Smoking has been used since ancient times as a method of food preservation. At that time, this method was primarily used to conserve meat, which was exposed to the smoke produced by the incomplete combustion of wood. Although it was a process that originally related to conservation, today we are looking for smoked notes not only in meat products, but also in the categories of snacks (cookies, potato chips, pasta salads), sauces (barbecue), soups, vegetables and various seasonings. In addition to the growing use in the food service world is an increased use in molecular gastronomy.
An element directly related to smoking and smoked products is fire, one of the most important inventions in history. Ancient man learned to dominate and use fire in various ways such as protection, light, obtaining tools and ceramics, as an energy source and, of course, for food.
Over time, and with the improvement of the techniques of using fire, foods that were originally consumed raw started to be baked, cooked, and smoked. As such, there was the possibility to modify the flavors of the food through these processes. Most of the eating habits we have today come from years of cooking preparations and inventions, where fire played a major role in flavoring. Some types of sauces, jellies, broths and even some drinks had their discovery and evolution in the way of preparation through this element, fire.
Small rural estates have always been the cradle of many smoked products, where even now several products are produced for private consumption or sale. They rely on the use of smokers on smaller scales or slow smoking on the wood stove. In Brazil, pork is the main raw material used in the production of sausages or smoked pieces. In these products, the smoking process is a way to increase value of the final product for the consumer.
In most of the smoking processes, the meat used is fresh and other ingredients that can be added to the process include: cooking salt and curing salts, sugar, herbs and spices.
In the past, smoking associated with brine was a guarantee of meat and fish conservation. Today, the use of smoked notes in both industrialized and gastronomic dishes is related primarily to the sensorial characteristics that the smoke confers after contact with the product for a certain time. This new sensory demand generated a new need, that is, to produce large-scale smoked foods, which is difficult to attain through the handmade process of smoking. This opened the door for the creation of specific ingredients that provide this benefit in a convenient and efficient way, leading to liquid smoke, or smoke flavors that allow us to accelerate the process while providing both flavor and color to foods.
In the United States in the 1960s, the industry of additives and ingredients for the food industry began the production of liquid smoke extracts, which consists of purified compounds generated in the pyrolysis of wood sawdust in water, where the temperature of the process, the concentration of oxygen and the humidity of the raw material are controlled variables. By definition, smoke is composed of solid particles dispersed in gaseous matter. The gases arise from the combustion of carbon-containing materials. Thus, as occurs in conventional smoking processes, wood is also the starting material from which the process of obtaining natural liquid smoke begins.
The raw material from hardwoods is selected and pre-dried before being fractionated into small uniform pieces (sawdust), guaranteeing maximum extraction of the aromatic compounds. Sawdust is burned in specially designed ovens, with control of oxygen tension, temperature and time, to avoid the total combustion and the consequent loss of the aromatic components. Combustible gases (such as methane) are eliminated and the aromatic gases (smoke) go to a condensing tower. The smoke is condensed with ice water, using a countercurrent flow of water, thus generating liquid smoke.
The liquid smoke remains for a certain time in a settling tank, an operation that aims to eliminate much of the tar. The product is then pumped to multi-stage filters to remove heavy oils and to obtain a clean and concentrated smoke solution, free of compounds harmful to human health, such as tar and benzopyrene.
The liquid smoke can be presented in an aqueous base, vegetable oil or organic solvents and can also be absorbed in solids such as salt, sugar, starches or herbs (dry, particulate or powdered products).
Brazilian legislation, regulated by Anvisa (the Brazilian Health Regulatory Agency) Resolution RDC No. 2 of January 15, 2007, approving the Technical Regulation on Aromatizing Additives, defines smoke flavors as: concentrated preparations, used to confer the flavor of smoked food. Smoke flavorings are produced from one or more of the following processes: subjecting untreated woods, barks and twigs to controlled combustion; dry distillation at temperatures ranging from 300 to 800 °C; or drag with reheated steam at a temperature between 300 and 500 °C, using the following species (the 20 species allowed are listed). As an example, we have the species of the genus Carya, which is known as Hickory wood (or American walnut), Eucalyptus sp. (a species of eucalyptus), Quercus alba L (a species of oak), among others. This legislation also lays down the maximum limit for a substance formed in the combustion process: 3,4-benzopyrene, and states that smoke flavors should not transfer more than 0.03 μg/kg of 3,4-benzopyrene to the final food. For the purpose of analytical control, this value will be determined from the concentration of the 3,4-benzopyrene present in the smoke flavor used, and as a function of the dose (amount) of the smoke applied to the food or product ready for consumption.
It is known that traditional wood smoke contains approximately 300 identified chemical compounds and can be grouped into six large families: acidic compounds, phenols, alcohols, carbonyl compounds, polycyclic aromatic hydrocarbons and gases. Around 20 phenolic compounds have been isolated and identified in wood smoke. They are responsible for the smoked flavor and have antioxidant action that acts in the preservation of meats, for example. The amount and nature of the phenols present are directly related to the pyrolysis temperature of the wood, as well as the technique used.
In order to choose the wood used in the smoking process, special attention must be paid, as it is responsible for the profile of the resulting flavor. Some must also be avoided because they confer unpleasant flavors if they contain certain types of resins in their composition. Some of the most recommended types for smoking are fruit trees such as cherry and apple, oak and chestnut. In addition to woods, other material such as herbs, green tea and even vanilla beans have been used by chefs to produce characteristics smoke flavors.
In today’s gastronomy, not only meats, but other ingredients such as rice, corn, cheeses, potatoes, carrots, nuts and fruits like pineapple and strawberry are now smoked to increasingly explore the diversity of flavors. Some restaurants have their own smokers or use smaller-scale techniques such as smoke in pans with grills, aluminum foil and lids directly on top of the stove, which can give the taste of smoke in minutes to certain foods.
Duas Rodas has developed and worked with its own natural smoke flavor for more than 30 years. The process of obtaining it is an industrial secret and is constantly evolving. This natural smoke flavor can be found in flavors, preparations or condiments that are applied in snacks, sausages, dairy products, seasonings, sauces and various other applications.
*Alessandro Alves França, Duas Rodas flavorist
*Catiani Berwanger Balbom Luiz, Duas Rodas flavorists
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