AU733776B2

AU733776B2 - Process for utilizing baked products

Info

Publication number: AU733776B2
Application number: AU32453/97A
Authority: AU
Inventors: Friedrich Meuser
Original assignee: MULLER BROT GmbH; Reimelt Dietrich KG
Current assignee: MULLER-BROT GmbH; REIMELT GmbH
Priority date: 1996-08-02
Filing date: 1997-08-01
Publication date: 2001-05-24
Anticipated expiration: 2017-08-01
Also published as: EP0821877B1; AU3245397A; ATE480996T1; EP0821877A2; DE19631180C1; EP0821877A3; ES2350037T3

Abstract

Process for utilising baked goods, especially stale and surplus bread and/or products made from similar ingredients, and especially breads based on milled wheat or rye products, comprises: (a) preparing the starting material; (b) preparing a fermentation substrate by enzymatic hydrolysis of the starting material; (c) fermenting the hydrolysate with acid-forming bacteria, and (d) performing \- 1 of the steps of: (i) recovering bakers's yeast, (ii) recovering an acid liquor, (iii) recovering ballast substances, (iv) recovering ethanol and (v) recovering CO2. The products of the process are recovered separately and \- 1 of the products is used for making baked goods.

Description

S F Ref: 385335

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATlON FOR A STANDARD PATENT

ORIGINAL

Name and Address of Applicant: Dietrich Reimelt KG Messenhauser Str. 37-45 63322 Rodermark

GERMANY

Muller-Brot GmbH Ludwig-Erhard-Str. 2-6 85375 Neufahren

GERMANY

Actual Inventor(s): Address for Service: E.H. Friedrich Meuser Spruson Ferguson, Patent Attorneys Level 33 St Martins Tower, 31 Market Street Sydney, New South Wales, 2000, Australia Process for Utilizing Baked Products, ParticularlyLeftover and Returned Bread Invention Title: The following statement is a full description of this invention, best method of performing it known to me/us:including the 5845 1 Process for Utilising Baked Products Background of the Invention 1. Field of the Invention The present invention relates to a process for utilising or processing baked products, particularly leftover bread and returned bread and/or products having a similar material composition as a starting material for the manufacture of products, particularly of breads of ground wheat and rye products.

2. Description of the Related Art A process of the above-described type is known, for example, from DE 36 23 896. In that case, a culture medium for baker's yeast in the form of a sugar syrup is produced from an amylaceous starting material, which may be, for example, leftover baked products and/or stale baked products. The amylaceous starting material is initially enzymatically liquefied, then enzymatically saccharified and subjected to a raffination by decantation, decolouring, filtration and the like. The sugar syrup manufactured by this process is then used as a culture or a nutrient medium for the aerobic manufacture of baker's yeast.

DE 34 02 778 describes a process for the manufacture of a bread dough using a scalded portion of leftover bread and grain portions, wherein the scalded e: portion is 1-50% by weight in relation to the dry substance of the grain components o o 20 used, and the scalded portion is subjected prior to mixing with the remaining dough components to an enzymatic treatment. For achieving a moist crumb, an improved fresh-keeping capacity and a taste which is typical of bread, the carbohydrates of a fraction of the scalded portion are amylolytically decomposed, subsequently isomerised and mixed with other dough components to prepare a dough.

EP 0 229 979 discloses a process for the enzymatic decomposition of leftover bread by means of amylases, proteases and amyloglucosidases for obtaining a final product which is used as a sweetening agent, browning agent or taste ooooo precursor, possibly also as a concentrate. Moreover, depending on the intended use, the final product can also be heated for enzyme inactivation or, when used as dough leavening agent, the final product can be leavened.

All these substrates are suitable for manufacturing baker's yeast. Dellweg, H., "Biotechnologie, Grundlagen und Verfahren" [Biotechnology Basics and Processes], VCH-Verlagsgesellschaft mbH, Weinheim, Germany, describes the manufacture of baker's yeasts by aerobic fermentation of sugar containing fermentation substrates, primarily molasses which is a by-product of the manufacture of sugar (sucrose) from sugar cane and sugar beets.

