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Smoking Methods for Meat Products – Impact on Quality and Safety

Summary

Because of more modern climate smoke houses and changes to the law, traditional smoking methods had to be optimized. For one, smoke should be produced in a standardized composition. In addition, the method of producing freshly developed smoke had to be improved with regards to environment protection, and the smoke composition. By now, the generation of pre-purified primary smoke condensate is a highly developed process, where initially, conventional smoke is
generated in a controlled environment by using standardized sawdust. Most of the chemical compounds present in this smoke, such as phenol or heterocyclic hydrocarbons, are desired components because of their – for meat products beneficial – characteristics such as taste, color, texture and preservation. The purified primary smoke condensates only differ from freshly generated smoke in that they remove the tar phase, which poses a potential health risk. The watery phase is nearly completely free from genetically changing and carcinogenic elements, whereas in the tar phase, various polycyclic aromatic hydrocarbons (PAH) are present, with some of them viewed as carcinogenic. A disadvantage of traditional smoking methods is that they require the cleaning of smokehouses with smoke resin removers, having therefore a negative impact on the sewage system. In addition, depending on the smoke-producing process in question, varying levels of exhaust emissions develop, requiring a cleaning or reburning in accordance with
the Federal Immission Control Act. Smokehouses operated with primary smoke condensate are not subject to these requirements.

Smoke flavors are used for different processes such as smoking (pulverizing / nebulizing), submerging and sprinkling as well as an addition to brines or roasting, or for the impregnation of sausage casings. From a microbiological point of view, with appropriate optimization there is no significant difference to conventional smoke. Overall, the environmental balance sheet of smoke flavors or primary smoke condensate turns out a lot more positive. Depending on the method, the use of smoke flavors could enable considerable cost reductions and quality improvements. When used externally, it is appropriate to declare smoke flavors as “smoke“. Based on experience, consumers understand the term “smoke flavor“ in an ingredients list as referring to the adding of flavor to a product, rather than smoke in a physical sense compared to conventional smoke.

Introduction

People have started smoking food around 9,000 years ago. However, the requirements to the process as well as to the quality of the end result have changed significantly. With preservation of food having been the main purpose for a long time, nowadays other elements have become important as well. Added to this are requirements to the reproducibility of results and strict environmental obligations. Those last two aspects in particular can hardly be met by traditional methods. Modern smoking processes with purified primary smoke condensate or smoke flavors offer significant benefits here.

1. Purpose of Smoking

Smoking does not have just a single purpose, it needs to fulfill various requirements. Next to color, texture and taste, the preservation of meat products is still a major consideration. In the future, the question of control over viruses in food products will become a center point.

2. Smoke

2.1 Smoke Material

The type of wood – or other materials respectively – has a substantial impact on flavor and quality of the smoke used for smoking. This includes hardwoods such as beech,hickory, maple, oak, mahogany, cedar, birch and cottonwood. Soft wood (often just as addition) such as spruce, fir, pine or cedar wood (including cones) is also used. Spices, heather, turf, rice husks or sugar cane are also added. The wood grain is also relevant for quality control.

2.2 Smoke Development

Smoke is being generated by incomplete burning in two stages. First pyrolisis (dry distillation), and  secondary  reactions  under  release  of  oxygen  with  oxidation,  polymerization  and condensation. 

2.3 Composition

Smoke  can  be  divided  into  two  ingredients:  gaseous  materials  like  phenol,  organic  acid  and carbonyl, and non-volatile, particulate materials such as tar, resin, ash and soot. About 48 per cent are made up of unwanted materials such as ash and tar. 

2.4 Development of Smokehouses

Triggered by industrial requirements for consistent smoke quality and large-scale application, smoke production developed further based on conventional smolder smoking. Next to steam smoking and smoking with wood chips, the production of friction smoke became a widely used method by the end of the 1970s

2.5 Cleaning Flue Gas

Smokehouses are, according to the Federal Immission Control Act, subject to authorization because of the development of toxic elements. The cleaning of flue gas is therefore an obligation regulated by law. Cleaning can be done in various ways:

Reburning
• Thermal
• Catalytic
• Additive to incinerators

Condensation
• Indirectly in coolers
• Directly in smoke washers
• Directly in closed recirculation systems

Absorption
• In smoke washers with absorption systems, containing oxidizing agents such as ozone,
chlorine dioxide, sodium peroxide or lye, such as soda lye

Adsorption
• To sorbents (solid materials with large inner surface, i.e. activated carbon

Combination methods
• Electrostatic deposit of particle phase
• Absorption or adsorption of gaseous phase

Biofilter

Additional costs for money and effort for the disposal of incurring materials must be considered.

3. Primary Smoke Condensate

3.1 Production

The  benefit  of  generating  smoke  for  primary  smoke  condensates  lies  in  the  centralized production. It simplifies the cleaning process and reduces the amount of emissions, therefore helping to protect the environment. To further protect the consumers’ health, undesired elements such as tar, resin, ash and soot can be removed from the condensate.

3.2 Application

When applying the primary smoke condensate, it needs to be distinguished between smoke flavor and smoke. Smoke aromas are added to the foods in liquid form, used to impregnate the inside of sausage casings, sprayed on foods, or the foods are dunked in aroma. Another process is to turn the  primary  smoke  condensate  back  into  smoke  by  using  pressurized  air.  If  this  smoke  is generated externally and passed in from outside the smokehouse, there is a smaller margin of error in the smoking process.

The transmission depends on: 

  • Smoke concentration 
  • Interface between recirculating air and product surface
  • Temperature of recirculating air
  • Relative humidity of recirculating air
  • Casing properties
  • Filling level
  • Diffusion properties of food
  • Duration of treatment

3.3 Smoke Components

The content of polycyclic aromatic hydrocarbons (PAH) such as benzo(a)pyrene in meat products has been constantly reduced in the course of the past decades. Influencing factors for toxicity are – amongst others – the type of wood, the moisture level of the wood and the temperature during smoke production. At the same time, desired ingredients such as the amount of phenol are also dependent on these factors, which means that there is always a weighing up between which characteristics are more desired. In principal, it can be said that smoke can only be produced in consistent quality when the individual parameters have been standardized.

4. Conclusion

Smoking with primary smoke condensate offers numerous advantages compared to conventional smoking methods. 

Process quality

  • Standardized primary smoke condensate
  • Diverse product varieties
  • No approval process according to Federal Immission Control Act required
  • Closed circuit, emission-free smoking
  • No costs for cleaning of flue gas and disposal (tar, ash)
  • Lower cleaning and sewage costs

 

Product quality and safety 

  • Lower PAK levels in finished product 
  • Smoke colour and taste adjustable to product characteristics
  • Inhibiting microbial effect (bacteria, yeast, mould)
  • Inhibiting antiviral effect 
  • Antioxidant effect

 

Declaration

  • On ingredients list: smoke