BACKGROUND OF THE INVENTION Field of the Invention The present invention is broadly concerned with calcium-enriched compositions and methods of supplementing food products with those compositions. More particularly, the inventive compositions include respective sources of phosphate ions, citrate ions, and calcium ions, a metal hydroxide, and water. The compositions have high solids contents and are in the form of substantially uniform, colloidal suspensions in which a high percentage of the available calcium ions remains dispersed.

Description of the Prior Art The food industry has long sought stable, water-dispersible forms of calcium which would allow significant amounts of calcium to be introduced into food products without substantially increasing the bulk of the product. To be effective in this context, the calcium- containing substances must be essentially odorless, colorless, tasteless, and producible at a relatively low cost. In addition, these substances must be stable under the extreme conditions dictated by formulation, processing, and storage of the food products.

Numerous food products would benefit from calcium enrichment. For example, animal milk products (particularly those formed from cow's milk) are already considered to be a good dietary source of calcium. However, these products contain only limited quantities of calcium in each serving, requiring the average person to consume a large portion of the product to obtain the recommended daily allowance (RDA) of calcium.

Furthermore, some people have medical conditions (e. g., osteoporosis) which require the consumption of calcium beyond that required for others. Therefore, supplemental products

which increase the amount of calcium in each serving of milk products at a low cost and without negatively affecting the quality of the milk product are always in demand.

Many people do not consume animal milk products for one reason or another. For example, some people are allergic to these products and cannot safely consume them. There are other people who simply do not consume animal milk products as a lifestyle choice.

Many of these people turn to soy milk as an alternative to animal milk products. While the taste and odor of soy milk has been substantially improved in recent years, soy milk does not naturally contain a significant amount of calcium. Thus, soy milk must be supplemented with calcium in order to provide many of these people with at least some calcium in their diets.

Certainly, many calcium supplements have been attempted in the past. The majority of the prior art calcium-enriched products are deficient in that they have extremely low solids contents, leading to products which are mostly water and is thus costly to ship and store. However, when the moisture levels of these products are reduced in order to make shipping and storing more feasible, the calcium generally precipitates out of solution, forming an unappealing sediment.

SUMMARY OF THE INVENTION The present invention overcomes these problems by broadly providing calcium- enriched compositions having high solids contents of soluble calcium with very little or no sedimentation. It has been discovered that the, order of mixing the various ingredients in forming the composition is critical, and thus, modifying the mixing order followed in prior art methods dramatically increases the solids contents of soluble calcium in the composition.

In more detail, the inventive compositions comprise a source of phosphate ions, a source of citrate ions, a source of calcium ions, a quantity of a metal hydroxide, and water.

The source of phosphate ions should be provided in sufficient quantities so that the composition comprises from about 5-28% by weight phosphate ions, and preferably from about 8-23% by weight phosphate ions, based upon the total weight of the solids in the composition taken as 100% by weight. The preferred sources of phosphate ions are phosphoric and polyphosphoric acids.

The source of citrate ions should be present in the composition at such a level that the composition comprises from about 5-32% by weight citrate ions, and preferably from about 8-25% by weight citrate ions, based upon the total weight of the solids in the composition taken as 100% by weight. The preferred sources of citrate ions are those selected from the group consisting of citric acid, calcium citrate, potassium citrate, and mixtures thereof, with citric acid being the most preferred source of citrate ions.

In combination with the foregoing citrate and phosphate ion concentrations, each of these concentrations should also be such that the molar ratio of citrate ions to phosphate ions is from about 1. 0 : 1. 35 to about 1. 0 : 2. 35, and preferably from about 1. 0 : 1. 75 to about 1. 0 : 1. 95. These ratios are important for obtaining the improved solids contents and calcium yields of the inventive compositions.

The source of calcium ions should be utilized in sufficient quantities to provide from about 2. 5-16. 5% by weight calcium ions, and preferably from about 4-15% by weight calcium ions, based upon the total weight of the solids in the composition taken as 100% by weight. Preferred sources of calcium ions are those selected from the group consisting of calcium hydroxide, calcium carbonate, calcium oxide, and mixtures thereof. The most preferred sources of calcium ions are calcium hydroxide and calcium oxide.

The metal hydroxide is preferably included in sufficient quantities in the composi- tions such that the compositions comprise from about 0. 5-7. 5% by weight of the metal ions, and more preferably from about 0. 8-6. 5% by weight of the metal ions, based upon the total weight of the solids in the composition taken as 100% by weight. Preferably the metal hydroxide is an alkali metal hydroxide, with potassium hydroxide and sodium hydroxide being particularly preferred.

Finally, water should be included in the composition at a level of from about 0. 1- 80% by weight, and preferably from about 2. 0-50% by weight, based upon the total weight of the composition taken as 100% by weight.

The inventive compositions are prepared by forming a precursor mixture comprising the source of citrate ions, the source of calcium ions, the metal hydroxide, and water. The order of addition of these ingredients during this stage is not critical, although it is preferred that the calcium ion source be added to the water initially, followed by the addition of the metal hydroxide and then the citrate ion source to the resulting mixture. Preferably, mixing

is carried out on the intermediate mixtures for about 2-3 minutes after the addition of each ingredient.

The source of phosphate ions is then added to the precursor mixture, followed by intense mixing and heating of the resulting composition to a temperature of about 190- 210 °F, and preferably about 200 °F until the desired solids content is achieved. That is, the solids content of the inventive compositions is at least about 20% by weight, preferably at least about 35% by weight, and more preferably at least about 45% by weight, based upon the total weight of the composition taken as 100% by weight. It has been discovered that adding the source of phosphate ions to the formed precursor mixture (i. e., after the source of citrate ions has been mixed with the other ingredients) dramatically increases the level of soluble solids in the composition, making these high solids contents obtainable. This improvement substantially lessens the quantity of moisture in the composition that must be shipped and stored and, therefore, will lessen the cost of shipping and storing the compositions.

The resulting compositions have a pH of from about 5. 5-7. 5, and preferably from about 6. 5-7. 0. Furthermore, the final compositions comprise at least about 3% by weight calcium ions, and preferably at least about 6% by weight calcium ions, based upon the total weight of the composition taken as 100% by weight. This high calcium ion concentration is a result of the fact that at least about 70%, preferably at least about 80%, and more preferably at least about 90% of the theoretically available quantity of calcium ions will remain dispersed in the unshaken composition (i. e., a composition that has been maintained essentially motionless for at least about 2 days) at ambient temperatures.

In applications where it is desired to produce a dry, reconstitutable product, it is generally preferred to subject the above-described aqueous composition to a drying process (e. g., spray drying or drum drying) until the moisture in the product has been reduced to a level of less than about 5% by weight, and preferably less than about 1% by weight, based upon the total weight of the composition taken as 100% by weight. The resultant solid powder, flake, or granular product can then be reconstituted in aqueous media by mixing it with water at levels of 1 part product with from about 1-4 parts water to form a composition which will exhibit substantially identical properties as those described above with respect to the original aqueous composition.

