MXPA99004632A - Method for production of stay-fresh baked goods - Google Patents

Abstract

The invention relates to a method for the production of baked goods from cereal products with use of enzymes, with the aim of preventing the baked goods from going stale. To this effect, a thermoactinomyces vulgaris alpha amylase is added, which makes possible targeted partial hydrolysis of the starch, and in the process prevents its retrogradation to a large extent, and is simultaneously deactivated by the baking process.

Description

PROCEDURE FOR THE ELABORATION OF BAKERY PRODUCTS OF CONSERVATION The invention relates to a process for the preparation of bakery products based on grain products, using enzymes, with the aim of preventing the aging of bakery products. Avoiding aging or, expressed in a positive way: ensuring the freshness of bakery products is a problem since bread is produced. Until now, the places of sale of bakery products, bakeries and even consumers have managed and accepted the fact that, for example, the bobbin must be bought and eaten the same day. A prolongation of freshness for several days would be desirable and would decisively modify the consumption behavior and the distribution strategy of this important staple food. In the course of the food technology innovation offensive of recent years, enzyme technology addressed this problem and has already proposed a series of solutions. The aging process of bakery products is very complex and by no means completely understood. Also the manifestation of the effect comprises several layers. The following disturbing phenomena are observed: 1. An increase in the hardness of the crumb. The bread gets hard. 2. The crust of bread becomes leathery or rubber. 3. Loss of bread aroma. Even a slight negative odor may appear. The specialized world agrees that the aging of bakery products depends on the retrogradation of the starch and the modification of the absorption of water linked to it. Starch is an essential component of bakery products, it is found in the dough in the form of grains coated with protein. Through the baking process, the starch turns into paste and absorbs water, while the protein coagulates. Immediately after baking, the starch begins to recrystallize (= to retrograde) releasing water. The strength of the crumb increases, which is still considered an advantage in the first four hours. Cutting capacity and chewing properties are first improved. It is assumed that the fraction of unbranched starch, ie amylose, crystallizes first, and with subsequent storage, also the fraction of branched starch, amylopectin. Thus, the crumb hardens and with the passage of time it becomes more and more viscoplastic, later drier and harder: the bread aged.

