Sugars filtration

H. S. Thatcher, Sugar Filtration—Improved Methods Filtration, Kieselguhr Co. of America, Lompoc, Calif., 1915. 

Figure 6.10 reproduced from Day, N. Why centrifuges play an important role in the production of sugar. Filtration and Separation, Vol. 41, Issue 8, pp. 28-30, October... 

The VaHez filter, originally developed in the United States for the sugar industry, rotates the leaves at about 1 rpm during the filtration operation to keep the soHds in suspension and acliieve a more uniform cake. 

Color. The visual color, from white to dark brown, of sugar and sugar products is used as a general indication of quaUty and degree of refinement. Standard methods are described for the spectrophotometric deterrnination of sugar color that specify solution concentration, pH, filtration procedure, and wavelength of deterrnination. Color or visual appearance may also be assessed by reflectance measurements. 

Insoluble Matter. Insoluble matter in sugar is deterrnined as the dry weight of material left on a filter or membrane after passage of a sugar solution. This may include bits of sand, filtration medium, plant material, and polymeric material. 

DecoloriZation. Filtration, often a refinery botdeneck, especially with poor-quaHty raw sugar, is foUowed by decolorization with bone char (traditional), granular activated carbon (now most common), ion-exchange resias, or any combination of these. Comparative merits and regeneration of these decolorizing systems are a frequent topic ia the Hterature (r6—r8,rll). 

Filtration. Diatomite is used as a filter aid for appHcations with difficult-to-filter soflds to improve permeabiUty of the filter cake, to prevent the blinding of filter elements, and where high clarity is required such as in the poHsh filtration of wine (qv) or beer (qv) before bottling. It is also used in sugar (qv) refining, water treatment, and in the production of fmit juices (qv) and industrial chemicals. 

In the filtration of small amounts of fine particles from liquid by means of bulky filter media (such as absorbent cotton or felt) it has been found that the preceding equations based upon the resistance of a cake of solids do not hold, since no cake is formed. For these cases, in which filtration takes place on the surface or within the interstices of a medium, analogous equations have been developed [Hermans and Bredee, J. Soc. Chem. Ind., 55T, 1 (1936)]. These are usefully summarized, for both constant-pressure and constant-rate conditions, by Grace [Am. In.st. Chem. Eng. J., 2, 323 (1956)]. These equations often apply to the clarification of such materials as sugar solutions, viscose and other spinning solutions, and film-casting dopes. 

In some process applications condensate becomes contaminated in sugar refining it may contain sugar, in paper manufacture and some other processes it may be contaminated with raw water, and where it feeds turbines or other machinery it is liable to contain oil or grease. In all these cases the condensate may still provide a better source of boiler feed than the available raw water, but it may need condensate filtration or softening plant before re-use. 

In the particular example shown, zinc sulfate and barium hydroxide are being dispensed into the test tube so as to precipitate the proteins. The filtrate obtained is the filtrate from 10 microliters of serum. This can be used for several purposes and in the application being referred to, an amount equivalent to 3 microliters is being used for sugar determination, by the hexokinase procedure and an amount equivalent to 3 microliters is being used for urea estimation with diacetylmonoxime (15). 

Prior to semi-preparative HPLC, matrix compounds may be present that require a purification step. In some cases, high sugar or salt contents and also pectic-like substances may preclude concentration and isolation precipitation using 2-propanol or ethanol is then required. Subsequent filtration will yield a pigment solution and a colorless filtrate that may be rinsed with a mixture of one part water and two parts alcohol for complete discoloration. The filtrate volume will be reduced under vacuum before further purification. Usually, precipitation precedes desalting. 

If we compare liquefaction to maceration, more activities are needed to liquefy the cell wall. Since 1991, new pectinases activities such as rhamnogalacturonase, pectin acetylesterase and xyloglucanases complex have been found to be important in the apple liquefaction by Henck Schols, Jean-Paul Vincken and Voragen [3]. The cellulose-xyloglucan complex accounts approximatively 57% of the apple cell-wall matrix. In a liquefaction process, an efficient enzymic degradation of this complex is crucial to increase the sugars extraction, to decrease the viscosity of the pulp then to be able to ultra-filtrate the juice without second depectinisation, at last to have negative alcohol tests required by some concentrate customers. 

Characterization of fractions obtained by procedure 3 PA-l-I was further treated with 0.1 M TFA at 40° C for 84 h, and gave four subfractions (PA-l-Ia, PA-l-Ib, PA-l-Ic and PA-l-Id) by gel filtration on Bio-gel P-6. About 50% of remaining TBA-positive material in PA-l-I was eluted in the small oligosaccharide fractions (PA-l-Ic and PA-l-Id). Glycosyl sugar composition... 

Acetyl esterase (AE) has been purified to homogeneity from orange peels. The purification steps included cation exchange chromatography and gel filtration. The enzyme has affinity for triacetin and sugar beet pectin with K, of 39 mM and of 26 mg/ml, respectively. AE has a MW of 42 kD and is a monomer. The isoelectric point is at pH > 9. 

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