Carbonated soft drinks, acidity

Aspartame (1) is the primary nonnutritive sweetener used in carbonated soft drinks. It is approximately 200 times sweeter than sucrose. Aspartame is the methyl ester of a dipeptide of T.-phenylalanine and L-aspartic acid. 

Acesulfame-K is 200 times as sweet as sugar and is not metabolized and is thus noncaloric. It is exceptionally stable at elevated temperatures encountered in baking, and it is also stable in acidic products, such as carbonated soft drinks. It has a synergistic effect when mixed with other low-calorie sweetners, such as aspartame. Common applications of acesulfame-K are table uses, chewing gums, beverages, foods, bakery products, confectionary, oral hygiene products, and pharmaceuticals. 

M hydrochloric acid solution, white vinegar, colorless carbonated soft drink, borax soap solution, distilled water grease pencil droppers (9)... 

Calculate the pH and pOH of a carbonated soft drink that is 0.0032 M carbonic acid solution. Assume that there are no other acidic or basic components. 

It would be possible to avoid these negative aspects of acidification by using L(-)lactic acid. This is listed as a food additive (E270) and meets the requirements of both the Food chemical Codex and the European Pharmacopoeia. Lactic acid is commonly used in the food and beverage industry, particularly as a substitute for citric acid in carbonated soft drinks, and is even added to some South African wines. 

Carbonated soft drinks owe their fizz to the presence of carbonic acid. We think nothing of drinking this acid. Even so, one of the authors of this book was confronted with the statement our lawyers won t let us have acids in a shopping maU due to liability problems when he proposed to do some chemical demonstrations involving carbonic acid as part of an observance of National Chemistry Week activities. There s that association with danger again. 

In many cases, a number of organic additives are added to carbonated soft drinks. These additives include sweeteners such as saccharin, acesulfam-K, or aspartame, preservatives such as benzoic acid, and flavors such as citric acid and caffeine. 

Some weak acids, such as carbonic acid, are diprotic acids that have two H, which dissociate one at a time. For example, carbonated soft drinks are prepared by dissolving... 

Polyethylene terephthalate (PET) is a linear thermoplastic polymer, which was initially commercialized for packaging carbonated soft drinks due to its excellent gas barrier properties that allows it to retain CO. Raw materials used for production of PET are ethylene glycol and terephthalic acid (or dimethyl terephthalate). Production of PET is a two-step process in the first step trans-esterification or esterification takes place, depending on whether terephthalic acid or dimethyl terephthalate is used, and in the second step polycondensation of resulting oligomers produces PET (Massa et al.,2011). 

Recall from Section 12.4 that the solubility of carbon dioxide, like that of other gases, increases with increasing pressure. Carbon dioxide under high pressure carbonates soft drinks. Under most conditions, less than 0.5% of the dissolved carbon dioxide reacts with water to form carbonic acid. This leaves most of the carbon dioxide as dissolved gas molecules, so the soft drink does not acquire much of a sour acidic taste. 

However, a well-controlled clinical study by Heaney and Rafferty using calcium-balance methods found no impact of carbonated soft drinks containing phosphoric acid on calcium excretion. The study compared the impact of water, milk, and various soft drinks (two with caffeine and two without two with phosphoric acid and two with citric acid) on the calcium balance of 20- to 40-year-old women who customarily consumed 3 or more cups (680 mL) of a carbonated soft drink per day. They found that, relative to water, only milk and the two caffeine-containing soft drinks increased urinary calcium, and that the calcium loss associated with the caffeinated soft drink consumption was about equal to that previously found for caffeine alone. Phosphoric acid without caffeine had no impact on urine calcium, nor did it augment the urinary calcium loss related to caffeine. Because studies have shown that the effect of caffeine is compensated for by reduced calcium losses later in the day, Heaney and Rafferty concluded that the net effect of carbonated beverages—including those with caffeine and phosphoric acid—is negligible, and that the skeletal effects of carbonated soft drink consumption are likely due primarily to milk displacement. 