In contrast, the crust loses the crunchiness when stored. It is assumed that with recrystallization water is released, it diffuses out of the crumb and moisturizes the crust. Thus, it becomes slimy and leathery. The loss of aroma of the old bread could be explained, among other things, by the inclusion of the aromatic substances in the helix of the starch. It is irrefutable that the key reaction causing all these manifestations of the aging of bakery products is retrogradation of starch. Inhibiting or evading it is the subject of a series of protection rights and publications. A strategy to at least partially avoid the strong solidification of the crumb with storage, has been known for a long time: the crumb is adjusted from a softer principle. Agents can be chosen as emulsifiers, such as lecithin, lysolecithin, diacetyltartaric acid ester or mono- and diglyceride ester, which are added to the dough and produce from the start a particularly soft crumb structure. It is also postulated that the mono- and diglyceride esters, on the one hand, absorb the water released by recrystallization, on the other, by association with amylose, they disturb their recrystallization in such a way that it can no longer be fully developed. Also the use of fungal alpha amylase, for example, Aspergillus oryzae, goes in that direction. It acts on damaged starch grains, reduces the viscosity of the dough and prepares fermentable sugar. The consequence is a high volume of finished bakery products, which is accompanied by a softer crumb: a particularly soft crumb does not allow the solidification process to appear as clearly as it ages. In addition to the fact that fresh bread is too soft, this strategy does not prevent or only very little the development of a rubber-like consistency of the crumb, as do the other details of bread aging. For this reason, another strategy is more promising, namely to avoid retrogradation by a partially enziotic hydrolysis of both starch fractions. It is assumed that the fractionated pieces formed with the hydrolysis of the starch are too short to be recrystallized. The fractionated pieces are associated with the remaining high molecular weight starch and also greatly prevent their recrystallization. According to the opinion of the specialized world, an enzymatic hydrolysis of the starch should be carried out as far as possible at the conversion temperature in paste, ie, above about 70 ° C. These temperatures are reached and exceed per se in the baking process. The dilemma of the enzymatic treatment is that only partial hydrolysis can take place: not too much or too little. A too low degree of hydrolysis does not lead to a conservation effect. It takes place when, for example, enzymes are used that dissociate the starch with a too low thermostability, such as the aforementioned fungal alpha amylase. In this case, the enzyme already lost activity when, in the course of the temperature loading of the baking process, the conversion to paste begins, so that the hydrolysis of the starch is too low. The use of alpha amylases of bacteria, for example, of Bacillus subtilis or Bacillus stearothermophilus, leads to high degrees of hydrolysis. They are very thermostable and almost not deactivated during the baking process, they are still active in the cooling phase. The consequence is a too pronounced decomposition of the starch, which is expressed as a wet and sticky crumb. By precise dosing only of this enzyme, control of the desired partial hydrolysis of the starch can be obtained. Thus, there is the objective of breaking down the starch only to a certain degree, with the condition of a sufficient dosage tolerance for the addition of enzyme. In US Pat. No. 4,416,903, it is proposed to make the well-known fungal alpha amylase usable for conservation purposes by incorporating it in a stabilizing sugar medium against the thermal load. The process can not abstain from using emulsifier and sugar and can not be used in a series of bakery products, where it is not desired to add sugar. The PCT application WO 89/08403 also refers to the use of fungal alpha amylase in the preservation of bread. In this document it is proposed to employ an acid-stable fungal alpha amylase, which, in the slightly acidic medium of the dough, still shows sufficient action, even in the case of the high temperatures of the baking process, ie, that dissociate starch to a certain degree of hydrolysis. The enzyme is isolated from Aspergillus strains of black spores and has an optimum pH of 3 to 5 at 60 to 70 ° C. In general, in the above-described use of fungal alpha amylases, relatively high dosages of enzymes must be used to obtain results. In US Pat. No. 6,654,216, an attempt was made to solve the problem of bread preservation by means of a particular specificity of the enzyme used. A pullulanase is used together with bacteria amylase or malt amylase. It is intended that, mainly, dissociates the branched amylopectin and, thus, support the action of the amylases. Since the enzymes used are thermostable, the problem of a very precise dosage of the enzyme is maintained, which leads to difficulties in practice. In the PCT application WO 91/04669 a solution is claimed that also applies the specificity of the enzyme used. In this case, maltogenic exoamylases are proposed, also called beta amylases, to prevent the aging of bakery products. This species of enzymes dissociates starch molecules exclusively from maltose. Two different beta-Bacillus amylases are indicated. Its source and preparation are described in European Patent EP 234 858 and US 4 604 355. Since these enzymes are very thermostable (after thermal loading