It will be appreciated that the inventive compositions (either in the concentrated or dried forms) are well-suited for supplementing food products with calcium. Preferred food products which can be supplemented with the calcium-enriched compositions include : dairy products such as milk (e. g., cow's milk) and sour cream ; imitation dairy products such as soy milk ; soy-based products (e. g., tofu) ; beverages such as coffee, tea, water, fruit juices, vegetable juices, and other carbonated or non-carbonated beverages ; soups ; infant foods (e. g., infant formula, baby food) ; and pursed foods (e. g., applesauce). Other preferred food products include animal foods (e. g., dog food, cat food), mineral or nutritional supplements, mineral tonics, condiments, syrup, sauces (e. g., spaghetti sauce), and dessert products (e. g., pudding, ice cream, whipped topping). Those skilled in the art will appreciate that virtually any product, food or otherwise, in need of calcium supplementation can be enriched according to the invention.

Advantageously, these food products can be supplemented by simply mixing the composition (either aqueous or dried) with the food product under ambient conditions. The supplemented products can be formulated to provide at least 100% of the RDA of calcium (i. e., 1000 mg of calcium ions per day is the RDA, thus, 1000 mg of calcium ions per quart of product would provide 100% of the RDA) or as much as 200% of the RDA of calcium, depending on the serving size. Thus, the food product can be supplemented to contain at least about 100 mg, preferably at least about 500 mg, and more preferably at least about 1000 mg, more calcium ions per serving (e. g., per liter or per gram of food product) than would otherwise be present in the non-supplemented product. This is preferably accomplished by mixing from about 12-60 cc of the aqueous composition or from about 6. 0- 12. 0 g of the dried composition with each liter of food product to be supplemented.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS EXAMPLES The following examples set forth preferred methods in accordance with the invention. It is to be understood, however, that these examples are provided by way of illustration and nothing therein should be taken as a limitation upon the overall scope of the invention.

The ingredients of Table 1 were combined, with continuous mixing, in the order indicated to yield a calcium-enriched composition having a citric acid : phosphoric acid molar ratio of 1. 0 : 1. 35 and a pH of 6. 0. The ingredients were added in 2-3 minute intervals. Upon the addition of the final component (i. e., the 75% phosphoric acid solution), the mixture was heated to a temperature of about 210 °F for 30 minutes, followedby furtherheating at212°F until the desired percent solids was achieved.

Table 1 Order of % by Anhydrous Anhydrous Weight in Ingredients addition weight moles molar ratio grams water 1 68. 07----1705 calcium hydroxide 2 6. 89 2. 33 2. 29 172. 5 45% KOH 3 10. 10 2. 03 2. 00 252. 9 solution citric acid, anhydrous 4 7. 79 1. 01 1. 00 195. 0 75% phosphoric acid 5 7. 16 1. 37 1. 35 179. 4 solution a % by weight based upon total weight of all ingredients taken as 100% by weight.

The resulting high percent solids final product was a very thick and viscous cream.

At a 10% dilution, the product was a colloidal suspension with a trace of sediment being present at the bottom of the container after sitting overnight. Table 2 sets forth the concentrations of the ingredients at various percent solids formulations. Table 3 lists additional properties of the product, with the percent calcium determined by atomic absorption spectrophotometric assays.

Table 2

Ions As 24. 59% solids As 20% solids As 35% solids As 100% solids Calcium 3. 72% a 3. 03% 5. 30% 15. 15% b Potassium 1. 42% 1. 16% 2. 03% 5.80%b Citrate 7. 66% 6. 23% 10. 90% 31. 15% b Phosphate 5. 21 % 4. 23 % 7. 41 % 21. 17% b a The percent weight of ions is based upon the percent solids taken as 100% by weight. b Percent of ions that would be available if the 100% solids product were diluted.

Table 3 Property Value pH 6. 0 % solids 31. 0% a % calcium 4. 9% a % yield 90. 7% b a % by weight based upon total weight of composition taken as 100% by weight.

'% yield of calcium ion based upon the quantity of calcium ion added during preparation of the composition.

EXAMPLE 2 The ingredients of Table 4 were combined, with continuous mixing, in the order indicated to yield a calcium-enriched composition having a citric acid : phosphoric acid molar ratio of 1. 0 : 1. 3 5 and a pH of 6. 7. The ingredients were added in 2-3 minute intervals. Upon the addition of the final component (i. e., the 75% phosphoric acid solution), the mixture was heated to a temperature of about 210 °F for 30 minutes, followed by further heating at 212°F until the desired percent solids was achieved.

Table 4

Ingredients Order of % by Anhydrous Anhydrous Weight in addition weighta moles molar ratio grams water 1 66. 89----5800 calcium 2 6. 76 7. 92 2. 29 586. 6 hydroxide 45% KOH 3 11. 67 8. 12 2. 00 1011. 7 solution citric acid, 4 7. 65 3. 45 1. 00 663. 0 anhydrous 75% 5 7. 03 4. 67 1. 35 610. 0 phosphoric acid solution a % by weight based upon total weight of all ingredients taken as 100% by weight.

The resulting high percent solids final product was a very thick, viscous liquid. At a 10% dilution, the product was a colloidal suspension with no sediment being present at the bottom of the container after sitting overnight. Table 5 sets forth the concentrations of the ingredients at various percent solids formulations. Table 6 lists additional properties of the product, with the percent calcium determined by atomic absorption spectrophotometric assays.

Table 5 Ions As 24. 94% solids As 20% solids As 35% solids As 100% solids Calcium 3. 66% a 2. 93% 5. 13% 14. 67% b Potassium 1. 65% 1. 32% 2. 31% 6. 60% b Citrate 7. 53% 6. 03% 10. 56% 30. 18% b Phosphate 5. 11% 4. 10% 7. 18% 20. 50% b a The percent weight of ions is based upon the percent solids taken as 100% by weight. b Percent of ions that would be available if the 100% solids product were diluted.

Table 6

Property Value pH 6. 7 % solids 52. 5% a % calcium 7. 2% a % yield 93. 5% b '% by weight based upon total weight of composition taken as 100% by weight. b % yield of calcium ion based upon the quantity of calcium ion added during preparation of the composition.

EXAMPLE 3 The ingredients of Table 7 were combined, with continuous mixing, in the order indicated to yield a calcium-enriched composition having a citric acid : phosphoric acid molar ratio of 1. 0 : 1. 35 and a pH of 7. 4. The ingredients were added in 2-3 minute intervals. Upon the addition ofthe final component (i. e., the 75% phosphoric acid solution), the mixture was heated to a temperature of about 210°F for 30 minutes, followed by further heating at 212 ° F until the desired percent solids was achieved.

Table 7 Ingredients Order of % by Anhydrous Anhydrous Weight in addition weight moles molar ratio grams water 1 66. 09----1160 calcium 2 6. 68 1. 58 2. 29 117. 3 hydroxide 45% KOH 3 12. 68 1. 79 2. 59 222. 6 solution citric acid, 4 7. 56 0. 69 1. 00 132. 6 anhydrous 75% 5 6. 99 0. 94 1. 35 122. 6 phosphoric acid solution a % by weight based upon total weight of all ingredients taken as 100% by weight.

