A METHOD OF PREPARING A FROZEN YEAST DOUGH PRODUCT

Abstract: Leavened yeast dough products obtain a long durability in a frozen condition by omitting using in the preparation thereof fermentable carbon hydrates, but the formation in situ of such fermentable carbon hydrates satisfactory to leaven the dough is ensured by adding one or more amylases to the dough. Upon freezing the activity of the amylase ceases and the concentration of fermentable carbon hydrates falls to such a low value that the proteinase forming activity of the yeast actually ceases. A possibly desired brown-colouring of the baked product may be ensured by the addition of amylases with an activity at a relatively high temperature.

Description: 1 A method of preparing a frozen yeast dough product. The invention relates to a method of preparing a frozen yeast dough product in which the dough is pre- pared from flour, water and yeast and one or more amy¬ lases and possibly other conventional dough ingredi¬ ents. For obvious reasons there is a need for a levened yeast dough product that may be marketed when frozen and having a long shelf life in such a condition and which by retailers, restaurants, cafes- etc. or by the consumers themselves may be baked without preceding thawing out and leavening to obtain a pastry having a look and organoleptic properties corresponding to those obtained by conventional baking methods, in -which the baking is effected immediately after the dough has risen without any intermediary freezing of the dough. A long series of experiments has " been carried out to fulfil said need. However, it has turned out to be particularly difficult to obtain satisfactory results if the dough product to be frozen contain yeast, and particularly if said yeast when the freezing is performed has a high activity level which is the case with a leavened dough. It has actually turned out that such yeast dough products when consisting of the hitherto used ingre¬ dients only stand storing when frozen for no more than a few months, and generally for a considerably shorter time, because they will then have been imparted such structual or textural changes that no commercially acceptable product will be obtained by baking. Various methods have been suggested of increas¬ ing the shelf life of frozen dough products in general. Thus, US patent No. 4 847 104 suggests using flour with more than 16% of wheat protein, calculated on the total flour content of the dough. It is stated that such a protein content may provide for obtaining a shelf life also of leavened, frozen yeast dough products for at least 16 weeks. However, the use of flour mixtures of selected types, particularly rich in proteins or with the addition of particularly gluten-containing pro¬ ducts, entails an increase of the costs and implies certain restrictions with respect to the organoleptic properties of the final products. Moreover, the impro¬ vement of the stability obtained even by large quan- tities of proteins, as demonstrated in the Example of the patent specification, is insuffient in connection with leavened yeast dough products. Other methods have been suggested for the res¬ triction of the undesired structural change, dough pro- ducts are being subjected to by freezing and cold stor¬ age. Thus, FR patent No. 2 481 072 deals with practis¬ ing special temperatures for the rising combined with very low freezing temperatures between -180°C and -100°C. Such a low freezing temperature only offers satisfactory results, provided the following storing be effected at temperatures lower than those practically coming into consideration. US patents Nos 4 374 151 and 4 406 911 suggest adding to the dough to be frozen considerable quan- tities of melting point lowering agents and hydrophile colloids, film-forming proteins and surfactants. Such additions are particularly effected with the view of obtaining a good rising in connection with the first part of the baking "oven spring" , and the results stated in said references do not reflect any par¬ ticularly long durability of the frozen products. It has been proposed to apply different enzymes in the preparation of dough to change the properties of the final products in a desired direction. It has for example been proposed to apply amylases in amounts of from less than 1 g to some few grams per 100 kg flour 3 in order to obtain a darker crust and to increase the amount of fermentable carbon hydrates in frozen dough products to obtain a more effective proving thereof after thawing. The use of enzymes in yeast dough to be subjected to rising followed by freezing has not been suggested. It has now turned out that a leavened yeast dough product having a longer durability when frozen than what applies to prior art leavened frozen yeast dough products may be obtained by a method which according to the invention is characterized in that any fermentable carbon hydrates which would conventionally be used in the preparation of the dough, are replaced by at least one amylase in an amount which by the decomposition of starch available in the flour generates fermentable carbon hydrate in a concentration sufficient to ensure the leavening of the dough product and which is substantially inactive