of 80 ° C for 30 minutes, both enzymes retain even more than 50% of their activity) is to be assumed, that its action is not limited in time, that is, that they act during the whole baking process and beyond. Thus, the enzymes can survive at least in part the baking process and, therefore, be contained in the active state in the finished bakery product. In food technology, value is placed on enzymes that are inactive in the product ready to be consumed, which in this case is not considered safe and is disadvantageous. In a quantitatively limited dissociation, the action of these enzymes could be maintained in the fractionated pieces of low molecular weight, which improve the water absorption capacity and, likewise, prevent the recrystallization of the residual starch. The reaction runs to the dextrin beta limit and stops. It is also disadvantageous that the products of the dissociation are exclusively sugars, which, if necessary, are not desired for flavor reasons. European Patent EP 412 607 also proposes thermostable exoglucanases, such as beta amylases or iloglycosidases, to prevent aging of bakery products. They can be supplemented or replaced with alpha-1, 6-endoglucanases, such as, for example, pullulanase. Also in this case, the enzymes are active during baking at between 80 and 95 ° C and its total deactivation at the end of the baking process is not sure. By choosing this specificity, it is above all intended to selectively hydrolyze the amylopectin component, the reaction also being able to go beyond the limit dextrin. In this way, also in this case there is the problem of a very precise dosage of the enzyme. Thus, the objective for the solution of the problem of the conservation of the bread consists in a controlled enzymatic partial hydrolysis of the starch. The following requirements must be met additionally: 1. enzyme dosages should not be required to achieve the effect. 2. The enzyme addition must be tolerant to dosing. 3. After the baking process, the enzyme must be completely deactivated. 4. Dissociation products should have as little flavor modification as possible, in particular they should not consist exclusively of sugar. 5. The aroma of bread should be preserved as best as possible. The objective is achieved by the use of an alpha amylase, which differs from the prior art in terms of origin, specificity and thermostability. This alpha amylase is produced by Thermoactinomyces vulgaris. The preparation of alpha amylase from Thermoactinomyces vulgaris was disclosed in document DD 288 395. It describes its production by fermentation of Thermoactinomyces vulgaris, as well as its use for the dissociation of starch forming maltose-rich hydrolysates, and maltotriose. The enzyme has an isoelectric point of 5.57, an optimum pH between 4 and 6 and a relatively low thermostability. Thus, after 20 minutes of thermal loading of the enzyme in aqueous solution at 70 ° C, no activity is observed. His dissociation pattern is extraordinary. It is described in document DD 287 732: with the hydrolysis of native wheat starch, soluble products composed of 4.3% of glucose, - 54.5% of maltose, 20.5% of maltotriose and as residue soluble starch fragments are obtained. Thus, a characteristic of the alpha amylase according to the invention is a 50 to 60% maltose content in the soluble dissociation products during the hydrolysis of wheat starch. The enzyme produced according to the procedure for obtaining the culture of Thermoactinomyces vulgaris described in. The above DD patents can be used directly for the purposes of the present invention, namely, in the process for the preparation of bakery products with improved preservation. In Hansen et al., Int. J. Pept. Protein Res. (1994), 44 (3), pp. 245-252, various properties of this enzyme are described, such as, for example, the molar mass and the Indica Km. The amino acid sequence is also documented, as well as the fact that the proteinase contained in Thermoactinomyces vulgaris can dissociate the alpha amylase in two fragments, both being active in the sense of the invention. However, it has been found that Thermoactinomyces vulgaris is not a particularly productive strain for obtaining alpha amylase. For this reason, successful trials have already been carried out to obtain this enzyme with genetic technology. In the works of, for example, Hofemeister and collaborators, Appl. Environ. Microbiol. (1994), 60 (9), pp. 3381-3389, the isolation of the alpha amylase gene from Thermoactinomyces vulgaris is described, its base sequence was documented and the expression of the gene in Escherichia coli and Bacillus subtilis was treated. B. subtilis is a particularly effective host organism. The gene of Thermoactinomyces vulgaris was introduced into the host organ with the help of a gene structure with a plasmid of B. subtilis as vector. The host organism was then cultured in a suitable nutrient medium, based on carbon, nitrogen and inorganic salts. Since the yield of enzyme in the procedure of the genetic technology for obtaining it is considerably better, it is preferred. Compared with the prior art, it was not expected that an alpha amylase with the above properties, namely, with the dissociation pattern in the aforementioned starch hydrolysis, which is approximately between that of an alpha amylase and a Beta amylase, as well as with such low thermostability, has such good effects on the preservation of bread. The action is independent of the type of bakery products. For bakery products are understood in the first line those that are made by adding yeast. It is, for example, white bread, mixed breads of wheat and rye or whole grain breads.

