US 3314818 A
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United States Patent diana No Drawing. Filed Mar. 27, 1964, Ser. No. 355,439
2 Claims. (Cl. 127-48) This invention relates to an improved process for the defecation of sugar solutions. More particularly, it relates to the use of iron or copper salts to remove undesirable impurities from sugar solutions prior to subsequent crystallization.
Crystalline sugar, such as crystalline dextrose, is generally obtained by well known crystallization techniques from sugar-containing solutions. Certain well known purification procedures are also employed to remove impurities from the sugar solutions prior to subsequent crystallization. Color impurities are removed by color refining agents, such as natural hone char, synthetic bone char, activated vegetable carbons and ion exchange resins. Ash It is also well known that certain other undesirable impurities which interfere with subsequent crystallization are also present in sugar solutions. These latter impurities, which are believed to be proteins, mucoproteins and high molecular impurities by adding lime to a pH of about 6.8-7.2 and process for removing substantially all undesirable coloring sugar solutions.
It is another object of the water-soluble compound until a floc is formed with the undesirable impurities and then separating the floc and the so-purified sugar solution. Preferably the water- 3,314,818 Patented Apr. 18, 1967 meat which is generally employed in sugar crystallization processes for ash removal. The resulting crystallized sugar is thus safe for human consumption.
The process conditions for carrying out this invention are not narrowly critical. As the temperature increases, the flocculation time tends to decrease. If the temperature is about 25 C., for example, the flocculation will require about 8 hours. If the temperature is about C., the flocculation time is about 30 seconds. After flocculation is complete, the sugar solution is of forming the fioc, sures above and below atmospheric can be employed if desired.
like; The ferric and cupric salts are preferred since it is believed that the metals must be in these valence states to form the floc with the impurities. When ferrous and cuprous salts are used, they should desirably be oxidized to the ferric and cupric states. This is conveniently self-initiating sponthat will occur during the heating of the sugar solution and water-soluble salt additive to form the floc. The expression water-soluble salts" refers to salts Which are soluble enough in water to provide sufficient metal ions to form the H00 with the impurities.
This invention is further described in the following examples:
Example 1 Crude slab sugar weight percent sugar solution having a pH of approximately 4.6.
Example 2 cent by weight glucose. Ferric citrate was then added in which sugar of improved properties can be obtained.
While the above examples were limited to use of spe- 3 cific iron and copper salts with solutions of crude slab sugar, it should be understood that other water-soluble iron or copper salts can be employed either alone or in admixture, and other sugar solutions, such as acid-converted starch, enzyme-converted starch and the like can be employed in this invention.
In summary, the present invention relates to an improved defecation process for removing undesirable impurities from sugar solutions. This improved process involves treating the sugar solution with a water-soluble salt of iron, copper or mixtures thereof to form a floc or precipitate with the impurities and then separating the sopurified sugar solution from the floc.
What is claimed is:
1. A process for defecation of sugar solutions containing undesirable impurities which consists essentially of adding ferric citrate to a sugar solution, said ferric citrate being added in an amount containing from about 50 to about 1000 parts by weight iron per million parts by weight sugar solution, mixing said sugar solution and said ferric citrate at a pH of from about 2.5 to about 5 until a floc is formed with the undesirable impurities, and then separating the floc and the so-purified sugar solution.
2. A process for defecation of sugar solutions containing undesirable impurities which consists essentially of adding cupric sulfate to a sugar solution, said cupric sulfate being added in an amount containing about 50 to about 1000 parts by weight copper per million parts by weight sugar solution, mixing said sugar solution and said cupric sulfate at a pH of from about 2.5 to about 5 until a floc is formed with the undesirable impurities and then separating the floc and the so-purified sugar solution.
References Cited by the Examiner FOREIGN PATENTS 1892 Great Britain. 1847 Great Britain.
OTHER REFERENCES Maumene: La Sucrerie Indigene et Coloniale, 1895,577.
Moreaux: Bulletin de lassociation des chimistes,
Oehlrichs: Zeitschrift etc. as above, 64, p. 802.
MORRIS O. WOLK, Primary Examiner. M. E. ROGERS, Assistant Examiner.