Flavor and Aroma Compounds

Flavor is defined as the blend of taste and smell sensations evoked by a substance in the mouth and is evaluated using sensory analysis. It results from the pCTception of (i) a few wate-soluble, taste compounds related to the five basic tastes (sweet, salty, bitta-, sour, and umami), and (ii) a diversity of aroma compounds, which are odorous volatile compounds, responsible for the variety of flavors encountered in fermented foods. 

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Table 10. Examples of Permeation of Flavor and Aroma Compounds in Selected Polymers at 25 C, Dry...

Methods of fixing the volatile aroma and flavor compounds separately from the instant coffee powder have been developed. The volatile mixture can be mixed with aqueous gelatin or gum arabic and spray dried. The oily droplets of the flavor and aroma compounds are coated with gelatin or gum arabic in a dry lattice. This powder can be mixed in with instant coffee powder and is relatively stable in the presence of air. Emulsification with sugar is also a highly effective way of trapping and preserving coffee volatiles, but is of limited use for instant coffees. 

The coffee beans with the most desirable flavor to many tastes are the highest grown Arabicas prepared by the wet method. Coffee beverages need to be prepared within 8 h of grinding the freshly roasted coffee beans if the volatile flavor and aroma compounds are to be retained. Brew... 

Although citric acid is present in milk in small amounts (0.07-0.4%), it is a required substrate for production of desirable butter-like flavor and aroma compounds in cultured products. Because seasonal variation in the citrate content of milk is sufficient to affect the flavor of cultured products (Mitchell, 1979), milk may need to be supplemented with citrate to produce cultured products with consistent flavor. Citric acid is metabolized by many organisms found in milk, including S. lactis subsp. diacetylactis, Leuconostoc spp., Bacillus subtilis, various lactobacilli, various yeasts, coliforms, and other enteric bacteria. 

TABLE 4. EXAMPLES OF PERMEATION OF FLAVOR AND AROMA COMPOUNDS IN SELECTED POLYMERS AT 25°Ca, DRYb... 

Even in this case, the use of a hybrid process combining NF, IE, and ED appears to improve the economics and performance of the tartaric stabilization of wines. For instance, Ferrarini (2001) proposed to split raw wine into a retentate and permeate by NF. The permeate, being richer in minerals, was processed by using in sequence cationic and anionic exchange resins and ED to reduce its potassium, calcium, and tartrate ion contents. By recombining the de-ashed permeate with the NF retentate, Ferrarini (2001) asserted to obtain a stabilized wine retaining almost all the flavor and aroma compounds originally present in raw wine. 

Garnero, J. In The Chemistry of Heterocyclic Flavoring and Aroma Compounds Vernin, G. Ed. John Wiley Sons New York,... 

K.-H. Engel, Stereodifferentiation of Chiral Flavor and Aroma Compounds. In Capillary Gas Chromatography in Food Control and Research R. Wittkowski, R. Matissek, Eds. Behr s Verlag Hamburg, 1992 pp 149-175. 

Biosynthesis of Chiral Flavor and Aroma Compounds in Plants and Microorganisms... 

Aside from deacidification, MLF may also influence the sensory qualities of a wine by the production of many flavor and aroma compounds (Davis et al., 1985, 1988 Henick-Kling, 1993 Kunkee, 1967 Rankine, 1977). However, there is still debate regarding the contribution of MLF to the sensory properties of a wine. Early work by Kunkee et al. (1964) and Rankine (1972) indicated that MLF may not have a measurable effect on the sensory properties of a wine. On the other hand, many other studies have shown that MLF causes significant changes in wine aroma and flavor (Boido et al., 2002 Delaquis-Pascal et al., 2000 De Revel et al., 1999 Gambaro et al., 2001 Henick-Kling, 1995 Laurent et al., 1994 Maicas et al., 1999 McDaniel et al., 1987 Nielsen and Richelieu, 1999). 

The RAPID emergence OF BIOTECHNOLOGY and its potential application in agricultural and food production has demonstrated the need for an interdisciplinary exchange in the area of biological generation of flavor and aroma compounds. 

Bowing to consumer demand for these products, the flavor industry is beginning to enlist the help of biotechnology to produce natural flavor and aroma compounds via fermentative routes. At this time, the production of these fermentation compounds is a largely untapped area of bioconversion research in which bioesterification has great potential as esters play a key role in flavors. 

Permeation of flavor (and aroma) compounds in polymers can be part of flavor management in two general ways. First, unintended species can enter the food by permeation from the environment or by migration from the package itself. 

Instrument. The analytical instrument for these experiments is shown schematically in Figure 1. This instrument was designed and built at The Dow Chemical Company for measuring the permeation of flavor and aroma compounds through polymer films. The gas handling section of the instrument contains the plumbing, containers of aroma solutions, and the experimental film. This enclosure is insulated, and the temperature can be controlled, + l C, from subambient to about 150 C. The detector is a Hewlett-Packard 5970 mass spectrometer. More details are available (2). 

Important flavor and aroma compounds can be lost to the food package by sorption. 

Gatfield, I.L., Production of flavor and aroma compounds by biotechnology, Food TechnoL, 40, 110, 1988. 

Industrial Fermentation. The primary and largest industry revolves around food products. Milk from cows, sheep, goats, and horses have traditionally been used for the production of fermented dairy products. These products include cheese, sour cream, kefir, and yogurt. More recently so-called probiotics appeared and have been marketed as health-food drinks. Dairy products are produced via fermentation using lactic bacteria such as Lactobacillus acidophilus and Bifidobacterium. Fungi are also involved in making some cheeses. Fermentation produces lactic acid and other flavors and aroma compounds that make dairy products taste good. 

Humidity. Hydrophilic polymers such as polyamides and EVOH ahsorh water from humid air. For example, water sorption isotherms for Nylon have been determined hy Hernandez and Gavara. The presence of water in a hydrophilic polymer affects the permeability of, oxygen, carbon dixide, organic vapor, and flavor and aroma compounds. An increase in moisture content increases oxygen permeability in EVOH (Fig. 11.6). Nylon 6, while for amorphous nylon the permeability tends to decrease (Fig. 11.12). 

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