NO132890B - - Google Patents

Description

The invention relates to a method for production

of a product that resembles fruit in taste and texture,

whereby an alginate or pectate sol, a source of calcium ions,

e.g. Poorly soluble or chelated calcium salts, as well as fruit material are mixed and brought to gel under essentially

equal to shear-free conditions. The procedure is characterized by the fact that a mixture of sun, calcium ion source, fruit

pulp or puree and an edible acid, further that the gelation under shear-free conditions starts no more than 2 minutes after the first contact between sun and acid, and that the amount of acid, where-

of at least a part is provided by the fruit mass or puree, is such that enough calcium ions are released for gelation of the mixture.

To obtain a product with uniform gel strength, the calcium ions that gelatinize the alginate or pectate sol should be evenly distributed in it. In a preferred method, a mixture of alginate or low-methoxy pectate sol and a calcium compound with an insufficient amount of free calcium ions to gelatinize the alginate or pectate is first prepared, and the mixture is rapidly mixed with fruit pulp or similar material and an agent having the ability to release calcium ions from the calcium compound.

The sol is gelatinized with the help of the thus released calcium ions.

Suitable calcium compounds are those which are practically insoluble under neutral conditions, but which become soluble under acidic conditions, e.g. normal calcium citrate, dicalcium phosphate (CaHPO^) and normal calcium tartrate. The agent used to release the calcium ions is then an acid, preferably a naturally occurring organic acid, e.g. citric acid, malic acid, lactic acid, tartaric acid or fumaric acid.

The fruit material can optionally be distributed together with the calcium source in the alginate or pectate sol before this is mixed with a calcium ion-releasing agent.

In each of the methods, an edible calcium-complexing agent is preferably incorporated, e.g. trisodium citrate, in the mixture being gelatinized, to ensure an accurate release of calcium ions when the insoluble calcium compound and the acidic calcium ion-releasing agent are brought together.

The fruit material contains edible water-insoluble solids of structurally degraded fruit. The structure is destroyed to release juice, but not all structural elements are destroyed, as such elements are needed to provide the appropriate fruit-simulating texture to the final product. Fruit which, when divided into slices or cubes, has a relatively uniform texture, e.g. apples, pears, peaches and apricots, can be more easily imitated than, for example, raspberries and citrus fruits. To obtain products that simulate fruit of the former type, fruit puree can be used. To get products that simulate e.g. raspberries, however, it is best to use the pulp that remains after raspberries have been subjected to light crushing so that most of the juice comes out, but where the cell sacs from which the juice is squeezed out otherwise remain intact.

The proportion of fruit material used to prepare the simulated fruit can vary within wide limits. A fruit puree is preferably used in an amount which constitutes at least 25% by weight of the simulated fruit. Material containing a large proportion of the fruit's solids, e.g. the pulp that remains after squeezing out fruit juice can be used to a somewhat lesser extent. When less fruit material is used, aromatics are preferably incorporated

and coloring agents in the simulated fruit.

The alginate or pectate used to shape the product according to the invention is preferably sodium alginate with a high molecular weight (of the order of 100,000). Alginates with a low content of mannuronic acid residues (mannuron:guluron ratio lower than 1:1) are particularly suitable. The proportion of alginate or pectate used varies with its gelatinizing ability (ie the gel strength achieved per unit weight) and with the texture desired in the final product. It has been found that when the preferred sodium alginate is used, it preferably comprises from 0.4 to 2% by weight of the simulated fruit to be made.

