Flavors reaction products

Further evidence of the importance of the Halliard reaction in the formation of volatile flavorants from meat precursors is gleaned by examining ingredients in reaction mixtures patented as synthetic meat constituents. Ching (31), examined 128 patents of meat flavor and found that 55 specified use of both amino acids and sugars. Cysteine, cystine, and glutamic acid were used in 39 such mixtures. Over 80 patents describe meat flavor "reaction products" (32). 

Maga (17D06) has reviewed the occurrence of oxazoles and oxazolines in a variety of processed food systems. Most of them possess green, sweet, and nutty aroma qualities and have been identified in coffee, soy sauce, wheat, and cooked beef and some of them have very low odor thresholds. In 1976, LefflngweU discussed how certain flavorants (reaction products) can be produced in tobacco and tobacco smoke (2337). 

MaillardReaction (Nonenzymatic Glycation), Browned reaction products ate formed by heating amino acid and simple sugar. This reaction is important in food science relating to coloring, taste, and flavor enhancement (79), and is iUustrated as follows ... 

Tea is second only to water in worldwide consumption. Annual production of about 1.8 million T of dry leaf provides world per capita consumption of 40 L of beverage (Table l).1 The scientific interest in tea is due in part to the unusual chemical composition of its leaf and the complex series of reactions that occur when these components are converted to those found in commercial dry tea. Many of the reaction products interact with caffeine, modifying flavor and contributing to the technical problems of tea processing, as will be shown later. 

Human perception of flavor occurs from the combined sensory responses elicited by the proteins, lipids, carbohydrates, and Maillard reaction products in the food. Proteins Chapters 6, 10, 11, 12) and their constituents and sugars Chapter 12) are the primary effects of taste, whereas the lipids Chapters 5, 9) and Maillard products Chapter 4) effect primarily the sense of smell (olfaction). Therefore, when studying a particular food or when designing a new food, it is important to understand the structure-activity relationship of all the variables in the food. To this end, several powerful multivariate statistical techniques have been developed such as factor analysis Chapter 6) and partial least squares regression analysis Chapter 7), to relate a set of independent or "causative" variables to a set of dependent or "effect" variables. Statistical results obtained via these methods are valuable, since they will permit the food... 

The perception of flavor is a fine balance between the sensory input of both desirable and undesirable flavors. It involves a complex series of biochemical and physiological reactions that occur at the cellular and subcellular level (see Chapters 1-3). Final sensory perception or response to the food is regulated by the action and interaction of flavor compounds and their products on two neur networks, the olfactory and gustatory systems or the smell and taste systems, respectively (Figure 1). The major food flavor components involved in the initiation and transduction of the flavor response are the food s lipids, carbohydrates, and proteins, as well as their reaction products. Since proteins and peptides of meat constitute the major chemical components of muscle foods, they will be the major focus of discussion in this chapter. 

Several methods have been introduced which express the degree of oxidation deterioration in terms of hydroperoxides per unit weight of fat. The modified Stamm method (Hamm et at 1965), the most sensitive of the peroxide determinations, is based on the reaction of oxidized fat and 1,5-diphenyl-carbohydrazide to yield a red color. The Lea method (American Oil Chemists Society 1971) depends on the liberation of iodine from potassium iodide, wherein the amount of iodine liberated by the hydroperoxides is used as the measure of the extent of oxidative deterioration. The colorimetric ferric thiocyanate procedure adapted to dairy products by Loftus Hills and Thiel (1946), with modifications by various workers (Pont 1955 Stine et at 1954), involves conversion of the ferrous ion to the ferric state in the presence of ammonium thiocyanate, presumably by the hydroperoxides present, to yield the red pigment ferric thiocyanate. Newstead and Headifen (1981), who reexamined this method, recommend that the extraction of the fat from whole milk powder be carried out in complete darkness to avoid elevated peroxide values. Hamm and Hammond (1967) have shown that the results of these three methods can be interrelated by the use of the proper correction factors. However, those methods based on the direct or indirect determination of hydroperoxides which do not consider previous dismutations of these primary reaction products are not necessarily indicative of the extent of the reaction, nor do they correlate well with the degree of off-flavors in the product (Kliman et at. 1962). 

He gave a lecture ((i) at the 36th Meeting of the Station in November, 1912. As soon as he knew of the report of Maillard (2 ), he made some experiments by the process of Maillard (nach dem Vorgange von Maillard). He obtained dark reaction products which were responsible also for flavor and aroma (cf. 7). 

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. 

Literature information about the sensory properties for nearly 450 Maillard reaction products has been compiled in a survey. It includes qualitative aroma and flavor descriptions as well as sensory threshold values in different media for the compounds, classified according to their chemical structure. 

Non-enzymatic browning reactions play a central role in the formation of food aroma and flavor, especially in heat-treated foods. The purpose of this work is to present sensory data, scattered in the literature, for volatile non-enzymatic browning reaction products and related compounds. The compilation has no pretensions to completeness and only a small part of the extensive patent literature has been covered. Anyhow, it is felt that a compilation of this kind, which has not been available hitherto, would be useful to workers in the field. 

The majority of the compounds in this compilation are Maillard reaction products and likewise recognized as important aroma and flavor substances in foods. 