The enzyme can be mixed already in the flour that is used for the preparation of bakery products. It can also be contained in the baking powder that is added to the flour or dough. However, it often mixes directly with the dough. In any case, it must be contained in the dough when starting the baking process. The preservation enzyme according to the invention must be added in an amount that is effective to prevent aging. The amount of enzyme is usually determined by the activity of the enzyme. This can be indicated, for example, in AZ units. One unit AZ corresponds to the activity of enzyme per gram of enzyme preparation, which catalyzes under the given conditions (pH = 5, 20 ° C, 6% solution of soluble starch as substrate) the dissociation of a number of glycosidic bonds equivalent to an oligosaccharide of 0.75 millimole. See also Willstátter, Waldschmidt-Leitz und Hesse, Z. f. physiol. Chem., Vol. 126, p. 143, 1922. The analysis is carried out in the following manner: In a 50 ml wide-neck bottle, 5.5 ml of 6% starch solution are placed (Merck, No.

Order 1252), which was almost completely dissolved by heating for a short time and adjusted with sodium acetate buffer to pH = 5. It is tempered at 20 ° C.

Subsequently, 2 ml of the enzyme solution to be determined is added under stirring and the reaction mixture is allowed to stand exactly 15 minutes at 20 ° C. Just at this moment the reaction is interrupted with 0.5 ml of 1 n hydrochloric acid. Then 10 ml of 0.1 n iodine solution and immediately 20 ml of 0.1 n sodium hydroxide solution are added to the reaction mixture. After stirring consciously, the load is allowed to stand 20 in. Subsequently, 5.2 ml of 1 n sulfuric acid are added and it is titrated with 0.1 n sodium thiosulfate solution until it is colorless. In parallel, a blind value is obtained by replacing the enzyme solution with simple water. The difference between main and blind value provides the consumption of iodine solution 0.1 n (V) in me, which is used in the following way in the calculation of the AZ activity: 0. 0011288 x V2 + 0.23736 x V AZ x 0.96 Heavy mass in g The heavy enzyme mass is selected in such a way that the V value is between 0.8 and 1.5 ml. Depending on the type of flour and the intended baked product, 100 to 20,000 AZ are used per 100 kg of flour. 100 to 10'000 AZ are preferred. Particularly preferred are 300 to 3000 AZ per 100 kg of flour. The preservation enzyme according to the invention can be added individually as the sole enzymatic active substance. Of course, other enzymes can also be added, such as, for example, other alpha amylases, glucosidases, proteinases, lipases, lipoxygenases, hemicellulases (pentosanas, xylanases), oxidases or transglutaminases. In this context, the addition of baking action xylanase was particularly effective. It increases the baking volume particularly effectively and leads to a particularly soft crumb. It is postulated that this enzyme makes a part of the insoluble pentoses soluble in water or at least water-swellable in water, and thus, these substances can perform the functions of water absorption, thereby reinforcing the action of conservation of the enzyme in accordance with the invention The xylanases are added in dosages of 0.100 to 20,000 units of xylanase per 100 kg of flour, advantageously together with the alpha amylase of Thermoactinomyces vulgaris. The unit of xylanase activity is defined as follows: 1 unit of xylanase is that amount of enzyme that in 1 minute releases at 30 ° C 1 μmol of xylose from soluble xylan. The xylan substrate comes from oat husks and, for analysis, is used in 0.25% solution at pH = 4.5. The determination of xylose can be carried out, for example, photometrically with hydrazide of p-hydroxybenzoic acid. Nor do we need to give up the other usual components in bread making, as for example, emulsifiers or preservatives known per se. In the bakery products prepared according to the process according to the invention, a preferable preservative effect is observed. Thus, for example, white bread can be evaluated as fresh even after four days of storage: the crumb remains soft and juicy, the crust does not become leathery. High enzyme dosages are not required to achieve the effect. Dosage tolerance is also good: even in the case of several overdoses, the defect known as alpha amylase from thermostable bacteria does not appear, consisting of a sticky, moist crumb. The enzyme according to the invention is completely deactivated after the baking process and can not be determined by an activity measurement in the finished bakery product. Although the starch fractions present in the dough passed through a partial hydrolysis, that is, a series of low molecular weight reaction products, similar to sugar, must have been produced, no change in taste was observed in the form of an increase in sweet. In total, during long storage, the softness of the crumb is perfectly maintained, as well as the taste and smell. The alpha amylase of Thermoactinomyces vulgaris according to the invention can be advantageously combined with the usual baking additives, such as other enzymes and / or baking emulsifiers, hydrocolloids and preservatives.