As the mixture of sol and other ingredients must be brought to gel under essentially shear-free conditions, gel formation must be avoided in the mixing equipment and in all pipelines through which the mixture passes on the way to the molds where the gel formation is to take place. If a solution containing free calcium ions is mixed with the sol, the gelation reaction between the calcium ions and the alginate or low-methoxy pectate proceeds so rapidly that the calcium cannot be distributed in the alginate or pectate before significant gelatinization takes place, resulting in the formation a gel of very uneven texture. Gelatinization is considerably slower in the system used in carrying out the invention, especially when the initiation of gelatinization is delayed by the incorporation of an edible calcium-complexing agent in the system, e.g. trisodium citrate. By

such a regulation of the concentration of free calcium ions is possible, without damaging the texture of the final product," to allow two minutes from the first contact (ie in the mixer) between the alginate or pectate sol and the calcium-binding agent and to the time when the mixture reaches a practically shear-free state in the molds in which the gelatinization is to take place. The preferred type of mixer is an "in-line" mixer with low volume, short residence time and high shear rate and without back mixing.

In order not to risk premature gelatinization, it is desirable to use a newly prepared mixture of alginate or pectate sol and the necessary calcium compound. A mixture that has stood for an hour or more will gelatinize much more rapidly than a sol to which the calcium compound has recently been added. It is preferable to prepare the mixture continuously so that it has a constant age when brought into contact with the calcium ion releasing agent.

When preparing the starting mixture of the alginate or pectate sol and the calcium compound, aeration must be avoided as much as possible to avoid the formation of a whipped end product. A suitable mixer for this first mixing step is a turbine mixer with baffles, and the mixing can be carried out under vacuum if desired.

In the gelatinization step, molds can be used from which the imitation fruit pieces can be cut into the desired shape. For certain simulated fruits, e.g. raspberries and strawberries, small single forms can be used which have a shape similar to that of the natural fruit. Alternatively, one can use continuous forms that move on a transport system below the mixer outlet. These can be rectangular shapes, in which case shaped pieces can be cut out of the gel block produced, or they can be oblong shapes, in which case the resulting gel rods can be cut out at angles to their length. The latter method is preferred when making apple, peach or apricot segments.

By an alternative method of forming which is suitable

for simulated cherries, the apparatus described in the description and drawings of British Patent No. 727,475 can be used to extrude the incipient gelatinous mixture of sol, calcium ions and fruit material into a bath of carrier liquid, which may contain calcium ions. In this method, calcium forms

the ions in the bath quickly form a gelatinous skin on the simulated cherries, while the calcium ions incorporated in the sun ensure that the simulated cherries gelatinize completely.

In addition to the ingredients already mentioned, others can be included to improve the properties of the simulated fruit and to make it even more similar to natural fruit. Sugar is usually used, and at least part of any sugar used is preferably incorporated at the stage where the alginate or pectate sol is made, as this helps the dispersion of the sodium alginate or low-methoxy pectate.

A small proportion, e.g. up to 0.2% of locust bean gum can be incorporated into the simulated fruit. This gives the product a less gel-like and more fruit-like texture and a more opaque appearance.

Spray-dried fat can be incorporated into the simulated fruit when the fruit used is one which in its natural state has a cream-like texture, e.g. bananas or avocado pears.

As indicated above, the preferred method for releasing calcium ions in the alginate or pectate sol is based on the action of an acid on a calcium compound which is insoluble under neutral conditions but soluble to some extent at pH in the acidic range. If you use fruit acid for this purpose, e.g. citric acid or malic acid, and if the acid is used in excess, the manufactured simulated fruit will have a sour, sharp taste similar to the taste of natural fruit. It has been found that the amount of acid present influences the texture of the simulated fruit, with a high proportion of acid leading to a firmer texture. However, the presence of a salt, e.g. sodium citrate, tend to produce a softer texture. Accordingly, the firmness and acidity of the simulated fruit can be varied by varying the amounts of the organic acid and sodium citrate present. The proportion of the organic acid in the fruit is preferably 0.5 to 1.5% by weight. If a higher acid concentration is used, special care must be taken to avoid premature gelatinization.

