BACKGROUND TO THE INVENTION Yogurt and yogurt containing beverages are an alternative calcium source for those who are lactose intolerant and therefore cannot have lactose containing milk based products. However, achieving enough calcium through a regular diet, especially for those who do not like milk or who are lactose intolerant, is often difficult. Taking dietary supplements requires a daily regimen involving taking calcium in divided doses for maximum effectiveness. The body typically absorbs only a minority of the calcium that is ingested. For example, if 250 milligrams of calcium are taken in a single dose, the body is only able to absorb about 5% to about 40% of the calcium, depending on the source of the calcium used.

Therefore, a pleasant tasting calcium supplement, which would supply more bioavailable sources of calcium and at the same time be a product the could be eaten 2 or 3 times a day, is desirable.

Calcium in the form of calcium citrate malate has been shown to be a more bioavailable source of calcium than calcium carbonate. See for example US 5,151,274 issued to Saltman, et. al., US 5, 468,506 issued to Andon and US 5,128,374 issued to Kochanowski.

Another problem with calcium supplementation of foods is the solubility of the calcium. High levels of insoluble calcium can impart significantly chalky mouth feel sensations of foods. In addition, insoluble calcium sources are generally less well absorbed than soluble forms. Furthermore for products such as yogurt containing beverages, soluble calcium sources are needed to prevent the calcium from settling at the bottom of the product. Calcium can also give a biting or burning sensation at higher levels and an aftertaste depending upon the source of calcium.

SUMMARY OF THE INVENTION A calcium fortified yogurt or frozen dessert which comprises an additional 3% to 100% RDA calcium per unit serving added as calcium citrate malate is claimed. The calcium citrate malate is added either with a fruit preparation, such as fruit syrup or fruit puree or to the sweetener component. In addition, the calcium citrate malate can be added to the yogurt directly during or after it is cultured.

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to yogurt and yogurt containing products including food and beverages and frozen yogurt.

Definitions The term"yogurt products"includes foods and beverages containing yogurt or milk, and frozen desserts, such as ice cream, ice milks, frozen tofu, sherbet, sorbets, frozen popsicles, flavored ices, and frozen juice bars. The term yogurt refers to fermented milk products or milk which has been treated with yogurt cultures.

By"nutritional"or"nutritionally supplemented"amount herein is meant that the calcium source used in the practice of these invention provide a nourishing amount of calcium. The nutritionally supplemented amount will generally comprise more than 3% of the Daily Allowance (RDA), preferably from about 10% to about 100% RDA, most preferably from 10% to about 50% of the RDA, per unit portion of the food or beverage product. Of course, it is recognized that the preferred daily intake of any mineral may vary with the user. For example, pregnant, lactating, or post menopausal women may require an increased calcium intake over the RDA. In general, the RDA of calcium will range from 360 mg to 1200 mg depending on the age of the individual.

Calcium Citrate Malate Compositions The compositions of this invention involve the use of a mixture of calcium with citric and malic acids, herein"calcium citrate malate". The calcium citrate malate may consist of a mixture of a calcium salt with citric and malic acids, a mixture of calcium citrate and calcium malate, a calcium citrate malate salt made by the acid base reaction between a calcium salt and citric and malic acids, or combinations thereof. Is it important that the calcium citrate malate be soluble in the product matrix and/or have a particle size which is small enough so as to prevent the sensation of grittyness in the product.

The molar ratio of calcium to total moles of citrate plus malate is from about 1 : 0.16 to about 1: 13.5, preferably from about 1 : 0.25 to 1 : 5, and most preferably from about 1 : 0.3 to 1 : 3 in the finished product. The ratio of moles citrate to moles malate is from about 95 : 5 to 5: 95, preferably from 80 : 20 to 20: 80, and most preferably from 70: 30 to 30: 70 in the finished product. The calcium citrate malate may contain other acid anions in addition to citrate and malate. Such anions may include, for example, hydroxide, carbonate, lactate, phosphate, gluconate, acetate, sulfate, fumarate, and mixtures thereof depending on the calcium source. The anions will affect the taste of the product and therefore should be kept within an acceptable taste threshold.

A significant advantage of yogurt products and frozen desserts with calcium citrate malate as a calcium source is that it permits formula flexibility in the fortification of calcium such that the desired taste properties can be achieved. The level at which the acid components are present and the ratio between the acids and calcium depend on the product involved, the level of calcium desired, source of calcium, and the taste properties desired. For example, for fruit flavored products which contain citrus fruit or citrus flavored type products, a greater total amount of acid will be present when compared to other generally lower acid containing or fruit flavored products such as, for example, peach. The amount and ratio of acids in the final product can also vary depending upon the flavor and sourness effects desired and the fruit or fruit flavored system used. Generally, the ratio between citric and malic acid will be skewed towards a profile that is similar to that naturally present in the fruit or fruit flavored system. For example, apples have naturally a lower ratio of citric to malic acids than do limes. Thus a product containing apple or apple flavoring would have an acidic composition with lower citric to malic mole ratio than a product containing lime. Fruit containing or fruit flavored ice creams have naturally lower total acid content than yogurts.

