Meat-like flavors

In their recent comprehensive review of natural and synthetic meat flavors, MacLeod and Seyyedain-Ardebili (20) listed 80 patents describing "reaction products" procedures that produced meat-like flavors upon heating. Approximately one-half of these precursor mixtures included amino acids and reducing sugars. Most of the mixtures described in patented procedures for synthetic meat flavor are modeled after ingredients found in the water-soluble dialy— zable fraction of fresh meat. These constituents serve as reagents for Maillard reactions. 

A maltol-ammonia browning reaction produced thirteen pyrazines, two pyrroles, two oxazoles, and one pyridine (12). The major products of this system were 2-ethyl-3-hydroxy-6-methylpyridine and 2-ethyl-3,6-dimethylpyrazine. It is difficult to construct possible formation mechanisms for these compounds from maltol and ammonia. All the carbon atoms must come from maltol. It is possible, then, that maltol degrades into smaller carbon units and that these fragments recombine to form larger carbon units, producing these compounds. Recently, the formation of thiophenones and thiophenes from the reaction of 2,5-dimethyl-4-hydroxy-3(2H)-furanone and cysteine or cystine was reported (13. 14). All these reaction mixtures were reported to possess a cooked meat-like flavor. 

Vhile the majority of Maillard technology patents deal vith the production of meat-like flavors (1), it is appropriate to comment on the significance of "reaction flavor" patents. During the past 30 years, several hundred patents have been granted vorldvide for processes and reaction products based on non-enzymatic brovning technology. Less than 100 of these are included in Chemical Abstracts, since subsequent patents are listed in patent concordance. 

Most of the original patents referring to meat flavors utilizing Maillard technology vere claimed by Unilever (48-52 56,57). More recent patents are involved with the production of meat-like flavors. While a majority of patents are concerned vith cysteine, cystine, or methionine as the sulfur source, others claim alternatives such as mercaptoacetaldehyde, mercaptoalkamines, etc. Several patents (53,54), declare the contribution to meat-like flavors produced from thiamine in the Maillard reaction. Alternately, a technical report describes the volatile flavor compounds produced by the thermal degradation of thiamine alone (55). 

Heterocyclic compounds are dominant among the aroma compounds produced in the Maillard reaction, and sulfur-containing heterocyclics have been shown to be particularly important in meat-like flavors. In a recent review, MacLeod (6) listed 78 compounds which have been reported in the literature as possessing meaty aromas seven are aliphatic sulfur compounds, the other 71 are heterocyclic of which 65 contain sulfur. The Strecker degradation of cysteine by dicarbonyls is an extremely important route for the formation of many heterocyclic sulfur compounds hydrogen sulfide and mercaptoacetaldehyde are formed by the decarboxylation and deamination of cysteine and provide reactive intermediates for interaction with other Maillard products. 

Flavor notes of products of amino compounds-sugars reaction were reviewed with emphasis on amino-ribose system. Meat-like flavor was imparted by browning reaction products of camosine-, citrul-line-, histidine-, glutamic-, 2-pyrrolidone-5-carboxylic-, methionine-, cysteine-, cysteic-, and taurine-ribose. Recent advancements in nitrogen-, oxygen- and sulfur hetercyclics and lipid browning were presented. 

Yu, T.H., Wu, C.M., and Ho, C.T., Meat-like flavor generated from thermal interactions of glucose and alliin or deoxyalliin,./. Agric. Food Chem. 42, 1005, 1994. 

The economical value and high popularity of meat lead to the production of meat-like flavors through process chemistry. Several heat-induced reactions lead to the formation of meat flavors. These reactions are the pyrolysis of peptides and amino acids, the degradation of sugars, the oxidation, dehydration, and decarboxylation of lipids, the degradation of thiamin and ribonucleotides, and interactions involving sugars, amino acids, fats, H2S, and NH3 [110],... 