DE 33 20 206 discloses a process and an apparatus for comminuting, mixing, homogenising and subsequently fermenting bread and rolls into sourdough. The starting products are subjected for a certain period of time to a circulating libc/02347 2 movement through comminuting tools and are subsequently subjected to a fermentative residual combination by adding water and inoculants. The sourdough produced by this process is used for the manufacture of bread.

DE 33 23 081 Al discloses a process and an apparatus for manufacturing a sourdough for preparing bread and baked products by using leftover bread. The starting product is subjected to a long fermentation process. The sourdough is also used for the preparation of bread and baked products.

Meuser, "Development of Fermentation Technology in Modern Bread Factories", Serial Foods World (40) 1995, 114-122, describes the manufacture of a liquid ferment which has been used in Russia in bread factories for several decades. The liquid ferment is composed of a liquid containing lactic acid in which the lactic acid bacteria are active and in which yeast is multiplied anaerobically.

Ministerstwo Chleboproduktow SSSR NPO "Chelebprom" Sbornik technolog itscheskich instruziij dlja proiswodstwa chleba i chlebobulotschnyk isdelij Prejckurantisdat. Moskwa, SSSR, 1989, discloses a process in which a mash is produced from malt and water, wherein the starch content of the mash is enzymatically decomposed to maltose or glucose with malt flour or amylolytically acting enzymes from microorganisms. The mash is leavened in the first .i fermentation stage under selective process conditions by the formation of lactic i 20 acid by means of lactic acid bacteria. The resulting lowering of the pH produces a condition in which no other bacteria can grow in the mash in addition to the dominantly present lactic acid bacteria. Consequently, the sour mash is stable S"without requiring supplemental measures far maintaining the microbiological state.

In this state, yeast cells are multiplied anaerobically in the second fermentation stage. By enriching the fermentation substrate containing lactic acid with yeast cells, a liquid ferment is created which is used directly for the manufacture of dough. Because the liquid ferment contains active lactic acid bacteria as well as lactic acid and because of the yeast cells homogeneously distributed in the ferment, the liquid ferment simultaneously serves to leaven and raising the doughs.

The process described above is not economical in the manufacture of baker's yeast because from the maltose or glucose available from the flour or a comparable other fermentation product, approximately 7 times more yeast can be produced aerobically than is possible anaerobically. In addition, the fermentation products ethanol and carbon dioxide are lost or are discharged to the environment during fermentation and baking. Moreover, while the fermentation system is highly adaptable to the continuous production of a certain type of bread to be manufactured in large quantities with sourdough, it cannot be used for the flexible production of a wide variety of breads, including individual types of bread manufactured with yeast and/or sourdough. The inflexibility of the system is also primarily due to the fact that it cannot react to special requirements of the libc/02347 fermentation time for different doughs because the yeast concentration in the liquid ferment is small and practically constant. Moreover, the solids content of the substrate which cannot be fermented must be transferred into the recipe of the bread. This constitutes an additional limitation of the use of the liquid ferment for a ,.ide variety of breads.

Summary of the Invention Therefore, it is the primary object of the present invention to provide a process of the above-described type which makes it possible in an economical manner and taking into consideration technical necessities to further use the starting materials i; n a discontinuous bread production for manufacturing a wide variety of breads.

Thus, according to the invention, there is provided a process for utilising baked products, particularly leftover and returned bread and/or other starchy baked products, as a starting material for the production of ingredients and materials for use in the manufacture of baked products, particularly of breads of wheat and rye flour products, said process comprising physical and enzymic breakdown of the leftover/returned bread and/or other starchy baked products thereby producing five different intermediate products, at least one of which is then used for manufacturing S• baked products, the process including aerobic and anaerobic fermentation stages, the process further including the recirculation of a liquid sourdough associated with .ooo0i a least one of said aerobic and anaerobic fermentation stages so as to preclude oo ~the introduction of a quantity of fresh water.

In accordance with the present invention, the products obtained by the process are produced separately from each other and at least one product is used further for manufacturing baked products.

