WO2003068006A1

WO2003068006A1 - Granulated product and process to prepare the same

Info

Publication number: WO2003068006A1
Application number: PCT/EP2003/000347
Authority: WO
Inventors: Anantha Subramony Narayan; Amitava Pramanik; Dattaram Prashant Shinde
Original assignee: Unilever N.V.; Unilever Plc; Hindustan Lever Limited
Priority date: 2002-02-13
Filing date: 2003-01-15
Publication date: 2003-08-21
Also published as: ZA200405376B; EP1474007A1; IL162903A; MXPA04007746A; BR0307177A; CN1722958A; AP2004003089A0; IL162903A0; AU2003202566A1

Abstract

The present invention provides a granulated, free flowing, comestible salt product comprising at least 96% wt. sodium chloride of primary particle size of less than 200 microns, up to 0.6% wt. of calcium and/or magnesium ions present as the chlorides and/or sulphates thereof, up to 6% wt. moisture, at least 30 ppm iodine present as an iodine containing salt and optionally other edible salts, vitamins, minerals and flavouring agents. A process for making the salt product is also provided. The salts of the invention have a good salty taste, a beneficial concentration of iodine and good flow properties. The invention also provides salt compositions comprising the salt product and at least one additional salt.

Description

Granulated product and process to prepare the same

Technical Field:

The present invention relates to a synergistically granulated, free flowing edible salt compositions having flow properties similar to common salt.

Background and Prior art:

Sodium chloride, known as common salt, is an ingredient generally used in cooking and approximately 5 million ton is the annual human consumption in India. Salt is generally produced by solar evaporation, or, multiple effect industrial evaporation of sea water or sub soil brine, or, a combination of these two methods and refined by the process of hydro milling. The process of hydro milling consists of milling the raw salt and then washing the same later with brine. The washed salt is centrifuged and generally dried in a fluid bed drier or vacuum drier to remove the moisture and obtain refined salt. During the process of milling and drying significant quantities of fine salt is formed. This is also referred to in the art and herein as salt fines. The fine salt is hygroscopic in nature and of a low particle size (less than 250 micron) and is commonly discarded. The salt fines contain iodine; an essential micronutrient rarely available in nature. While discarding the fines ensures that the commercially available common salt is obtained in a free flowing form, the iodine present in the fines is wasted.

The particle size of the commercially available salt is generally in the region of from 150-850 microns. Salt fines generally contain large quantities of hygroscopic magnesium salts that tend to absorb moisture and inhibit flow properties. Further, the lower the particle size of the fines, the more difficult it is to include it in common salt as its free flow properties are severely impaired. However, throwing away the fines leads to wastage of material and relatively high cost of the salt.

Our co-pending application WO 02/13631 discloses granulated salt comprising sodium salt and potassium chloride and other optional ingredients and a process to make the same. The sodium chloride is preferably in the form of fines that have a particle size less that 500 microns. The granulated salt has saltiness equivalent to that of common salt. The salt is also free flowing and rich in iodine.

Iodine is one of the three most essential micro-nutrients. However, it is also commonly deficient in most diets, causing a host of diseases commonly called iodine deficiency disorders. The easiest and most inexpensive method of delivery of the same through food was found to be iodisation of common salt. Salt is normally iodized by spraying potassium iodate solution onto salt .

EP-A-090 571 (Morton Thiokol, Inc.) discloses flowable flaked salt compositions comprising 30-70% wt . sodium chloride and 70- 30% wt . potassium chloride.

FR-2,773,955 discloses a table salt comprising 35-55% wt . potassium chloride and 10-40% wt . sodium chloride. US 4,220,667 discloses non-caking nutritional compositions comprising a granular condiment selected from sodium chloride and mixtures of sodium chloride and potassium chloride and wherein the condiment is substantially coated with saliva- insoluble, physiologically acceptable zinc salts.

US 5,288,510 discloses salt substitutes comprising calcium ascorbate as the major component with minor components which may be selected from sodium chloride or potassium chloride.

