Carbohydrate Taste Interactions

While carbohydrates may impart a sweet taste, their presence in a food will potentially influence the other taste sensations as well [25]. This influence can be the result of competition for sensory receptors, cognitive inhibition, or a mass transfer effect [26]. 

In terms of competition for sensory receptors, it is recognized that sensory receptors generally are sensitive to more than one class of stimuli (See Chapter 1). For example, a bitter receptor will also respond to sweetness [27]. Thus, if there is sugar in a sample, the sugar may reach the bitter receptors first (or just overwhelm) and thereby tie up the receptors so they do not respond to the bitter stimuli. Thus, sugars may mask the bitterness of a sample. This type of interaction amongst taste stimuli is fairly common. 

The final means for carbohydrate taste interactions to occur is through their effect on mass transfer in the mouth. While hydrocolloids are quite tasteless, they are often used to contribute viscosity to a food and thereby reduce mass transfer from the food to the taste receptors. Pangbom et al. [29] reported that a sample viscosity greater than 12-16 cP results in a significant reduction in sweemess. Work by Vaisey et al. [30] showed that not only is intrinsic viscosity important but the overall rheological properties of the food. For example, hydrocoUoids that readily shear thin (e.g., Gelan gum) reduce sweetness less than those hydrocolloids that do not shear thin. 

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The discussion for protein taste interactions would parallel that of the discussion on carbohydrate taste interactions. One finds literature on sweet proteins and more recently proteins that make sour substances taste sweet. The addition of proteins or a change in type of protein used in a food will influence the taste of that food [35,36]. 

This volume contains the papers presented in a symposium on carbohydrate-protein interaction. The symposium was devoted to an exploration of protein-glycoconjugate interaction in a wide range of biological phenomena the interaction of enzymes, antibodies, and lectins with complementary carbohydrate molecules the recognition of carbohydrate-containing structures by chemoreceptors such as taste and other plasma membrane proteins and the role of carbohydrates in the organization of connective tissue. 

That the sweet and bitter responses are intimately associated is clear from the results of gustatory studies of all of the conformationally defined sugars and of other organic compounds. If a carbohydrate has any taste at all, this is invariably sweet, bitter-sweet, or bitter. Chemical modification may alter the taste of a sweet compound so that the product is bitter-sweet or bitter, and it is now generally agreed that the two basic tastes may each be a feature of a single compound. It appears, therefore, that the interactions of these polyfunctional stimulants involve two different sets of receptor sites, representing sweet and bitter modalities. ... 

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. 

Taste. Taste Is the human perception of chemicals In the mouth due to their Interaction with receptors on the tongue. Taste consists of four dimensions sweet, salty, sour and bitter. Taste Is affected by odor and texture, which makes it a complicated, subjective quality attribute, difficult to measure objectively (22). In fruits and vegetables, taste Is mostly determined by the types and amounts of carbohydrates, organic acids, amino acids, lipids and phenolics (5.71). CA combinations, to the degree that they modify changes in these constituents, can affect the taste of stored fruits and vegetables. Usually, extremely low O2 or high CO2 will result In off-flavors and reduced quality due to anaerobic respiration. The specific effect of CA on flavor depends on the crop Involved (2). 

The quality of flavor in food is attributed to low concentrations of volatile compounds in its head-space. The headspace concentration of volatile flavors in foods is determined by several factors vapor pressure of the flavor compound, its interaction with other components of the food, and temperature. Carbohydrates, fats, and proteins are all known to affect the vapor pressure of flavors. In addition to odor, the perceived flavor, i.e., taste, of foods is significantly affected by different rates and extent of flavor release (volatility and temperature) when food is chewed [79]. 

The apparent molal volumes and molal compressibilities of several monosaccharides, disaccharides and methyl pyranosides in dilute aqueous solution have been studied at 5, 15, and 25°C. The results were discussed in the light of solute-solvent interactions and a model for the hydration of galactose and lactose was proposed.The molal volumes of small carbohydrate molecules have been measured in an attempt at elucidating the relationship between molecular properties and sweetness. Molal volumes reflect fine differences in structure fe.q., axial or equatorial disposition of particular hydroxy groups) which are in turn related to differences in taste. In order to interpret differences in sweetness the viscosimetric constants and the heats of dilution of three monosaccharides, three disaccharides and the very sweet chlorinated sugar (21) have been determined, and their i.r. and Raman spectra have been recorded. The osmotic... 

Diastereomers interact with highly specific sensory receptors. For example, D-marmose, a carbohydrate, exists in two diastereomeric forms that differ in the configuration of a hydroxyl group at one center. The two isomers are designated (X and p. The a form tastes sweet, but the P form tastes bitter. 

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