Liquid Smoke Application to Cured

James C. Schneck*

It is believed that the natural process dates back to The possible reactions that take place during the combus- very early man. Fire for warmth in the dwellings of these early tion of the giant molecules of the three major components of people was a prime ingredient for survival. Meat products (, and ) result in over 200 were hung in these dwellings and, thus, quite by accident, the different identifiable compounds. In general, however, all of benefits of smoking were realized-the initial benefit being the chemical components of smoke can be grouped into four that of preservation from spoilage organisms. We might, major classes. These classes are the acidic compounds, the therefore, speculate that smoke could be classified as the first phenolic compounds, the carbonyl compounds, the hydro- meat additive. carbons. The first three classes of compounds contribute to In modern meat technology, the use of smoking for preser- the smoke coloring and flavoring reactions while the fourth, vation has been superseded by cooling, freezing and canning, the hydrocarbons, are undesirable. as well as sanitary processing, packaging transportation and The origin of these compounds from the particular wood storage. The desire for smoked meat and color, how- fractions can only be generalized, as all wood fractions do ever, still exists, and smoke flavoring and coloring are definite contribute to all smoke components. Lignin, is however, the processing steps in modern meat technology. primary contributor of the phenolic fraction and the smaller Smoke by definition is a system of solid particles dispersed carbonyl molecules. The hemicellulose fraction contributes to in a gaseous medium. The gases result from the combustion the larger more reactive carbonyl compounds. The cellulose of carbonaceous materials. Historically, this carbonaceous fraction, as well as the other two, contributes the acid fraction material has ranged from sheep manure to and cherry which also is characteristic of natural smoke. The primary wood. The wide range of cellular components from these acid is or . combustibles will certainly result in different smoke compo- nent percentages. A brief review of the relationship between How They Contribute smoke components and plant cellular components will be In general, the ways these groups of compounds contribute covered later. to the smoke flavoring reactions are as follows: One of the more significant studies on the nature of wood smoke is that of Foster and Simpson in 1960-61. These inves- Besides contributing to the “smoky” flavor, the acidic tigators showed that wood smoke consisted of two discrete compounds accelerate the nitrite reaction, with the result- phases-a dispersal liquid phase (smoke particles), and a dis- ing more rapid pink color formation (cure reaction). The persing gas phase (smoke vapors). These phases were in gen- acidic substances of smoke also contribute to the skin for- eral equilibrium with each other, with the individual smoke mation on the surface of wieners, which, among other constituents distributed between them according to their re- things, aids in peeling. spective partition coefficients. The phenolic substances are the main contributors to the More importantly, however, Foster and Simpson proved ”smoky” flavor. They vary greatly in their flavor potencies that the flavor and color reactions that smoke undergoes with and astrigencies and sometimes over-contribute to the meat are almost entirely due to the products in the vapor point of being medicinal in aspect. They also react with phase. They were able to precipitate electrostatically the par- the carbonyl compounds to form resinous substances ticulate phase from smoke and found that it made very little which give a sheen to the surface of smoked . difference in the smoke flavoring and coloring of . Accord- The carbonyls contribute some sharpness to the flavor of ingly, the conclusion can be drawn from the Foster and smoke, but probably their main contribution is to the Simpson study that the portion of smoke that you can see is “smoky” brown color and sheen. The primary reaction in not the most important component when it comes to smoke forming the ”smoky” brown color is the well-known flavoring meat; instead, the most important component is the “browning” reaction between the carbonyls of the smoke vaporous phase which you cannot see. and the amino groups of the meat protein. The hydrocarbons, especially the polycyclic compounds such as benzyprene, that are formed in trace amounts dur- ing the of wood are undesirable because they are *lames C. Schneck, Ked Arrow Products Company, Man- carcinogens. itowoc, WI 54220 We have generally defined the basic characteristics of Reciprocal Meat Conference Proceedings, Volume 34, natural smoke components and their contributions to the 1981 natural smoking process.

