Fructose crystallization

No nucleatlon occurs provided the supersaturation is kept below a value equivalent to 35 C of subcooling. There Is a size spread effect, but it decreases with high ethanol contents. The results Indicate that a practical process Is feasible to grow large fructose crystals by the addition of ethanol to aqueous fructose solutions. 

Two methods are employed industrially to produce crystalline fructose, aqueous crystallization and alcoholic crystallization. Yields of fructose crystallized from water syrups are only of the order of 50%, due to the very high water solubility of the sugar, while the high viscosity of the concentrated solution results in long crystallization times, typically 50 hours or more (2). The second process requires the addition of lower alcohols (eg. ethanol) to a concentrated fructose syrup, generally 90% total solids or more, at temperatures of 50 C to 80""c and then cooling to cause crystallization. Fructose yields are from 70 to 80% and the total time involved is 8 to 12 hours (3). However, large quantities of... 

Recently, Edye et al, (4) described a fermentation process which used a mutant strain of Zymomonas mobilis to produce high concentrations of fructose and ethanol when grown on a concentrated sucrose medium. Johns and Greenfield (5) proposed ethanolIc crystallization as a means of recovering the fructose from the broth. The kinetic behaviour of fructose crystallization from ethanolIc solution has not been previously reported, and this work Investigates these crystallization kinetics. 

Figure 3. Cumulative number size distributions of samples from fructose crystallization for Run 5.

Figure 5. Growth rate vs C for fructose crystallizing from aqueous ethanol. Also shown are the results of Shiau and Berglund (10) for aqueous solution.

Figure 8. Size spread coefficient, q vs E/W for fructose crystallization from aqueous ethanol solutions.

The kinetic behaviour of fructose crystallization from aqueous ethanolIc solutions, typical in composition to those operated on an industrial scale, is strongly dependent on supersaturation, solvent composition and temperature. Provided the supersaturation is kept below 35 C of subcooling, nucleation does not occur. 

High growth rates (fim/min) can be achieved. The supersaturation required is less for the higher alcohol contents. The high growth rates in the absence of nucleation means that a practical industrial crystallization process can be developed to grow large fructose crystals. 

Inulin prebiotic Inulin dietary fiber Inulin ingredient Inulin ingredient Oligofructose prebiotic Fructose (crystallized)... 

In aqueous solution, the equilibrium composition of fructose as determined by 13C NMR spectroscopy is (3-pyranose (3-furanose a-furanose a-pyranose in about 6 3 l trace ratio.145 Other compositions in different solvents and temperatures have been reported.146 D-Fructose crystallizes in the (3-pyranoid form. 

Fructose crystallizes well when pure. It is much more soluble and considerably sweeter than common sugar. It is a physiological sugar in every sense of the word. Now that we have analytical methods capable of distinguishing fructose from glucose certainly, it has been shown that fructose is normally present in human blood (71). In embryonic and newborn infants, the level is much higher than in adults (5). Fructose is also the predominant sugar of seminal fluid and its concentration has an important effect upon the motility of spermatozoa (38). 

Another example of the crystallization of chemically related compounds is found in the commercial separation of fructose from the impurity difructose dianhydride (Chu et al. 1989). Fructose undergoes irreversible dehydration during the crystallization process to yield several forms of difructose dianhydride impurities. Since the difructose dianhydride molecule consists of two fructose moieties, it exhibits some of the chemical and structural features of the host fructose molecule. In an analogous fashion to a tailor-made additive, the difructose dianhydride impurities appear to incorporate into the crystal (at < 1 wt% level), thus inhibiting the subsequent adsorption and growth of fructose molecules. The resulting fructose crystal growth rates are so low that the crystallization time in fructose manufacture is often on the order of days. 

Corn syrup, high fructose crystallization control agent, pharmaceuticals Corn syrup, high fructose crystallization inhibitor, biodeg. plastics Maltitol... 

D-fructose, C HijOo. Crystallizes in large needles m.p. 102-104 C. The most eommon ketose sugar. Combined with glucose it occurs as sucrose and rafftnose mixed with glucose it is present in fruit juices, honey and other products inulin and levan are built of fructose residues only. In natural products it is always in the furanose form, but it crystallizes in the pyranose form. It is very soluble in... 

Benzoates. Benzoyl chloride has a very limited application as a reagent in the sugar series, but it is useful for the preparation of a crystal line derivative of glucose and of fructose. 

Dissolve 0-2 g. of fructose in 10 ml. of water, add 0-6 g. of cw-methyl-phenylhydrazine and sufficient rectified spirit to give a clear solution. Since the fructose may not be quite pure, warm the mixture slightly, allow to stand, preferably overnight, so that any insoluble hydrazones may separate if present, remove them by filtration. Add 4 ml. of 50 per cent, acetic acid to the filtrate it will become yellow in colour. Heat the solution on a water bath for 5-10 minutes, and allow to stand in the dark until crystalUsation is complete it may be necessary to scratch the walls of the vessel to induce crystalUsation. Filter the crystals and wash with water, followed by a little ether. RecrystaUise the orange-coloured methylphenylosazone from benzene m.p. 152°. 

Fractional crystallization, 413 Freezing point lowering, 325, 393 Freon, 362 Frequency of light, 246 relation to wave length, 251 Fructose, 423 Fumaric acid, 428 properties, 308 structure, 316... 

The raw materials from which di-D-fructose dianhydrides can be obtained in appreciable yield are readily available from comparatively inexpensive agricultural feedstocks. Thus, these compounds are attractive as chiral-starting materials for chemical synthesis. Their stability to acid and heat, and their relative rigidity, because of the conformational constraints covered here, are also features that might be exploited during syntheses.119 A series of variously substituted di-D-fructose dianhydrides has been prepared,119 starting from 6,6 -dideoxy-6,6 -di-halosucroses. The properties of these and other derivatives of di-D-fructose dianhydrides are summarized in Tables XIV-XX. Two of these derivatives, 48 and 56, exhibit thermotropic liquid-crystal properties.119... 

Stereostructures of a co-crystal of (li )-l- 4-[(9aA)-perhydropyrido[l,2- ]pyrazin-2-yl]phenyl -2-phenyl-7-hydroxy-l, 2,3,4-tetrahydroisoquinoline with ERa-LBD301-553/C — S triple mutant <2005JME364> and iV-[2-(4-hydroxyphenyl)ethyl]-a-propyl-3-[(4-hydroxyphenyl)methyl]-l,4-dioxo-l,2,3,4,ll,l la-hexahydro-67/-pyrazino[l,2- ]isoquinoline-3-acetamide with fructose-1,6-biphosphatase <2003JBC51176> were determined by X-ray crystallography. The structure of a complex formed from 3-[( -methylphenyl)amino]-4-[(4-methylphenyl)imino]-4//-pyrido[l,2-tf]pyrazine with sodium bis(trimethylsilyl)amide and (norbornadiene)Mo(CO)4 in THF was characterized by single crystal X-ray diffraction <1995JPR38>. 

D. Erion, S- J- Pilkis, M. R. El-Maghrabi, and W. N. Lipscomb, The allosteric site of human liver fructose 1,6-bisphosphatase. Analysis of six AMP site mutants based on the crystal structure, J. Biol. Chem. 269 27732 (1994). 

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