Starch sweetener conversion

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). 

Physical properties of a syrup depend heavily on its carbohydrate profile. The carbohydrate profile, in turn, is determined by the type of conversion and the nature of the enzyme treatment (previously discussed). Table 21.2 gives typical DE and carbohydrate profiles of syrups in common production today. Because enzyme treatments can provide sweeteners with different carbohydrate profiles but the same DE value, it is usual to refer to a product using more than one descriptor, e.g. a 43 DE, high-maltose syrup. This issue becomes particularly important when addressing functional differences and applications of starch-derived sweeteners. 

The isomerization of glucose to fructose opened the way for starch hydrolyzates to replace cane or beet sugar (Dziezak 1987). This process is done with glucose isomerase in immobilized enzyme reactors. The conversion is reversible and the equilibrium is at 50 percent conversion. High-fructose com syrups are produced with 42 or 55 percent fructose. These sweeteners have taken over one-third of the sugar market in the United States (Olsen 1995). 

Figure 4-21 Production Process for the Conversion of Starch to Sorbitol and Maltitol. Source Reprinted from H. Schiweck and S.C. Ziesenitz, Physiological Properties of Polyols in Comparison with Easily Metabolizable Saccharides, Advances in Sweeteners, T.H. Grenby, ed., p. 90, 1996, Aspen Publishers, Inc.

Liquefaction, starch Name of the enzymatic process in which a starch slurry is treated with a-amylase. During the reactions, the viscosity of the gelatinized starch slurry significantly decreases due to the conversion of large starch molecules into dextrins. Starch liquefaction is critically important in the production of syrups, sweeteners, and fuel ethanol. 

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