Sugar – starch – and carbohydrates – Processes – Carbohydrate manufacture and refining
Reexamination Certificate
1999-10-13
2001-04-17
Brunsman, David (Department: 1755)
Sugar, starch, and carbohydrates
Processes
Carbohydrate manufacture and refining
Reexamination Certificate
active
06217664
ABSTRACT:
The present invention relates to a fractionation process for treating an aqueous sucrose syrup (hereinafter syrup). More particularly, the present invention relates to the treatment of an aqueous sucrose syrup having, on a dry basis, an initial sucrose content of at least 30 w/w %. The syrups of interest are primarily those encountered in the cane sugar and beet sugar industries.
For the purposes of the present invention, these syrups will be treated as consisting of water(W), sucrose(S) and non-sucrose(NS). This last category comprises a large variety of chemical compounds originating in cane sugar and in beet sugar, or formed during processing, and are present in variable amounts in syrups. These comprise, inter alia, carbohydrates other than sucrose, amino acids, proteins, inorganics etc. as reported extensively in the relevant literature. For the purposes of the present invention all of these are included within the term “non-sucrose”.
Two examples of typical compositions are listed below:
Syrup
W
S
NS
blackstrap molasses
17-25
30-40
35-53
affination syrup
26-28
63-66
4-11
The carbohydrates in the non-sucrose (NS) fraction consist primarily of glucose and fructose and are customarily referred to as “Invert”. This designation applies to (glucose+fructose), without implying that these are necessarily in equimolar proportions. “Invert” will be used in this sense in the present specification.
In treating syrups for the purpose of upgrading their value through fractionation, the recovery and distribution of the Invert between the fractions may represent an important feature of the process. Thus, since Invert is fully fermentable, it will be a desirable constituent of syrup-derived products directed to fermentation industries. It will be, however, an undesirable constituent of a syrup-derived product intended for further recovery of sucrose by evaporation, since Invert negatively affects sucrose crystallization. One of the useful aspects of the process is the capability it provides in recovering Invert-enriched and Invert-depleted products.
In the text and examples below, whenever figures for Invert (or for glucose and fructose separately), are given they should be understood as representing part of the non-sucrose (NS) of the particular syrup discussed.
As is known, sugar in its purest (and most desirable) form consists of 100% sucrose. In processing cane or beet for sugar the manufacturer naturally strives to approach complete recovery of sucrose in pure form. A large and costly part of processing consists of separating sucrose from non-sucrose by repeated crystallization of sucrose, pushing the non-sucrose into successive mother liquors of increasing contents of non-sucrose which are syrups as defined above. Complete recovery of sucrose by crystallization, however, is not feasible and sucrose in economically significant amounts inevitably reports to low value molasses. This in turn is sometimes subjected to a special separation process, such as chromatography over ion-exchange but the practice has not become universal due to marginal economics.
The foregoing indicates that a simple process to separate syrups into fractions that are either higher in sucrose content than the initial syrup, or lower in sucrose content could be useful in sugar manufacture and refining as well as in molasses upgrading.
Elimination of non-sucrose from a syrup stream in a crystallization sequence of sugar manufacture will obviously improve sucrose recovery. Such elimination need not be complete for the contribution to be significant.
Molasses has uses in which its sucrose content is the main contributor to its value and other uses in which various non-sucroses (such as vitamins and amino acids) are the main contributor to its value. Fractionation of molasses could thus enhance its value by providing products that are tailored to specific end uses.
The present invention provides a simple and effective fractionation of sucrose syrups as postulated above. It is based on the surprising discovery that certain liquid compounds which, per se, are non-solvents of sucrose can be efficient solvents for the fractionation of syrups. Alkanols, ketones and esters were found to be effective compounds in this respect. Particularly useful are alkanols, ketones and esters that have in their molecule a total number of carbon atoms of three to eight.
Thus, according to the present invention, there is now provided a fractionation process for treating an aqueous sucrose syrup having, on a dry basis, an initial sucrose content of at least 30 w/w % comprising combining said syrup with a solvent selected from the group consisting of alkanols, ketones; and esters having 3 to 8 carbon atoms and mixtures thereof to form a system having at least two liquid phases in contact with a sucrose-containing solid phase and separating said phases, whereby there are obtained at least two products from said liquid phases, a first of which is characterized by a sucrose content, on a dry basis, greater than said initial content and a second of which is characterized by a sucrose content, on a dry basis, less than said initial content, in addition to a product obtained from said sucrose-containing solid phase.
The term “sucrose-containing solid phased” as used herein, refers to the fact that during and at the end of the fractionation process varied amounts of sucrose will be found in the solid phase, wherein at the end of the process said amount can be driven down to about 1%.
As will be realized, the present process provides a tool which enables economic decisions as to the amount of sucrose desired in each of the final phases.
In preferred embodiments of the present invention non-sucrose constituents separate into an immiscible phase as described and exemplified hereinafter.
In another preferred embodiment of the present invention, at least one of said phases is a solvent containing liquid phase, which phase is dehydrated to induce preferential precipitation of sucrose therefrom.
In, yet, another preferred embodiment of the present invention, the process is modified by re-combining two products, or more, into a single product.
In especially preferred embodiments of the present invention said solvent is selected from the group consisting of alkanols, ketones, esters having between 3 and 6 carbon atoms and mixtures thereof.
The invention is best understood with reference to the systems formed by sucrose-water-solvent. These systems were found to have specific shared features that are described with reference to FIG.
1
. appended hereto.
Therefore, the invention will first now be described in connection with certain preferred embodiments with reference to the following illustrative figure so that it may be more fully understood.
With specific reference now to the FIGURE in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of the preferred embodiments of the present invention only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the invention.
REFERENCES:
patent: 2000202 (1935-05-01), Vasquez
patent: 2022824 (1935-12-01), Reich
patent: 3174877 (1965-03-01), Bohrer
patent: 3325308 (1967-06-01), Othmer
patent: 4116712 (1978-09-01), Othmer
patent: 5002614 (1991-03-01), Myagi et al.
patent: 5454875 (1995-10-01), Clarke
patent: 6051075 (2000-04-01), Kochergin et al.
patent: 983262 (1965-02-01), None
Brunsman David
Ostrolenk Faber Gerb & Soffen, LLP
Tate & Lyle Public Limited Company
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