101 102 American Association

The physical phenomena (what happens on the meat sur- ply the cost of , Following is a list of the important face during smoking) has also been extensively investigated cost considerations with natural smoke: through the work of Foster and Simpson. They proved rather 1. Smoke generator purchase and maintenance with mainte- conclusively that the vapor phase of smoke dissolves in the nance probably being the most important cost factor. surface and interstitial water of the meat forming a smoke SO- 2. Smokehouse cleaning costs: Detergent and labor. lution; the smoke solution then becomes the effective smok- 3. Effluent control: Purchase and maintenance of after- ing agent. The active or good coloring potential carbonyls burners or scrubbers, their energy requirements. react with the amino groups of the protein giving the charac- 4. Additional smokehouse maintenance due to heavy use of teristic brown Maillard type reaction. The water soluble cleaner. and acids are also present to impart the characteristic smoke flavor. There is also a percentage of fat or oil soluble A detailed study on the costs of natural smoking was made phenols that when deposited impart the characteristic yellow by a large processor in an environmentally controlled area on or golden color to the fat on the meat surface. It is important the West Coast. Their report indicated that natural smoking to note, however, that this type of smoke color is derived from cost them approximately $0,37/cwt. of product. Approxi- the color of the phenols themselves and does not represent a mately half of these costs were incurred from their after- brown Maillard type reaction. A good example of this is the burner. Liquid smoke processing is certainly competitive, with color obtained on the fat side of . The general nature an average cost in the range of $0.08-$0.20 cwt. of product. and mechanisms of smoke and smoking of food, as outlined, The application of smoke flavoring can be divided into two thus conclude that the important vaporous components are general areas-outside smokehouse application and inside absorbed in the product surface moisture and thus a liquid smokehouse application. smoke is produced. The popular use of liquid smoke as a replacement for the Outside the House-Direct Addition natural smoking process has been a rather recent develop- The easiest and most accurate method of liquid smoke ap- ment. The use of a crude form of liquid smoke (pyroligneous plication is direct product addition. Until recently, this type of acid) does, however, date back several thousand years. In an- application has generally been limited to or chopped cient Egypt pyroligneous acid was used as one of the primary type products. This method has ranged from direct addition of ingredients in mummification. As we know, this gave tremen- the aqueous type products at the chopper to spray application dous body shelf-life regardless of accurate body code dating. to the inside of the container prior to product addition such as Today the modern liquid smoke products differ from with canned . pyroligneous acid in their ability to produce the brown smoke Malto Dextrins and vegetable oil have also been used suc- color and a more mellow smoke flavor. This is accomplished cessfully as carriers for the various smoke components. In ad- primarily through controlled oxidation of the natural smoke dition to the specific physical advantages of these products, soon after production. they also have selective absorptive qualities for the various smoke components from the aqueous phase. This gives them distinct smoke flavor characteristics for specific applications. Liquid Smoke Application Usage levels of these products depend upon the smoke flavor used and the results desired. In general, however, levels I would now like to outline briefly some of the advantages in the range of 4-8 OZ. of flavoring per 100 Ibs. of product will in the use of liquid smoke, as I see them; then I shall proceed produce the desired results. with descriptions of some of the modes of liquid application. The direct addition of aqueous smoke to the pickle These advantages are as follows: for pumped products such as and bacon is not recom- mended. The acid fraction in the aqueous product combines The uniformity of the smoke flavored product is generally with the nitrate liberating parsonous nitric oxide gas. Nitrite much better once the means and level of liquid smoke levels in the pickle are also substantially reduced. application have been established. In other words, it is Recently a unique new smoke flavor has been developed much easier to establish and standardize the addition of a for this direct application method. It a very low acid con- known liquid flavoring than to reproduce the vaporous has smoking process. centration while retaining a high flavor profile. The product utilized Tween 80 as carrier for complete pickle The use of liquid smoke is generally acknowledged to be a simpler and more sanitary than dealing with the mess of solubility. It is also classified as a natural smoke flavor. Usage sawdust handling, smokehouse cleaning, etc. levels in the range of 1-2 oz. per 100 Ibs. of product has produced satisfactory results. The use of liquid smoke is a possible solution to the smoke emission problem. To my knowledge, the use of our prod- The major disadvantage to direct addition is that the liquid ucts as a replacement for natural smoking has met every smoke is dispersed throughout the product, which dilutes its national, state, and local EPA air quality standard. effect on surface color. From a smoke flavor standpoint, how- The use of an approved liquid smoke avoids the apprehen- ever, direct addition certainly satisfied the requirement. sion over whether smoke adds a significant level of recog- When smoke flavoring is added as an ingredient in this nized carcinogens to meat. manner, the meat inspection regulations state that the product shall be marked with the words, “Smoke Flavoring Added.” When considering the costs of natural smoking compared The ingredient statement must also acknowledge the smoke to liquid smoke many factors must be eialuated. It is not sim- flavor in order of priority. 34th Reciprocal Meat Conference 103