S, 5 By separately producing the products obtained by the process according to- Sthe invention, used for the manufacture of bread, the products provide a" high flexibility with respect to adjustment to the special requirements of the various recipes for bread. Consequently, the returned bread and the leftover bread generated in a bread factory are reused in the manner of a circular operation in the manufacturing process for bread, wherein, when being subjected to the process according to the invention, the leftover and returned bread is used in the products obtained by the process in a changed form and in a new function. Depending on the composition of the individual types of bread, the various products are added in quantitatively precisely determined amounts to the different dough mixtures.

~It has been found useful if the process includes the following process steps: preparing the starting material; manufacturing a fermentation substrate by enzymatic hydrolysis of the starting material; R:\LI BA102347.doc:DKM fermentation of the hydrolysate with acid-forming bacteria; and at least one of the following process steps: producing baker's yeast; producing a liquid sourdough; producing roughage substances; producing ethanol; and producing carbon dioxide.

The preparation of the leftover and returned bread initially includes checking whether the bread is hygienically safe, particularly checking the expiration date and i, unpacking the bread if necessary. subsequently, the leftover and returned bread is mechanically comminuted and mixed with water in the known manner. The resulting mash is subjected to an enzymatic hydrolysis, wherein the temperature and o o S o o o g [R:\LI BA]02347.doc:DKM and optimum pH of the used enzymes must be observed. High-molecular components are hydrolysed into low-molecular decomposition products. In this manner, after decantation of the solids which cannot be liquefied, a fermentation substrate is obtained which meets the requirements of lactic acid bacteria and yeast with respect to growth and reproduction. By a fermentation with lactic acid bacteria, the fermentation substrate is initially leavened and, subsequently, a yeast culture is reproduced aerobically as well as anaerobically in the substrate. The yeast is obtained as a baker's yeast and serves as an essential recipe component with a functional effect for the manufacture of bread. This makes it possible for the bread factories to essentially supply this valuable raw material themselves in a closed material cycle. The sour liquid remaining after the distillation of the ethanol formed during the anaerobic fermentation is added as liquid sourdough directly, either completely or at least partially, to the bread manufacturing process in the form of water poured into the dough for leavening the dough. The components of solids which cannot be liquefied obtained by the process of the invention by .decantation from the hydrolysate serve to act as roughage substances. These substances are particularly suitable for improving the taste and/or the nutritional value of bread. The ethanol and carbon dioxide produced by anaerobic 00 fermentation are used after the distillation or liquefaction. If no use having a higher 20 value can be found, the ethanol is used as fuel. The carbon dioxide is used for cooling, for example, of dough, and for packing.

The separate production of the products obtained by the process according to the present invention represents an important possibility for the bread factories for utilising the returned and leftover bread which can no longer be sold as fodder in an S. 25 economical manner within the framework of a total concept of manufacture and sale.

In order to utilise the dry substance of the returned bread in an optimum manner for the formation of metabolic products and the formation of yeast substance, the present invention provides that the starting material is subjected to an amylolytic and proteolytic hydrolysis. The conversion of the carbohydrates in the bread, particularly of the starch, into carbohydrates which can be breathed and fermented by the yeast and of the protein into N-compounds resorbable by the protein are limited by the type and extent of the hydrolysis, so that this also influences the cell mass formation of the yeast. Used as amylolytically acting enzymes are an alpha-amylase and an amyloglucosidase. The proteolytic decomposition is carried out by means of a protease.

The enzymatically hydrolysed returned bread is heated for inactivating the enzymes and is subsequently subjected to a fermentation with lactic acid bacteria which cause a lowering of the pH value to 4.0. It has been found to be libc/02347 advantageous if the fermentation is carried with lactic acid bacteria of the type Lactobacillus delbruckii.

The present invention further provides that the sour sugar-containing hydrolysate is used as a fermentation substrate for yeast reproduction. It has been found advantageous to carry out the yeast reproduction in two stages under aerobic and anaerobic conditions. These process steps provide the advantage that the sour hydrolysate can be utilised in an optimum manner by the yeast for forming metabolic products and yeast cell mass.

