Smoking
1.Smoking has a preservative effect on meat preservation and has been used for this purpose since
nomadic days.

2.It has the following functions–

• Develops aroma and flavor
• Preservation
• Creation of new products
• Development of color
• Formation of protective skin on emulsion type sausages
• Protection from oxidation

2.Composition of smoke –

• Smoke from wood has more than 300 different compounds which are produced at different stages as the
  temperature of combustion rises, conditions in the combustion chambers, and oxidative changes in
  compounds formed.
• The presence of these compounds in smoked meat products is determined by several factors.

3.The most commonly present chemical compounds in wood smoke are -

i)Phenol– About 20 phenols have been isolated from the wood smoke and identified although there are
several others too. The phenols have the following actions in the meat products-

• they act as antioxidants
• contribute to color and flavor
• they have a bacteriostatic effect

ii)Alcohols – Many alcohols are found in wood smoke like primary, secondary and tertiary alcohols but
the most common one is methanol. Alcohols in meat products serve as carrier for the volatile components.
They also have some bacteriocidal effect.

iii)Organic acids – the 1- 10 carbon organic acids are present in whole smoke but only 1- to 4- carbon acids
are commonly found in the vapor phase of smoke and the 5 to 10 carbon acids are in the particle phase of
whole smoke. The organic acids have little preservative action which is a result of lower pH on the surface of
the meat products. These do have effect on surface coagulation and help in the same.

iv)Carbonyls– About 20 carbonyls have been identified to be present in smoke which occur in steam distill able
fraction and particle phase. Although the largest fraction is of the non steam distill able ones but the steam distill
able ones contribute to the specific aroma and flavor of smoked products. They contribute to the characteristic
aroma, flavor and color.

v)Hydrocarbons – There are several polycyclic hydrcarbons present in smoke. Out these benz(a)pyrene
and dibenz(a,h)anthracene have been found to be carcinogenic. They don't contribute to preservative or
organoleptic properties.

vi)Gases – Most of the gases have yet not been found to have any significant effect on the meat products.
The CO2 and CO are readily absorbed on the surface of fresh meat and react with the pigments to produce
bright red pigments carboxymyoglobin and carbon monoxide-myoglobin . The nitrous oxide present in smoke
has significance as it has been associated with the formation of nitrosamines and nitrites. In case of low pH
meat products the condition are unfavorable for the formation of nitrosamines. Apart from this the cure
accelerators erythorbate and ascorbate are known to prevent formation of nitrosamines.

4.Effect of smoke on nutritive value of meat – As the phenols and polyphenols react with the sulfhydryl
groups of the proteins and the carbonyl groups react with the amino groups which are likely to cause losses
of amino acids like lysine.

5. Smoke generation – is done using wood or saw dust. the temperature has a bearing on the contents of
smoke . As the temperatures increase over 575 F the ratio of acids to phenols is reduced since acids are
produced at lower temperature and phenols at higher temperatures. The best quality smoke is produced at
a temperature of 650 - 750 F with subsequent oxidation temperature of 480 F. Temperatures around 750 F
encourage the production of the polycyclic hydrocarbons. To reduce the production of these a more practical
temperature for smoke production might be closer to the 650 F temperature.

6.Humidity during smoking – the humidity during smoking in the smokehouse is important as it effects
the smoke deposition on the product.

• High humidity favors smoke deposition but also tend to limit color development.
• With high humidity there is higher amount of smoke penetration.
• When it is too low the smoke is deposited on the surface only and desirable color is not achieved. Its
  likely to acquire a dull brown tan.
• High humidity do not necessarily reduce shrinkage of the products rather it may encourage fat rendering.
• In case of animal or collagen casings somewhat higher humidity give good results.
• With collagen casings smoking with low humidity hardens the surface and produce a low quality product.
• where as too high humidity soften the surface therefore a balanced humidity application has to made.
• In a gravity house humidity is controlled by opening the dampers.
• In air- conditioned house the humidity is controlled by adding steam or water vapor and using the dampers.

7. Air circulation in a smokehouse — it is critical as it promotes uniform heating of the product. High air
velocities tend to produce more rapid drying along with rapid heating and it is also difficult to maintain high
air velocities unless the dampers are kept tightly closed to prevent the loss of smoke.

8.Liquid smoke application – These are used mainly to streamline the operations such as frankfurters and
braunschweiger production on continuous production lines. Most commonly the aqueous solution of natural
hardwood smoke is used.These aqueous smoke solutions are available in various acid strengths.

9.Direct addition of liquid smoke – It is used in case of relatively low flavored products like frankfurters and
bologna and added upto 2 - 4 oz per 100lbs of the 6 percent liquid smoke. The liquid smoke flavoring should
be diluted with some water and added at end of the chopping or the blending cycle.

10.Surface applications – consist of spraying or heat regeneration of the liquid smoke solution. Surface
application is helpful in coagulation of surface proteins particularly in case of skinless products.
Spray application is done at 100 F. If liquid smoke is applied in this manner they cannot be labeled as
smoked products.

11. Regenerated smoke – The liquid smoke is used for smoke generation using heat systems meant
for this purpose.