CH632904A5 - Composition for dog food - Google Patents

Description

This invention relates to a composition for dog food having for them a pleasant flavor and particularly relates to the use of the two isomers of an amino acid, lysine, and their respective salts, as an agent. improvement in taste, but preferably the isomer 1- and its salts.

Since the 1- isomer is often supplied mixed with the d- isomer, this invention also refers to the use of mixtures of the d- and 1- isomers.

The commercial development of pet food, especially dog food, has increased in recent years to the point that this field has become a separate science. It should be noted that the sense of taste and that of smell in dogs, far exceeding, in sensitivity and specificity, those of humans and most other animals, represent the crucial point of this highly competitive. The ability of a company to discover and improve means of stimulating these senses jointly advances the industry and individual companies. In fact, the publication of such progress is a favorable addition to the development of pet food, particularly when such progress is as surprising as that described in this invention.

Although there is still a lot to learn in the field of pet food and in particular that of the dog as regards the flavor of its food, some factors are already well known. The dry preparations which are sold commercially have a relatively low water content of about 15% by weight and therefore provide an excellent nutritional value because of the little water which they contain, which makes it possible to achieve a high degree of nutritious ingredients. In general, these dry preparations are blown and obtained by extrusion. The technique of cooking during extrusion has been an important factor in the growth of the dry pet food market, as this process results in more complete cooking, better mixing of ingredients and desired texture in the product. extradited.

Such products are generally well accepted by the animal, but they have a significantly weaker flavor than that of canned food which generally contains meat and has a high water content, greater than 55% by weight.

So while a dry dog product is extremely easy to use for the owner and is of exceptional nutritional value, there has always been a need for additives or ingredients that can be included in the preparation for '' enhance the flavor, but without reducing the nutritional properties.

An obvious solution to remedy the poor flavor of the products mentioned above is to increase the water content in such a way that the dog is more willing to accept it, but however not beyond a content such as the setting canned or sterilization becomes necessary for reasons of bacteriological stability. This has been achieved satisfactorily with so-called food with an intermediate water content, where this content is greater than 12%, with values frequently between 15 and 55% by weight. Thus, the activity of water is controlled so as to ensure bacteriological stability and protection against mold.

Foods using sugary solutions or water-soluble compounds for bacteriological stabilization are described in U.S. Patents A. Nos. 3202514.3482985, 3516838, 3615652 and 3653908.

Other preservatives suitable for food, which are bactericidal in nature, can be used to destroy the colonies of bacteria and thus stabilize the product. While these types of products are more attractive to dogs than those of the low water type, however, they cannot be compared with products with high water content, as they have the disadvantage that the addition of preservative ageijt required by this type of product lowers the desired effect below that obtained by the same product without preservative. In addition, the formulation of these dry and intermediate products becomes exceptionally critical and cannot usually be changed by the use of ingredients of equivalent nutritional value, unless it is certain that the new ingredient does not reduce the flavor of the product. 'food. The composition of this type of product therefore becomes complex since each ingredient must be evaluated not only on its structure and nutritional properties, but also on its effects on the flavor of

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the food, which of course reduces the choice of possible compositions desired by the manufacturer. Therefore, the need to have an additive that enhances taste was not eliminated simply by the introduction of a food with an intermediate water content. The invention in question represents significant progress in the field of improving the flavor of dry dog preparations and even preparations with an intermediate water content. This effect is obtained by adding a flavor-enhancing element, namely 1-lysine, d-lysine, mixtures of d- and 1-lysine as well as their salts or mixtures of their respective salts.

The object of this invention is therefore to provide a composition of dog food which is more palatable to them than their traditional preparations.

The composition of dog food according to the invention is defined in claim 1. It comprises, as flavor enhancer, 1-lysine, d-lysine, mixtures of d- and 1-lysine , their salts or mixtures thereof.

Lysine is an amino acid considered essential for life. It has the formula C6HI4N202 and is known by the names 2,6-diaminohexanoic acid or a, e-diaminocaproic acid, according to the nomenclature used. Commercially available lysine is obtained from several sources. It can be isolated in the form of picrate resulting from the hydrolysis of proteins in an acid medium; synthesized from malonic ester and chlorobutyronitrile; synthesized from benzoylpiperidine; synthesized from pyridine; produced by the action of yeast on aminoadipic acid; produced by microbial transformation of d, l-aminocaprolactam or by separation from d, 1-lysine via the 1-glutamate salts.