In accordance with an advantageous further development, the liquid sourdough which has been freed of ethanol is utilised for diluting the fermentation substrate.

In order to illustrate this finding, it is pointed out that the aerobic reproduction of yeast from flour or returned bread is limited by the available portion of nitrogencontaining compounds from the protein for the formation of yeast cell mass from these materials. However, even under the condition that this component is completely resorbable by the yeasts under the process conditions, the yeast reproduction is significantly smaller than the carbohydrate component available for the aerobic cell mass formation. For example, when starting with a wheat flour S. which relative to its dry substance has a starch content of 78% and a protein 20 content of 14% (Nx5.7), a complete enzymatic hydrolysis of the starch into glucose would produce from 1000g dry substance of flour 866.7g glucose, which, in the case of an aerobic yeast formation of 0.54g dry substance from 1.00g glucose, would result in 468.Og yeast dry substance. However, this would not be possible because 210.6g resorbable nitrogen-containing compounds from the protein in flour 25 would have to be present for this yeast dry substance which would have a protein content of 45%. However, since actually only 140.Og protein would be available, at most only 311.1g dry substance could be formed and correspondingly 576.1g glucose could be breathed without the addition of another nitrogen source in the fermentation starter. Consequently, 290.6g glucose remain which cannot be breathed or which could be fermented. Since the cell mass formation in the case of fermentation of glucose is 7.2 times smaller than in the case of breathing, 21.8g, yeast dry substance could be produced from the 290.6g glucose if 9.8g resorbable N-compounds were to be made available for this purpose. This would make it necessary to limit the aerobic fermentation.

It follows from the above considerations that when combining an aerobic fermentation with an anaerobic fermentation of glucose from a hydrolysate of flour or returned bread, an optimum ratio between both fermentations exists in which a maximum resorption of the N-compounds and a correspondingly maximum cell mass formation of the yeast takes place. The resorption of N-compounds remains smaller than would correspond to the existing mass of protein.

libc/02347 6 These considerations are equally applicable to the use of bread or products of comparable composition as a source for fermentable carbon compounds and nitrogen compounds.

In accordance with an optimum feature of the present invention, the sour hydrolysate is divided into two material flows and the aerobic and anaerobic yeast reproduction is carried out continuously and successively. In accordance with this feature, the material flow emerging in the underflow of a first decanter is divided and conducted to the aerobic fermentation stage and to the anaerobic fermentation stage. It must be observed that the flows are to be conduced in such a way that the high dilution of the fermentation substrate required in the aerobic stage for lowering the sugar concentration is possible to the permissible level for the aerobic fermentation. The maximum concentration of the material flow is adapted to the sugar concentration which in the aerobic fermentation leads to a complete conversion of the sugar to ethanol and carbon dioxide. For this purpose, the bread hydrolysate which is acidified with lactic acid bacteria and with a solids concentration of about 40% has a concentration of glucose of about 22%, is diluted with a liquid solid. The dilution of the material flow of the aerobic stage is carried out in the same manner.

000. The present invention further provides that the division of the sour hydrolysate 20 into the material flows takes place on the basis of the content of nitrogen-containing compounds which are released from the protein content of the starting material by proteolysis and are resorbable by the yeast. The smallest cell mass formation occurs in the purely anaerobic fermentation. This is accompanied by the smallest resorption of nitrogen compounds and greatest formation of ethanol. consequently, 25 the cell mass formation can be carried out while achieving the complete conversion of the carbohydrate content.

It has been found advantageous to select the ratio between aerobic and anaerobic yeast reproduction between 5-95 and 60-40. It has been found that, within certain limits which under practical conditions are particularly determined by the content of resorbable N-compounds in the substrate, any chosen ratios between aerobic and anaerobic fermentation can be adjusted for the manufacture of yeast and ethanol. For illustrating this possibility, Fig. 1 shows a theoretical example which relates to a bread factory which could process a certain quantity of returned bread in accordance with this process. In Fig. 1, the points of intersection between the curves for the protein requirement of the yeast and the curves for the assumed protein available from the substrate, are equivalent to the maximum quantity of glucose which could be fermented aerobically. For example, if the ratio between anaerobic and aerobic fermentation of the glucose is 55-45, about 1000kg yeast dry mass (corresponding to about 4000kg moist yeast) and 720kg ethanol would be produced.

libc/02347 The process according to the present invention is carried out in an optimum manner if the ratio between aerobic and anaerobic yeast reproduction is 25-75.

