Flavor chemical spaces

The concept of activity landscapes can also be extended to property landscapes where any set of measurable molecular properties can be added as another dimension to the chemical space of a compound dataset [146], In line with the concept of activity cliffs, odor cliffs [181] and flavor cliffs [182] have been recently described. 

It is possible to draw a direct analogy between chemical space and flavor space. A thorough discussion of chemical space is described elsewhere [9], while a comprehensive discussion of flavor and fragrance-relevant chemical space is discussed by Reymond et al. in Chap. 2 of this book. 

A persistent idea is that there is a very small number of flavor quaUties or characteristics, called primaries, each detected by a different kind of receptor site in the sensory organ. It is thought that each of these primary sites can be excited independently but that some chemicals can react with more than one site producing the perception of several flavor quaUties simultaneously (12). Sweet, sour, salty, bitter, and umami quaUties are generally accepted as five of the primaries for taste sucrose, hydrochloric acid, sodium chloride, quinine, and glutamate, respectively, are compounds that have these primary tastes. Sucrose is only sweet, quinine is only bitter, etc saccharin, however, is slightly bitter as well as sweet and its Stevens law exponent is 0.8, between that for purely sweet (1.5) and purely bitter (0.6) compounds (34). There is evidence that all compounds with the same primary taste characteristic have the same psychophysical exponent even though they may have different threshold values (24). The flavor of a complex food can be described as a combination of a smaller number of flavor primaries, each with an associated intensity. A flavor may be described as a vector in which the primaries make up the coordinates of the flavor space. 

In the time and space available to me, I shall largely confine my comments to the origin of the chemical studies on this remarkable element. In so doing I shall include quotations from my Journal in order to help capture some of the flavor of this pioneering work. 

Obtaining relevant physicochemical parameters. The choice of physicochemical parameters to relate to MDS spaces is crucial if the properties found to be mathematically important are indeed appropriate chemical predictors for future design of molecules with desired flavor properties. Unfortunately, we often have no idea what physicochemical properties are indeed important, although many of the parameters described in the examples below as well as those given in Table I (see are probably... 

This chapter discusses some of the more important natural products terpenes, steroids, alkaloids, fats, and prostaglandins. (Fats are primary natural products, but it is convenient to include them in this chapter.) The structures and various aspects of their biosynthesis and chemical reactions are presented in subsequent sections. Because entire books have been written on each of these groups of compounds, the coverage here is necessarily incomplete. However, the intent is to present some of the flavor of their chemistry. Many other classes of naturally occurring organic compounds are not included for reasons of space. 

Figure 4. Projection of flavor samples into the space of the first three principal components with data acquired using the headspace chemical sensor.

Flavor compounds (aroma compounds). Term for volatile compounds in food that are perceived by osmoreceptors (see aroma chemicals) either directly in the nose (smelling, nasal perception) or in the pharyngeal space on eating or drinking (retronasal perception). Together with the generally non-volatile taste compounds (sour, sweet, bitter, salty, or spicy tasting compounds). F. c. make a decisive contribution to the taste of a food, the consistency of the food also contributes to the complete sensory impression. 

Yeretzian, C., Jordan, A., Brevard, H., and Lindinger, W. 2002. Time-resolved head-space analysis by proton-transfer-reaction mass-spectrometry. In Flavor Release. Eds. Roberts, D. D., Taylor, A. J. ACS Symposium Series 763. American Chemical Society Washington, DC, pp. 58-72. 

In 2011, a Scottish whisky distillery sent unmatured spirit and charred oak in two separate samples into space in a Russian cargo ship. Once in orbit, the contents were mixed and left to mature over two years under zero gravity conditions. In collaboration with space scientists, the experiment hopes to learn much about how flavors develop, with applications to food and perfume chemistry. For scotch fans, it may lead to the discovery of new chemical building blocks adding to the tasting spectrum. 

II. CHEMICAL COMPOSITION OF FOODS AND FOOD PRODUCTS FLAVOR OBJECTS AND THE NATURE OF FLAVOR SPACE... 

The effects of dentifrice components on flavor release in vitro using static head-space had previously been studied (36-37). Recently consumer emphasis on long-lasting flavor has led to extensive work in understanding the release of flavor in the oral cavity (38). Atmospheric pressure chemical ionization techniques have... 

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