Degradation during derivative

Com and rice starches have been oxidized and subsequently cyanoethylated (97). As molecular size decreases due to degradation during oxidation, the degree of cyanoethylation increases. The derivatized starch shows pseudoplastic flow in water dispersion at higher levels of cyanoethylation the flow is thixotropic. Com and rice starches have been oxidized and subsequently carboxymethylated (98). Such derivatives are superior in the production of textile sizes. Potato starch has been oxidized with neutral aqueous bromine and fully chemically (99) and physically (100) characterized. Amylose is more sensitive to bromine oxidation than amylopectin and oxidation causes a decrease in both gelatinization temperature range and gelatinization enthalpy. 

Concentration. The concentration of fmit juice requites removal of solvent (water) from the natural juice. This is commonly done by evaporation, but the derived juices may lose flavor components or undergo thermal degradation during evaporation. In freeze concentration, solvent is crystallized (frozen) in a relatively pure form to leave behind a solution with a solute concentration higher than the original mixture. Significant advantages in product taste have been observed in the appHcation of this process to concentration of certain fmit juices. 

The aim of this chapter is to provide a concise synopsis of the factors that promote degradation during post-harvest handling, processing, and storage, and the strategies to preserve the green color of the most commonly consumed chlorophyU-rich foods. Some considerations about the production and characteristics of natural and semisynthetic chlorophyll derivatives for use as food colorants are also presented. 

Degradation by proteases derived from the same microorganism or from contamination during purification must be avoided. Once a protease contaminates an enzyme solution, the desired enzyme is degraded during purification and might disappear. To prevent degradation by proteases, it is helpful to add protease inhibitors like PMSF (SH protease) and EDTA (metal protease). 

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