Good results were achieved with the process according to the present invention if Saccharomyces cerivisiae were used as yeast culture. When using this yeast strain, the two-stage yeast reproduction according to the present invention under aerobic conditions and subsequently under anaerobic conditions resulted in a good yield of baker's yeast and ethanol. Moreover, it must be mentioned that, in relation to the same solids content, the leavening power of the yeast produced with the process according to the invention is substantially the same as that of a conventionally produced baker's yeast. However, the leavening power was at least of a conventionally produced baker's yeast. Accordingly, the bread factories were able to meet their own requirements of baker's yeast as an essential raw material in the manufacture of bread by using the process of the invention. By utilising all of the products produced by the process of the invention, the invention provides an increase of value of the returned and leftover bread which could not be achieved conventionally as a use as fodder or fermentation substrate.

In accordance with another feature, the liquid sourdough produced by the process is used for diluting the sour hydrolysate. This feature has already been Sdiscussed above in connection with the dilution of the two material flows for 20 reducing the sugar concentration. The excess derived from the aerobic reproduction and obtained after a decantation is returned for diluting the hydrolysate content to be fermented aerobically. The same is true for the anaerobic S yeast reproduction, wherein, in this case, the decantation of the yeast is followed by a distillation for removing the ethanol. The liquid which has been freed of S 25 ethanol is also used for diluting the hydrolysate content to be fermented aerobically.

The liquid sourdough obtained by carrying out the process according to the invention can also be used for different purposes. It is apparent that the sourdough can be used for directly leavening doughs of wheat and rye flours as well as of doughs of mixtures of wheat and rye flours. This results in cost savings which cause the manufacture of bread to be more economical. It has been found as a result of experiments that the liquid sourdough produced by the process can be utilised in the sense of leavening operations for indirectly leavening doughs of wheat and rye flours and mixtures of wheat and rye flours. It has also been found that the liquid sourdough obtained in the process can be utilised for sourdough operations by utilising its active flora of microorganisms.

The material flow of liquid sourdough is divided into the portion to be conducted into the cycle and the portion to be removed from the cycle such that aerobic fermentation is maintained stable with minimum fresh water supply. The various possibilities of further processing the liquid sourdough obtained by the libcd02347 process of the invention as described above show that this product can be used up essentially completely. Accordingly, it is achieved also in connection with this process product that a valuable intermediate product is obtained for the manufacture of bread from the secondary raw material in the form of leftover bread and returned bread.

This is also true for the roughage substances. These substances can be used in the manufacture of any baked products, particularly in recipes for baked products which are rich in roughage. This product is obtained by twice decanting the sour hydrolysate. In this manner, the roughage substances are concentrated by displacing dissolved substances.

For conserving the roughage substances, it has been found useful to convert the substances into a flour-like dry product by drying and grinding or by drying while grinding. Drying and grinding of the roughage substances prevent them from spoiling. It has also been found useful to further process the flour-like dry product by using thermal methods, such as roasting and extruding in order to develop its properties as a flavour carrier.

.":The use of these products exceeds the area of bread manufacture and is possible and significant in many fields of the entire foodstuff production.

In accordance with a preferred feature, the present invention provides that the 20 ethanol obtained by carrying out the process is produced by distillation and further used within the plant as a fuel. The carbon dioxide obtained by carrying out the process is liquefied and further used as a cooling agent.

The various features of novelty which characterise the invention are pointed out with particularity in the claims annexed to and forming a part of the disclosure.

25 For a better understanding of the invention, its operating advantages, specific objects attained by its use, reference should be had to the drawing and descriptive matter in which there are illustrated and described preferred embodiments of the invention.