1-lysine is easily soluble in water, slightly soluble in alcohol and practically insoluble in ether.

Examples of 1-lysine or d, 1-lysine salts are 1-lysine monohydrochloride, 1-lysine dichlorohydrate and d, 1-lysine dichlorohydrate. It should be understood that the use of protein hydrolyzate containing the taste enhancing element in the form of lysine is included in this invention.

The means described here for improving the flavor of dog preparations is applicable to foods containing up to 55% water and also to dry products and with an intermediate water content.

Various methods and methods for including lysine or its compounds in dog preparations can be used. These include, without limitation, the application of lysine or its compounds before or after coating the food with a layer of fat, in aqueous solution or in powder form.

It should be understood that the amount of the flavor enhancing element is in excess of that already present for nutritional purposes.

The composition and the flavor improvement methods described here are intended for balanced nutritious mixtures of farinaceous and protein-rich ingredients whose water content of the final product varies up to 55% by weight.

It can therefore be said that this invention applies to pet food, food of the dry type or with an intermediate water content, it being understood that these latter terms can be understood by a person working in this field.

The compositions of the dog food described in the proposed invention which contain a flavor enhancement additive should not be restricted (other than by the meaning of the claim) by a specific list of ingredients since they are very varied and depend entirely on the nutritional balance sought in the rations as well as on the manufacturer's supply possibilities.

Generally, in addition to the additives used to achieve the nutritional balance of products of this type, such as vitamins and mineral salts or of additives such as preservatives, emulsifiers or other similar products, preparations for dogs contain for the most part two types of ingredients which can be called floury matters and matters rich in proteins.

Protein-rich material can be defined as any ingredient that has a protein level of at least 15% by weight, while farinaceous material has a rate below this figure and consists mainly of starch or carbohydrates. Examples of protein-rich materials used industrially for making pet food, and more particularly dog food, are protein flours of vegetable origin, obtained from soybean and cotton seeds, peanuts; proteins of animal origin such as casein, albumin, and of course meat products including both fresh meat and scrap, and flours such as fish, poultry, meat, marrow and bone and other similar products.

Other types of protein-rich materials include proteins of bacterial origin such as yeast and other kinds of proteins such as wheat or corn gluten.

Corn, millet, wheat, soybean pods and countless other grains that contain little protein are typical examples of farinaceous materials.

Many other materials can enter into the composition of dog food which do not necessarily fall into the two categories mentioned above, such as dried whey or other remains of dairy products or carbohydrates. As stated above, the invention cited here cannot be limited by a specific combination of ingredients usually encountered in the formulation of dog food.

Although the description which follows cannot be a limitation of the method, since it is not directly related to the function of the additive used to enhance the flavor, such a description is necessary for understanding the present invention.

The terms dog food compositions or dog preparations apply only to commercially available products which are nutritionally balanced and which are intended for food, including snack-type products.

Note, however, that snack-type products can be prepared with a lower than normal protein level. Therefore, products which meet the above definition can be characterized by a minimum level of protein (with the possible exception of snacks) necessary for the proper nutrition of the dog, when the latter receives for all food only these products . Commercial dog preparations therefore have a minimum level of protein which is linked to the age of the animal and being intended for procreation. While puppies and females for procreation need a minimum of 20% protein by weight,

and preferably between 20 and 25% by weight, dogs that do not fall into these two categories above require a minimum of protein of 15% by weight, based on the amount of material dried to 90%.

These figures are based on the assumption that dog food is the only food for it; therefore, commercially available preparations usually contain a minimum protein content of 15% by weight, based on 90% dried matter, so as to ensure the correct feeding of any dog. However, dog food containing more than 25% protein also falls within the scope of this publication.

This minimum level of protein that characterizes commercial dog food contrasts with the level of cat food, which is also nutritionally balanced, since the latter generally contain more protein.

For example, industrial cat food preparations have a minimum protein content of around 20% by weight,

based on 90% dried matter, and usually have a higher proportion than that because, during gestation and lactation, the cat needs a minimum of 28% by weight of protein, based on the material dried to 90%, and that the kittens are practically in the same case. Adult cats, on the other hand, who are not intended for procreation need a minimum protein level of around 20% by weight, based on 90% dried matter, depending on the source of protein used; this rate will preferably be at least 25% by weight or,

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more preferably, at least 30% by weight, based on the 90% dried product. This is just one of several differences that allow us to distinguish between dog and cat food. As mentioned above, the figures are based on the assumption that cats only receive food as planned.

