Sucrose, which is a common form of sugar, is widely used in the food industry. The usual source for this compound is found in the juice of sugar cane, sugar beets and other sucrose-containing materials. After the readily recoverable sucrose has been extracted from these sources, the mother liquors which are generally termed "molasses" will still contain a relatively large amount of sucrose along with other sugars such as glucose, fructose, raffinose, etc. The latter compounds constitute crystallization inhibitors which make the recovery of the remaining sucrose difficult to accomplish and thus make the recovery of the sucrose no longer economically practical. In addition, the impurities which are present impart a taste to the molasses which renders the same inedible for human consumption.
Sugar beet molasses may contain approximately 50% sucrose and, therefore, it is highly desirable to extract this sucrose from the aforesaid molasses. Inasmuch as hereinbefore set forth, the molasses is bitter to human taste, the residual molasses is used in animal feed or as a fertilizer, and therefore a relatively low sucrose content is an acceptable feature of the molasses. At the present time there are only a few methods for extracting the sucrose present in molasses from the compounds of the type hereinbefore set forth. One such process which is utilized is the Steffan's process in which the beet molasses is diluted to about 20% solids, refrigerated, and treated with a calcium compound such as calcium oxide. This results in the reaction of the sucrose present with a calcium oxide to form tricalcium sucrate which is an insoluble granular precipitate. This precipitate can then be removed from the diluted molasses solution by filtration followed by washing, to remove adhering impurities. The tricalcium sucrate is returned to the beet processing operation by adding to the incoming hot beet juice. Under such conditions the tricalcium sucrate decomposes, releasing the sucrose to solution so that the calcium oxide has acted as a purification agent. However, a disadvantage which is inherent in the process is that certain impurities are recycled, particularly raffinose, which is a trisaccharide. With the continual recycling of the tricalcium sucrate the amount of raffinose present begins to accumulate and, as hereinbefore discussed, will retard the desired crystallization of the sucrose, thus making it necessary to discard a certain amount of circulating molasses from time to time.
In addition to the Steffan process it is also possible to separate sucrose by utilizing non-continuous chromographic procedures which employ ion exchange resins to isolate sucrose from the molasses. However, neither of the procedures results in a complete separation of the sucrose even though high purity can be obtained. One of the processes employs a strong acid, polystyrene ion exchange resin in the potassium form while the other process uses the calcium form of a similar resin. A disadvantage which is present in both processes lies in the fact that both processes require periodic back-flushing and regeneration of the ion exchange resin.
It has now been discovered that sucrose may be separated and recovered from other sugars present in molasses by an adsorption--desorption technique utilizing, as the adsorbent therefor, shaped replications of particle aggregates.