Smoking was originally used to preserve protein-rich foods such as meats and fish for long-
term storage at room temperatures. These traditional products are still produced in some
countries, but now the main reason for smoking foods in many countries is to change their
flavour and colour, and these smoked foods are preserved by refrigeration. Smoking is a
relatively low-cost process that can add value to foods and is highly suitable for small-scale
The most commonly smoked foods are fish and seafoods (e.g. tilapia, mackerel, trout, black
cod, sturgeon, tuna and mussels); meats and meat products (e.g. duck, venison, game birds,
pork, sausages, bacon, ham and pastrami (pickled, spiced and smoked beef brisket)); and
many types of smoked cheeses. Other smoked foods include vegetables such as chipotles
(smoked jalapeño peppers) and nuts (e.g. cashews and macadamia nuts, hickory smoked
There are three types of small-scale smoking processes:
1. Cold smoking, below 33°C in which the food is not cooked. This process is typically
used for salmon, salamis, hams, frankfurters and cheeses.
2. Warm smoking at around 30-40oC, used for bacon, sirloin and some types of sausage
(e.g. Mettwurst and Teewurst).
3. Hot smoking at 60-80oC, which cooks the food and destroys contaminating micro-
organisms. This process is used for meats, some types of sausage (e.g. kielbasa,
mortadella) and fish such as herring, Nile perch or eel.
A fourth process involves dissolving smoke chemicals in water to make smoke concentrate or
‘liquid smoke’ and spraying it onto foods, but this is rarely done at a small scale.
The smoking process
Smoke from burning wood is a mixture of gases and vapours together with tiny particles of
smoke. Some of the particles are deposited onto the surfaces of foods, but this is of little
importance for the smoking process: the important chemicals are the gases that are absorbed
into the foods, which give the characteristic colour and flavours. Shavings, sawdust or logs
made from hardwoods (e.g. oak, beech, chestnut or hickory) produce the best flavours and
colours in smoked foods. Sometimes aromatic woods, such as apple, juniper or cherry, or
aromatic herbs and spices are also used to produce distinctive flavours. All wood should be
free from wood preservatives or saw lubricants. Softwoods, especially pine and fir, are not
suitable for smoking because they contain resins that produce harsh-tasting flavours when
There are more than 300 chemical compounds in hardwood smoke: some have sweet, flowery
and fruity aromas, whereas others have spicy, pungent, smoky flavours and aromas. The wood
also contains small amounts of proteins that produce roasted flavours when it is burned. The
types of flavours in the smoke depend on both the temperature of the fire and the moisture
content of the wood: the best results are obtained using lower temperature, smouldering fires
with a restricted air supply and dampened or soaked wood. These produce dense smoke and
the desirable smoke flavours. High-temperature fires break down the flavours in smoke to
produce unpleasant tasting compounds.
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