The resulting high percent solids final product was a viscous, colloidal liquid. At a 10% dilution, the product was a colloidal suspension with a moderate amount of sediment being present at the bottom of the container after sitting overnight. Table 8 sets forth the concentrations of the ingredients at various percent solids formulations. Table 9 lists additional properties of the product, with the percent calcium determined by atomic absorption spectrophotometric assays.

Table 8 Ions As 25. 17% solids As 20% solids As 35% solids As 100% solids Calcium 3. 62% a 2. 88% 5. 03% 14. 38% b Potassium 1. 79% 1. 42% 2. 49% 7. 11 % b Citrate 7. 44% 5. 91% 10. 34% 29. 54% b Phosphate 5. 08% 4. 04% 7. 06% 20. 18% b a The percent weight of ions is based upon the percent solids taken as 100% by weight. b Percent of ions that would be available if the 100% solids product were diluted.

Table 9 Property Value pH 7. 4 % solids 46. 7% a % calcium 6. 6% a % yield 99. 0% b ° % by weight based upon total weight of composition taken as 100% by weight. b% yield of calcium ion based upon the quantity of calcium ion added during preparation of the composition.

EXAMPLE 4 The ingredients of Table 10 were combined, with continuous mixing, in the order indicated to yield a calcium-enriched composition having a citric acid : phosphoric acid molar ratio of 1. 0 : 1. 86 and a pH of 5. 9. The ingredients were added in 2-3 minute intervals. Upon the addition of the final component (i. e., the 75% phosphoric acid solution), the mixture was

heated to a temperature of about 210 °F for 30 minutes, followed by further heating at 212 °F until the desired percent solids was achieved.

Table 10 Ingredients Order of % by Anhydrous Anhydrous Weight in addition weighta moles molar ratio grams water 1 67. 61----7000 calcium 2 7. 08 9. 89 2. 78 733. 0 hydroxide 45% KOH 3 10. 39 8. 63 2. 43 1076. 2 solution citric acid, 4 6. 59 3. 55 1. 00 682. 5 anhydrous 75% 5 8. 33 6. 60 1. 86 862. 2 phosphoric acid solution a % by weight based upon total weight of all ingredients taken as 100% by weight.

The resulting high percent solids final product was a very viscous liquid. At a 10% dilution, the product was a colloidal suspension with a moderate amount of sediment being present at the bottom of the container after sitting overnight. Table 11 sets forth the concentrations of the ingredients at various percent solids formulations. Table 12 lists additional properties of the product, with the percent calcium determined by atomic absorption spectrophotometric assays.

Table 11

Ions As 24. 59% solids As 20% solids As 35% solids As 100% solids Calcium 3. 83% a 3. 12% 5. 45% 15.58%b Potassium 1. 47% 1. 19% 2. 09% 5. 97% b Citrate 6. 49% 5. 28% 9. 24% 26. 3 9% b Phosphate 6. 05% 4. 92% 8. 61% 24. 62% b a The percent weight of ions is based upon the percent solids taken as 100% by weight. b Percent of ions that would be available if the 100% solids product were diluted.

Table 12 Property Value pH 5. 9 % solids 38.6% % calcium 6. 4% a % yield 95. 0% b a % by weight based upon total weight of composition taken as 100% by weight.

'% yield of calcium ion based upon the quantity of calcium ion added during preparation of the composition.

EXAMPLE 5 The ingredients of Table 13 were combined, with continuous mixing, in the order indicated to yield a calcium-enriched composition having a citric acid : phosphoric acid molar ratio of 1. 0 : 1. 86 and a pH of 6. 8. The ingredients were added in 2-3 minute intervals. Upon the addition ofthe final component (i. e., the 75% phosphoric acid solution), the mixture was heated to a temperature of about 210 °F for 30 minutes, followed by further heating at 212 °F until the desired percent solids was achieved.

Table 13

Ingredients Order of % by Anhydrous Anhydrous Weight in addition weighta moles molar ratio grams water 1 66. 40----5600 calcium 2 6. 96 7. 92 2. 79 586. 6 hydroxide 45% KOH 3 12. 00 8. 12 2. 86 1011. 7 solution citric acid, 4 6. 47 2. 84 1. 00 546. 0 anhydrous 75% 5 8. 18 5. 28 1. 86 689. 9 phosphoric acid solution a % by weight based upon total weight of all ingredients taken as 100% by weight.

The resulting high percent solids final product was a very thick, viscous liquid. At a 10% dilution, the product was a colloidal suspension with no sediment being present at the bottom of the container after sitting overnight. Table 14 sets forth the concentrations of the ingredients at various percent solids formulations. Table 15 lists additional properties of the product, with the percent calcium determined by atomic absorption spectrophotometric assays.

Table 14 Ions As 24. 96% solids As 20% solids As 35% solids As 100% solids Calcium 3. 76% a 3. 01% 5. 27% 15. 07% b Potassium 1. 69% 1. 36% 2. 37% 6. 78% b Citrate 6. 37% 5. 11% 8. 94% 25. 53 % b Phosphate 5. 95% 4. 76% 8. 33% 23. 82%' a The percent weight of ions is based upon the percent solids taken as 100% by weight. b Percent of ions that would be available if the 100% solids product were diluted.

Table 15

Property Value pH 6. 8 % solids 44. 2% a % calcium 5. 63% a % yield 84. 6% b a % by weight based upon total weight of composition taken as 100% by weight.

'% yield of calcium ion based upon the quantity of calcium ion added during preparation of the composition.

EXAMPLE 6 The ingredients of Table 16 were combined, with continuous mixing, in the order indicated to yield a calcium-enriched composition having a citric acid : phosphoric acid molar ratio of 1. 0 : 1. 86 and a pH of 7. 6. The ingredients were added in 2-3 minute intervals. Upon the addition ofthe final component (i. e., the 75% phosphoric acid solution), the mixture was heated to a temperature of about 210 ° F for 3 0 minutes, followed by further heating at 212 ° F until the desired percent solids was achieved.

Table 16 Ingredients Order of % by Anhydrous Anhydrous Weight in addition weighta moles molar ratio grams water 1 69. 77----1413. 0 calcium 2 6. 05 1. 65 2. 79 122. 5 hydroxide 45% KOH 3 11. 43 1. 86 3. 14 231. 5 solution citric acid, 4 5. 61 0. 59 1. 00 113. 7 anhydrous 75% 5 7. 14 1. 11 1. 86 144. 5 phosphoric acid solution a % by weight based upon total weight of all ingredients taken as 100% by weight.

The resulting high percent solids final product was a viscous liquid. At a 10% dilution, the product was a colloidal suspension with no sediment being present at the bottom of the container after sitting overnight. Table 17 sets forth the concentrations of the ingredients at various percent solids formulations. Table 18 lists additional properties of the product, with the percent calcium determined by atomic absorption spectrophotometric assays.