The flavor additive described in this invention consists of 1-lysine, mixtures of d- and 1-lysine, their salts and respective salt mixtures, but preferably 1-lysine monohydrochloride. Preference is given to this salt because it can be obtained most easily. Lysine is included in order to enhance the flavor of the product and is preferably distributed over the surface of the preparation. This in amounts varying between 0.00008 and 0.5% by weight with an optimum of 0.1% by weight, based on the amount of lysine present relative to the total weight of the preparation. Lysine, at this optimal rate, causes an improvement in flavor compared to preparations of identical formulation which do not contain it. Lysine or its compounds are not supposed to be limited in their current concentration (in the case where aqueous solutions are used), their physical state (solid, liquid, amorphous, crystalline, etc.) nor their purity, provided that the indicated amount of the identifiable acid or salt (as opposed to the amount generally found in protein-rich matter) is present in the preparation.

Fat is usually introduced into industrial dog preparations as a source of energy for the animal.

This fat is generally distributed in a surface layer on the product.

However, although in some cases better nutritional and animal response results may be obtained by adding fat, this should not be interpreted as a critical factor in l 'improvement of flavor, since it has been determined that the effect resulting from the use of lysine is independent of the effect due to the addition of fat. Similarly, the type of fat which can be used in the preparations described by the invention is also not considered to be critical since the exact type used will depend entirely on the supply conditions and the desired proportion of free fatty acids.

Bacon and tallow are such examples of fat. The fat content is also not critical in the flavor enhancement effect obtained by the use of lysine in preparations (for dogs) having the desired nutritional properties. The usual proportion of fat that goes into the composition of dog food varies between 5 and 20% of the total weight of the product.

With regard to the manufacture of dry pet food according to the described flavor enhancement process, the blown or extruded type food particles are dried to a water content of less than about 15% by a stream of forced air, then transferred by a belt conveyor, while still hot, to a spray chamber. If it is desired to apply lysine and grease by separate sprays, successive spray chambers can be installed. Lysine can be applied in any way, but preferably in an aqueous solution after the fat has been added. The particles are then placed in a rotating drum to ensure the uniformity of the outer layer, then cooled to room temperature and packaged.

The inclusion of lysine in a dog food in order to make the flavor more pleasant and in an amount of about 0.00008 to 0.5% by weight, with an optimal packaging of 0.1%, gives statistically or numerically significant results in terms of response to the taste of dogs, in comparison with products not containing this reinforcing additive. Notable progress in pet food formulations is achieved by the use of this additive, since the pleasant taste perceived by the animal is usually the key factor in the success of such a product.

In order to make this invention more understandable, the following examples illustrate the results in an illustrated, but not limiting, manner.

Example 1:

Dog food prepared according to the method of the invention has a pleasant enhanced flavor and a marked and unexpected attraction. Dogs, free to choose their food, will often consume three or four times more of the product of the invention than an untreated product having the same composition of nutrients. The tables summarize a series of tests carried out during 5 d with standard rations of dog food. Tests are carried out in parallel with products which do not contain the taste enhancement additive. Portions of rations obtained commercially, raw data (without additive) in pasture, were compared with the same rations treated by the method of the invention. It is apparent, particularly in Table I, that rations treated with lysine have increased appeal, due to an improvement in flavor, completely unexpected and unprecedented.

The samples in Table I were prepared as follows:

Dry and extruded grains having a water content of 10.5%, a protein content of 22.5% and a floury content of 62%, were transported at the temperature of 120 ° F by a conveyor belt. belt to the top of a spray chamber. The grains fell from the conveyor forming a ribbon through the spray chamber. Sprayers on both sides of this grain ribbon spread a dispersion of melted tallow over the hot grains. Then, at 120 ° F, an aqueous solution of 1-lysine monohydrochloride was sprayed onto the grains to obtain amounts of 1-lysine monohydrochloride varying from 0 to 0.5%, based on the total weight of the grain. Note, however, that the amounts in Table I indicate the amount of salt (other examples, however, are specific). The exact amount of lysine would be 80%. So 0.001% is 0.0008% lysine. The sprayed grains are collected at the bottom of the chamber and transferred to a rotating drum. The beans were rotated about 12 rpm for about 3 min. The beans are then removed from the drum and cooled to room temperature. 35 Table I, as well as the other tables, gives a summary of the results and their statistical significance (PI <0.01). This statistical significance threshold indicates that there is less than 1% chance that no preferential behavior has been demonstrated. In other words, more than 99 times out of 100 a dog will prefer the ration treated to the ■ 40 control. The abbreviation N.S. means not statistically significant, but corresponds to a numerical response (based on consumption and the number of dogs showing preference).