Despite the acknowledged importance of these furan- and thiophenethiols and their disulfides in meat-like flavors, it is only recently that compounds of this type have been reported in meat itself (8-10). Grosch and co-workers (11) have suggested that the 2-methyl-3-furanthiol and its disulfide are more important in the aroma of boiled meat than in roast beef where alkylpyrazines, 2-acetyl-2-thiazoline and 2,5-dimethyl-4-hydroxy-3(2 -fiiranone make greater contributions. 

The term processed flavor is used in different contexts to describe (a) products where the natural raw materials lack a characteristic flavor profile and the desired aromatic profile is achieved only by deliberate processing (e.g., coffee) (b) flavorings created as a result of Maillard and other related reactions between amino acids and sugars (e.g., meat-like flavors) (c) flavorings resulting from controlled enzymatic reactions (e.g., enzyme-modified dairy products) (d) products made by fermentation (e.g., wines, vinegar) and (e) products of thermal reactions of lipids (e.g. French fry flavor). 

The reproduction of meat-like flavors through process chemistry has been a primary target of the flavor industry for many years. Meats are expensive, and thus there is a strong financial incentive to develop substitute flavorings. The chemistry of raw and cooked meat flavor has been the subject of considerable research over the past 30 years, and this has provided the flavor indusfiy with invaluable data for the recreation of process meat-Uke flavorings [14-18]. 

The development of meat-like flavorings has been an evolutionary process [19], Early meat-like flavorings would probably more correctly be called meat extenders and were largely made from spice blends. The manufacturer would use spices normally associated with specific meats and sell them as meat enhancers or extenders. In the U.S. culture, one can envision sage being associated with pork, turmeric and celery with chicken, and onion and black pepper with beef. The use of these spice combinations did little to enhance the true meat flavor, but at least there was a flavor. Meat extracts have found some use in the industry and still do today. These byproducts of the meat processing industry (e.g., corned beef) provide little desirable flavor but contribute to a label statement of meat being present. 

Acids are typically used to adjust the pH of the reaction system. Meat-like flavorings are generally thermally processed at pHs around 5.2, similar to the pH of meat. Phosphoric acid is most commonly used since it is known to be a catalyst of the Maillard reaction. Other inorganic adds also may be used such as hydrochloric or sulfuric acids. Numerous organic adds appear in the patent literature. These acids typically contribute a flavor of their own and may be used to not only produce a given pH but also add a desired sensory note. Cittic, lactic, acetic, propionic, maUc, succinic, and tartaric acids appear in the patent literature. 

Some of the earlier research on meat flavors demonstrated that the common meaty characteristic of cooked meats can be reproduced by heating the water soluble components of the meats [33-35,16]. However, the differentiation amongst species was found when the lipid portion of the meat was heated. This has resulted in most meat-like flavorings using a similar base meat reaction system but then using added lipid to provide the unique species character of the meat, lamb or fish, for example. 

These common components of meat-like flavorings are nearly universally used in the industry [19]. While there has been and continues to be a negative consumer attitude towards the use of MSG and HVP, their use continues since they are essential to the sensory character of meat-hke flavorings. (MSG is associated with the Chinese... 

Colorants — There is little rationale to add colorants (e.g., caramel color) to a meat-like flavoring other than for the convenience of the final user. The colorant would be added to color the final product, thus the choice of the colorant and its usage level would be customer product dependent. 

Many of these products can be further enhanced by the use of top noting. This is similar to the process as it is applied to meat-like flavorings. Pure chemicals are added to the EM dairy product to provide notes not obtained in subsequent EM treatment. This process can greatly strengthen and round out an EM dairy flavoring. The availability of numerous natural dairy flavor chemicals often permits these top noted products to carry a natural label. 

In the indnstry, a large portion of the process flavorings (meat-like flavors) are dried by tray drying. This process involves a substantial amount of heat that continues the reaction process and also retains a high amount of aroma components. This drying process is well suited to thermoplastic/hygroscopic materials, which includes the majority of meat-like flavorings. 

W. Grosch and G. Zeiler-Hilgart, Formation of meat-like flavor compounds. Flavor Precursors—Thermal and Enzymatic Conversations (R. Teranishi, G. R. Takeoka, and M. Giintert, eds.), Washington, DC, 1992, p. 183. 

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