Brief Description of the Drawing In the drawing: Fig. 1 is a diagram representing the manufacture of yeast and ethanol in dependence on the ratio of the anaerobic and aerobic fermentation of bread syrup; and Fig. 2 is a simplified flow chart for the manufacture of baker's yeast, liquid sourdough, ethanol, carbon dioxide and roughage substances from returned bread.

Description of the Preferred Embodiments Fig. 1 of the drawing shows that, within certain limits which are determined under practical conditions particularly by the content of resorbable N-compounds in the substrate, any chosen relationship between aerobic and anaerobic fermentation libc/02347 can be adjusted for the manufacture of yeast and ethanol. The illustrated example is that of a bread factory which could process a certain quantity of the returned bread in accordance with the process of the invention.

In Fig. 1, the points of intersection between the curves for the protein requirement of the yeast and the curves for the assumed protein offered by the substrate are equivalent to the maximum quantity of glucose which could be fermented aerobically. For example, if the ratio between anaerobic and aerobic fermentation of the glucose is 55-45, about 1000kg yeast dry mass (corresponds approximately to 4000kg moist yeast) and 720kg ethanol would be produced.

A preferred embodiment is described in connection with Fig. 2.

In a container of an agitating mechanism with heated walls, 2000L water are stirred daily into 4000kg returned bread in the known manner. The dry mass of the returned bread is 2400kg. Of this mass, 1680kg are starch and 288kg are protein (Nx5.7). The mixture is adjusted to a pH of 5.2 and an a-amylase (for example, optiamyl L 840 manufactured by Solvey Enzymes) having an temperature optimum of 70°C is added. The mixture is heated to 70°C and is maintained at this temperature for three hours in order to liquefy it. Subsequently, the mixture is cooled to 60°C and amyloglucosidase (for example, glucoamylase L 200 manufactured by Solvey Enzymes) is added. The mixture is saccharified at pH5.2 20 for 18h. As a result, at least 80% of the starch are decomposed to glucose, so that the mixture contains 1493kg glucose in the example with 80% starch hydrolysis.

After the saccharification, the mixture is cooled to 45°C and, for decomposing its protein content into soluble low-molecular peptides and amino acids, a protease, for example, corolase PN-L sold by Rohm, is added which acts as an 25 endopeptidase and exopeptidase. The enzyme is allowed to act for 21h at pH5.2.

During this time, at least 70% of the protein are decomposed into soluble Nsubstances. Subsequently, the mixture is heated to 1000C to inactivate the enzymes and is maintained at this temperature for 30 minutes.

Subsequently, the mixture is cooled to 50°C and acidified with Lactobacillus delbruckii. For this purpose, 10% of a previously acidified mixture as related to its volume are added. The acidification with the active lactic acid bacteria flora leads after 24h to a lowering of the pH to 4.0. At this pH, the degree of acidity in the mixture is about 12-140S, so that about 5% of the glucose present in the mixture are converted to lactic acid. Relating to the example, 1418kg glucose are then still present in the mixture, wherein the glucose is fermented aerobically and anaerobically.

The aerobic and anaerobic fermentations take place continuously, wherein all statements hereinbelow refer to the example described above. As shown in Fig. 2, the fermentation takes place in two fermenters at about 300C Dwell time and volumetric flows through the fermenters result from the generation period of the libc/02347 yeast under the respective fermentation conditions, which also determines the volumes of the fermenters. In the usual manner, the anaerobic fermenter is operated with a concentration of glucose in the substrate of about 20g glucose/litre, and the anaerobic fermenter is operated with about 125g glucose/litre. The yeast concentration is about 40g/L is both fermenters. Fig. 2 does not show any intermediate storage and buffer containers or pumps. It must be particularly mentioned in this regard that the process may also be carried out in such a way that the process sequence is discontinuous up to the preparation of the sour, diluted and decanted fermentation mixture.