(Tables on the following pages)

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Wilcoxon's method

The statistical significance threshold is processed by the Wilcoxon test. This test is a well-known method of determining the threshold of statistical significance of a behavior, such as that which the animal exhibits when it can choose to consume one type of food rather than another, having both at his disposal. The animals used in these tests are healthy, medium-sized dogs. They are chosen from the following breeds: pointer, English setter, labrador, whippet and poodle, because the dogs of these 55 breeds have demonstrated, after more than 50 years of research, better sensitivity and a constant response to taste. Their taste preferences can be used faithfully to determine what the total population will prefer. On the other hand, we cannot generally trust certain breeds, such as the beagles for example. Twenty dogs of the selected breeds mentioned above were placed in individual boxes. Two bowls were placed in each compartment for 4 d intervals. Each bowl contained more food than the dog could eat during this time so that the dog did not eat from a bowl 65 simply because the other was empty. Although the dogs were free to choose their food, the two bowls were swapped daily to eliminate the possibility that a dog would prefer to eat at a specific location. The consumption of each dog was recorded.

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Table I

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Number of dogs

Dry supplied ration

Early books consumed showing a preference (eating more than one)

Number of dogs without preference

Number of dogs

Meaning

Witness

16.1

2

0

20

P <0.01

Control plus 0.001% lysine

37.5

18

Witness

4.3

0

0

20

P <0.01

Control plus 0.01% lysine

27.8

20

Witness

Control plus 0.1% lysine

6.8 40.9

0 20

0

20

P <0.01

Witness

16.3

1

0

20

P <0.01

Control plus 0.5% lysine

54.4

19

Witness

Control plus 0.0005% lysine

20.5

33.6

3

17

0

20

P <0.01

Ration supplied wet

Witness

Control plus 0.001% lysine

27.5 53.0

3 16

0

19

P <0.01

Witness

Control plus 0.01% lysine

47.8 61.1

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2

20

N.S.

Witness

Control plus 0.1% lysine

29.8 75.2

3

17

0

20

P <0.01

Witness

Control plus 0.5% lysine

19.8 110.5

0 20

0

20

P <0.01

Witness

Control plus 0.0001% lysine

44.7 83.4

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19

0

20

P <0.01

Table II

Storage

Ration

Provided

Books consumed

Number of dogs showing preference

Without preference

Total number of dogs

Meaning

5 days 5 days

Control + 0.08% dry dry lysine

30.0 25.2

8 11

0

19

N.S.

5 days 5 days

Control + 0.08% wet moist lysine

34.2 50.4

4 16

0

20

P <0.1

6 weeks 6 weeks

Control + 0.08% dry dry lysine

22.7 50.3

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17

0

20

P <0.1

6 weeks 6 weeks

Control + 0.08% wet moist lysine

49.0 66.8

6 14

0

20

N.S.

3 months 3 months

Control + 0.08% dry dry lysine

30.3 40.8

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12

1

20

N.S.

3 months 3 months

Control + 0.08% wet moist lysine

65.8 81.0

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15

0

20

N.S.

very separately. The differences in consumption between the control and the test sample (reported below simply as differences) were recorded for each dog during the period. Each difference was given a sign, depending on whether the control (+) or the test sample (-) were consumed.

Then we assign a rank between 1 and 20 to each difference (given that there are 20 dogs, there are therefore 20 differences) which depends on the value of the difference, but not on its sign. In other words, the smallest difference was assigned rank 1, that immediately

60 higher rank 2, and so on regardless of whether the sign of the difference can be + or -. In the case where several dogs had the same difference in consumption, we averaged the ranks that would have been attributed to this difference.

