CA2238925C

CA2238925C - Salt formulation and process for production thereof

Info

Publication number: CA2238925C
Application number: CA002238925A
Authority: CA
Inventors: Levente Laszio Diosady
Original assignee: Individual
Current assignee: Individual
Priority date: 1998-05-28
Filing date: 1998-05-28
Publication date: 2007-08-21
Anticipated expiration: 2018-05-28
Also published as: IN191070B; CA2238925A1

Abstract

A novel formulation with improved resistance to the breakdown and loss of iodine from fortified food components, especially salt, has been developed. The salt formulation relies on the encapsulation of the iodine compound in a digestible, inert matrix that forms a physical barrier around the iodine compound, and thus prevents reaction of the iodine compound with other components in food, salt or atmosphere, which would otherwise lead to loss of iodine. An especially preferred embodiment is useful in the double--fortification of salt with iodine and iron.

Description

BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION

In one of its aspects, the present invention relates to a salt formulation. In another of its aspects, the present invention relates to a process for producing a salt formulation.
More particularly, in a preferred embodiment, the present invention is concerned with the provision of food grade salt formulations.

DESCRIPTION OF THE PRIOR ART

Iodine deficiency causes several serious health problems that can lead to disabling and/or retarded development, and to the onset of a variety of diseases. In developed countries, it has been known for a number of years to fortify the food grade salt supply with iodine. More specifically, this is known to lead to a dramatic improvement in the iodine status of the general population. Further, plans are under way to introduce salt iodization in many developing countries, under programs initiated by UNICEF, the World Health Organization, governments and private initiatives.

Food grade salt is an ideal vehicle for micronutrient distribution, since its consumption and use is not linked to economic status. Further, per capita intake within a society is almost constant. Iodine is normally added in the form of: (i) potassium iodide in developed countries, and (ii) potassium iodate in developing countries.

Iodide readily oxidizes in the presence of oxygen or oxidizing agents to elemental iodine, which sublimes at a relatively high vapour pressure. This leads to the rapid loss of iodine from salt. It is known in the art to mitigate this problem by the addition of a reducing agent, such as dextrose, and/or by reducing the moisture content of the salt through drying or by a desiccant. If the salt contains impurities which absorb water from the air, or which catalyze the oxidation of iodide, the iodine produced therefrom will readily evaporate from the moisture. Further, it is known that iron compounds catalyze these reactions leading to the loss of iodine. This is especially unfortunate since salt would be an ideal carrier for other micronutrients, such as iron.

In developing countries with tropical and subtropical climates, iodine is added in the form of iodate, which is an oxidized iodine compound. As is known, iodate resists the release and loss of elemental iodine through air. Recent studies on the stability of iodine in salt iodized by potassium iodate indicate that, in the presence of impurities typical of local salts in many developing countries, most of the added iodine is lost within 6-12 months under humid conditions typical of these countries - see Diosady et al., Food and Nutrition Bulletin, Dec. 1997 issue, the contents of which are hereby incorporated by reference.

Over the past decade there have been many unsuccessful attempts at "double fortification" of salt with: (i) iron to prevent anemia, and (ii) iodine for the prevention of iodine deficiency disorders. The Micronutrient Initiative, created by the International Development Research Centre of Canada has been in the forefront of promoting double fortification.

Iron is best absorbed in the form of ferrous iron compounds. Unfortunately, these are reducing agents, that will readily reduce the potassium iodate added to salt to elemental iodine which, as discussed above will then evaporate. This problem is compounded by the fact that, during the process, the ferrous iron is oxidized to the ferric form resulting in a decrease in the bioavailability of iron.

In light of these deficiencies, it would be desirable to have an improved fortified salt formulation.

SUMMARY OF THE INVENTION

It is an object of the present invention to obviate or mitigate at least one of the above-mentioned disadvantages of the prior art.

Accordingly, in one of its aspects, the present invention provides an encapsulated salt formulation comprising a salt and a nutrient, the nutrient being encapsulated in a digestible matrix such that the salt and the nutrient are physically independent.

In another of its aspects, the present invention provides a process for producing an encapsulated salt formulation the process comprising the step of admixing a salt and a nutrient, the nutrient being encapsulated in a digestible matrix such that the salt and the nutrient are physically independent.

Thus, the present inventor has developed a novel approach for the fortification of salt in a salt formulation. Generally, the novel approach relates to encapsulating at least one nutrient in a digestible matrix which is then combined with the salt. As used

-2-throughout this specification, the term "digestible matrix" is intended to have a broad meaning and encompasses any material which is non-reactive with the nutrient and the salt but will disintegrate or otherwise breakdown in the digestive tract of the individual consuming the salt formulation. Once the nutrient is encompassed by the digestible matrix, the latter forms a physical barrier around the nutrient effectively preventing contact with the salt and/or other nutrients and/or impurities in the salt.

