Smoking for Food Preservation

Smoke curing, commonly referred to as smoking, is a time-honored method for preserving food. It encompasses the exposure of food to smoke generated by burning materials, typically wood, with the intention of infusing flavor, aiding in cooking, and extending the product's shelf life. Throughout this procedure, interactions occur between the food and the smoke, yielding a distinctive taste. The approach involves subjecting the food to controlled environments, combining steps such as salting, drying, heating, and smoking within specialized chambers.

The smoke, produced by the controlled smoldering of materials like hardwood chips, herbs, fruit peels, or spices, serves a multitude of purposes. It acts as a deterrent to bacterial growth and possesses antioxidants, thus contributing to the prolonged preservation of products. Furthermore, the smoke imparts an exclusive blend of flavor, aroma, texture, and visual appeal to the food. This tradition continues to be prevalent in safeguarding fish, meat, and other consumables.

Diverse fish species demand varying methods of preparation. For example, salmon requires backbone removal and splitting, while bottom-dwelling fish are filleted. Smaller fish like herring are commonly gutted and decapitated prior to undergoing brining.

The genesis of smoke involves the incomplete combustion of wood, which subsequently results in the thermal degradation of complex organic compounds into volatile, smaller substances. Smoke is composed of two phases: a dispersed phase containing droplet-like particles and a gaseous phase. The particles in the dispersed phase exhibit an average diameter spanning from 0.196 to 0.346 µm.

The smoking process instigates interactions between the food and smoke, culminating in the formation of an additional layer on food or meat products. This supplementary layer introduces volatile compounds that not only impede bacterial proliferation but also infuse a distinctive flavor. The range of temperatures for the smoking process generally extends from 65°F to 250°F.

The practice of smoking food aligns with the revival of traditional crafts and an amplified consciousness regarding the contents of the food we consume. This trend promotes high-quality, unhurried victuals composed of local, unadulterated constituents, bereft of chemical additives. Smoking functions as a valuable avenue for farmers, smallholders, hunters, and fishermen to effectively utilize surplus meat or fish during specific time frames.
Smoking for Food Preservation

Curing: Preservation process of food

Postharvest technology is concerned with handling, preservation, and storage of harvested foods, and maintaining its original integrity, freshness, and quality. The methods of preservation depend on the origin of foods—particularly whether they are of plant or animal origin.

The basic concept in curing of foods like meat, fishes and vegetables is to reduce the moisture contents by osmosis process. When moisture contents in any food are much low, there are much lesser chances of getting microbial infection and subsequently growth.

Curing is also done for flavoring. It is done by adding salt, nitrates, sugar, nitrites in combinations which are capable of dehydrating the food. Higher salt used for curing also dehydrates bacteria resulting in their killing.

For crops, curing is a postharvest healing process of the outer tissues of root crops by the development of a wound periderm by application of heat.

The purposes of curing are
*to heal wounds of tubers and bulbs sustained during harvesting,
*to strengthen the skin,
*to dry superficial leaves, such as onion bulbs to prevent microbial infection during storage and distribution,
*to develop desired skin color (onion),
*to reduce water loss during storage in potatoes, sweet potatoes, cassavas, yams, onions, and garlic.

In term of meat process, curing is the treatment of meat with preservative chemicals that restrict or prevent the growth of spoilage bacteria and food poisoning bacteria. It is used together with processes that use heat, smoke or low temperatures to give the required shelf life of cured meats. Meat can be defined as the edible flesh of a number of species of mammal or bird, both wild and domesticated.

The cure ingredients can be rubbed on to the food surface, mixed into foods dry (dry curing), or dissolved in water (brine, wet, or pickle curing). In the latter processes, the food is submerged in the brine until completely covered. With large cuts of meat, brine may also be injected into the muscle.
Curing: Preservation process of food

Food preservation by curing process

Preserving food by various methods has been practiced throughout human history. Curing was originally developed to preserve certain foods by the addition of sodium chloride. In the food industry, the application of curing is related only to certain meat, fish and cheese products.

Meat curing, as commonly performed in products such as ham, or sausage involves the addition of mixtures containing salt, nitrite and other preservatives. Today sodium chloride and sodium and potassium nitrite are considered as curing salts.

Over several millennia additional processes concomitant with curing have evolved, notably fermentation, smoking, drying and heating. Most of these methods work through removing moisture from the meat and replacing it with salt and preserving agents that inhibit the growth of bacteria and decay.

Food treated by curing must be re-hydrated and carefully rinsed before use. It is also still considered raw, so meats will still require cooking.

An important benefit to curing meat for use in the home is to maintain a readily available source of meat when the electricity goes out and there is no refrigeration.

For some people, the greatest benefit might be to known that their family will not be exposed to some of the various chemicals that are found in commercially prepare meats.
Food preservation by curing process

Process of smoking

Smoking foods is one of the most ancient food preservation processes and is some communities one of the most important. The use of wood smoke to preserve food is nearly as old as open air drying.

At first smoking of food could be considered a side effect due to preservation by drying in the fireplace. Later on, the process was developed and changed and was combined with other processes such as salted dried, and fermented.

Smoking has been mainly used with meat and fish. The main purpose are it imparts desirable flavors and colors to the foods and some of the compound formed during smoking have a preservative effect due to the presence of a number of compounds. 

Depending to the smoking procedure, the moisture drops 10-40%. Compounds present in smoke with bactericidal and antioxidative properties are deposited on and penetrate into the food especially meat. 

Important smoke ingredients include phenols, acids and carbonyl compounds.

Smoking of meat uses the heat of burning wood to cook the meat while adding flavor to the meat through the variety of wood being used. The wood used to generate the smoke should be of the hardwood species. In America, the wood varieties that are used are hickory, mesquite, oak, pecan, alder, maple, apple, cherry and plum.

Curing and smoking of meat are closely interrelated and are often practiced together, that is cured meat is commonly smoked and vice versa.

Meat exposed to temperature s of 165 to 185 degrees will fully cook. The best methods ensure meat in the smoker is fully cooked is to use a meat thermometer and probe into the deepest part of the cut to ensure the heat has reached all the way to the center.
Process of smoking

Meat curing process

Curing refers to modifications of the meat that affect preservation, flavor color, and tenderness due to added curing ingredients.

The curing process is achieved by adding a number of curing agents to the meat, each ingredient having unique characteristics and playing an important role in the process.

Cured meats are attractive in their color, flavor, texture, and are popular because they combine variety with convenience of relatively long shelf –life and storage stability.

The major ingredients include salt, sugar, nitride and /or nitrate sodium ascorbate and often phosphate.

The characteristics cured meat color that develops is attributed to the formation of heat-stable nitrogen monoxide complexes with muscles myoglobine.

Technologies used for curing were greatly refined during the 1950s and 1960s; automation of processes and use of reducing agents, such as ascorbates and erythorbate, was introduced to speed up the curing process. 

Curing is designed to grossly alter the nature of the meat and produce distinct products such as smoked and salted bacon, ham, corned beef and highly flavored sausages including bologna and frankfurters.
Meat curing process