For example, if the three smallest differences had the same 65 value and had to have ranks 1,2 and 3, they actually have rank 1 + 2 + 3/3 = 2, so rank 2. Then, we give to each row the sign of the corresponding difference. For example, if the dog with the smallest difference in consumption ate more

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of the witness that of the sample tested, its rank of 1 would therefore become +1 due to the + sign recorded for this type of difference. Then the positive and negative ranks are added separately. The largest total and the corresponding number of dogs, indicating this preference, are used to determine the level of statistical significance based on a Wilcoxon probability table. This statistical analysis is of course repeated for each sample tested. The Wilcoxon sign rank test is assigned the best statistical probability to determine whether there was in fact a marked preference.

Example 2:

Flavor tests were carried out with samples of dog food containing a higher percentage of proteins, that is 26%, with a corresponding reduction in the level of floury matter. The samples also differ from those of Example 1 in that the 1-lysine monohydrochloride was added to the fat rather than to the surface thereof.

Other than that, the samples were prepared in a similar manner to that of Example 1, and the same Wilcoxon method was used to determine the threshold of statistical significance for the taste response. The first column of Table II indicates 5 different storage times.

(See previous page)

The conclusion drawn from these results is that, with the exception of an io test (5 d of storage, dry feeding), there is a strong numerical preference for samples with lysine, and even a statistically significant preference in two of the tests; moreover, this distribution of preferences does not decrease over time. In fact, if lysine had been sprayed on the surface of the fat, which is preferred, rather than in the fat, the trend would have been even more marked. Consequently, tests were carried out on samples identical to those in Table II, stored for 6 and 9 months. The results are transcribed in Table III.

Table III

Storage

Ration

Provided

Books consumed

Number of dogs showing preference

Without preference

Total number of dogs

Meaning

6 months 6 months

Control + 0.08% dry dry lysine

19.6 35.3

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15

0

20

P <0.01

6 months 6 months

Control + 0.08% wet moist lysine

31.0 87.0

0

20

0

20

P <0.01

9 months 9 months

Control + 0.08% dry dry lysine

20.5 49.9

3

16

1

20

P <0.01

9 months 9 months

Control + 0.08% wet moist lysine

51.4 88.3,

3

17

0

20

P <0.01

The results of these tests carried out on products stored during a guaranteed shelf life are excellent and show a statistically significant preference, whether with dry food or with wet food.

It has been convincingly shown that the shelf life of the flavor enhancing agent is excellent.

It thus proves that the effect of reinforcement of the aroma felt by dogs is independent in the broadest sense of the technique of application (whether in the fat or on its surface), even though we may prefer spray the lysine onto the surface of the grease layer for more consistent results. In addition, a higher proportion of proteins does not eliminate the flavor enhancement effect.

40 Example 3:

A product of minced meat and an intermediate water content for dogs, containing 55% water, has been subjected to comparative flavor studies. A procedure identical to that of the Wilcoxon method, given in Examples 1 and 2, was followed, except that the controls and the samples tested were products with an intermediate water content. Lysine was included in the sample by dispersing an aqueous solution in the fat layer after the latter was sprayed onto the product. The results in Table IV show a marked preference for products containing lysine.

Ration with intermediate water content

Data

Total consumption (pounds)

Number of dogs preferring

Number of dogs

Meaning

Witness

Control + 0.075% lysine as is as is

58.6 102.4

4 16

20

P <0.01

Example 4:

Rations similar to those of Example I were prepared, and the effect of lysine was measured relative to another flavor enhancer, phosphoric acid.

Table V clearly shows that phosphoric acid does not fall

65 the flavor of dog food (unlike what we find with cat food) and that the addition of lysine significantly improves the flavor and even eliminates the effect of phosphoric acid.

I 632904

Table V

Ration

Data

Consumption in pounds

Number of dogs preferring

Number of dogs

Significance level

Witness

+ dry dry phosphoric acid

23.5 24.4

11 9

20

N.S.

