Crystallization of starch

Ziegler GR, Nordmark TS, Woodling SE. 2003. Spherulitic crystallization of starch influence of botanical origin and extent of thermal treatment. Food Hydrocoll 17 487-494. 

The only pectic enzyme thus far obtained in crystalline form is the endo-D-galacturonanase from Acrocylindrium.209 Crystallization of the enzyme from a solution of ammonium sulfate was preceded by chromatography on calcium phosphate, Duolite CS 101, and DEAE-cellulose, and by starch-gel electrophoresis. 

The problem of crystallizing dextrose from starch conversion liquor in a form which would allow separation from the viscous mother liquor was attacked in the latter part of the nineteenth century by various workers. The most successful efforts were made by Behr in 1881.3 Corn starch was hydrolyzed at low concentration, the refined product was concentrated, seeded with a very small proportion of pure anhydrous dextrose crystals, and it was then allowed to stand without agitation in heated rooms. Care was taken to exclude any traces of dextrose hydrate crystals. After several days the crystalline magma was separated and washed in centrifugal filters. By this means individual crystals of anhydrous dextrose of suitable size were obtained and the product... 

Anhydrous alpha dextrose may be obtained by drying the hydrate in a stream of warm air.6 For a very pure grade of the anhydrous product a better method is used which consists of crystallizing from solution in a vacuum pan at a temperature above 50°C.1314 This temperature is the hydrate-anhydrous transition point. Dextrose from the first crystallization of the starch conversion liquor is dissolved in water to give about a 60 % solution which is treated with a small quantity of activated carbon... 

Very highly purified preparations of alpha amylase of malted barley give a value of approximately 4 to 1 for the ratio of their dextrinogenic to their saccharogenic activities when the measurements are made at 40° with Lintner s soluble potato starch.81 Under the same conditions approximately the same value is obtained with products precipitated by alcohol from malted barley extracts which had been treated to inactivate beta amylase.23 81 However, a constant value for these ratios is not proof that beta amylase is entirely absent. There is at present no satisfactory way of making certain that malted barley alpha amylase is not contaminated with traces of beta amylase. The crystallization of alpha amylase from malted barley has been reported since this manuscript was written.79... 

This chromalographic method is convenient and useful in a number of cases. Crystals of quartz which are chiral exhibit different adbsoptive power for several antipodes and so also starch has been employed. Gas-liquid chromatography (GIC) is also employed to resolve racemates. For example to separate racemic a amino acids they are converted into esters with optically active alcohols like (-)2 butanol or trifluroracetyl devivatives, which are then separated by GLC. 

Starch crystallinity is caused by paraUely arranged starch polymers which act as crystals. No evidence has been presented in published literature to describe the actual physical nature of "starch crystallites." It should not be considered that starch granules contain "crystals" or "crystallite particles" formed by starch polymers. Starch crystallinity represents the relative arrangement of starch polymers in granules, not the presence of physical "crystals."... 

Sponsler, O. L. (1923). Structural units of starch determined by X-ray crystal structure method. The Journal of General Physiology. 5, 757-776. 

Nordmark, T. S., Ziegler, G. R. (2002). Spherulitic crystallization of gelatinized maize starch and its fractions. Carbohydr. Polym., 49,439 48. 

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