at temperatures below 0°C, and in that the dough product after forming is made to rise and subeseguently subjected to freezing. The term amylase is in this respect used for enzymes which in suitable circumstances decompose gelatinized or mechanically degraded starch by the generation of considerable amounts of fermentable car¬ bon hydrates, said enzymes comprising both α- and β- amylases and amyloglucosides. The invention is not restricted by any theory as to the reason why a frozen product with a very high durability is obtained by the method just described. It is, however, supposed that the predominant reason why conventional yeast dough products after rising only have a short durability when frozen consists in that the proteinases of the yeast decompose the structure or texture forming proteinaceus substances, in par¬ ticular gluten, also at temperatures at which frozen food products are generally stored, i.e. between -18°C and -25 C C, but that this activity is particularly effi¬ cient when fermentable sorts of sugar are available for the yeast in a certain amount. However, when the amount of fermentable carbon hydrates is below a certain level, the activit of the yeast at the temperatures in question is so low that the yeast will not form con¬ siderable amounts of extracellular proteinase attacking the gluten. By omitting the addition of fermentable carbon hydrate, e.g. in the form of saccharose, glucose or maltose (available in malt flour or in malt extract), by the method according to the invention, but by adding instead amylase, there is formed fermentable carbon hydrate in the dough in an amount sufficient to ensure a yeast activity satisfactory to obtain the desired leavening, but these fermentable carbon hydrates formed by the amylase are consumed approximately at the same rate as formed, and when the leavened yeast product is frozen the activity of the amylase ceases, following which there will be no substantial amounts of fermen¬ table carbon hydrate available in the dough, thereby causing the activity of the yeast cells to almost cease so that they only to a very small degree liberate glu- ten decomposing proteinases. Yeast dough products produced by the . method according to the invention have been stored in frozen condition for more than one year, but nevertheless after baking they resulted in products, particularly of the Danish pastry type, that were commercially accept¬ able. Professionals have hitherto taken for impossible to obtain such a long freeze preservation for leavened yeast dough products. Amylases of the type coming into consideration with respect to the method according to the invention are preferably of a fungal origin. Such amylases are commercially available with activity within various ranges of temperatures and with different thermo- stability. If an amylase is used that is inactivated at temperatures exceeding 50 to 55°C which applies to a number of commercially available amylase products, active yeast will be present in the dough until the formation of the amylase of fermentable carbon hydrate ceases during the first part of the baking and said fermentable carbon hydrate will therefore to a substan¬ tial degree be consumed by the yeast and the amount present in the dough upon reaching the temperatures at which the formation of a coloured crust takes place will be very small. In view of the fact that the formation of a satisfactorily brownish crust requires the presence of monosaccharides or reducing disaccharides participating in a Maillard-reaction the crust will in such cases, as regards certain products, appear too pale and the invention therefore further relates to an embodiment of the above process for the preparation of a yeast pro¬ duct which upon baking assumes a desired brown- colouring, said embodiment being characterized by adding the dough preparation an amylase enzyme pre- serving its activity for the decomposition of starch to fermentable carbon hydrates at temperatures above 55°C, but which becomes inactive at temperatures above 80 to 85°C. The latter feature, i.e. the enzyme is to be activated at temperatures exceeding 80 to 85°C, is essential, since no remaining enzymatic activity is desired in the final baked product. However, even if some enzymatic activity should be present in the baked product this is not regarded as involving any health risk. The final product thus has a "natural" com¬ position without the addition of chemical preser- vatives, contrary to what applies to the products obtained by certain of the above described prior methods. The method according to the invention has been tested, in particular in connection with the prepara¬ tion of Danish pastry, croissants and the like, and extremely good results have been obtained by a method incorporating instead of fermentable carbon hydrates, an amylase that becomes inactive by heating to 55 to 60°C and, together with an amylase which is an amy- loglucosidase that becomes inactive only at 80 to 85°C. The amounts of enzymes to be used obviously vary, inter alia in dependence on their activity. Tests reflect that the amylase which becomes inactive at 55 to 60°C is to be used in an amount of at least 3500 SKB units per kg of flour and