The publication "Dry mixing technique for the large scale production of fortified salt in India", by S. Ranganathan et al. Asia Pacific J. Clin Nutr (1997) 6(2): 92-94 discloses dry mixing techniques used in the manufacture of iodised salts. The level of iodation was 30ppm.

The publication "Salt iodization for the elimination of iodine deficiency" by M.G. Venkateshmannar and John T. Dunn, published in 1995 by International Council For Control of Iodine Deficiency Disorders, discloses the level of iodisation recommended in various countries for good health.

There is thus a need in the art for edible salt compositions which are substantially free flowing and/or which comprise beneficial amounts of iodine. There is a particular need in the art for edible salt compositions which are substantially free flowing and comprise beneficial amounts of iodine. Furthermore, there is especially a need for such compositions which comprise high levels of sodium chloride.

It is an object of the present invention to address one or more of the above-mentioned problems. In particular, the present invention seeks to provide synergistic, iodine fortified, edible salt compositions having free flow properties similar to common salt, which compositions are in a granulated form.

The present invention also seeks to provide synergistic, fortified, edible salt compositions having enhanced saltiness and a beneficial amount of iodine in a granulated form.

The present invention further seeks to provide a method for making the above-mentioned salt compositions.

For the purposes of this invention, the term 'granulated salt' refers to the salt of the invention and the term 'common salt' refers to salt obtained by conventional processing after discarding the fines. The term 'salt fines' refers to the discarded salt from common salt of particle size less than 200 microns. The term 'edible salt' refers to all salts, including sodium chloride, that are suitable for human consumption.

Summary of the invention

The present applicants have now surprisingly found that a free flowing salt composition in granulated form can conveniently be produced from salt fines having particle size of less than 200 microns. The particle size of the final granulated salt is preferably from 150 microns to 2 mm and advantageously, can be made to match that of the commercially available salt. Thus, as the fines produced during refinement of salt can be employed in the production of the synergistic formulation of the present invention, the material which otherwise would be discarded as waste can be converted into a commercially useful material. The salt fines are rich in iodine and are thus useful for inclusion in a diet which is potentially otherwise low in iodine. The granulated salt thus obtained can be sold as such or mixed with salt conventionally produced after discarding the fines.

The present invention thus relates to a synergistic, granulated, free flowing salt composition comprising sodium chloride of primary particle size less than 200 microns, calcium and/or magnesium salts, water and a source of iodine. Other optional ingredients may also be present in the salt. The process of making the granulated salt provides for a method that converts naturally hygroscopic salt fines into a free flowing edible salt. The granulated salt can be obtained by mixing salt fines with optional ingredients, adding water and/or an aqueous solution of an edible salt and then granulating the mass. The granulated salt so obtained is free flowing in nature. Its saltiness can be increased by use of an appropriate edible salt during processing. The granulated salt of the invention can be made to match the characteristics of common salt and is preferably added to common salt.

Thus, according to the first aspect of the invention, there is provided a granulated, free flowing, comestible salt product comprising: i. at least 96% by weight sodium chloride (on dry basis) of primary particle size of less than 200 microns, ii. up to 0.6% by weight of calcium and/or magnesium ions present as the chlorides and/or sulphates thereof, iii. up to 6% by weight moisture, iv. at least 30 ppm iodine, present as an iodine containing salt, and v. optionally other edible salts, vitamins, minerals and flavouring agents. It is especially preferred that the comestible salts of the first aspect comprise up to 0.3% by weight of calcium and/or magnesium ions present as the chlorides and/or sulphates thereof and up to 4% by weight moisture.

According to a second aspect of the invention, there is provided a free flowing, comestible salt composition comprising: (i) the granulated salt of the first aspect of the invention and, (ii) at least one additional salt.

The at least one additional salt is/are one(s) not according to the invention and preferably comprises common salt. It is preferred, according to the second aspect, that the granulated salt (i) is present in an amount of from 0.1 to 95% by weight of the salt composition. The balance of the salt composition comprises the at least one additional salt.

