Synthetic taste compounds

Synthetic Taste Compounds. Of the several synthetic sweeteners available, sodium saccharin has been used in tiiste preference studies with the three species which are our chief concern. 

FIGURE 2-30. Comparison of lemon oils. Use of synthetic lemon oils gives lemon-flavored beverages an off taste. Natural lemon oils contain high molecular weight, nonvolatile components which are normally absent from synthetics. These compounds do not show up on the survey print of lemon oil No. 3, indicated by the arrow. This sample is probably synthetic. All the samples were identical by GC. 

Synthetic noncarbohydrate compounds can also produce a sweet taste. Saccharin, a synthetic compound, tastes 400 times as sweet as sucrose and has the following structure ... 

Saccharin, the first synthetic sweetener, was discovered by Ira Remsen and his student Constantine Fahlberg at Johns Hopkins University in 1878. Fahlberg was studying the oxidation of ortho-substituted toluenes in Remsen s laboratory when he found that one of his newly synthesized compounds had an extremely sweet taste. (As strange as it may seem today, at one time it was common for chemists to taste compounds in order to characterize them.) He called this compound saccharin, and it was eventually found to be about 300 times sweeter than glucose. Notice that, in spite of its name, saccharin is not a saccharide. 

An essential requirement of ice cream products is that they taste appealing. The flavours used in ice cream manufacture are usually supplied as solutions of aroma and taste compounds. Some flavour molecules are fat soluble, whereas others are water soluble. This affects the perception of flavour in ice cream water-soluble flavours are present in the matrix and are released rapidly on consumption, whereas fat-soluble flavours are released more slowly. Flavours may be natural, i.e. extracted from sources such as plants, or synthetic. The latter can be nature identical (artificially produced but identical to the naturally occurring form) or artificial (artificially produced and not occurring in nature). They are used to impart flavour to products, to enhance inherent flavours and to ensure uniformity of flavour between batches. Fruit acids, such as citric or malic acid are added to fruit flavoured water ice products to give them extra bite , by making them sour. The three most important ice cream flavours are vanilla, chocolate and strawberry. 

Home Filtration Systems. The same filtration and purification methods used in large water treatment plants have been downscaled for home use. Faucet-mount filters use carbon filtration, ion-exchange filtration, and submicron filtration to reduce sediment, chlorine, lead, mercury, iron, herbicides, pesticides, insecticides, industrial solvents, volatile organic compounds, synthetic organic compounds, and tri-halomethanes (THMs, chlorine and its by-products). These apparatuses rapidly provide filtered water that tastes and smells better with less cloudiness. Shower filters typically use copper-zinc oxidation media and carbon filtration to remove chlorine for softer skin and hair. Whole-house-use water filters are plumbed into the main water line and commonly include a sediment pre-filter, then copper-zinc oxidation media and crushed mineral stone or natural pumice to reduce chlorine, then activated carbon to remove other chemicals. 

Most of the volatiles in wine, more than 800 compounds, with a total concentration of 0.8-1.2 g/1, has been identified. For the wines Gewurztraminer and Scheurebe, it has been found that the compounds listed in Tables 20.16 are so odor active that they can produce the aroma in each case. This could be confirmed for Gewurztraminer in a model experiment. A synthetic mixture of odor and taste compounds in the concentrations given in Table 20.16 and 20.17 reproduced the aroma and the taste of Gewurztraminer. 

There is no shortage of compounds nat ural or synthetic that taste sweet The most familiar are naturally occurring sugars especially su crose glucose and fructose All occur naturally with... 

Abandoning the hunt for linear, fiber-forming molecules, he turned to polymer ring compounds. Before Carothers, cyclic compounds were so difficult to make that no one studied them, but his group had tasted scientific blood and was happily publishing papers. When they discovered a series of ring compounds that produce synthetic scents, Du Pont sold the compounds to the perfume industry. The cyclic compounds were the last of Carothers fundamental scientific studies. After completing them, he drifted for a while, unclear as to what direction his research should take. 

Most sweet compounds including the commercial sweeteners, are small molecular weight compounds but there are also sweet macromolecules both synthetic and natural. It was thought that compounds with molecular masses over 2 500 would generally be tasteless. It was assumed that macromolecules such as proteins could elicit a sweet taste similar to small molecules such as sucrose and stevioside until the discovery of miraculin. 

While "natural" is the current catch-phrase of today s consumer, research must still be performed for the development of synthetic compounds that can lower the cost of production of food that can be utilized to develop other less costly food items. Amino acids or proteins with O-aminoacyl sugars as part of their residue have been examined for their taste impact Chapter 12). Several of these components have been shown to be potential replacements for salt (NaCl) this would have a significant impact for individuals with high blood pressure or with a propensity to other coronary or renal problems. Some glycosides, represented by some sucrose esters, are approved by the United States Food and Drug Administration for food use. These glycosides have potential use in the preparation of food materials and can lead to more cost effective means of production Chapter 18). 

For estimating the contribution of volatile compounds to bread aroma Rothe and coworkers (S) defined "aroma value" as the ratio of the concentration of some volatile compounds to the taste threshold value of the aroma. This concept was further developed by Weurman and coworkers (9) by introducing "odor value", in which aroma solutions were replaced by synthetic mixtures of volatile compounds in water. These mixtures showed the complexity of the volatile fractions of wheat bread, because none of them resembled the aroma of bread. Recently two variations of GC-sniffing were presented (10-11), in which the aroma extract is stepwise diluted with a solvent until no odor is perceived for each volatile compound separately in the GC effluent. The dilution factors obtained indicate the potency of a compound as a contributor to the total aroma. 

Nature-identical aroma substances are, with very few exceptions, the only synthetic compounds used in flavors besides natural products. The primary functions of the olfactory and taste receptors, as well as their evolutionary development, may explain why artificial flavor substances are far less important. The majority of compounds used in fragrances are those identified as components of natural products, e.g., constituents of essential oils or resins. The fragrance characteristics of artificial compounds nearly always mimic those of natural products. 

It is not yet possible to design a molecule with specific odor (or taste) characteristics because the relations between sensory properties of flavor compounds and their molecular properties are not well understood. As a consequence, the development of compounds with desired flavor qualities has had to rely on relatively tedious synthetic approaches. Recent advances, however, in computer-based methods developed by the pharmaceutical industry to study QSAR (quantitative structure-activity relationships) may ultimately be helpful in the rational design of new flavor-structures with predictable sensory attributes. Results from QSAR studies may also provide insight into the mechanism of the molecule-receptor interaction. 

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