Calcium alginate^ or the pectate gels of the products according to the invention are not heat-reversible. When an alginate with a low mannuronic acid content is used, the gel is sufficiently heat-stable to withstand canning or frying.*,;The simulated fruits exhibit some syneresis upon freezing.and. thawing. Although a small degree of syneresis may be acceptable to give the fruit a slightly moist texture, it is preferred to incorporate a freeze/thaw stabilizer into the simulated fruit when it is to be used in frozen products. The preferred freeze/thaw stabilizer is a cooked starch, e.g. pre-cooked, potato starch, which can be used in a concentration of 1 to 5%, preferably 1 to 2%. Alternatively, sodium carboxymethyl cellulose or a non-ionic cellulose ether, e.g. methyl cellulose or ethyl cellulose, are used. For fruits such as strawberries, a simulated fruit can be made that preserves its texture during freezing and thawing better than the natural fruit. In some simulated fruits, e.g. banana, a cooked starch, e.g. cooked cornmeal is mixed into the simulated fruit to improve its texture, regardless of whether the fruit is to be frozen or not.

The proportion of the ingredients used can be varied so that

you get products with different gel strengths. For example, gel-. the strength (measured in a Bloom gelometer) of simulated apple pieces for use in a pie, preferably made from 80 to 200 g, especially from 110 to 180 g, for simulated strawberry pieces for incorporation into yogurt from 40 to 80 g, and for simulated tangerine pieces from 50 to 100 g. The minimum gel strength for a food product according to the invention is in practice approx. 30 g.

Particularly suitable applications of the simulated fruit are in fruit pies and the like, which can be frozen or not as desired, in dairy products such as yogurt, curd, fromage and ice cream, in canned fruit products, especially those sold as fillings for pies and the like, and in jam and

:fruit sauces.for the provision of clear pieces of fruit. The simulated fruit can be pasteurized (preferably with steam enrichment) while it hardens, but freezing must be avoided before the hardening is, so to speak, complete.

The following examples illustrate the preparation of self-supporting gel products from a variety of fruit materials.

EXAMPLE 1.

An algihat sol containing a calcium compound with an insufficient amount of free calcium ions for gelatinization of the alginate was prepared as follows. ingredients:

The sodium alginate, dicalcium phosphate, sodium citrate and honey were mixed in dry .Viistand in a powder mixer and then dispersed in water to form a sol in a continuous turbine mixer with baffle plates.

An applesauce mixture containing citric acid (which has..the ability to

to release calcium ions from the calcium compound contained in.-, above-mentioned sol) was prepared by mixing the following ingredients. in a conventional.-batch mixer.

The alginate sol and the fruit puree mixture were pumped separately, each at a flow rate of 68.0 kg per hour. hour to an "in-line" mixer with short residence time and high cutting, e.g. an Oakes 4M mixer. The resulting mixture was passed through a small

parts into a set of oblong molds with a semi-circular cross-section which were transported on a belt. The time between mixing

none of the alginate sol with the fruit puree mixture and the discharge of the mixture from the dispenser was less than 30 seconds, and practically no gelatinization of the mixture occurred during this time

room. The mixture was allowed to gelatinize in a shear-free state in the molds,

so that semicircular rods of calcium alginate gel were made with fruit puree evenly distributed. The sticks were cut up so that they were shaped like apple boats, and these were then frozen and mixed into a frozen pie. When the pie was thawed and cooked, it turned out that the apple pieces had a texture very similar to the texture of cooked, natural apple pieces. The applesauce used in this example,

was obtained by boiling apples which were then finely divided and sieved

(1.6 mm sieve) .

Example

An alginate sol was prepared according to the procedure from example 1, following ingredients:

A fruit pulp mixture was prepared largely as described in example 1, from the following ingredients:

The alginate sol and fruit pulp mixture were then pumped, each at a flow rate of 68.0 kg per hour. hour, to an Oakes 4M mixer. The resulting mixture was passed through a small distributor to a flat conveyor belt with side walls. This belt constituted a mold in which the mixture could gelatinize under shear-free conditions. The time spent in the mixer and distributor was less than 30 seconds and practically no gelatinization occurred during this time. The mixture was pasteurized while gelatinization took place. When gelatinization was more or less complete, a sheet of calcium alginate gel was obtained with strawberry pulp evenly distributed throughout it, and this sheet was cut into small simulated strawberry pieces that had a texture very similar to pieces of natural strawberries. They were suitable for mixing into a fruit yoghurt. If 1.5% of a pre-cooked starch (based on all the ingredients) is mixed into the strawberry mass, you get simulated strawberry pieces suitable for inclusion in frozen products.