According to a third aspect of the present invention, there is provided a process for the preparation of a granulated, free flowing, comestible salt product, the process comprising the steps of: i. mixing salt fines of primary particle size of less than 200 microns with optionally an edible salt, vitamins, minerals and/or flavouring agents or a mixture thereof, ii. adding 5 to 15% by weight, based on the weight of the composition of water, and/or an aqueous solution of an edible salt, iii. granulating the mass of step ii, iv. optionally drying the granulated mass to a moisture content of up to 6% by weight, v. optionally breaking the granulated product of step (iii) or (iv) to a particle size in the range of from 150 microns to 2000 microns.

It is especially preferred that the aqueous solution of an edible salt added in step (ii) of the process comprises one or more magnesium salts. Preferably the magnesium salt is magnesium chloride and/or sulphate.

It is especially preferred that the granulating of the mass of step (ii) is carried out by extrusion or compaction.

Detailed description of the invention

(i) Granulated salt product

It is especially preferred that the salt product comprises magnesium ions present as the chlorides or sulphates thereof.

It is possible to include other edible salts, for example potassium chloride, magnesium chloride, magnesium sulphate, calcium chloride etc. in the granulated salt. It is also possible to fortify the granulated salt by adding vitamins and minerals. Water soluble and water insoluble salts of zinc, calcium, strontium, iron etc. are suitable for fortification. It is also possible to incorporate flavours such as garlic, ginger, pepper or any other spice, condiment or herbal flavours during granulation and the stability and homogenity of these flavours will be enhanced due to the granulated form of the product.

Optionally, flow aids like precipitated silica, magnesium or calcium salts or carbonate, phosphate and silicate, zeolite, amorphous aluminosilicate etc. can be added to the granulated salt.

(ii)Salt composition The salt composition according to the second aspect of the invention, comprises the granulated salt of the first aspect and at least one additional salt.

The salt composition most preferably comprises from 1 to 50% by weight of the granulated salt product of the invention, more preferably from 5 to 15% by weight. The balance of the salt composition comprises at least one additional salt and may further comprise the optional ingredients as detailed for the first aspect of the invention.

When the granulated salt of the invention is incorporated into common salt, according to the second aspect of the invention, it is preferred that the particle size range of the granulated salt and the common salt are similar. It is especially preferred that the granulated, free flowing salt has a particle size of from 150 microns to 850 microns, to match that of common salt.

(iii) Process The process according to the third aspect of the invention is further described below.

The salt fines (wherein the primary particle size of the sodium chloride is less than 200 microns) are mixed with water or an aqueous solution of an edible salt. Preferably an aqueous solution of calcium chloride, calcium sulphate, magnesium chloride or magnesium sulphate or a mixture thereof is mixed with the salt fines. The mixing is generally carried out in a mixer chosen so that it ensures uniform mixing of the particles. The mixer could have any or a combination of agitator designs including ribbon, sigma, plough share, helical, planetary or screw type.

It is especially preferred to use "bittern" in step (iii) of the process. By bittern is meant the mother liquor left after salt is harvested by solar evaporation of salt sources like sea water or sub soil brine. The bittern is rich in magnesium chloride and sulphate.

Preferably the particle size of the granules of the salt obtained after step (v) is from 150 microns to 2mm, more preferably from 150 microns to 1000 microns and most preferably from 150 microns to 850 microns.

The mixing is preferably carried out at a temperature in the range of from 5-50°C. The material is mixed for a period of from 5 minutes to 120 minutes, preferably for from 30-45 minutes to ensure homogeneity.

The water and/or the aqueous solution of the salt, is preferably sprayed onto the salt fines mixture from the first step of the process for a uniform coating before or during mixing. The spraying mechanism may be any system that ensures uniform coating of the solution/water on the particles and could include single or multiple fluid atomising nozzles, ultrasonic atomisers, pressure atomisers or any such devices.

It is preferable to continue mixing for a period of about 15 minutes after the water or the solution of the soluble salts, is added. The granulation of the mass of the second step of the process can be done as a batch or continuous or semi-continuous process using any suitable equipment known in the art. Preferably the mass is extruded or compacted.

