Process flavor

Aromas obtained by heating aroma precursors are used in the aromatization of foods. An important aim of process flavors is the production of odor qualities similar to those of meat. This is achieved especially on heating cysteine with ri-bose, as shown in Table 12.26. Glucose is less effective and rhamnose promotes the formation of HD3F. 

For economic reasons, attempts are made to replace individual precursors with inexpensive materials, e. g., a relatively inexpensive protein hy- 

Fats or oils are added to produce the carbonyl conqtounds which contribute to the animal species specific note of meat aroma. 

If cooked meat is stored for a short time, e. g., 48 h at ca. 4 °C, an aroma defect develops, which becomes unpleasantly noticeable especially after heating and is characterized by the terms metallic, green, musty and pungent. This aroma defect, also called warmed over flavor (WOF), is caused by lipid peroxidation (cf. 12.6.2.1). The indicator of this aroma defect is hexanal, which increases as shown in Table 12.27. 

Other changes which contribute to the aroma defect are the increase in metaUic/musty smelling epoxydecenal, which, like hexanal, is formed in the peroxidiation of linoleic acid (cf. 3.7.2.1.9), and the decrease in HD3F. The latter is probably due to the reaction of its enolic OH group with peroxy radicals. 

---

These evaporators operated somewhere between 48.9° and 82.2°C (120°-180°F). Fruit solids remained in these evaporators for a minimum of 30 minutes hence, the products produced on such evaporators were of poor quality and exhibited a strong heat processed flavor. 

The sugars, which contribute much to the acceptability of citrus juices, under adverse conditions can play a major role in the formation of off flavors that reduce the acceptability of the citrus juices and their products. The sugars, primarily the hexoses, can participate in "browning" reactions that cause darkening of the juice and these reactions give rise to components that are described generally as apricot-like or pineapple-like in flavor. In general,the more processed flavor that a citrus product exhibits, the less acceptable it becomes to the consumer. 

What is the current use of the research results Needless to say, the food industry has found use for a great deal of the information. The industry has used the knowledge to control processes and hence to develop better tasting food products. However, one of the most intriguing uses of the information has been in the development of flavorings. The first patent for the use of the Maillard Reaction to create processed flavor, as the Flavor Industry refers to it, was... 

The A,A-dimethylaminomethylene derivatives (81) of ten HAA listed in Table 2.B-C were analyzed by GC-MS or GC-NPD. All mass spectra showed the [M]+ peak. More convenient was analysis with NPD for which the LOD for injection were in the range of 2 pg for 25a to 15 pg for 23a, with good linearity from 0.5 to 10 ng in all the studied cases170. This method was used in detection and estimation of 25a, 28b and 30a in the Danube River106. A routine search for the carcinogenic HAA of Table 2.B-C in meat and process flavor products was proposed, based on the cleanup methods for such samples mentioned in Section III.A.5, derivatizing with 3,5-bis(trifluoromethyl)benzyl bromide (82), and capillary GC-SIM-ESI-MS143. 

Manley, C. Process flavors. In Source book of flavors, Reineccius, G. (Ed.), Chapman Hall, New York, 1994, 139-154. 

Manley, C. Process flavors and precursor systems commercial preparation and use. In Thermally generated flavors Maillard, microwave, and extrusion, Parliment, T.H., Morello, M.J., McGorrin, R.J. (Eds.), American Chemical Society, Washington, DC, 1994, 16-25. 

Baek, H.H., Kim, C.J., Ahn, B.H., Nam, H.S., Cadwallader, K.R. Aroma extract dilution analysis of a beeflike process flavor from extruded enzyme-hydrolyzed soybean protein. J. Agric. Food Chem. 2001, 42, 790-793. 

From thousands of flavor raw materials, 20-50 items are commonly selected and mixed with different ratios to blend a flavor. This is called flavor compounding, which is a kind of formulation. The raw material may be organic chemicals, essential oils, extracts, oleoresins, or processed flavors. Knowledge of their nature, physical and organoleptic properties, and applications is needed by flavorists. Flavor compounding requires at least 3-5 years of training. 

Process flavors include processed (reaction) flavors, fat flavors, hydrolysates, autolysates, and enzyme modified flavors. Production of dairy flavor by enzyme modification of butterfat is an example (Lee et al., 1986 Manley, 1994), while meat flavor produced by enzymatic reactions has a much longer history. 

Process flavors are very successful in some cases, but unsuccessful in many others. Natural flavor materials such as meat extract or aromatic chemicals may be added to process flavors to enrich some notes or to increase the overall intensity. 

International Organization of the Flavor Industry, IOFI guidelines for the production and labeling of process flavorings, in Code of Practice for the Flavor Industry, 2nd ed., International Organization of the Flavor Industry, Geneva, 1990, p. FI. 

Considerable progress has been made in chmcterization of process flavors, study of flavor precursors, and flavor regulation. Nevertheless, die growing demand for authentic and ethnic foods in the western world calls for renewed efforts in process and reaction flavors. Moreover, although work is underway to elucidate structure and properties of taste-active compounds in process and reaction flavors, more work remain to be done. This symposium reports recent significant findings in process and reaction flavors. 

Process flavors are widely used in prepared foods to enhance the taste and odor of these products. Process flavors were identified as potential dietary sources of heterocyclic amines, both monocyclic heteroaromatic amines (MHAs), and polycyclic heteroaromatic amines (PHAs). MHAs are innocuous substances, some of which have flavoring characteristics. However, PHAs are reported to be potent mutagens and animal carcinogens (Munro et aL, 1993) and have been the subject of significant interest regarding their potential human health risk. 

An assessment of the potential presence of PHAs in process flavors, and the implications for the safety assessment of these flavors, was sponsored by the Flavor and Extract Manufacturers Association of the United States (FEMA). The assessment was conducted in three stages (1) identification and quantification of PHAs in process flavors (2) identification of the food categories which could potentially contain process flavors and calculation of their respective daily per capita intakes and (3) determination of the daily per capita intake of PHAs through consumption of foods identified as sources of naturally-occurring PHAs compared to foods containing process flavors. 

This report describes work done during the 1990s to provide an indication of the degree to which PHAs are present in process flavors through normal manufacturing processes. Much of the analytical work was performed by the... 

Process flavors are most often prepared by the heat processing of foods or food ingredients followed by isolation and purification. In general, process flavors mimic flavors present naturally in cooked foods. Process flavors are used at low levels because of their powerful organoleptic qualities. Manley (1999), and Janiec and Manley (2003) have reviewed various aspects of process flavor production and use. 

Intake of process flavors from foods in various categories was determined based on the Nationwide Food Consumption Survey (NFCS) database, which was derived from surveys of U.S. food consumption conducted by the U.S. Department of Agriculture (USDA) in 1977-1978. Although 1987-1988 data were available, the 1977-1978 data were considered to be more representative of the general population (n= 30,770 n = 28,006 for individuals providing a 3-day diet history) than the more recent 1987-1988 data (n = 10,193 total n = 8,224 with a three-day diet history). Data were not available for the years after 1988 at the time the analyses reported here were performed. 

---