A particularly preferred embodiment of the present salt formulation is in the double fortification of salt with (i) iron to prevent anemia, and (ii) iodine for the prevention of iodine deficiency disorders. In this preferred embodiment, the iodine IS

independently encapsulated such that, when converted into a salt formulation, there is no physical contact between the salt/iron and iodine, nor is the iodine able to contact the atmosphere or moisture in the salt. Thus, iodine loss from the present salt formulation is obviated or mitigate, even in the presence of moisture.

As will be illustrated below, this double fortified system has been tested with a number of encapsulating agents, and a series of iodine and iron compounds.
Successful application of this system will make it possible to administer iodine and iron to high-risk populations through nutritional means without involvement of the limited health-care system in developing countries.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

For the successful administration of iodine, it is preferred that the iodine be dispersed homogeneously in the salt. This helps to prevent great variation in the daily intake by the consumer. As the daily requirement is only in the order of 150,ug, the iodine must be very finely dispersed.

As discussed above, in order to protect the iodine from breakdown and release from the salt formulation, it is important that it be protected from contact with either moisture and/or with reactive additives or impurities present in the salt.

The iodine, added either as iodate or iodide, can be encapsulated in a moisture-proof, digestible matrix to protect it from breakdown. The encapsulation technique used is not particularly restricted and is within the purview of a person skilled in the art. Thus, encapsulation may be achieved using one or more of the conventional techniques: spray

-3-drying, coating in a fluidized bed, coating in a conventional rotary drum, coacervation and the like. Of course, this is merely a non-limiting list of possible encapsulation techniques. Those of skill in the art will recognize that the intent is to achieve encapsulation and that the precise mode of achieving encapsulation is not particularly critical.

It is desirable that the encapsulated particles of encapsulated iodine be similar in size to the particles of local salt, as small or large particles would segragate from the salt during transport. This could result in very high local concentration of iodine. Since a particle of the size of a typical grain of salt weighs up to several thousand micrograms, singlegrains of encapsulated potassium iodide or potassium iodate can contain several times the recommended daily intake of iodine. Thus, it is preferred that the iodine compounds be diluted in the encapsulated particles by a factor of 5-200.

To facilitate safe administration of encapsulated iodine compounds, several techniques have been developed (illustrated hereinbelow) that enable the production of encapsulated particles similar in size to local salts, with an iodine content in the range of from about 1% to about 5% by weight.

The preferred encapsulating technique is spray drying. To achieve this, potassium iodide or potassium iodate is preferably dissolved in an aqueous system, together with an encapsulating agent. The solution may then be spray dried to produce microcapsules of a digestible encapsulating agent, in which the iodine compound is distributed, without contact with the surrounding air or solution.

The encapsulating agent (which give rise to the digestible matrix) may be any digestible compound. The preferred agents are readily soluble in warm aqueous systems, but exhibit substantially no degradation in the presence of moisture absorbed from the air by hygroscopic impurities that may be present in salt. Thus, the encapsulating agent may be a moisture resistant, digestible food grade material selected from the group comprising a carbohydrates (e.g., a modified starch), a fat (e.g., hydrogenated mono-glycerides, hydrogenated di-glycerides and mixtures thereof), proteins (e.g., zein), inorganic compounds (e.g., sodium hexametaphosphate), a polymeric compound (e.g., natural or artificial polymeric materials, such as shellac). The preferred encapsulating agents include dextrins, other modified starches, shellac, zein and mixtures thereof.

-4-Iron may also be encapsulated. In the case of ferrous fumarate and ferrous sulfate, the encapsulation would serve to stabilize these compounds from slow oxidation, thus improving bioavailability, improving the colour of fumarate, and the taste of ferrous sulfate. The encapsulation technques are conventional.

Embodiments of the present invention will be described with reference to the following Examples which are provided for illustrative purposes only and should not be used to construe or otherwise limit the scope of the present invention.

Potassium iodide was dissolved in a hot 10% (w/v) aqueous solution of dextrin with a low dextrose equivalent. The solution was spray dried with an air temperature of 160 C in a NiroTM pilot scale spray drier. This resulted in the production of 12 kg of fine powder having a potassium iodide content of 2.1 % by weight.

The encapsulated iodine was added to fine granular salt (Toronto Salt Chemical Co.) in a ribbon blender, at a ratio which resulted in a final iodine content of 50,ug/g.
Some of this salt was mixed with ferrous fumarate to a final concentration of 3000,ug ferrous fumarate per gram of salt. The salt samples were subjected to a series of stability tests at high temperature and humidity.