Granulation can also be carried out using a pan granulator or drum granulator. The granulated salt so obtained is generally crystalline and obtained as regular/ irregular/ spherical granules. Alternately the salt mix could be extruded in a single or twin screw extruder, a die extruder with various configurations or a pellet mill, to obtain noodles. Alternately a sieve granulator with a suitable mesh size could be used. Compaction type equipment like roll compactor and briquetting type machines are also suitable for preparation of the granulated salt of the invention. An alternate process includes taking the wet salt mix from the mixer and granulating it using a tableting method.

It is particularly preferred to use an extrusion type machine which could be of the die, screw of pellet mill type.

The granulated salt so obtained is optionally dried. Up to 6% by weight moisture may be present in the granulated salt of the invention. The drying is done in any conventional dryer such as tray dryer, tunnel dryer, rotary dryer, vacuum dryer, fluid bed dryer or a flash dryer. These dryers could be of batch, continuous or semi-continuous mode of operation. Alternately the product could be air dried or sun dried. A combination of the above mentioned methods can also be employed. Optionally, the granulated salt can be broken to an irregular size in the range of from 150 to 2000 microns, preferably, in the range of from 150 to 1000 microns. The breaking or crushing can be done in one of several machines used for the said purpose and may include impact, cutting, shear, compaction or tensile type crushers. Mills with controlled power input and powdering methodology such as kitchen mixers, multimills, hammer mills, pin mills, airjet mills may also be used for the crushing. Alternately, the noodles may be subjected to a process that causes it to round off to spheres. This could be done in an equipment which is a combination of mechanical or pneumatic methods.

The material is optionally sieved to obtain the product in in desired size range. The oversize can be further crushed by any of the above mentioned methods. The undersize can be further processed in a manner similar to that of salt fines. The granules as such or its mixture with processed common salt, are suitable for selling either in packed form that may be in form of suitable plastic packaging like polyethylene bags, paper pack, PET jars, jute bags or any other suitable form or can be sold loose.

In the most preferred aspect of the invention, the process of the invention is so carried out as to obtain granulated salt matching the shape and particle size characteristics and appearance of common salt. The granulated salt so obtained can be mixed with common salt. The salt so obtained contains the required amount of iodine. The invention is described in detail by the following non- limiting examples. Further examples within the scope of the invention will be apparent to the person skilled in the art.

Examples :

Comparative Examples A, B and C:

Salt fines of particle size less than 150 microns were taken as Comparative Example A.

100 grams of the salt fines were mixed with 1 kg of common salt obtained from the market to give the salt of Comparative Example B.

Common salt procured from the market was taken as Comparative Example C.

Example 1 :

2 kg of salt fines with particle size less than 150 microns was taken in a kitchen mixer. 200 ml of water was added slowly under agitation to the salt fines, ensuring uniform mixing.

The wet salt mix was then extruded into noodles using a sieve granulator having a sieve of 500 micron. The noodles were dried in a tray dryer at 100°C to a final moisture content of 2%. The dried mixture was crushed in a multimill fitted with a 30 mesh sieve. The salt was further sieved to obtain granulated salt of particle size range 200 to 1000 microns.

Example 2 : 1 kg of the salt of Example 1 was mixed in a ribbon mixer with 20 kg of common salt obtained from the market. Example 3 :

2 kg of salt fines of particle size less than 150 microns was taken in a planetary mixer. 20 grams of magnesium chloride of a similar particle size was mixed with the salt fines. The mixture of salts was then sprayed with 200 ml of bittern. The salt mix prepared was then extruded in a die extruder with a die diameter of 1 mm. The salt granules formed were dried at 100°C in a tray dryer until the moisture content dropped to 1%. The sample was crushed in a kitchen mixer. The material was then sieved to obtain salt in the particle size range of 200 to 850 micron.

Example 4 :

100 grams of the salt of Example 3 was mixed manually with 2 kg of common salt obtained from the market.

