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Coldsmoking

Coldsmoking - is the process of flavoring, cooking, or preserving food by exposing it to the smoke from burning or smoldering plant materials, most often wood. Meats and fish are the most common smoked foods, though cheeses, vegetables, and ingredients used to make beverages such as whisky and lapsang souchong tea are also smoked.
In Europe, alder is the traditional smoking wood, but oak is more often used now and beech to a lesser extent. In North America, hickory, mesquite, oak, pecan, alder, maple, and fruit-tree woods such as apple, cherry and plum are commonly used for smoking.
Other fuels besides wood can also be employed, sometimes with the addition of flavoring ingredients. Some North American ham and bacon makers smoke their products over burning corncobs. Peat is burned to dry and smoke the barley malt used to make whisky and some beers. In New Zealand, sawdust from the native manuka (tea tree) is commonly used for hot smoking fish.
Historically, farms in the western world included a small building termed the smokehouse where meats could be smoked and stored. This was generally well-separated from other buildings both because of the fire danger and due to the smell of the smoke.
Cold smoking temperatures should typically be maintained below 38 °C (100 °F). In this temperature range, the food will not cook and will take on a rich, smokey flavour and develop a deep mahogany colour. Coldsmoked foods tend to retain a relatively moist texture.

Hot smoking - exposes the foods to smoke and heat in a controlled environment. Although foods that have been hot smoked are often reheated or cooked, they are typically safe to eat without further cooking. Hams and ham hocks are fully cooked once they are properly smoked.
Hot smoking occurs within the range of 165°F/74°C to 185°F/85°C. Within this temperature range, foods are fully cooked, moist, and flavorful. If the smoker is allowed to get hotter than 185°F, the foods will shrink excessively, buckle, or even split. Smoking at high temperatures also reduces yield, as both moisture and fat are "cooked" away.
"Cold smoking" Ia the process of imparting a smoke flavour to food without cooking it. The smoke also helps to preserve the food as it contains anti-septic qualities. Cold smoking can be used to flavour pork chops, beef steaks, chicken breasts, salmon and scallops. Cold smoking can be a relitively short process, just long enough to impart a touch of flavour, or it can take a day or so in the case of fine smoked salmon. It must be remembered that cold smoking is not a cooking process and meats like pork, beef and chicken will require further cooking before they are safe to eat.

The Smoking Process - Hardwoods are made up mostly of three materials: cellulose, hemicellulose, and lignin. Cellulose and hemicellulose are the basic structural material of the wood cells; lignin acts as a kind of cell-bonding glue. Some softwoods — especially pines and firs — hold significant quantities of resin, which produces a harsh-tasting soot when burned. Because of this, these woods are generally not used for smoking.
Cellulose and hemicellulose are aggregate sugar molecules; when burnt, they effectively caramelise, producing carbonyls, which provide most of the colour components and sweet, flowery, and fruity aromas. Lignin, a highly complex arrangement of interlocked phenolic molecules, also produces a number of distinctive aromatic elements when burnt, including smoky, spicy, and pungent compounds like guaiacol, phenol, and syringol, and sweeter scents like the vanilla-scented vanillin and clove-like isoeugenol. Guaiacol is the phenolic compound most responsible for the "smokey" taste, while syringol is the primary contributor to smokey aroma.Wood also contains small quantities of proteins, which contribute roasted flavors. Many of the odor compounds in wood smoke, especially the phenolic compounds, are unstable, dissipating after a few weeks or months.
A number of wood smoke compounds act as preservatives. Phenol and other phenolic compounds in wood smoke are both antioxidants, which slow rancidification of animal fats, and antimicrobials, which slow bacterial growth. Other antimicrobials in wood smoke include formaldehyde, acetic acid, and other organic acids, which give wood smoke a low pH — about 2.5. Some of these compounds are toxic to people as well, and may have health effects in the quantities found in cooking applications.

Wood Smoke Flavour - Since different species of tree have different ratios of components, various types of wood impart different flavours to food. Another important factor is the temperature at which the wood burns. High-temperature fires see the flavour molecules broken down further into unpleasant or flavorless compounds. The optimal conditions for smoke flavour are low, smoldering temperatures between 300 and 400 °C (570 and 750 °F). This is the temperature of the burning wood itself and not the temperature of the smoking environment, which sees much lower temperatures. Woods that are high in lignin content tend to burn hot; to keep them smoldering requires restricted oxygen supplies or a high moisture content. When smoking using wood chips or chunks, the combustion temperature is often lowered by soaking the pieces in water before placing them on a fire.

Preservation - Smoke is a antimicrobial and antioxidant, but smoke alone is insufficient for preserving food by itself. The main problem is that the smoke compounds adhere only to the outer surfaces of the food; smoke doesn't penetrate very far into meat or fish. As mentioned earlier, smoking is carried out for its flavour enhancement qualities. Smoked salmon for instance undergoes a process of salt or brine curing before being subjected to the cold smoke.

Coldsmoking - was is useful preservation tool, in combination with salt-curing or drying. For some long-smoked foods, the smoking time also serves to dry the food. Drying, curing, or other techniques can render the interior of foods inhospitable to bacterial life, while the smoking gives the vulnerable exterior surfaces an extra layer of protection. For oily fish, smoking is especially useful, as its antioxidant properties delay surface fat rancidification. (Interior fat isn't as exposed to oxygen, which is what causes rancidity.) Salt or brine curing serves two main purposes, Firstly it acts as an anticeptic and anti bactieial preventing the fish from spoiling and secondly, the process of salt curing renders water from the fish fillet reducing its overall writht and firming up the meat, improving the texture of the flesh,