While a comparative salt formulation to which the potassium iodide was added directly (with or without ferrous fumarate) lost more than 90% of its iodine content within 9-12 months, the salt samples produce in this Example (i.e., with encapsulated iodide) retained 75-90% of the added iodine after 12 month storage at 40 C
under 100%
humidity.

Laboratory tests with rats, and later human trials confirmed the bioavailability of the encapsulated iodide.

Potassium iodate was dissolved in a hot 10% (w/v) aqueous solution of dextrin with a low dextrose equivalent. The solution was spray dried with an air temperature of 160 C in a BuchiTM laboratory scale spray drier. A variety of fine powders, with

-5-potassium iodate contents ranging from 0.5% to 2.1% by weight, were produced, depending on the initial iodide content.

The encapsulated iodine was added to fine granular in a 3 kg laboratory ribbon blender, at a ratio which resulted in a final iodine content of 50gg/g. Some of this salt was mixed with ferrous fumarate to a final concentration of 3000,ug ferrous fumarate per gram of salt. The salt samples were submitted to a series of stability tests at high temperature and humidity.

While a comparative salt formulation to which the potassium iodide was added directly (with or without ferrous fumarate) lost more than 90% of its iodine content within 9-12 months, the salt samples produce in this Example (i.e., with encapsulated iodide) retained 75-90% of the added iodine after 12 month storage at 40 C
under 100%
humidity.

The methodology in Example 2 was repeated using sodium hexametaphosphate as the encapsulating agent. A stable formulation was obtained.

The methodology in Example 3 was repeated using potassium iodide as the iodine source. A stable formulation was obtained.

Samples of sodium chloride crystals containing 2-10% potassium iodide were prepared, by both co-precipitation of the sodium chloride with the iodide.
These crystals were coated with zein, an alcohol soluble protein, by spraying a solution of 10% zein in ethanol on to salt suspended in a fluidized bed held at 90 C.

The alcohol evaporated leaving an encapsulated salt sample, stable under the high temperature, high humidity storage conditions.

-6-The methodology of Example 5 was repeated with 2-10% potassium iodate. A
stable formulation was obtained.

The methodology of Example 5 was repeated with food grade shellac replacing the zein as a coating agent. A stable formulation was obtained.

The methodology of Example 6 was repeated with food grade shellac replacing the zein as a coating agent. A stable formulation was obtained.

The methodology of Example 5 was repeated, using a tumble drier instead of a fluidized bed reactor. A stable formulation was obtained.

The methodology of Example 6 was repeated, using a tumble drier instead of a fluidized bed reactor. A stable formulation was obtained.

The methodology of Example 7 was repeated, using a tumble drier instead of a fluidized bed reactor. A stable formulation was obtained.

The methodology of Example 8 was repeated, using a tumble drier instead of a fluidized bed reactor. A stable formulation was obtained.

The methodology of Example 9 was repeated, using a molten mixture of mono-and di-glycerides from hydrogenated soybean oil as the coating agent. The coating agent solidified on cooling, resulting in a stable formulation.

-7-The methodology of Example 10 was repeated, using a molten mixture of mono-and di- glycerides from hydrogenated soybean oil as the coating agent. The coating agent solidified on cooling, resulting in a stable formulation.

The methodology of Example 9 was repeated, using salt prepared by coating salt grains with potassium iodide to a bulk concentration of 3% by weight. A stable formulation was obtained.

The methodology of Example 15 was repeated, using salt prepared by coating salt grains with potassium iodate to a bulk concentration of 3% by weight. A stable formulation was obtained.

Thus, as described above, the preferred embodiment of the invention relates to a novel stable iodide or iodate containing salt formulations that protects the salt from loss of iodine during extended storage under conditions typical of tropical and subtropical countries. The stability of the system is not influenced by typical salt impurities, or added micronutrients such as the ferrous or ferric compounds.

While this invention has been described with reference to illustrative exemplary embodiments, the description is not intended to be construed in a limiting sense. Various modifications of the illustrative embodiments, as well as other embodiments of the invention, will be apparent to persons skilled in the art upon reference to this description.
It is therefore contemplated that the appended claims will cover any such modifications or embodiments.

-8-

Claims

What is claimed is:

1. An encapsulated salt formulation comprising a salt and a nutrient, the nutrient being encapsulated in a digestible matrix such that the salt and the nutrient are physically independent.