Table 17 Ions As 22. 9% solids As 20% solids As 35% solids As 100% solids Calcium 3. 27% a 2. 86% 5. 00% 14. 28% b Potassium 7. 95% 6. 94% 12. 15% 34. 72% b Citrate 5. 52% 4. 82% 8. 44% 24. 10% b Phosphate 6. 92% 6. 05% 10. 59% 30. 25%' a The percent weight of ions is based upon the percent solids taken as 100% by weight.

Percent of ions that would be available if the 100% solids product were diluted.

Table 18 Property Value pH 8. 0 % solids 22. 9% a % calcium 4. 22% a % yield 99. 0% b a % by weight based upon total weight of composition taken as 100% by weight. b % yield of calcium ion based upon the quantity of calcium ion added during preparation of the composition.

EXAMPLE 7 The ingredients of Table 19 were combined, with continuous mixing, in the order indicated to yield a calcium-enriched composition having a citric acid : phosphoric acid molar ratio of 1. 0 : 2. 33 and a pH of 5. 7. The ingredients were added in 2-3 minute intervals. Upon the addition ofthe final component (i. e., the 75% phosphoric acid solution), the mixture was

heated to a temperature of about210°F for 30minutes, followedby furtherheating at212°F until the desired percent solids was achieved.

Table 19 Ingredients Order of % by Anhydrous Anhydrous Weight in addition weighta moles molar ratio grams water 1 72. 07----6600 calcium 2 6. 40 7. 91 3. 25 586. 4 hydroxide 45% KOH 3 8. 30 6. 10 2. 50 760. 0 solution citric acid, 4 5. 11 2. 44 1. 00 468. 0 anhydrous 75% 5 8. 12 5. 69 2. 33 743. 2 phosphoric acid solution a % by weight based upon total weight of all ingredients taken as 100% by weight.

The resulting high percent solids final product was a very thick viscous liquid. At a 10% dilution, the product was a colloidal suspension with a trace amount of sediment being present at the bottom of the container after sitting overnight. Table 20 sets forth the concentrations of the ingredients at various percent solids formulations. Table 21 lists additional properties of the product, with the percent calcium determined by atomic absorption spectrophotometric assays.

Table 20

Ions As 21. 34% solids As 20% solids As 35% solids As 100% solids Calcium 3. 46% a 3. 25% 5. 68% 16. 23% b Potassium 1. 17% 1. 10% 1. 92% 5. 49% b Citrate 5. 03% 4. 71% 8. 25% 23. 57% b Phosphate 5. 90% 5. 53% 9. 67% 27. 64% b

a The percent weight of ions is based upon the percent solids taken as 100% by weight. b Percent of ions that would be available if the 100% solids product were diluted.

Table 21 Property Value pH 5. 7 % solids 34. 5% a % calcium 5. 7% a % yield 86. 4% b a % by weight based upon total weight of composition taken as 100% by weight. b % yield of calcium ion based upon the quantity of calcium ion added during preparation of the composition.

EXAMPLE 8 The ingredients of Table 22 were combined, with continuous mixing, in the order indicated to yield a calcium-enriched composition having a citric acid : phosphoric acid molar ratio of 1. 0 : 2. 33 and a pH of 7. 2. The ingredients were added in 2-3 minute intervals. Upon the addition ofthe final component (i. e., the 75% phosphoric acid solution), the mixture was heated to a temperature of about 210 °F for 30 minutes, followed by further heating at 212 °F until the desired percent solids was achieved.

Table 22

Ingredients Order of % by weighta Anhydrous Anhydrous Weight in addition moles molar ratio grams water 1 66. 12----5480 calcium 2 7. 08 7. 92 3. 25 586. 6 hydroxide 45% KOH 3 12. 19 8. 11 3. 33 1010. 7 solution citric acid, 4 5. 65 2. 44 1. 00 468. 2 anhydrous 75% 5 8. 96 5. 68 2. 33 742. 4 phosphoric acid solujtion a% by weight based upon total weight of all ingredients taken as 100% by weight.

The resulting high percent solids final product was a very thick viscous liquid. At a 10% dilution, the product was a colloidal suspension with a moderate amount of sediment being present at the bottom of the container after sitting overnight. Table 23 sets forth the concentrations of the ingredients at various percent solids formulations. Table 24 lists additional properties of the product, with the percent calcium determined by atomic absorption spectrophotometric assays.

Table 23 Ions As 24. 93% solids As 20% solids As 35% solids As 100% solids Calcium 3. 83% a 3. 07% 5. 38% 15. 36% Potassium 1. 72% 1. 38% 2. 42% 6. 90%b Citrate 5. 56% 4. 46% 7. 81% 22. 3 I% b, Phosphate 6. 51% 5. 22% 9. 14% 26. 12% b a The percent weight of ions is based upon the percent solids taken as 100% by weight. b Percent of ions that would be available if the 100% solids product were diluted.

Table 24

Property Value pH 7. 2 % solids 52. 1 % a % calcium 8. 1% a % yield 90. 0% b a % by weight based upon total weight of composition taken as 100% by weight.

'% yield of calcium ion based upon the quantity of calcium ion added during preparation of the composition.

EXAMPLE 9 The ingredients of Table 25 were combined, with continuous mixing, in the order indicated to yield a calcium-enriched composition having a citric acid : phosphoric acid molar ratio of 1. 0 : 2. 33 and a pH of 7. 2. The ingredients were added in 2-3 minute intervals. Upon the addition of the final component (i. e., the 75% phosphoric acid solution), the mixture was heated to a temperature of about 210 °F for 30 minutes, followed by further heating at 212 °F until the desired percent solids was achieved.

Table 25 Ingredients Order of % by Anhydrous Anhydrous Weight in addition weighta moles molar ratio grams water 1 69. 45----6600 calcium 2 6. 21 7. 96 3. 26 590. 0 hydroxide 45% KOH 3 11. 59 8. 83 3. 62 1101. 3 solution citric acid, 4 4. 94 2. 44 1. 00 469. 0 anhydrous 75% 5 7. 82 5. 68 2. 33 742. 7 phosphoric acid solution a % by weight based upon total weight of all ingredients taken as 100% by weight.

The resulting high percent solids final product was a viscous liquid. At a 10% dilution, the product was a colloidal suspension with a trace amount of sediment being present at the bottom of the container after sitting overnight. Table 26 sets forth the concentrations of the ingredients at various percent solids formulations. Table 27 lists additional properties of the product, with the percent calcium determined by atomic absorption spectrophotometric assays.

Table 26 Ions As 22. 22% solids As 20% solids As 35% solids As 100% solids Calcium 3. 36% a 3. 36% 5. 29% 15. 12% b Potassium 1. 64% 1. 47% 2. 58% 7. 36%" Citrate 4. 86% 4. 37% 7. 65% 21. 86% b Phosphate 5. 68% 5. 11% 8. 95% 25.57%b a The percent weight of ions is based upon the percent solids taken as 100% by weight. b Percent of ions that would be available if the 100% solids product were diluted.

