Our tongues will always find new tastes. The taste for food differs from person to person. Therefore, food manufactures are willing to use artificial food additives in order to increase the taste, appearance and aroma of their products. But some people don’t like to consume food which are enriched with artificial flavours enhancers since they have an adverse effect on our health. From ancient times, people have preferred adding some flavors to food since they increase palatability. As a result they have followed different food processing practices over several centuries.
Smoking of food products can be identified as one of the oldest food processing systems. This method is used in food preservation activities to avoid loss of surpluses in produce and to add value to food products. Smoking is a method which offers diversified advantages in food industry. For example; it adds flavour, colour, reduces moisture content, improves texture and preserves food through the use of natural preservatives. The most common smoked food are fish, meats, shell fish, jackfruit and breadfruit In the coconut oil industry most of the coconut oil manufactures use this technique to dry copra efficiently and effectively.
Smoking is a physical process and sometimes we see the use of chemicals. When the latter is the method smoke compounds interact with food compounds. Smoke from burning wood contains a number of compounds formed by the incomplete combustion of wood constituents. Phenols, carbonyls, furans, alcohols, and esters, lactones and polycyclic aromatic hydrocarbons (PAH) are prominent chemical compounds which can be found in smoked food. Among these smoked compounds, PAHs in food directly cause adverse health effects. As a result smoked food must be strictly monitored.
According to the recent publications by many researchers, most of the PAHs have identified as cause for cancer and genetic abnormalities for human while some are not. The most considered toxic PAH compound is Benzopyrene.
In most rural areas, the smoking process is accomplished by exposing food into direct smoke by keeping them on a wooden rack built over the hearth or hanging such food over a fire; often the source here being burning wood. As a result all toxic compounds in generated flue gas will absorb into the food.
As mentioned in many research publications, the composition and quantity of PAHs depend on several factors such as composition and type of wood, moisture content, oxygen accessibility, temperature of smoke generation, smoking duration, distance of heating, fat content of food, heat source etc.
When we consider wood composition, a low content of wood lignin is highly affected to huge deposition of PAHs in smoked food. Therefore, scientists are highly recommending the use of hardwoods than softwood during smoking practices. Some researchers have channeled their efforts to investigate the types of wood species can be generate flue gas which does not contain huge amount of PAHs compounds during the smoking practice.
For this study they have used 05 different types of commonly used wood species named Mango, Jack, Coconut shells, Cinnamon and Madan. This study indicates that smoke generated by all five types of wood species were not safe for humans since those flue gases are rich with PAHs compounds in large quantities.
Other than that, smoke temperature plays a significant role in PAHs generation. In the concentration of PAHs, in smoke formed during use of high temperature, (400-1000°C), most of the fats in raw meat and fish generates PAHs and eventually that become deposited on smoked fish and meat. Fat pyrolysis is decomposition of fats in food by high temperature during cooking.
In addition, high moisture content in products may accelerate the production of toxic Benzopyrene. Moreover, fat content of food contributes to accumulation of huge level of PAHs residuals in smoked food since PAHs are lipid soluble in nature and usually accumulate in the fatty tissues of organisms. Furthermore, degradation of other organic matter such as proteins and carbohydrate in food under high temperature may involve to form PAHs while fat degradation under high temperature is a major contributor for PAHs production.
The short distance between the source of heat and food and longer smoking time also affect to increase the level of PAHs residuals in smoked product. However domestic smoking is not only the major source of PAHs accumulation in food. Drying, roasting, baking, barbecue, frying or grilling are the other types of food preparation methods which contribute to generate PAHs.
Epidemiological studies show a correlation between the increased occurrence of cancer in intestinal tract and the regular intake of smoked food. Actually, this is a major threaten to the rural people of our country who live around inland water resources since traditional food smoking is very popular among them as food preservative practices to save surpluses of seasonal harvest for non-season as well.
As a solution for this burning health problem, researchers in other countries have been developing modern smoking ovens such as liquid smoker as a substitute for traditional smokers while this innovative smoker remove all PAHs compounds and other undesirable compounds by using condensing and filtering techniques. And also one of the groups of scientists has proved that the use of charcoal filters, zeolite filters and gravel filters are helpful to decrease and remove the PAHs compounds produced during the using of ancient smoking methods.
Moreover, few scientist in our country also made attempts to build a new food smoker by modifying conventional smoke with natural filters which can reduce the PAHs compounds in smoked food. Furthermore, the development of proper food packaging materials which can be used in smoking practices and have the ability to absorbed PAHs in emission smoke without penetrating into food could be a remarkable solution to protect food from PAHs. This is because in general, the highest concentrations of PAHs in smoked food occur in the food surface.
Even today, in some rural areas of our country the practice of smoking food using traditional smoking methods continues. These users don’t adopt modern technological methods due to lack of knowledge and also economic difficulties.
Therefore, still there is a requirement for development of efficient, safe, cost effective, and user friendly smoking methods which can be used in resource limited settings.