EXAMPLES Carrying out baking tests In a spiral mixer (Ke per brand), a dough comprising 1,500 g of flour, 870 ml of water, 45 g of yeast, 30 g of salt and 5 g of ascorbic acid is prepared. To do this, knead 2 min with the low level 1 and 6 in with the upper level 2. An eventual addition of enzyme takes place at the beginning of the kneading process in the water phase. The temperature of the dough is 26-27 ° C. After letting the dough rest for 20 min, it is divided into 4 fragments of 600 g respectively for the production of white box bread, placed in the molds and fermented 75 min at 32 ° C and 80% relative humidity, Then it is baked at 230 ° C. The strength of the crumb is determined with a compressimeter on the bread after cooling, that is, approximately after three hours, after 24 hours and after four days. The low numbers indicate a softer crumb and, thus, a better conservation.

Description of the measurement with the compressor A compressor of the Company is used. Watkins Corporation, West Caldwell, USA. The apparatus measures the compressibility of the bread crumb. Indicates the force in parts of scale that is required to press the crumb to a certain depth. A slice of bread 15 mm thick is placed in the appliance and centered under the compression seal. With the right screw, the D scale is set to zero. For fresh bread, a penetration depth of 3 mm is adjusted, for old bread (storage time of 1 to 4 days), 1.5 mm. For the measurement, the engine is started, which presses the seal with the help of a wire pull.

When the desired depth of penetration, which is indicated on scale D, is reached, the motor is turned off and the applied force is read on the J scale. The parts of the scale correspond approximately to the weight in grams with which the seal compressed the crumb. The low numbers indicate a soft crumb and, thus, also the best conservation.

Examples 1 to 3 According to the above baking prescriptions, it is baked with the following enzyme additives: Example 1: without enzyme additive (= comparative example). Example 2: with 1.3 g of alpha amylase from Thermoactinomyces vulgaris (TV-A) / 100 kg of flour with an activity of 785 AZ per gram. Example 3: with 2.6 g of alpha amylase from Thermoactinomyces vulgaris (TV-A) / 100 kg of flour with an activity of 785 AZ per gram. The measurement of the conservation effect was carried out with the compresimeter in the manner described above.

Table 1: Compressor measurements Result: The best compressibility and, with it, the greater softness of the crumb after adding alpha amylase from Thermoactinomyces vulgaris is clearly observed, even after four days. The application amounts, referred to 100 kg of flour, were in Example 2 of 1020 AZ, in Example 3 of 2040 AZ.

Claims (8)

NOVELTY OF THE INVENTION Having described the foregoing invention, the content of the following is claimed as property: CLAIMS

1. A process for the preparation of bakery products with a better preservation, characterized in that the flour used for the preparation of the bakery products or the baking powder that is added to the flour or dough, or to the dough before of the baking process, alpha amylase that comes from Thermoactinomyces vulgaris is added, adding to the mass 20-20'000 units of AZ activity of the enzyme referred to 100 kg of flour.

2. A method according to claim 1, characterized in that the enzyme was produced from a host organism, which contains the alpha amylase gene of Thermoactinomyces vulgaris.

3. A method according to claim 2, characterized in that the enzyme was produced from a strain of Bacillus subtilis, which contains the alpha amylase gene of Thermoactinomyces vulgaris.

4. A process according to one or more of claims 1 to 3, characterized in that one or more of the baking enzymes known per se are added to the dough, such as proteinases, amylases, hemicellulases, oxidases and transglutaminases.

5. A process according to one or more of claims 1 to 3, characterized in that xylanases are additionally added to the mass with a dosage of 0.100 to 20,000 units of xylanase.

6. A process according to one or more of claims 1 to 5, characterized in that baking emulsifiers known per se are additionally added to the dough.

7. Flour for the preparation of bakery products with improved preservation according to claim 1, characterized in that alpha amylase is contained in Thermoactinomyces vulgaris.

8. Baking powder for the production of bakery products with improved preservation according to claim 1, characterized in that alpha amylase is contained that comes from Thermoactinomyces vulgaris.