Table 27 Property Value pH 7. 2 % solids 34. 9% a % calcium 6. 0% a % yield 85. 7% b I a % by weight based upon total weight of composition taken as 100% by weight. b % yield of calcium ion based upon the quantity of calcium ion added during preparation of the composition.

In each of the following three examples (Examples 10-12) different types of ingredients were utilized.

EXAMPLE 10 In this example, 115% polyphosphoric acid was used in place of a 75% phosphoric acid solution. The ingredients of Table 28 were combined, with continuous mixing, in the order indicated to yield a calcium-enriched composition having a citric acid : phosphoric acid molar ratio of 1. 0 : 1. 86 and a pH of 7. 0. The ingredients were added in 2-3 minute intervals.

Upon the addition of the final component (i. e., the 115% polyphosphoric acid solution mixed with water), the mixture was heated to a temperature of about 210 °F for 30 minutes, followed by further heating at 212°F until the desired percent solids was achieved.

Table 28 Ingredients Order of % by weiglita Anhydrous Anhydrous Weight in addition moles molar ratio grams water 1 70. 27----1700 calcium 2 6. 73 2. 20 2. 78 162. 8 hydroxide 45% KOH 3 11. 56 2. 24 2. 84 279. 8 solution citric acid, 4 6. 27 0. 79 1. 00 151. 6 anhydrous 115% polyphos-5 5. 17 1. 47 1. 86 125. 1 phoric acid solution + 200 ml of water from step 1 a % by weight based upon total weight of all ingredients taken as 100% by weight.

The resulting high percent solids final product was a viscous liquid. At a 10% dilution, the product was a colloidal suspension with a slight amount of sediment being present at the bottom of the container after sitting overnight. Table 29 lists additional properties of the product, with the percent calcium determined by atomic absorption spectrophotometric assays.

Table 29

Property Value pH 7. 0 % solids 24. 5% a % calcium 3. 64% a % yield 99. 0% b a % by weight based upon total weight of composition taken as 100% by weight.

*'% yield of calcium ion based upon the quantity of calcium ion added during preparation of the composition.

EXAMPLE 11 In this example, sodium hydroxide was used in combination with potassium hydroxide. The ingredients of Table 30 were combined, with continuous mixing, in the order indicated to yield a calcium-enriched composition having a citric acid : phosphoric acid molar ratio of 1. 0 : 1. 87 and a pH of 7. 4. The ingredients were added in 2-3 minute intervals.

Upon the addition of the final component (i. e., the 75% phosphoric acid), the mixture was heated to a temperature of about 210 °F for 30 minutes, followed by further heating at 212 °F until the desired percent solids was achieved.

Table 30

Ingredients Order of % by Anhydrous Anhydrous Weight in addition weighta moles molar ratio grams water 1 72. 83----1432. 8 calcium 2 6. 25 1. 65 2. 80 122. 9 hydroxide 45% KOH 3 5. 87 0. 93 1. 57 115. 54 solution sodium 4 1. 90 0. 93 1. 57 37. 4 hydroxide citric acid, 5 5. 78 0. 59 1. 00 113. 8 anhydrous 75% 6 7. 37 1. 10 1. 87 144. 9 phosphoric acid solution a % by weight based upon total weight of all ingredients taken as 100% by weight.

The resulting high percent solids final product was a viscous liquid. At a 10% dilution, the product was a colloidal suspension with a trace amount of sediment being present at the bottom of the container after sitting overnight. Table 31 lists additional properties of the product, with the percent calcium determined by atomic absorption spectrophotometric assays.

Table 31 Property Value pH 7. 4 % solids 20. 3% a % calcium 3. 45% a % yield 99. 0% b a % by weight based upon total weight of composition taken as 100% by weight. b % yield of calcium ion based upon the quantity of calcium ion added during preparation of the composition.

EXAMPLE 12 In this example, calcium carbonate was used instead of calcium hydroxide. The ingredients of Table 32 were combined, with continuous mixing, in the order indicated to yield a calcium-enriched composition having a citric acid : phosphoric acid molar ratio of 1. 0 : 1. 88 and a pH of 9. 0. The ingredients were added in 2-3 minute intervals. Upon the addition of the final component (i. e., the 75% phosphoric acid), the mixture was heated to a temperature of about 210 °F for 30 minutes, followed by further heating at 212 °F until the desired percent solids was achieved.

Table 32 Ingredients Order of % by Anhydrous Anhydrous Weight in addition weighta moles molar ratio grams water 1 69. 85----1595 calcium 2 7. 16 1. 65 2. 80 163. 5 carbonate 45% KOH 3 11. 63 2. 13 3. 60 265. 4 solution citric acid, 4 5. 00 0. 59 1. 00 113. 9 anhydrous 75% 5 6. 36 1. 11 1. 88 145. 13 phosphoric acid solution '% by weight based upon total weight of all ingredients taken as 100% by weight.

The resulting high percent solids final product was a viscous liquid. At a 10% dilution, the product was a colloidal suspension with a slight amount of sediment being present at the bottom of the container after sitting overnight. Table 33 lists additional properties of the product, with the percent calcium determined by atomic absorption spectrophotometric assays.

Table 33

Property Value pH 9. 0 % solids 20. 6% a % calcium 2. 98% a % yield 99. 0% b a % by weight based upon total weight of composition taken as 100% by weight. b% yield of calcium ion based upon the quantity of calcium ion added during preparation of the composition.

EXAMPLE 13 The ingredients of Table 34 were mixed together in the order indicated to yield a calcium-enriched composition having a citric acid : phosphoric acid molar ratio of 1. 0 : 1. 67 and a pH of 6. 5. The ingredients were added in 2-3 minute intervals. Upon the addition of the final component (i. e., the 75% phosphoric acid solution), the mixture was heated to a temperature of about 200 °F and mixing was continued for 30 minutes. Then, the mixture was further heated to 212°F and stirring was continued until a 45% solids content was achieved. Mixing was carried out utilizing an INDCO mixer (INDCO, Inc., New Albany, Indiana). The 1000-gallon, jackeed mixer was equipped with a 2-speed, 3-to 6- horsepower, gear-head which drove a sweep agitator blade and a 10-horsepower motor belt drive that powered a 10-inch, design D, INDCO dispersion blade.

Table 34

Ingredients Order of % by Anhydrous Anhydrous Weight in addition weighta moles molar ratio grams water 1 73. 83----1900. 0 calcium 2 5. 38 1870. 11 2. 59 138. 6 hydroxide 45% KOH 3 9. 29 1917. 13 2. 66 239. 0 solution citric acid, 4 5. 38 721. 29 1. 00 138. 6 anhydrous 75% 5 6. 12 1205. 28 1. 67 157. 5 phosphoric acid solution a % by weight based upon total weight of all ingredients taken as 100% by weight.

The resulting high percent solids final product was a very thick viscous liquid. At a 10% dilution, the product was a colloidal suspension with a trace amount of sediment being present at the bottom of the container after sitting overnight. Table 3 5 lists additional properties of the product, with the percent calcium determined by atomic absorption spectrophotometric assays.

Table 35 Property Value pH 6. 5 % solids 45. 5% a % calcium 6. 6% a % yield 98. 4% b a % by weight based upon total weight of composition taken as 100% by weight.