The studies reviewed demonstrate that browning products produced on retorting of meat inhibit development of WOF, so that canned meat products are not subject to this flavor defect. The flavor of canned meat is less desirable, however, than that of freshly cooked meat. Nevertheless, the strong inhibitory action of the Maillard reaction products against WOF suggests that they could be useful in preventing development of WOF, so further research in this area could be fruitful. 

Knox Ingredients Technology (KIT), successor to Knox Gelatine, a wholly owned subsidiary of Thomas J. Lipton, Inc., is a major producer of HVP s, and of a line of "Tastemaker Natural and Artificial Flavorings" based on them. Recent press releases by KIT are quite explicit about the role of Maillard reaction products in the more sophisticated versions of these flavoring agents. 

Wm. M. Bell Co., Melrose Park, Illinois, is one of the companies active in this technology. They incorporate Maillard reaction products into a variety of flavors, including chocolate. 

Some pyrrole derivatives have pleasant flavor. For example, pyrrole-2-carboxaldehyde gives a sweet and corn-like odor and 2-acetylpyrrole has caramel-like flavor. However, some pyrroles have been found to contribute to off-flavor of food products (24). Pyrroles have not received as much attention as flavor components as other heterocyclic Maillard reaction products such as pyrazines and thiazoles even though the number of derivatives identified is almost the same as that of pyrazines (Figure 1). Proposed formation mechanisms of pyrroles in the Maillard reaction systems are similar to those of thiophenes (Figures 2). 

The importance of Maillard reaction products to the flavor of foods has received considerable attention. One group of Maillard products, the alkylpyrazines, are thought to contribute roasted, toasted and nutty flavor notes to a variety of foods. Several reviews have detailed the presence of pyrazines in a wide variety of foods (1-7). Considerable work has previously focused on mechanisms of formation and the effects of various parameters on pyrazine formation (8-17). Part one of this study reported on the effects of type of amino acid and type of sugar on the kinetics and distribution pattern of pyrazines formed (18). The current study investigates the effect of pH and water activity on the kinetics of alkylpyrazines formation. 

The thermal reaction of cystine and DMHF is important for the generation of meat flavors. The products of this reaction, their flavor compounds, aroma profiles and yields, however, vary according to the reaction parameters. This study focused on determining the effect of the reaction medium, duration, water content, temperature, pH and oxygen on the products of this reaction. 

Thus, the potential role of DMHF as a flavor impact compound and as an intermediate to form additional flavor compounds in heat-abused citrus products should be carefully considered. 2,3-Dihydro-3,5-dihydroxy-6-methyl-4-H-pyran-4-one was also isolated from dehydrated orange juice (37) and is known as a novel nonenzymic browning reaction product. This pyranone has a high threshold value, over 200 ppm (38), and appears to possess negligible odor character. 

A series of alcohols (C4 - Cll) were identified in the tail meat. Odor threshold concentrations were generally higher for alcohols than the aldehyde counterparts. Except for 1-pentanol, the remainder of alcohol peaks were very small and might not be significant in overall arctna of boiled crayfish tail meat. Josephson et al. (23-25) found l-octen-3-ol, an enzymatic reaction product derived from lipids, to be one of the volatile ccxnponents widely distributed in fresh and saltwater fish. The compound 2-butoxyethanol identified in crayfish tail meat (3) has been reported in beef products (26-27). GC aroma perception of standard 2-butoxyethanol gave a spicy and woody note, hence this compound could be an important flavor component of the boiled crayfish tail meat. 

The sensory properties of nearly 450 volatile Maillard reaction products and related compounds have been compiled (45). The review includes quantitative aroma and flavor descriptions, as veil as sensory threshold values for different media, classified according to chemical structure. 

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. 

There is increasing evidence that the interaction of lipids with the Maillard reaction is relevant to the generation of flavor in many cooked foods. For instance, the removal of lipids from coconut has been shown to cause flavor changes in the roast material (12). Uncooked coconut contained significant amounts of lactones as the main aroma components on roasting pyrazines, pyrroles and furans were also found in the aroma volatiles which added a strong nut-like aroma to the sweet aroma of the unroasted coconut. When ground coconut was defatted and then roasted, the sweet aroma due to lactones disappeared and the product possessed a burnt, nut-like aroma. A marked increase in the number and amount of Maillard reaction products, in particular pyrazines, was found. 

It has been known for many years that Maillard Reaction products can behave as antioxidants in food systems (13,14), and they have been shown to inhibit warmed-over flavor development in cooked meat which is caused by the autoxidation of lipids, especially phospholipids. There has been a significant amount of research examining the Maillard reaction products and intermediates from model systems which may have antioxidative properties. 

The extruder is a continuous high-temperature short-time reactor. Ingredients, moisture, temperature, pressure, and shear can interactively produce many Mail lard-type flavor compounds. As the extrudate exits the extruder, many of the volatile reaction products may be lost with steam since the extrudate passes from a zone of relatively high pressure within the extruder to atmospheric pressure. By controlling formulation variables, the extruder can serve as a useful tool to thermally produce volatile and nonvolatile compounds which make significant contributions to overall flavor. 

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