the amylogucosidase in an amount of at least 60 AGU per kg of flour. The unit SKB, an abbreviation of Sandstedt, Kneen and Blish, corresponds to 1/35 FAU (Fungal Amylase Unit) and is determined by comparing with an enzyme standard. The unit AGU is defined as the amount of enzyme which hydrolyzes 1 micro-mol maltose for a half hour at pH 4.3 and 25°C. A series of satisfactory experiments has been carried out by incorporating in the dough product the enzyme "Fungamyl" R MG 35000 together with the enzyme AMG 300 MG. Both of said enzymes are marketed by Novo-Nordisk, Copenhagen, Denmark. Fungamyl is declared to be active up to 55 to 60°C, while AMG is active up to 80 to 85°C, i.e. at a temperature exceeding the tem¬ perature at which a gelatinization of the starch of the flour sets in. Due to the fact that the gelatinized starch is easily attacked by the heat resisting amylase there is obtained in this stage where the presence of mono- and disaccharides is desired in respect of the colour and taste of the product, a strong formation of such saccharides. However, the negative effect with respect to the durability of the frozen dough prodμct occurring by the addition of mono- or disaccharides during the dough preparation in conventional methods is eliminated. In a preferred embodiment of the method with the view of preparing frozen products to be baked as Danish pastry products and the like, 0.05 to 0.1% by weight of Fungamyl MG 35000 and 0.1 to 0.2% by weight of AMG 300 MG are incorporated in the dough products, in both cases calculated on the weight of flour. These quantities of said two enzymes are about 100 times larger than the quantities coming into con¬ sideration in the application hitherto practised of such enzymes in bakery articles. In said prior applica¬ tions use is made of Fungamyl MG 35000, an α-amylase, to lower the fall number in strong flour. Said enzyme is produced by the mould fungus Aspergillus oryzae and decomposes the starch to dextrines and fermentable carbon hydrates. The enzyme AMG 300 is a glycoamylase extracted from the mould fungus Aspergillus niger decomposing starch and dextrines into glucose that participates in the brown-colouring Maillard-reactions. Also with dough types to which it has hitherto been considered absolutely inevitable to add ferment¬ able carbon hydrates in the form of mono- or disacchar¬ ides, such as cold-rolled fat containing doughs for Danish pastry, croissant and the like, it is possible to obtain a satisfactory leavening of the dough pro- ducts at the ordinary rising temperature, i.e. 30 to 37°C only with the addition of enzymes as stated. At this temperature fermentable carbon hydrates are obtained in a sufficient amount for yeast propagation and C0 2 -generation for rising the dough blank. When the leavening period has elapsed and the temperature is lowered to less than 0°C the yeast activity will almost completely stop when the fermentable carbon hydrates have been consumed by the yeast, and that is the reason why the risen yeast product may be stored for a long time, e.g. at -18°C as explained above. When said frozen yeast products are to be used they are put into the oven in a frozen condition, e.g. at 220°C. The thawing setting in in step with the baking, effects a decomposition of a limited proportion of the starch into fermentable sorts of sugar, e.g. by the enzyme Fungamyl, in particular in the temperature range from 27 to 55°C, in which temperature range a proving is being effected. At about 55°C the yeast cells die and the carbon hydrates, in particular glu¬ cose produced by the heat resisting enzyme, e.g. AMG, while the internal temperature of the product rises to 80 to 85°C and the starch partially gelatinizes, serve to impart to the final bakery product a suitable colour and taste. The invention will now be illustrated in detail by the following examples and examples of comparison. EXAMPLE 1 A Danish pastry dough was prepared by mechanical kneading of the following ingredients: The dough was kneaded for four minutes, following which it rested for 15 minutes at 5°C. For rolling in 1600 g margarine was used and the rolling was effected in an ordinary mannner, using three-doubled folding three times, thereby obtaining a total of 27 layers. After a rest period of 15 minutes and forming the dough, it was made to rise at 35°C for 40 minutes at a relative air humidity of 80 to 85%. The dough was then subjected to freezing at -2 °C. To test the durability of the frozen leavened yeast dough products, test bakings were effected 7 days and 28 days, respectively, after the freezing. The test bakings were carried out in an oven at 220°C for 12 minutes. To determine the change of volume by the baking, the volume was determined by the frozen dough blanks prior to baking and by the finished Danish pastry imme¬ diately after baking. The baking result was moreover visually and organoleptically evaluated. The following results were obtained: Volume: Before baking After baking Increase After 7 days 120 cm 3 390 cm 3 225% After 28 days 77 cm 3 219 cm 3 184% In view of the fact that it has turned out in practice that by this type of Danish pastry the best bakery result is obtained when the volume increase by