Thus, given the same fruit system or fruit flavoring, a calcium citrate malate flavored ice cream will have less total added acids than a yogurt product. The calcium source and level of calcium fortification will also partially dictate the amount of the acid component that gives the desired taste and sourness attributes.

Calcium salts with high acid neutralizing capability, such as calcium hydroxide, calcium carbonate, and calcium oxide, will require a greater acid component to be used to achieve the desired tartness in the final product compared to using calcium phosphate or calcium sulfate. Conversely, a lower acid component will be used for products with little or no tartness flavor of the final product. When calcium oxide, calcium hydroxide, and/or calcium carbonate are used, the portion of these calcium salts neutralized by citric and malic acids yield the byproducts of carbon dioxide and/or water. The preferred source of calcium is calcium oxide, calcium hydroxide and calcium carbonate. The most preferred calcium sources are calcium oxide and calcium hydroxide.

Preferably, the calcium citrate malate compositions for use in the methods of this invention may be provided in solid, semi-solid, or liquid forms. Calcium citrate malate can be made, for example, by first dissolving citric and malic acids in the desired molar ratios in water. Calcium carbonate can then be added to the solution, in such amount that the ratio of moles calcium to moles citrate and malate is as desired.

Carbon dioxide will be evolved during the acid base neutralization reaction and the calcium citrate malate formed can be collected, dried, milled to the desired particle size and added to the product or to a component of the product which is subsequently blended into the final product. See U. S. 5,186,965 (Fox, 1993) for a method of making a soluble calcium citrate malate. In order to enhance the solubility of this material in the yogurt or the fruit base, it may be necessary to reduce the particle size to 80 microns are less.

Alternatively, calcium citrate malate can be made in situ by adding a calcium source, citric, and malic acids as dry materials or as a wet slurry directly to the product in desired ratios. The water used in preparing the slurry needs to be taken into account in the final product. If desired, citric and malic acids may be added first and followed by the addition of calcium. The calcium source, citric and malic acid can also be added to a fruit or sweetener component of the product. Calcium citrate malate can be added to the fruit component of the product in desired ratios and amounts, usually a fruit syrup or fruit puree, and then this calcium citrate malate fortified fruit preparation can be added to the yogurt product or frozen dessert in the conventional process. A fruit concentrate product can be prepared as described in Burkes et al, US 5,401,524 (1995) or US 5,422,128 (1995) or Zuniga et al., 5,389,387 (1995). Whole fruit pieces or fruit puree can be used in the place of the juice in these products.

The total amount of calcium, citric acid, and malic acid comes from the combination of added ingredients along with that indigenously present in the final product. For example, the inclusion of a fruit preparation, such as a syrup or puree, can be a source of some or all of the total acids present in the final product. Calcium citrate malate can be added to the sweetener component of the product, such as corn syrup, in the desired amount and with the desired ratios of calcium, citric acid, and malic acid, and then this calcium citrate malate fortified sweetener can be blended into the product. See US 5,445,837 issued to Burkes et al. which describes a calcium fortified sweetener composition.

When calcium citrate malate addition is to a component of the final product, the amounts of calcium, citric acid, and malic acid in the component are adjusted so that the final product contains the desired calcium, citric, and malic acid levels. The component is diluted in the final product by the other components of the product. For example, the fruit puree is diluted by the yogurt base.

Yogurt Beverages Yogurt containing beverages are prepared by first making a sweetened and flavored calcium citrate malate fortified concentrate as described in the patents of Heckert 4,722,847 (1988) or Nakel et al, U. S.

4,551,342 or the Burkes et al. patents referenced above. This concentrate of product is then blended with a milk product or yogurt to make a yogurt containing beverage.

In a similar manner frozen desserts are made by adding the calcium citrate malate to the fruit or fruit puree before it is added to the yogurt or milk mixture or by adding it to the dessert mix before freezing.

EXAMPLE I Calcium citrate malate fortified blueberry yogurt is prepared ad follows: yogurt is prepared from milk using standard, yogurt culturing techniques and equipment. After the yogurt has been cultured, a commercially available blueberry puree flavoring product is blended into yogurt to yield 8oz of yogurt with the given desired sweetness and flavor. A dry powder blend of calcium citrate malate is prepared by admixing 0.463 g calcium hydroxide supplying 250 mg of elemental calcium, 0. 314g citric acid, and 0.510 g of malic acid per 8 oz serving of yogurt. The calcium citrate malate is added to the yogurt and blended to uniformity. This product contains about 0.15% calcium.