Sour substances

Curculin which is extracted with 0.5 M sodium chloride from the fruits of Curculigo latifolia and purified by ammonium sulphate fractionation, CM-sepharose ion-exchange chromatography and gel filtration.The protein acts as a low calorie sweetener and has a maximum sweetness equal to 0.35 M of sucrose. In addition to its sweetness, curculin also has taste modifying abilities since water and sour substances elicit a sweet taste after consumption of curculin. Currently, there is no other protein that has both sweet taste and taste modifying abilities. 

Figure 1.2. Scheele isolated a family of naturally occurring sour substances. Subsequently, the elemental composition of each substance was determined using Lavoisier s combustion method and later the different structures were proposed. Each member contains common structural element, a carboxylic acid group which gives each its sour taste. The two-dimensional representation of chemical structures as shown is convenient but can be misleading. Also shown is the structure of urea, the first naturally occurring substance to be made in the laboratory by Wohler (shown), who provided the first experimental challenge to the concept of vitalism.

Vinegar (acetum) and all that kind of sharp or sour substances are rendered subtle and purified, and their virtue or effect improved by distillation. ... 

The pattern of each taste substance is different, and hence each taste substance can be easily discriminated The reproducibility is very high, because the standard deviations are smaller than 1 % or so. The taste sensor shows similar response patterns to the same group of taste. As examples of sour substances, HC1, citric acid and acetic acid show similar response patterns. Bitter substances such as quinine, MgS04 and phenylthiourea show similar patterns. 

Sour and metallic tastes in pharmaceuticals also can be reasonably masked. Sour substances containing hydrochloric acid are most effectively neutralized with raspberry and other fruit syrups. Metallic tastes in oral liquid products (e.g., iron) are usually masked by extracts of gurana, a tropical fruit. Gurana flavor is used at concentrations ranging from 0.001 to about 0.5% and may be useful in solid products as well (e.g., chewable tablets and granules). 

Although not very numerous, sweet macromolecules, both natural (Morris, 1976) and synthetic (Zaffaroni, 1975), are crucial for an understanding of the mechanism of the sweet receptor. The best known among proteins with a very strong sweet taste are brazzein (Ming and HeUekant, 1994), monellin, and thaumatin (Kurihara, 1992). Figure 5 shows molecular models of these three proteins. Other two known sweet proteins are mabinlin (Kurihara, 1992) and hen egg white (HEW) lysozyme (Maehashi and Udaka, 1998), whereas miraculin and curculin, which taste sweet when combined with sour substances, can be better described as taste-modifier proteins (Kurihara, 1992). 

Flavor is a combination of taste, sensation, and odor transmitted by receptors in the mouth (taste buds) and nose (olfactory receptors). The stereochemical theory of odor is discussed in the essay that precedes Experiment 16. The four basic tastes (sweet, sour, salty, and bitter) are perceived in specific areas of the tongue. The sides of the tongue perceive sour and salty tastes, the tip is most sensitive to sweet tastes, and the back of the tongue detects bitter tastes. The perception of flavor, however, is not so simple. If it were, it would require only the formulation of various combinations of four basic substances—a bitter substance (a base), a sour substance (an acid), a salty substance (sodium chloride), and a sweet substance (sugar)—to duplicate any flavor In fact, we cannot duplicate flavors in this way. The human possesses 9,000 taste buds. The combined response of these taste buds is what allows perception of a particular flavor. 

Acids taste sour. The German word for acid is sauer. Remember that tasting acids can be extremely dangerous Do not taste an acid unless a teacher or chemist says that it is safe. You may have tasted sauerkraut. Sauerkraut is cabbage that has been preserved in its own lactic acid. Vinegar is another sour substance in the kitchen. Vinegar has acetic acid that gives it its sour taste. 

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]. 

These basic taste sensations arise at relatively specialised receptors located in different places of the mouth. Sweet substances are perceived primarily at the tip of the tongue, salty substances in defined areas of the upper surface of the tongue, sour substances to the sides and bitter substances in the root of the tongue and soft palate. Taste receptors also respond to other stimuli (tastes) that are incorporated virtually in the whole oral cavity ... 

Sour Substances. Data on the acceptance of sour solutions are sparse. Where they are found, very few preferences for acids have been reported. Acids are found in many fruits yet there are no reported sour preferences among frugivores (a poorly studied herbivorous subset), and the armadillo rejected. 001 N formic acid (53) which is found in high concentrations in its natural diet, ants. Wild and domestic cavies preferred no concentration of citric acid, but did not reject any until concentrations of. 062 M and. 031 M, respectively, were reached. Cats also rejected. 06 M citric acid, the lowest concentration tested (37). This concentration has a very strong taste to humans. The addition of citric acid to diets lowered acceptance by both wild and hooded rats (48). 