the baking ranges from 100 to 300%, calculated on the volume of the dough blank when put into the oven, the above results are absolutely satisfactory and the obtained Danish pastry presented in all respects the same quality as Danish pastry produced from a fresh non-frozen dough. EXAMPLE OF COMPARISON 1 Exactly the same procedure was practised as in the above Example 1 with the variation that the two enzymes AMG 300 Mg and "Fungamyl" Mg 3500 were can¬ celled from the dough mixture which was instead mixed with 150 g sugar (corresponding to 6.8% of the flour weight) and 30 g salt. Thus, the composition of the dough was in all respects in conformity with the conventional recipe of Danish pastry preparation of the type in question. The following results were obtained: Volume: Before baking After baking Increase After 7 days 190 cm 3 300 cm 3 58% (2 pieces) (2 pieces) After 28 days 102 cm 3 159 cm 3 56% As it appears, the volume increase obtained by the baking was considerably smaller than was the case in the above Example 1 and considerably smaller than considered desirable. The resulting Danish pastry thus had not obtained the desired size and moreover pre¬ sented untisfactory organoleptical properties. EXAMPLE 2 A dough for another similar bakery product, in Danish termed "smørbirkes" because it is sprinkled with poppy seeds, was prepared from the following ingre¬ dients: The dough was kneaded mechanically for six minutes, following which it rested for 15 minutes at 5°C and was rolled with 920 g margarine to obtain a laminated dough consisting of 27 layers. Then the dough rested for 30 minutes and after forming the dough it was leavend at 34°C for 30 minutes at a relative air humidity of 85%. The freezing temperature was -30°C. Test bakings were carried out after 7 days and after 28 days. The following results were obtained by the volume determinations: Volume: Before baking After baking Increase After 7 days After 21 days After 28 days The final product was in all respects satisfac- tory and corresponded to commerial products prepared from non-frozen dough. EXAMPLE OF COMPARISON 2 Exactly the same procedure was practised as in the above Example 2 with the variation that the two enzymes (AMG 300 Mg and "Fungamyl" Mg 3500) were can¬ celled from the dough mixture which was instead mixed with 75 g sugar (corresponding to 2.9% of the flour weight) and 30 g salt. Test bakings were carried out after the frozen dough samples had been store for 3, 7, 21 and 28 days. The following results were obtained: Volume: As it appears, the baking of the samples frozen for 21 and 28 days results in a volume decrease, meaning that the gluten components of the dough are extensively decomposed and the obtained baking result must be characterized as worthless, since it could not be baked through and was pasty in its interior whereas the surface became strongly dark coloured.

Claims: PATENT CLAIMS 1. A method of preparing a frozen yeast dough product in which the dough is prepared from flour, water and yeast and one or more amylases and possibly other conventional dough ingredients, characterized in that any fermentable carbon hydrates conventionally used in the preparation of the dough, are replaced by at least one amylase in an amount which by the decom¬ position the starch available in the flour generates fermentable carbon hydrate in a concentration suf¬ ficient to ensure the leavening of the dough product and which is substantially inactive at temperatures below 0°C, and in that the dough product after forming is made to rise and subsequently subjected to freezing. 2. A method as claimed in claim 1 for the pre¬ paration of a yeast dough product assuming a desired brown-colouring upon being baked, characterized in adding to the dough an enzyme preserving its activity for the decomposition of starch into fermentable carbon hydrates at temperatures above 55 β C, but which becomes inactive at temperatures above 80 to 85°C. 3. A method as claimed in claim l or 2 by which a fat containing cold-rolled dough product is prepared for the production of Danish pastry and the like, and of the type which by conventional methods is mixed with fermentable mono- or disaccharides, characterized by incorporating into the dough, on one hand, an amylase which is inactivated by heating to 55 to 60°C and, on the other hand, an amylase that is an amyloglucosidase that becomes inactive only at 80 to 85°C. 4. A method as claimed in claim 3, characterized in that the amylase becoming inactive by heating to 50 to 55°C is used in an amount of at least 3500 SKB units per kg of flour and the amylogucosidase is applied in an amount of at least 60 AGU per kg of flour. 5. A method as claimed in claim 3 or 4, char¬ acterized by incorporating in the dough product the enzyme "Fungamyl" R MG 35000 and the enzyme AMG 300 MG. 6. A method as claimed in claim 5, characterized by incorporating in the dough product 0.05 to 0.1 % by weight of Fungamyl MG 35000 and 0.1 to 0.2% by weight of AMG 300 MG, in both cases calculated on the weight of flour.

Inventors: LARSEN PETER, LARSEN, PETER
Applicants: KAMA DANISH PASTRY AS, KAMA DANISH PASTRY A/S
Application year: 1990
Main classification: A21D8
IPC codes: A21D6, A21D8