'% yield of calcium ion based upon the quantity of calcium ion added during preparation of the composition.

For the following two examples (Examples 14-15), low percent solids formulations with a citric acid : phosphoric acid ratio of 1. 0 : 2. 0 were prepared by varying the order of addition of the acids.

EXAMPLE 14 In this example, a prior art formulation (Formula 65 of U. S. Patent No. 4, 214, 996) was prepared as described in that patent in order to compare that formulation's solids content and calcium level to those of the instant invention. The ingredients of Table 36 were combined, with continuous mixing, in the order indicated to yield a calcium-enriched composition having a citric acid : phosphoric acid molar ratio of 1. 0 : 2. 0. The ingredients were added in 2-3 minute intervals, with mixing being carried out for about 2 minutes after the addition of each ingredient. Upon the addition of the final component (i. e., the citric acid), the mixture was heated to a temperature of about 200°F and mixing was continued for 30 minutes.

Table 36 Ingredients Order of % by Anhydrous Anhydrous Weight in addition weighta moles molar ratio grams water 1 89. 80----5160 calcium 2 2. 12 1. 65 3. 0 122. 0 hydroxide 45% KOH 3 3. 75 1. 73 3. 0 215. 4 solution 75% 4 2. 20 1. 10 2. 0 143. 4 phosphoric acid solution citric acid, 5 1. 84 0. 55 1. 0 105. 6 anhydrous I a % by weight based upon total weight of all ingredients taken as 100% by weight.

The resulting low percent solids final product was a white opaque suspension. At a 10% dilution, the product was a colloidal suspension with a substantial amount of sediment being present at the bottom of the container after sitting overnight. Table 37 lists additional properties of the product, with the percent calcium determined by atomic absorption spectrophotometric assays.

Table 37 Property Value pH 7. 45 % solids 8. 27% a % calcium 0. 38% a % yield 34. 5% b a % by weight based upon total weight of composition taken as 100% by weight. b% yield of calcium ion based upon the quantity of calcium ion added during preparation of the composition.

EXAMPLE 15 This test was similar to that described in Example 14, except that the order of ingredient addition was modified so that phosphoric acid was added last. The ingredients of Table 38 were combined, with continuous mixing, in the order indicated to yield a calcium-enriched composition having a citric acid : phosphoric acid molar ratio of 1. 0 : 2. 0.

The ingredients were added in 2-3 minute intervals, with mixing being carried out for about 2 minutes after the addition of each ingredient. Upon the addition of the final component (i. e., the 75% phosphoric acid solution), the mixture was heated to a temperature of about 200°F and mixing was continued for 30 minutes (i. e., heating was not carried out to obtain a particular solids content).

Table 38

Ingredients Order of % by Anhydrous Anhydrous Weight in addition weighta moles molar ratio grams water 1 89. 68----5110 calcium 2 2. 14 1. 65 3. 0 122. 2 hydroxide 45% KOH 3 3. 80 1. 74 3. 0 216. 3 solution citric acid, 4 1. 86 0. 55 1. 0 105. 7 anhydrous 75% 5 2. 53 1. 10 2. 0 143. 9 phosphoric acid solution a % by weight based upon total weight of all ingredients taken as 100% by weight.

The resulting low percent solids final product was a colloidal suspension with a moderate amount of sediment being present at the bottom of the container. Table 39 lists additional properties of the product, with the percent calcium determined by atomic absorption spectrophotometric assays.

Table 39 Property Value pH 7. 60 % solids 9. 37% a % calcium 1. 64% a % yield 99. 0% b a % by weight based upon total weight of composition taken as 100% by weight.

'% yield of calcium ion based upon the quantity of calcium ion added during preparation of the composition.

A comparison of Examples 14 and 15 indicate that the soluble calcium content of the prior art formulation is substantially lower than the soluble calcium content achieved when phosphoric acid is added as the last ingredient according to the instant invention.

EXAMPLE 16 Calcium Supplementation of Soy Milk In this example, samples of soy milk were supplemented with a calcium-enriched composition according to the instant invention. That is, an amount of a calcium-enriched composition as prepared in Example 5 was added to soy milk which had not been previously supplemented with calcium. In each of these instances, the calcium-enriched composition was added in sufficient quantities to give a theoretically expected yield of 98 mg of calcium ions per 100 g of the soy product. The supplemented products were then tested for the actual calcium content by atomic absorption spectrophotometric assays. These results are set forth in Table 40.

Table 40 Commercially available Expected calcium ion Actual calcium ion content soy milk content (mg Ca/100 g (mg Ca/100 g product i 10 product) mg) Furama chocolate (shaken 98 160 top portion) Furama plain (unshaken 98 160 top portion) Furama chocolate 98 160 (unshaken top portion) Next, commercially available, calcium-enriched soy products were obtained and tested for their actual calcium ion content. These results are shown in Table 41.

Table 41

Commercially available Expected calcium ion Actual calcium ion content soy milk content (mg Ca/100 g (mg Ca/100 g product) product)' Silk plain (unshaken top 98 48 portion) b Silk plain (shaken 98 140 portion) b Soy Dream (unshaken top 98 35 portion)" Soy Dream (shaken top 98 89 portion)" "according to product label. calcium source obtained from calcium carbonate according to product label. calcium source obtained from tricalcium phosphate according to product label.

As shown in Table 41, all of the products except the shaken, Silk plain soy milk had a lower actual calcium ion content than indicated on the label. This was particularly true when the product was not mixed prior to testing, indicating that the calcium was precipitating out of solution. This was not true with the soy milks enriched with the inventive compositions (see Table 40) which each provided high soluble calcium contents in the Furama, even without shaking of the product.

EXAMPLE 17 Calcium Supplementation of Dairy Products In this example, daily products were supplemented with a calcium-enriched composition according to the invention and compared with control samples. That is, an amount of a calcium-enriched composition as prepared in Example 5 was added to cow's milk (Belfonte 2% fat milk, labeled as containing 30% of the RDA of calcium per cup or 300 mg of calcium per serving). The inventive composition was mixed with the milk in sufficient quantities to increase the calcium in the milk to about 50% of the RDA of calcium (about 500 mg of calcium per 8 ounces of milk). Three such samples were prepared and are hereinafter referred to as Samples B, E, and H, respectively.

Three additional samples (referred to as Samples C, F, and I) were prepared with sufficient tricalcium phosphate to fortify the milk to about 50% of the RDA of calcium per serving. Samples A, D, and G were the control samples.

Each of the samples was refrigerated and tested at various time intervals to determine the concentration of calcium in the sample. The tested portions of the samples were taken from the unshaken, top portions of the liquid. These results are shown in Table 42.