Outside the House-Dipping or Spraying smoke. The atomization process generally occurs under static house conditions to prevent loss of smoke flavoring to the The most efficient method for imparting a smoke color and environment. Following atomization the house is restarted flavor to a meat product is by dipping or spraying-totally and the cooking cycle continues. wetting the meat surface with smoke flavoring. On a continu- The primary disadvantage of this process is its inefficiency ous wiener line, for example, liquid smoke can be substituted relative to the dipping or spraying method. In-house atomiza- for the acid in the coagulation area to produce a uniform con- tion will also result in more cleaning and, in general, a trolled smoke color and flavor. The acid fraction of the smoke lengthening of processing time. solution will also aid product peelability. The primary advantage is its simplicity of installation and a general guideline a 25 to 40 percent CharSol C-10 As uninterrupted product flow to the smoke house. solution is used for wiener products with a 45-75 second con- tact time. The spray solution is also heated to a temperature of lnside the House-Vaporization 100’ to 110°F to improve casing penetration. With batch houses the entire tree can be sprayed in a suitable spray The second inhouse application method which has had cabinet. limited success is the Jenson or vaporization method of appli- Coating the cage with epoxy paint or having stainless cages cation. With this procedure the smoke flavor is atomized or is recommended to prevent corrosion. A stick sprayer to sprayed onto a heated surface. The surface temperature is in handle sausage items has also been developed, if application the 700°F range. The smoke flavor upon contact with the is more operationally acceptable near the stuffing area. heated surface immediately vaporizes into a true smoke Ham-type products can also be sprayed satisfactorily, but cloud, which is then introduced into the house through blow- modifications to the equipment may be necessary to accom- ers or existing smoke house duct work. modate the different cage dimensions. Casing boneless ham The primary disadvantage with this method is the con- products may be successfully smoked with CharSol by soak- tinued existence of an exterior smoke generator and con- ing the casings in a smoke solution prior to stuffing. tinued maintenance of such equipment. Bacon products, in general, do not lend themselves to The primary advantages are improved efficiencies in smoke spraying or dipping directly after combing, as the wet surface deposition as compared to the atomization process. condition of this product produces a muddy smoked appear- The results obtained from both atomization and vaporiza- ance. If the product is staged for four to six hours before tion are closely related to the cooking conditions available in spraying to dry the product surface, a brighter, cleaner smoke the smoke house. Because of the smoke house variable it is color will result. not possible to recommend one cooking or smoking schedule The primary disadvantage of this application method, espe- that will be satisfactory to all processors. cially in batch operations, is that the product flow may be We have found that the relative humidity conditions nor- interrupted or delayed between stuffing or hanging and the mally achieved during heat processing with natural vaporous smokehouse. Custom equipment designed for particular ap- wood smoke generally do not apply when using liquid plication needs has, however, minimized this effect. smoke. With vaporous wood smoke increased dehydration The advantage of this process is that the contact time and occurs because of the distillation of hot organic vapors over solution concentration can be varied to suit the product; the the product surface. Therefore, with liquid smoke processing smoke solution can be recycled and thus more fully utilized. a lower house relative humidity is necessary before applica- The smoking process has also been separated from the cook- tion. Following application, a low house humidity is also rec- ing process which should also minimize house cleanup. I will ommended to compensate for the excess humidity during discuss the effects of the smokehouse on smoke color devel- smoking. opment a bit later. With the development of commercial smoke flavors, one of the smoking variables, the smoke itself has been eliminated. It lnside the House-Atomization is important to note, however, that the other variable, the heat processing chamber, still exists. This method of applying liquid smoke to meat products has Many technical advancements have been made by the attracted considerable attention because of its simplicity and smoke house manufacturers but in many cases the lack of ease of adaptation. This method commonly known as the proper maintenance of this equipment results in product var- “Zestismoke” process (U.S. Patent No. 3,503,760) atomizes iability regardless of the smoking method. the smoke flavoring into the house after the product is A smoke house is required to operate for long periods of warmed and the meat surface dried. time in a hot, humid and smoky environment which is con- One or more atomization nozzles, producing the majority ducive to equipment malfunctions. Cleaning with strong de- of liquid droplets in the 100 micron range or smaller are tergents also takes its toll on panel and door seals, bearings, placed inside the smoke house. Air and aqueous smoke flavor black iron air make-up units and floors. Liquid smoke will are then supplied to the nozzles from outside the house. The certainly reduce many problems, but satisfactory results from resulting atomized cloud envelopes and reacts with the prod- its use are still dependent, in many cases, on the smoke house uct surface in a manner that visually represents vaporous itself.