Sweetener conversion

Fructose—Dextrose Separation. Emctose—dextrose separation is an example of the appHcation of adsorption to nonhydrocarbon systems. An aqueous solution of the isomeric monosaccharide sugars, C H 2Dg, fmctose and dextrose (glucose), accompanied by minor quantities of polysaccharides, is produced commercially under the designation of "high" fmctose com symp by the enzymatic conversion of cornstarch. Because fmctose has about double the sweetness index of dextrose, the separation of fmctose from this mixture and the recycling of dextrose for further enzymatic conversion to fmctose is of commercial interest (see Sugar Sweeteners). 

Early applications of crystalline fructose focused on foods for special dietary applications, primarily calorie reduction and diabetes control. The latter application sought to capitalize on a signiftcandy lower serum glucose level and insulin response in subjects with noninsulin-dependent diabetes melUtus (21,22) and insulin-dependent diabetes (23). However, because fmctose is a nutritive sweetener and because dietary fmctose conversion to glucose in the hver requires insulin in the same way as dietary glucose or sucrose, recommendations for its use are the same as for other nutritive sugars (24). Review of the health effects of dietary fmctose is available (25). 

Conversion Processes. Most of the adsorption and absorption processes remove hydrogen sulfide from sour gas streams thus producing both a sweetened product stream and an enriched hydrogen sulfide stream. In addition to the hydrogen sulfide, this latter stream can contain other co-absorbed species, potentially including carbon dioxide, hydrocarbons, and other sulfur compounds. Conversion processes treat the hydrogen sulfide stream to recover the sulfur as a salable product. 

Alitame (trade name Adame) is a water-soluble, crystalline powder of high sweetness potency (2000X, 10% sucrose solution sweetness equivalence). The sweet taste is clean, and the time—intensity profile is similar to that of aspartame. Because it is a stericaHy hindered amide rather than an ester, ahtame is expected to be more stable than aspartame. At pH 2 to 4, the half-life of aUtame in solution is reported to be twice that of aspartame. The main decomposition pathways (Fig. 6) include conversion to the unsweet P-aspartic isomer (17) and hydrolysis to aspartic acid and alanine amide (96). No cyclization to diketopiperazine or hydrolysis of the alanine amide bond has been reported. AUtame-sweetened beverages, particularly colas, that have a pH below 4.0 can develop an off-flavor which can be avoided or minimized by the addition of edetic acid (EDTA) [60-00-4] (97). 

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. 

Increasingly, biochemical transformations are used to modify renewable resources into useful materials (see Microbial transformations). Fermentation (qv) to ethanol is the oldest of such conversions. Another example is the ceU-free enzyme catalyzed isomerization of glucose to fmctose for use as sweeteners (qv). The enzymatic hydrolysis of cellulose is a biochemical competitor for the acid catalyzed reaction. 

Cyclohexylamine is a metabolite of the artificial sweetener sodium cyclamate, with the amount of conversion varying considerably from person to person. ... 

In the context of the strong commercial interest in alternative sweeteners, in particular isomaltulose (which is produced industrially by the conversion of sucrose with the sucrose isomerase SmuA from Protaminobacter rubrum, a GH 13 enzyme), the complex with 1-deoxynojirimycin (2, 10 pM) was investigated (PDB 3GBE)278... 

The acidic bodies are objectionable because of their smell and corrosive nature and are responsible for a crude oil or a distillate being given the term sour. Their conversion by refining is normally termed sweetening. Refiners were chiefly concerned with sweetening, before many of the less desirable properties now known to characterize sul-furous distillates were appreciated. 

There are two fundamental conditions for life. First, the living entity must be able to self-replicate (a topic considered in Part III) second, the organism must be able to catalyze chemical reactions efficiently and selectively. The central importance of catalysis may surprise some beginning students of biochemistry, but it is easy to demonstrate. As described in Chapter 1, living systems make use of energy from the environment. Many of us, for example, consume substantial amounts of sucrose—common table sugar—as a kind of fuel, whether in the form of sweetened foods and drinks or as sugar itself. The conversion of sucrose to C02 and... 

Trehalose is a relatively new bulk sweetener with potential for use in soft drinks. It is a di-glucose sugar and it occurs in nature in shellfish and mushrooms, where it confers a degree of protection to plant and animal cells in conditions causing dehydration. This led to its use as a cryoprotectant in freeze-drying systems in the pharmaceutical industry. In food markets, its potential use is as a bulk sweetener. It is manufactured using the Hayashibara patented process using starch as a raw material. The process involves enzymatic conversion and crystallisation to the trehalose dehydrate crystal (LFRA, 2001). 

Cellulose hydrolysis and its product, glucose, play a central role in the conversion of renewable resources to foods, fuel, and chemical feedstocks. This is illustrated in Figure 1. Cheap glucose would not only find a demand in the food sweetener market but could serve as a substrate... 

The enzymatic synthesis approaches are discussed in more detail in Chapter 19. A protease can be used to catalyze the synthesis of a peptide bond (Scheme 31.21). When the stoichiometry of the reactions is such that two moles of phenylalanine methyl ester are used with one mole of Z-Asp, the Z-APM PM product precipitates and shifts the equilibrium to >95% conversion.232 This is the basis of the commercial TOSOH process operated by Holland Sweetener that uses thermolysin.233 One significant variation has been the use of racemic PM instead of the L-isomer. Because the enzyme will only recognize the l-PM isomer to form the peptide bond, the unreacted d-PM isomer forms a salt and then, after acidification, the d-PM can be chemically racemized and recycled. 

Early work by Hoover52 provides a framework for determining how physical properties would change on the basis of the degree of conversion of the sweetener being considered (Table 21.6). At that time, most syrups were divided into loose classifications... 

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