Table 42 Sample Day 1 Sample Day 7 Sample Day 14a Average Expected Percent Average Dispersed A 1200 D 1200 G 1100 1200 1200 100% B 2100 E 1900 H 2300 2100 2000 100% C 1200 F 1100 1 1200 1200 2000 55% a mg of calcium per quart of milk product The samples fortified according to the invention (i. e., Samples B, E, and H) had higher calcium concentrations than any of the other samples throughout the entire period of examination. Furthermore, samples B, E, and H achieved the expected, enriched levels of 2000 mg of calcium per quart of milk product. This is due to the fact that all of the calcium in Samples B, E, and H remained suspended while much ofthe tricalcium phosphate utilized in Samples C, F, and I settled to the bottom of the container. Thus, the latter samples fortified with tricalcium phosphate provided only 1200 mg of calcium per quart of milk product while the samples fortified with the inventive composition achieved the expected 2000 mg of calcium per quart of milk.

EXAMPLE 43 Bioavailability of Calcium in Supplement Milk In this example, a calcium salt in accordance with the invention was tested by feeding the salt in milk consumed during meals.

Methods Eighteen adult men (coded R-001 through R-018, respectively) ranging in age from 23 to 59 years, were recruited from a volunteer pool, by word of mouth, and by telephone solicitation. (The target sample was 16 subjects and the sample was over-recruited slightly to allow for possible subject loss.) Potential subjects were screened to exclude major medical illnesses, possibly interfering regular medications, and extremes of weight for height. The targeted 16 triple studies were completed, and full data was obtained for the other two subjects as well. The mean age of the 18 subjects ( S. D.) was 42. 2 y (9. 5 y).

Although there was inevitably some fluctuation in weight over the 4-5 week course of the project, it tended to be very small.

The design for the study was a randomized cross-over involving three test meals in each subject, spaced nominally two weeks apart. Subjects were randomly assigned to one of six sequences : mrc, mcr, rcm, rmc, cmr, or crm, where"m"stands for milk,"r"for the complex salt of the invention, and"c"for the combination of the two. Sequence randomization to the subjects was performed using the random number function of EXCEL.

All tests were performed in the morning after an overnight fast of 9-12 hours' duration. All participants were requested to abstain from alcohol for at least 36 hours prior to testing. The first tests were separated by seven weeks. Stragglers who had intercurrent medical problems or schedule conflicts were studied out of the regular schedule.

The meal consisted of buttered, ORC-baked, low calcium white bread, toasted, and water, tea or coffee (with artificial sweetener if desired). Commercial white bread is fortified with certain B-vitamins in the U. S., and the carrying agent for the vitamin mixture is commonly a calcium salt. Accordingly, a specially baked, unenriched white bread was used in order to minimize meal calcium sources other than that tested. Meals were used because interindividual variance in absorption is reduced and absorption is optimized under meal conditions. The tracer-labeled calcium source, either the salt of the invention, a serving of milk or the combination, was consumed at the mid-point of the breakfast. The labeled calcium load in all tests was 300 mg. This was provided by 262. 8 g skim milk and by 3. 72 g of the product of the invention (see below). In the test meal using the fortified milk, 150 mg of the Ca load came from the milk (131. 4 g), and 150 mg from the labeled salt of the invention (1. 86 g). Meal and fluid volume were held constant in all subjects by

adding suitable quantities of deionized water, as needed. The doses of the inventive salt were individually weighed on a tared black plastic spoon, and the spoons were placed in the subjects'mouths. The spoons were thoroughly licked by the subjects. The black plastic background facilitated identification of any residue ; licking was continued until there was no perceptible residue.

For the tests of the combined source in Visit 1, the product of the invention was added to the milk 14 hours before feeding and the combination stored in the refrigerator.

The resulting product, next morning, left a very viscous film on the serving container that was not possible to rinse off with water (usual method to ensure quantitative transfer of the dose into the subjects). Accordingly, the residue in the serving containers was removed in the laboratory and its radioactivity separately analyzed. These counts were then subtracted from the calculated tracer dose for each subject before calculating absorption from the measured serum level of tracer. In light of this difficulty, it was decided to give all subsequent combination product doses by co-ingestion, i. e., by feeding the product of the invention separately from the milk, without pre-mixing. Specifically, subjects drank approximately half the milk, then ingested 1. 86 g of the salt, then immediately took the remainder of the milk. Mixing of the calcium sources, then, occurred in the stomach.

Skim milk for the milk-only meal was labeled-16 hours prior to dosing, by adding to the individual servings a carefully measured, submicrogram quantity of high specific activity 45CaCl2 salt (Amersham, Oak Ridge, IL) dissolved in 5 ml deionized water. For the two meals containing the complex salt of the invention, the label was incorporated into the salt alone and was accomplished at the time of the synthesis of the salt itself, by adding high specific activity 45CaCl2 to the reaction mixture of the Ca (OH) 2 stage, prior to addition of the other reactants.

The resulting product was analyzed and had the following characteristics : percent solids-46. 63 ; percent Ca-8. 07 ; and radioactivity. Two samples were taken for both stable and radioactive calcium analysis. The CV for calcium was 1. 3%, and for specific radioactivity, 1. 2%, indicating very satisfactory homogeneity of the product.

"Ca was analyzed by liquid scintillation counting on a Packard Model No. 1900TR instrument (Packard Instrument Corporation, Meriden, CT) against suitable blanlc samples (for background) and counting standards prepared from the dosing stock solution. This

method allows radioactivity in the serum samples to be expressed as a fraction of the ingested dose. By bracketing the unknowns with dose standards, decay was automatically adjusted with time. All counting vials were saved until the end of the study for reanalysis if needed to double-check outliers (not necessary in this instance). Stable calcium in serum and in the calcium sources was analyzed by atomic absorption spectrophotometry (AAnalyst 100, Perkin-Elmer, Norwalk, CT).

Because 45Ca is an isotope with a relatively long half life (163 days), it is necessary to correct the serum radioactivity values obtained at subsequent tests for residual radioactivity remaining from previous tests. This correction was accomplished by obtaining a blood sample prior to the test breakfast at the second and third sessions, analyzing the serum for its 45Ca, and subtracting this count level from the values obtained five hours later, after feeding a new test dose. The correction is small, but if it were not made, values measured at second (and subsequent) tests would slightly over-estimate absorption. A further correction was undertaken when the f-hour time point was not precisely hit (usually because of difficult venipuncture). Measured counts were adjusted by use of a variable function of the time lapse factor based on extensive laboratory data describing the exponential character of tracer concentration versus time.

True fractional absorption was measured from the radioactivity level in the 5-hour sample, using published algorithms (Heaney et al. ; Estimation of true calcium absorption ; Annals Int Med; 103 : 516-521 (1985) and Heaney et al. ; Estimating true fractional calcium absorption ; Letter to the Editor :, Annals IntMed ; 108 : 905-906 (1988). Briefly, absorption fraction is given by : FxAbs = (SA50.92373) * [0.3537 * (Ht0.52847) * (Wt0.37213)], in which FxAbs equals absorption fraction; SA5 equals 5-hour serum calcium specific radioactivity (fraction of oral dose per gram calcium) ; Ht equals height (meters) ; and Wt equals weight (kilograms). The bracketed factor at the right of the equation serves, in effect, to adjust the measured SA5 values for body size differences (i. e., different volumes of distribution). This calculation is not strictly necessary in a cross-over design, since the paired specific activity data contain the only significantly varying values between substances. Nevertheless, expressing the data as true fractional absorption facilitates comparison with other published reports.