Control + phosphoric acid 0.075% dry dry lysine

19.1 56.0

2 17

19

P <0.01

Example 5:

This test uses lysine from a protein hydrolyzate. Two different hydrolysates are used. One comes from the hydrolysis of casein by hydrochloric acid and contains, among other amino acids, 12.8 g of lysine per gram. The second comes from an enzymatic digestion of casein which contains autolyzed residues of pig glands as well as yeasts resulting from hydrolysis. It has an estimated content of 64.6 mg of lysine per gram, among other 25 free amino acids. The hydrolyzate was included in a ration of the same composition as that of Example 1, by dusting. Tables VI (first hydrolyzate) and VII (second hydrolyzate) show the quantities consumed and the excellent results obtained,

even if statistical significance has not been determined. 30

Table VI (Hydrolyzate HCl)

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Table VII (Hydrolyzate enzyme

Ration

Consumption (g)

Amount of lysine (weight%)

Witness

+ 0.1% hydrolyzate

2406 3989

0.0064%

Witness

+ 0.25% hydrolyzate

2281 5093

0.016%

Witness

1356

0.32%

+ 0.5% hydrolyzate

5269

Example 6:

This test was carried out with a control ration prepared according to Example 2, except that the lysine was sprayed on the layer of fat as in Example 1, and this ration was compared with another identical to which we have added d-lysine monohydrochloride to see if the d- isomer of lysine also enhances flavor. As Table VIII indicates, the results have been excellent.

Ration

Consumption (g)

Amount of lysine (weight%)

Witness

1686

0.0013%

+ 0.1% hydrolyzate

3584

Witness

988

0.0032%

+ 0.25% hydrolyzate

4843

Witness

1280

0.0064%

+ 0.5% hydrolyzate

5052

Ration

Data

Total consumption (g)

Number of dogs preferring

Without preference

Witness

Control + 0.01% of dry dry d-lysine

1724 3651

8

22

2

Table VIII

This test was carried out with a control prepared as in Example 2, except that the lysine and its compound were sprayed onto the layer of fat as in Example 1. This test was

was used to compare the effects of 1-lysine with those of 1-lysine monohydrochloride and the control.

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Table IX

Ration

Data

Total consumption (g)

Number of dogs preferring

Without preference

Witness

Control + free dry dry base

2299 4297

9 23

0

Control + HCl form Control 4- dry free base

2503 4156

11 20

1

The samples in Table X were included in these same series of tests in order to study the effect of 1-lysine dihydrochloride and the results are positive.

Paintings

Ration

Data

Total consumption (g)

Number of dogs preferring

Without preference

Witness

Control + form 2HC1

dry dry

1367 2437

5 10

1

R

Claims (20)

632904 1. Composition of dog food, comprising a mixture of proteinaceous and farinaceous materials and up to 55% humidity, characterized in that it contains an amino acid chosen from d-lysine, 1-lysine, mixtures of d, l -lysine and their salts. 2. Composition according to claim 1, characterized in that the amino acid is 1-lysine monohydrochloride. 2 3. Composition according to claim 1, characterized in that the amino acid is present as a component of a protein hydrolyzate. 4. Composition according to claim 1, characterized in that the moisture content is less than 15%. 5. Composition according to claim 1, characterized in that the moisture content is 15 to 55%. 6. Composition according to claim 1, characterized in that the protein content is at least 20% by weight on a dry matter basis at 90%. 7. Composition according to claim 6, characterized in that the protein content is 20 to 25%. 8. Composition according to claim 1, characterized in that the protein content is at least 15% by weight on a dry matter basis at 90%. 9. Composition according to claim 1, characterized in that the amino acid content is at least 0.00008%. 10. Composition according to claim 1, characterized in that the amino acid content is between 0.00008% and 0.5%. 11. Composition according to claim 1, characterized in that the amino acid content is approximately 0.1%. 12. Composition according to claim 1, characterized in that the mixture is in the form of grains covered with a coating of grease. 13. Composition according to claim 12, characterized in that the amino acid is present in the coating of fat. 14. Composition according to claim 12, characterized in that the amino acid is present on the coating of grease. 15. Composition according to claim 12, characterized in that the amino acid is present between the mixture constituting the grain and the coating of fat. 16. A method of preparing a dog food composition according to claim 1, characterized in that it consists in adding, to a mixture of proteinaceous and farinaceous materials and at most 55% humidity, an amount of 'an amino acid chosen from d-lysine, 1-lysine, mixtures of d, 1-lysine and their salts. 17. The method of claim 16, characterized in that the amino acid is incorporated into fat and the whole is sprayed onto the food. 18. The method of claim 16, characterized in that the food is covered with a layer of fat and an aqueous solution of the amino acid is sprayed onto the composition. 19. The method of claim 16, characterized in that the food is covered with grease and the amino acid is applied by dusting on the composition. 20. Method according to claim 16, characterized in that the amino acid is applied, then the composition is covered with grease.