indicate a statistical correlation between the increased occurrence of cancer of the intestinal tract and the frequent intake of smoked foods. The implication of this is not far-fetched in Nigeria, as research by WHO shows non-communicable diseases (NCD) prevalence is about 29%, Cardiovascular(heart-related) diseases at 11%, cancer 4% and diabetes 2%.


Popoola Kabirat, a registered nutritionist and founder of NutritionBridge, highlighted that consumption of smoked foods increases the risk of colorectal cancer; however, the evidence is stilllow.

Dr Oluseyi further said that the health effects of smoked foods that can be caused by exposure to PAHs depend on how much / what concentration of PAHs has entered the body; how long someone has been exposed to PAHs; and how the body responds to PAHs, which leads to either short-term or long-term health complications. "Although, it has not been confirmed that PAHs cause short-term health effects. However, during smoking of food, other potentially toxic compounds commonly found with PAHs may be released into the environment, which could cause short-term symptoms such as eye irritation, nausea, vomiting, diarrhoea, and confusion, as well as long term effects including cataracts, kidney, and liver damage, and jaundice," she added.


Should We Stop Eating Smoked or Roasted foods?: Casting Way-forward

A glance at the Nigerian smoked fish market and economic potential showed that the total demand for fish and fish products is higher in Nigeria than in many other West African countries. The Food and Agriculture Organization (FAO) of the United Nations conducted a research indicating that the quantity of dried and smoked fishes exported from West Africa to the United Kingdom is estimated at over 500 tonnes per year, with a retail value of nearly $20 million, and Nigeria alone exports about 5 tonnes of smoked fish per month, via airfreight.


Combining the abroad and domestic demand of the smoked fish, it clearly shows the economic potential of Nigerian smoked fish, and the economic potential of investment is guaranteed as well. This shows that smoked foods should not be banned but should be regulated and monitored.


Whether one calls it smoked or roasted foods, it's no secret that they are always in season and farmers and petty traders are making fortunes with it. Some pretty traders have changed their regular businesses to preparing roasted/smoked foods, which could be taken as in-between meals, snacks or even like a full meal.


"The two important issues with smoked food vendors are sources of smoke and hygiene. Use of rubber, plastic and automobile tyres should be discouraged, as well as ensuring utmost hygiene when preparing and handling foods," Popoola said. "Smoked foods produced from high-quality raw materials in controlled conditions, in kilns or tunnels supplied with smoke generated at a temperature not exceeding 400°C, do not create any health hazards if consumed before the end of shelf life."


Shotibi Otitoola, a registered nutritionist, highlighted that foods should not be exposed to heat for a longer period; be in direct contact with the heat source, as well as limiting fat drip flare-ups that can char the meat or fish. "As long as there is good airflow so that the heat is less intense on the food; right burning materials and a short period of heating, the food becomes safer and allow less carcinogenic activity," Otitoola added.


Dr Oluseyi, who is also a fellow of African Science Literacy Network, encourages eating more antioxidant-rich fruits and vegetables because the toxic chemicals (HCAs and PAHs) don't form on grilled fruits and vegetables. "So, grill them on their own or with meat, fish, or poultry to enjoy their many health benefits," she said. "When grilling hot dogs, sausages or pre-packaged hamburgers, look for natural foods free of additional nitrates and preservatives (such as carrots, spinach, lettuce etc)," she added.


"In addition, smoke food vendors should take precautions and avoid inhaling the smoke/flame generated. Nutrition professionals, food safety and hygiene officers should embark on regular sensitisation programmes for smoke food vendors," Popoola added. "With these measures in place, both the health of the public and livelihood of smoked food vendors will be guaranteed."