The foregoing algorithm has been explicitly calibrated for women. Since men have, on average, a higher proportion of body water per unit weight, this algorithm underestimates true absorption in them by-10-15%. However, since this project is designed as a within- subject comparison, this systematic departure from true fractional absorption has no effect on the conclusions.

One subject (ID09) developed a febrile respiratory infection at the time of the scheduled third visit. The visit was postponed for one week at which time the subject was in good health. There were no adverse reactions to the products tested.

Data were characterized by simple descriptive statistics, using the various functions supplied by EXCEL (Microsoft Corp., Redmond, WA) or by the Crunch 4. 04 Statistical Package (Crunch Software Corp., Oakland, CA). Additionally, data were analyzed by ANOVA using SAS (SAS Institute, Cary, NC) employing treatment and order as possible independent variables.

Results Table 43 presents the fractional absorption data for the three test substances, by subject. Across all 18 subjects, absorption fraction averaged 0. 238 for the milk, 0. 182 for the salt of the invention alone, and 0. 223 for the combination of the labeled salt of the invention in milk. The mean (i SEM) within-subject difference between milk alone and milk fortified with the salt of the invention was-0. 0146 ( 0. 0202), and between milk alone and the salt of the invention alone,-0. 0561 (0. 0092). There was no significance to the small difference between milk alone and milk fortified with the salt of the invention.

However, the difference between the salt of the invention alone and milk alone was highly significant. These results were also tested for an effect of study order and no effect was found.

Two batches of the complex salt of the invention was used in this study. One was a sample supplied by the manufacturer at the time this project was designed (Lot C151 XL), and the other was a batch synthesized in the laboratory. The two batches seemed to behave differently. The first batch remained fully stable at room temperature for several months, while the second developed visible particles (apparently crystals) on standing for the several weeks between synthesis and the final test day. (This made dose aliquotting difficult for the

second and third test days, because the product was no longer physically homogeneous, but was corrected by stirring thoroughly before taking the dose aliquots.) Also, as noted under Methods above, the combination of milk and the product of the invention became very viscous when stored in the refrigerator overnight. (This was not true at three hours, at which time the combination still exhibited gross pourability comparable to milk alone.) This apparently did not happen to product prepared by this manufacturer.

Because the combination was pre-mixed for only one-third of the subjects, any reaction taking place between the milk matrix and the fortificant would not have occurred in the two-thirds of the subject who received the two sources concurrently (but not pre- mixed). The fractional absorption values comparing the two dosing methods for the combination were observed for the possibility of an effect. Those receiving the pre-mixed product absorbed significantly less efficiently than those ingesting the two products without pre-mixing (0. 1634 vs. 0. 2531). However, the subjects ingesting the pre-mixed product were not a random sample of the combination dosing group, and, as it turned out, the subjects absorbed the milk calcium somewhat less efficiently as well (0. 214 vs. 0. 25).

Discussion These results demonstrate that the complex salt of the invention, when ingested by itself in the batch tested, was absorbed at about 76% the efficiency of the same quantity of calcium ingested as milk. When the product of the invention was co-ingested with milk, keeping total calcium load constant and confining the analysis to the same 12 subjects for both sources, absorption was identical for the two sources (0. 2495 for milk alone, vs 0. 2510 for the co-ingested combination). In those same 12 subjects, absorption from the salt of the invention ingested alone was still significantly lower (0. 1919). Thus, eliminating the possibly confounding effect of the pre-mixed source, and confining the statistical analysis to those subjects dosed only by co-ingesting for the combination, the same conclusions are reached : milk calcium and the salt of the invention absorbed identically while the salt of the invention alone is less well absorbed.

This finding is unusual, in that more commonly the food matrix, if it has any effect at all, reduces the absorbability of an added product. The opposite appears to be the case here.

While the salt of the invention by itself, was not as bioavailable as milk calcium, the actual difference was not large. to achieve the same quantity of calcium absorbed, one need only ingest # 30% more of the salt of the invention.

Table 43<BR> Individual Values for Absorption Fraction for the Three Sources Milk Milk + Inventive Salt Inventive salt Alone ID Ht Order Wt Cas Absfx Order Wt Cas Absfx Order Wt Ca5 Absfx 001 169.5 2 165.5 9.59 0.2129 1 168.5 9.58 0.2064 3 164.0 10.06 0.1727 002 183.1 3 226.0 9.74 0.2155 2 223.0 9.45 0.2271 1 220.5 9.32 0.1584 003 182.2 1 212.5 9.64 0.2603 3 213.5 9.85 0.3629 2 212.0 10.03 0.1751 004 179.7 1 198.5 9.33 0.2856 2 195.5 9.81 0.1827 3 199.0 10.03 0.1990 005 191.2 2 216.0 9.92 0.1712 1* 214.0 9.80 0.2997 3 215.0 9.79 0.1675 006 171.5 1 182.5 10.17 0.2390 2 183.5 10.13 0.2043 3 184.0 10.13 0.1499 007 185.0 2 194.0 10.04 0.1893 1 195.0 10.19 0.2834 3 193.5 10.34 0.1808 008 182.5 1 219.5 10.23 0.2289 3 217.5 9.85 0.2685 2 219.0 10.28 0.2040 009 160.9 1 152.0 9.75 0.2261 3 150.5 10.03 0.2769 2 153.0 9.77 0.1748 010 177.3 2 197.5 9.56 0.1569 1* 193.5 9.34 0.1640 3 195.5 9.64 0.1412 011 173.7 1 200.5 9.88 0.3286 3 199.5 9.74 0.2273 2 204.0 9.59 0.2039 012 177.3 2 173.5 9.89 0.3047 3 175.0 9.91 0.2295 1 175.5 9.67 0.2101 013 167.2 3 217.0 9.92 0.3304 1* 213.5 9.91 0.1955 2 214.5 9.74 0.2892 014 187.7 3 229.5 9.78 0.2739 2 229.5 9.56 0.3493 1 226.0 9.89 0.2465 0.15 176.1 3 169.5 9.32 0.2005 1* 169.0 9.70 0.1535 2 169.0 9.53 0.1422 016 186.7 3 178.5 9.72 0.1827 1* 180.0 9.42 0.0765 2 180.5 9.40 0.1088 017 179.8 3 213.5 9.43 0.2448 1* 212.0 9.54 0.0912 2 213.0 9.31 0.1190 018 161.3 1 174.0 9.62 0.2298 2 175.0 9.37 0.2195 3 177.0 9.43 0.2275

Mean 177.4 195.6 9.75 0.2378 194.9 9.73 0.2232 195.3 9.78 0.1817 StDev 8.7 23.1 0.259 0.0512 22.2 0.256 0.0768 21.8 0.319 0.0449 N 18 18 18 18 18 18 18 18 18 18 *Salt of the invention and milk pre-mixed and stored at refrigerator temperature for 14 hours prior to serving