2. The formulation defined in claim 1, wherein the nutrient comprises at least one non-toxic iodine compound.

3. The formulation defined in claim 1, wherein the nutrient comprises potassium iodide.

4. The formulation defined in claim 1, wherein the nutrient comprises potassium iodate.

5. The formulation defined in any one of claims 1-4, wherein the nutrient is present in an amount of from about 0.5% to about 10%.

6. The formulation defined in any one of claims 1-4, wherein the nutrient is present in an amount of from about 1.0% to about 5.0%.

7. The formulation defined in any one of claims 1-4, wherein the nutrient is present in an amount of from about 1.5% to about 2.5%.

8. The formulation defined in any one of claims 1-7, wherein the digestible matrix is selected from the group comprising a carbohydrate, a fat, a protein, an inorganic compound, a polymeric compound and mixtures thereof.

9. The formulation defined in claim 8, wherein the carbohydrate is a modified starch.

10. The formulation defined in claim 8, wherein the fat is selected from the group comprising hydrogenated mono-glycerides, hydrogenated di-glycerides and mixtures thereof.

11. The formulation defined in claim 8, wherein the protein is zein.

12. The formulation defined in claim 8, wherein the inorganic compound is sodium hexametaphosphate.

13. The formulation defined in claim 8, wherein the polymeric material is natural.

14. The formulation defined in claim 8, wherein the polymeric material is synthetic.

15. The formulation defined in claim 8, wherein the polymeric material is shellac.

16. The formulation defined in any one of claims 1-15, wherein the digestible matrix is present in an amount in the range of from about 2% to about 25% by weight.

17. The formulation defined in any one of claims 1-16, wherein the salt comprising sodium chloride.

18. The formulation defined in any one of claims 1-17, further comprising a supplementary nutrient.

19. The formulation defined in claim 18, wherein the supplementary nutrient is a compound comprising iron, the supplementary nutrient being encapsulated or unencapsulated.

20. The formulation defined in claim 19, wherein the compound is selected from the group comprising ferrous fumarate, ferrous sulphate, metallic iron, ferrous citrate and mixtures thereof.

21. The formulation defined in any one of claims 1-20, wherein the digestible matrix encapsulates the nutrient and a portion of the salt.

22. The formulation defined in any one of claims 1-20, wherein the digestible matrix encapsulates the nutrient and a sodium chloride.

23. A process for producing an encapsulated salt formulation the process comprising the step of admixing a salt and a nutrient, the nutrient being encapsulated in a digestible matrix such that the salt and the nutrient are physically independent.

24. The process defined in claim 23, wherein the nutrient is selected from the group comprising potassium iodide, potassium iodate and mixtures thereof.

25. The process defined in claim 23, wherein the nutrient comprises potassium iodide.

26. The process defined in claim 23, wherein the nutrient comprises potassium iodate and mixtures thereof.

27. The process defined in any one of claims 23-26, wherein the nutrient is present in an amount of from about 0.5% to about 10%.

28. The process defined in any one of claims 23-26, wherein the nutrient is present in an amount of from about 1.0% to about 5.0%.

29. The process defined in any one of claims 23-26, wherein the nutrient is present in an amount of from about 1.5% to about 2.5%.

30. The process defined in any one of claims 23-29, wherein the digestible matrix is selected from the group comprising a carbohydrate, a fat, a protein, an inorganic compound, a polymeric compound and mixtures thereof.

31. The process defined in claim 30, wherein the carbohydrate is a modified starch.

32. The process defined in claim 30, wherein the fat is selected from the group comprising hydrogenated mono-glycerides, hydrogenated di-glycerides and mixtures thereof.

33. The process defined in claim 30, wherein the protein is zein.

34. The process defined in claim 30, wherein the inorganic compound is sodium hexametaphosphate.

35. The process defined in claim 30, wherein the polymeric material is natural.

36. The process defined in claim 30, wherein the polymeric material is synthetic.

37. The process defined in claim 30, wherein the polymeric material is shellac.

38. The process defined in any one of claims 23-37, wherein the digestible matrix is present in an amount in the range of from about 2% to about 25% by weight.

39. The process defined in any one of claims 23-38, wherein the salt comprising sodium chloride.

40. The process defined in any one of claims 23-39, further comprising a supplementary nutrient.

41. The process defined in claim 40, wherein the supplementary nutrient is a compound comprising iron, the supplementary nutrient being encapsulated or unencapsulated.

42. The process defined in claim 41, wherein the compound is selected from the group comprising ferrous fumarate, ferrous sulphate, metallic iron, ferrous citrate and mixtures thereof.

43. The process defined in any one of claims 23-42, wherein the digestible matrix encapsulates the nutrient and a portion of the salt.

44. The process defined in any one of claims 23-42, wherein the digestible matrix encapsulates the nutrient and a sodium chloride.