The fermentation mixture produced discontinuously in the daily rhythm results for the continuous fermentation in a mass flow of acidified mixture of 250kg/h. The mixture is adjusted to a glucose concentration of 15% by adding 144kg liquid sourdough. Consequently, the mass flow is increased to 394kg/h at the inlet into the first decantation where the insoluble solids (roughage substances) are separated. This mass flow contains 59.1kg/h glucose. In relation to the glucose content in the fermentation substrate, the mass flow is divided in the ratio of 25:75 .to the two fermentation stages, so that theoretically 14.8kg/h reach the aerobic stage and 44.3kg/h reach the anaerobic stage. Since, however, the washing out of oooo the roughage substances prior to the second decantation takes place with a certain 20 excess of glucose as well as of dissolved protein, which is about 5% of the mass of the glucose and the protein, the actual mass flows of glucose are only 14.1kg/h to the aerobic stage and 42.1kg/h to the anaerobic stage. The same is true for the mass flow of N-compounds which theoretically is 12.0kg/h, but practically only 11.4kg/h.

25 During the fermentation, 7.6kg yeast are produced in the aerobic fermentation S stage in relation to the dry substance and 3.2kg yeast are produced in the anaerobic stage. The available N-compounds are absorbed to 40-45% by the yeast and the yeast dry mass has a protein content (Nx6.25) of 40-45%. In addition, 19.6kg ethanol/h, 18.5kg carbon dioxide/h and between 20 and 24kg/h dry substance as roughage substance are obtained. The yield of ethanol and carbon dioxide relates to a degree of efficiency of the distillation or liquefaction of of the ethanol or carbon dioxide contained in the mass flow of the anaerobic fermentation stage. In addition, about 220-240kg/h liquid sourdough having a degree of acidity of 8-10°S are obtained. This quantity of liquid sourdough is obtained in the flow equilibrium of the fermentation if the dilution of the mass flow of the first fermentation stage is carried out with the discharges from the first and second stages without the addition of fresh water. This takes into consideration the mass conversion of glucose and protein into the end products. In addition, the mass discharge is taken into consideration which takes place through the moist mass of the yeast and the roughage substances.

libdc102347 In summary, it can be stated that returned bread, and baked products which are comparable as seen in the trade and with respect to the composition of contents, can be utilised for the manufacture of bread and other baked products by enzymatically and fermentatively processing of the raw and auxiliary materials produced by the process in order to carry out a circulating operation. In this process, the returned bread is essentially completely used in the process steps for the manufacture of bread, beginning at the preparation of the dough and ending in baking and packing of the product. The particular advantage is to be seen in the fact that the conversion of the returned bread into essential raw materials for the manufacture of bread, particularly yeast, constitutes an increase in value which could not be achieved when the returned bread were to be used in the conventional manner as a fodder or fermentation substrate. Another advantage of the invention is that the energy required for carrying out the process can be kept small by using the excess heat of the bakery stoves. Finally, it is to be mentioned that the use of the process constitutes an environmentally protective measure :.oO.because it contributes to the use of raw and auxiliary materials for the manufacture ":of products in economical and nutritative physiological manner.

While specific embodiments of the invention have been shown and described in detail to illustrate the inventive principles, it will be understood that the invention 20 may be embodied otherwise without departing from such principles.

**o o* libc/02347

Claims

1. A process for utilising baked products, particularly leftover and returned bread and/or other starchy baked products, as a starting material for the production of ingredients and materials for use in the manufacture of baked products, particularly of breads of wheat and rye flour products, said process comprising physical and enzymic breakdown of the leftover/returned bread and/or other starchy baked products thereby producing five different intermediate products, at least one of which is then used for manufacturing baked products, the process including aerobic and anaerobic fermentation stages, the process further including the recirculation of a liquid sourdough associated with at least one of said aerobic and anaerobic fermentation stages so as to minimise the need for introduction of fresh water into said at least one fermentation stage.

2. The process according to claim 1, comprising subjecting the starting material to an amylolytic and proteolytic hydrolysis.

3. The process according to claim 1 or claim 2, comprising the following S.:i process steps: preparing the starting material; manufacturing a fermentation substrate by an enzymatic hydrolysis of the starting materials; 2:3"i fermenting the glucose-containing substrate with acid-forming bacteria to produce a mixture comprising insoluble roughage substances and a sour glucose- containing hydrolysate; and further separating and fermenting this substrate to produce a combination of the following products: baker's yeast; liquid sourdough; roughage substances; ethanol; and carbon dioxide.