Odors are characterized by quaUty and intensity. Descriptive quaUties such as sour, sweet, pungent, fishy, and spicy are commonly used. Intensity is deterrnined by how much the concentration of the odoriferous substance exceeds its detection threshold (the concentration at which most people can detect an odor). Odor intensity is approximately proportional to the logarithm of the concentration. However, several factors affect the abiUty of an individual to detect an odor the sensitivity of a subject s olfactory system, the presence of other masking odors, and olfactory fatigue (ie, reduced olfactory sensitivity during continued exposure to the odorous substance). In addition, the average person s sensitivity to odor decreases with age. 

Enhancers and Inducers. A sweetness enhancer is defined as a compound that imparts no taste per se, but when combined with a sweetener in small quantities, increases sweetness intensity. A tme sweetness enhancer has yet to be found. However, a good sweetness inducer, miraculin [143403-94-5] or [125267-18-7] (124), is known. Miraculin is a glycoprotein found in the fmit (called Miracle Fmit) of a West African shmb, chardella dulcifica. By itself, miraculin imparts no sweetness. When activated in the mouth by acidic substances, however, a sucrose-like sweetness is perceived. Thus, sour lemon, lime, grapefmit, rhubarb, and strawberry taste sweet when combined with miraculin. The taste conversion effect can last an hour or longer. 

An acid is classically known as a substance whose aqueous solution (i) turns blue litmus red (ii) neutralizes bases (iii) reacts with active metals with the evolution of hydrogen and (iv) possesses a sour taste. A base is again classically known as a substance which in aqueous solution (i) turns red litmus blue (ii) neutralizes acids (iii) tastes offensive and (iv) gives a soapy feel. These given descriptions of acids and bases may also be regarded as being operational or or experimental definitions. 

The world as we know it could not function without acids and bases. These chemical compounds are used extensively, from the chemical laboratory to the manufacturing industry. They are necessary for the proper functioning of the human body and for the health of the environment, too. Acids taste sour, break down metals, and react with bases. Without acids, soft drinks, lemonade, and tomato sauce would not taste the same way. Bases taste bitter, feel slippery, and react with acids. Without bases, cakes would be hard and flat, and laundry detergent would not clean. Both acids and bases can change certain vegetable substances a variety of different colors, and they can burn through human skin if not handled properly. Without acids and bases, we would not have dynamite, some heart medications, and fertilizers. On the other hand, without acids, we would not have damaging acid rain. And... 

All add solutions taste sour and are more or less corrosive and chemically quite reactive they react with most metals, many of which are corroded and dissolved by acids. Alkaline solutions, also chemically reactive, are caustic (they burn or corrode organic tissues), taste bitter, and feel slippery to the touch. Both acids and bases change the color of indicators (substances that change color, hue, or shade depending on whether they are in an acid or basic environment). 

Sour dough bread has a range of flavours that are not present in other bread also it keeps relatively well. The keeping properties, no doubt, originate from some of the products of the side-reactions that have taken place in the dough. There is no need to add propionic acid as a mould inhibitor as some is likely to be present naturally. Quite possibly, some of the substances produced by the fermentation would not be permitted as additives ... 

Taste test. Cocaine has a bitter taste and the addition of any cut will tend to alter that taste. A milk sugar cut will sweeten the cocaine although dextrose has a tendency to sweeten the substance more than lactose. Procaine will be bitter to the taste but will tend to numb the gums and tongue quicker and longer than cocaine. Salt has an after taste and epsom salts are a bit more sour in taste and sandy in texture. 

Acids and bases are extremely common substances, as are their reactions with each other. At the macroscopic level, acids taste sour (that is, lemon juice) and react with bases to yield salts. Bases taste bitter (that is, tonic water) and react with acids to form salts. 

Acid Substance which increases the acidity of a foodstuff and/or imparts a sour taste to it... 

Uses Manufacture of acetate rayon, acetic anhydride, acetone, acetyl compounds, cellulose acetates, chloroacetic acid, ethyl alcohol, ketene, methyl ethyl ketone, vinyl acetate, plastics and rubbers in tanning laundry sour acidulate and preservative in foods printing calico and dyeing silk solvent for gums, resins, volatile oils and other substances manufacture of nylon and fiber, vitamins, antibiotics and hormones production of insecticides, dyes, photographic chemicals, stain removers latex coagulant textile printing. 

The role of these tastes has been nicely summarized Taste is in charge of evaluating the nutritious content of food and preventing the ingestion of toxic substances. Sweet taste permits the identification of energy-rich nutrients, umami allows the recognition of amino acids, salt taste ensures the proper dietary electrolyte balance, and sour and bitter warn against the intake of potentially noxious and/or poisonous chemicals. ... 

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