Evaluation of the salt:

The salts of Examples 1-4 were found to have good free flow, acceptable granularity and very good salty taste impact.

i . Saltiness :

A food preparation (cooked lentil) was prepared using 0.8% of Comparative Example A-C and Examples 1-4. A panel of trained members tasted the samples and evaluated the same for saltiness. The salts of Example 3 and 4 were found to have higher saltiness as compared to the salts of Examples 1 & 2 and Comparative Examples A-C. The salts of Examples 1 and 2 had saltiness similar to common salt (Comparative Example C) .

The free flow properties of the salts of Comparative Examples A-C and Examples 1-4 were measured as follows:

The salts of Comparative Example A-C and Examples 1-4 were packed in polyethylene bag under ambient condition (25°C) . The dynamic flow rate of the samples were measured at the end of 24 hours using a flow meter. The salts of Comparative Example A-B and Examples 1-4 were then stored in packed condition for three months at ambient temperature and 75% humidity. The dynamic flow rate of the samples was again measured using a flow meter at the end of this period.

The results are presented in Table 1. Table 1

The results presented in Table 1 show that the granulated salt of the invention has superior flow properties to common salt even without adding flow aids. The granulated salt can be added to common salt to give a salt mixture with good flow properties . Thus the present invention provides for a granulated salt with improved flow properties, saltiness and a desirable level of iodine. The granulated salt of the invention can be incorporated into common salt to provide a salt composition. The invention also provides for an effective process for converting low value salt fines that are discarded into a granulated salt with improved flow properties and saltiness.

Claims

1. A granulated, free flowing, comestible salt product comprising:

(a) at least 96% by weight sodium chloride of primary particle size of less than 200 microns,

(b) up to 0.6% by weight of calcium and/or magnesium ions present as the chlorides and/or sulphates thereof,

(c) up to 6% by weight moisture,

(d) at least 30 ppm iodine, present as an iodine containing salt, and

(e) optionally other edible salts, vitamins, minerals and flavouring agents.

2. A salt product according to claim 1, wherein the salt product comprises up to 0.3% by weight of the calcium and/or magnesium ions and up to 4% by weight moisture.

3. A salt product according to either one of claims 1 or 2, wherein the product comprises magnesium ions present as the chlorides and/or sulphates thereof.

4. A salt product according to any one of claims 1 to 3, wherein the salt product has an average particle size of from 150 to 1000 microns

5. A free flowing, comestible salt composition comprising (i) the granulated salt of any one of claims 1 to 4 and (ii) at least one additional salt.

6. A salt composition according to claim 5, wherein the salt composition comprises of from 0.1 to 95 % by weight of the granulated salt (i) .

7. A salt composition according to claim 6, wherein the salt composition comprises of from 5 to 15% by weight of the granulated salt (i) .

8. A salt composition according to any one of claims 5 to 7, wherein the at least one additional salt comprises common salt.

9. A process for the preparation of a granulated, free flowing, comestible salt product, the process comprising the steps of:

(a) mixing salt fines of primary particle size of less than 200 microns with optionally an edible salt, vitamins, minerals and/or flavouring agents or a mixture thereof,

(b) adding 5 to 15% by weight, based on the weight of the composition, of water and/or an aqueous solution of an edible salt,

(c) granulating the mass of step b,

(d) optionally drying the granulated mass to a moisture content of up to 6% by weight,

(e) optionally breaking the granulated product of step (c) or (d) to a particle size in the range of from 150 microns to 2000 microns.

10. A process according to claim 9, wherein the aqueous solution of an edible salt comprises one or more magnesium salts, calcium chloride or calcium sulphate.

11. A process according to claim 10, wherein the magnesium salt comprises magnesium chloride and/or sulphate.

12. A process according to claim 11, wherein the magnesium salt comprises bittern.

13. A process according to any one of claims 9 to claim 12, wherein in step e) the granules of the salt are broken to a particle size in the range of from 150 microns to 1000 microns .

14. A process according to any one of claims 9 to claim 13, wherein the water and /or the aqueous solution of an edible salt is sprayed onto the mixture from step a) .

15. A process according to any one of claims 9 to claim 14, wherein the granulating of the mass of step b) is carried out by extrusion or compaction.

16. A process according to any one of claims 9 to 15, wherein the mixing in step a) is carried out for a period of from 30 to 45 minutes.