4. The process according to claim 3, comprising fermenting the substrate with lactic acid bacteria. The process according to claim 4, comprising fermenting the substrate with Lactobacillus delbrueckii.

6. The process according to claim 3, comprising utilising the separated sour glucose-containing hydrolysate for yeast reproduction.

7. The process according to claim 3, comprising diluting the enzymic hydrolysate (fermentation substrate) with the liquid sourdough freed of ethanol.

8. The process according to claim 3, comprising a yeast reproduction in 3s two stages under aerobic conditions and anaerobic conditions, respectively.

9. The process according to claim 8, comprising utilising the liquid sourdough freed of ethanol after anaerobic fermentation for diluting the fermentation substrate of the aerobic fermentation. o 10. The process according to claim 9, comprising carrying out backcoupling Of the anaerobic fermentation to the aerobic fermentation by selecting a mass flow [R:\LIBA]02347.doc:DKM through both fermentation stages which is connected with the dilution with the liquid sourdough.

11. The process according to claim 8, comprising carrying out the aerobic and anaerobic yeast reproductions continuously and successively with the sour hydrolysate divided in two flows.

12. The process according to claim 11, comprising dividing the sour hydrolysate into the mass flows on the basis of the content of nitrogen-containing compounds released from the starting material by proteolysis and which can be assimilated by the yeast.

13. The process according to claim 8, comprising selecting a ratio between aerobic and anaerobic yeast reproduction between 5 to 95 and 60 to

14. The process according to claim 13, wherein the ratio between aerobic and anaerobic yeast reproduction is 25 to The process according to claim 3, comprising using Saccharomyces cerevisiae as yeast culture.

16. The process according to claim 3, comprising using the liquid sourdough obtained in the process for diluting the sour hydrolysate. •17. The process according to claim 16, comprising carrying out the dilution of the mass flow of the hydrolysate under steady-state running conditions of the continuous aerobic and anaerobic fermentations without supplying fresh water Sexclusively by returning the liquid sourdough freed from the yeast and freed from the ethanol in the case of the anaerobic yeast reproduction.

18. The process according to claim 3, comprising utilising the liquid sourdough obtained as an intermediate product for directly leavening doughs of 0, 25 wheat and rye flours and of doughs of mixtures of wheat and rye flours.

19. The process according to claim 3, comprising utilising the liquid S* sourdough obtained as an intermediate product for indirectly leavening doughs of wheat and rye flours and mixtures of wheat and rye flours. The process according to claim 3, comprising utilising the liquid sourdough obtained as an intermediate product for sourdough preparation by proliferating the active flora of microorganisms present in the liquid sourdough.

21. The process according to claim 3, comprising utilising the roughage substances obtained as an intermediate product for manufacturing baked goods, particularly baked goods which are rich in roughage.

22. The process according to claim 3, comprising producing the roughage substances by a twofold decantation of the sour hydrolysate.

23. The process according to claim 3, comprising converting the roughage substances by drying and grinding into a flour-like dry product. [IRA:\LI BA 102347.doc: DKM

24. The process according to claim 23, comprising producing a flavouring carrier by subjecting the flour-like product to a thermal process, particularly roasting and extruding. The process according to claim 3, comprising converting the roughage s substances with a dryer-mill into a flour-like dry product.

26. The process according to claim 3, comprising distilling the ethanol obtained as an intermediate product and further using the ethanol as fuel for use in the manufacture of baked products.

27. The process according to claim 3, comprising liquefying the carbon dioxide obtained as an intermediate product and further using the carbon dioxide as cooling agent in the manufacture of baked products.

28. A process for utilising leftover and returned bread and/or other starchy baked products, substantially as hereinbefore described with reference to the accompanying drawings. is 29. A baked product produced by the process of any one of claims 1 to 28. Dated 22 August 2000 i: DIETRICH REIMELT KG O"o MOLLER-BROT GMBH Patent Attorneys for the Applicants/Nominated Persons SPRUSON&FERGUSON o *o e o [R:\1I,13A]02347.doc:DKM