EXAMPLE 3.

An alginate gel was prepared from the following ingredients, generally as described in Example 1:

Eri banana puree mixture bis prepared as described in example 1, from the following ingredients:

The alginate sol and the fruit puree mixture were then pumped separately

to an Oakés 4M mixer. The sun was pumped into a flow velocity-

heat of 61.0 kg per hour. The mixture that was made was passed through a small distributor to a conveyor belt with folded edges as described in example 2. The time that the mixture to-

brought into the mixer and distributor, was shorter than 30 seconds,

and no significant gelatinization took place during this time-"

room. The mixture was pasteurized during the gelatinization, and after the gelatinization was virtually complete, the resulting sheet of calcium alginate gel with fruit puree in it was cut into small pieces. The simulated banana pieces that were created had a texture very similar to that of natural banana pieces.

EXAMPLE 4.

An alginate sol was prepared according to the method from example 1, from the following ingredients:

A free mass mixture was prepared in general as described in example 1, from the following ingredients:

The alginate sol and fruit pulp mixture were then pumped, each i

a flow rate of 68.0 kg per hour, to an Oakes 4M mixer. The resulting mixture was passed through a small distributor into a series of individual hemispherical moulds. The mixture was allowed to gelatinize in these forms under shear-free conditions. The time spent in the mixer and distributor was less than 30 seconds and practically no gelatinization occurred during this time. When the gelatinization was more or less complete, simulated apricot halves were obtained comprising calcium alginate gel with apricot pulp evenly distributed in it. These simulated apricot halves were canned in sugar brine and sterilized using a "hot fill" method, and the resulting product had a texture similar to canned apricots

EXAMPLE 5.

A low-methoxy pectate sol containing

an insufficient amount of free calcium ions for gelatinization of the pectate, of the following ingredients by first mixing the la v~ me to rc— sypectate, dicalcium phosphate, sodium citrate and sugar in a dry state and then dispersing the mixture in. water.

An applesauce mixture containing citric acid was prepared by mixing the following ingredients in a conventional batch mixer:

The low-methoxy pectatazole and applesauce mixture were then mixed in a bowl using vigorous stirring with a hand mixer for 30

seconds. During this time, no significant gelatinization took place. The mixture was then allowed to gelatinize and a calcium-low-methoxy pectate gel was made with applesauce evenly distributed in it. This gel turned out to have a texture similar to canned apple boats.

Claims (5)

1. Process for producing a product resembling fruit in taste and texture, in which an alginate or a pectate sol, a source of calcium ions, e.g. poorly soluble or chelated calcium salts, and fruit material is mixed and allowed to gel under essentially shear-free conditions, characterized by the rapid formation of a mixture of the sun, the calcium ion source, fruit juice e-1 j .-i-ure and an edible acid, that the gel ring under it jæ/. free conditions start no more than 2 minutes after it. first contact between the sun and the acid, and that the amount of acid, at least a part of which is provided by the fruit pulp or puree, is such that enough calcium ions are released for gelation of the mixture. 2. Procedure as stated in claim 1, charac- characterized by the use as sol of an alginate sol which contains a ratio between mannuronic acid residues and guluronic acid residues of less than 1:1, whereby improved heat resistance is achieved. 3. Method as a.ig tt in claim 1, characterized in that it uses; - an alginate which has a molecular weight of the order of 100,000. 4. Method as stated in any of the preceding claims, characterized in that the aqueous system is formed rapidly by preparing an aqueous mixture of an alginate or low-methoxy pectate sol and calcium ion source and by rapidly mixing the aqueous mixture with acid and fruit puree or pulp. 5. Method as stated in claim 4, characterized in that an aqueous mixture containing a complexing agent for calcium ions is used.