Many of the products you use at home contain weak acids. In carbonated soft drinks, CO2 dissolves in water to form carbonic acid, H2CO3, a weak acid. A weak add such as H2CO3 contains mostly H2CO3 molecules and a few H30 and HC03 ions. A weak acid such as carbonic acid, H2CO3, is written with a double arrow. Carbonic acid is a diprotic acid that has two which ionize one at a time. Because HCO3 is also a weak acid, a second ionization produces another hydronium ion and the carbonate ion, C03. ... 

As you might expect, the carbonated soft drink is acidic. 

Sodium and potassium benzoate are substances that may be added direcdy to human food and are affirmed as GRAS (33—35). Benzoic acid and sodium and potassium benzoate are now used as preservatives in such foods as sauces, pickles, cider, fmit juices, wine coolers, symps and concentrates, mincemeat and other acidic pie fillings, margarine, egg powder, fish (as a brine dip component), bottled carbonated beverages, and fmit preserves, jams, and jellies. The popularity of diet soft drinks has led to increased demand for both benzoate salts. 

Carbon Dioxide. Carbon dioxide [124-38-9] provides soft drinks with a pungent taste, acidic bite, and sparkling fizz. Carbon dioxide (qv) also acts as a preservative against yeast, mold, and bacteria. The carbon dioxide used ia soft drinks must be food-grade and free of impurities that may affect the taste or odor of the final product. 

Inorganic Acids. Strong inorganic acids have little antimicrobial activity in themselves but inhibit microorganism growth by lowering the pH. Disinfectant toilet bowl cleaners that contain 9.5% HCl or more are antimicrobial. Carbonic acid [463-79-6] in soft drinks provides some antibacterial preservation. Sulfurous acid [7782-99-2] is an effective preservative used to preserve wines (see Wine), fmit juices (qv), and dried fmits. 

By far the greatest consumption of pure aqueous phosphoric acid is in the preparation of various salts for use in the food, detergent and tooth-paste industries (p. 524). When highly diluted the free acid is non-toxic and devoid of odour, and is extensively used to impart the sour or tart taste to many soft drinks ( carbonated beverages ) such as the various colas ( 0,05% H3PO4, pH 2,3), root beers ( 0.01% H3PO4, pH 5,0), and sarsaparilla ( 0.01% H3PO4, pH 4.5). 

Acids are added to soft drinks for extra bite. The primary acid used in colas is phosphoric acid, while the one used in citrus-flavored drinks is usually citric acid. Carbonated water (water that has the gas carbon dioxide dissolved in it under pressure) is also mildly acidic (it is chemically carbonic acid, H2C03). 

H2C03(aq) is named carbonic acid and is one of the reasons that most carbonated beverages are slightly acidic. It is also the reason that soft drinks have fizz, because this carbonic acid can easily revert to carbon dioxide and water. 

There is a recent trend towards simultaneous CE separations of several classes of food additives. This has so far been applied to soft drinks and preserved fruits, but could also be used for other food products. An MEKC method was published (Lin et al., 2000) for simultaneous separation of intense sweeteners (dulcin, aspartame, saccharin and acesulfame K) and some preservatives (sorbic and benzoic acids, sodium dehydroacetate, methyl-, ethyl-, propyl- and isopropyl- p-hydroxybenzoates) in preserved fruits. Ion pair extraction and SPE cleanup were used prior to CE analysis. The average recovery of these various additives was 90% with good within-laboratory reproducibility of results. Another procedure was described by Frazier et al. (2000b) for separation of intense sweeteners, preservatives and colours as well as caffeine and caramel in soft drinks. Using the MEKC mode, separation was obtained in 15 min. The aqueous phase was 20 mM carbonate buffer at pH 9.5 and the micellar phase was 62 mM sodium dodecyl sulphate. A diode array detector was used for quantification in the range 190-600 nm, and limits of quantification of 0.01 mg/1 per analyte were reported. The authors observed that their procedure requires further validation for quantitative analysis. 

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