NL2024582B1 - PROCEDURE FOR CONVERTING STARCHES (RESIDUAL) STREAMS TO HIGH-QUALITY PROTEINS - Google Patents

Abstract

Method for converting starchy (residual) streams into high-quality proteins, by means of the following steps: - converting the starchy (residual) products (2) in a first and anaerobic fermentation (6), with the formation of fatty acids, sugars and oligosaccharides; - converting the reaction product of the first and anaerobic fermentation (6) into a protein concentrate (24) in a second but now aerobic fermentation (20), using a culture of microorganisms (18); - optionally separating the microbial mass from the obtained reaction product (21), which mass contains a concentrate of cellular protein fragments (24) for use as fish feed, animal feed, pet food or in food for human consumption.

Description

METHOD FOR CONVERTING STARCH-CONTAINING (RESIDUES) STREAMS TO HIGH-QUALITY PROTEINS The present invention relates to a method for converting starch-containing (residual) streams into high-quality proteins. More specifically, the invention is intended for converting (residual) products which are formed, for example, during the processing of potatoes, into high-quality proteins.

It is known that starchy (residual) products are formed during the processing of potatoes, such as potato peelings, process water, cutting water and potato chips. Traditionally, these residual products are not processed further unless as low-value animal feed or as auxiliary substances for agriculture. The object of the present invention is to convert the aforementioned low-value starchy (residual) products into high-quality protein-rich products having a higher nutritional value. a method for converting starch-containing (residual products from, for example, potatoes into high-quality proteins, whereby these (residual) products are converted by means of a two-stage fermentation process, namely a first and anaerobic fermentation with which starch into intermediates such as (fatty) acids, alcohols, sugars and oligomers such as oligosaccharides are converted and a second but now aerobic fermentation using bacteria and yeasts, preferably in a single cell protein reactor or fermenter to obtain a protein rich reaction product. For this purpose, the invention relates to a process for the conversion. and from starchy (residual) streams to high-value proteins, the method comprising the following steps: - converting the starchy (residual) products by means of a first and anaerobic fermentation, which converts the insoluble and soluble starch components into intermediates such as (fatty) acids , alcohols, sugars and oligomers such as oligosaccharides; - converting the reaction product of the first and anaerobic fermentation into a protein concentrate by means of a second but now aerobic fermentation, using a culture of microorganisms which, in addition to bacterial strains, may also include yeasts, whereby a microbial mass is obtained, which is a concentrate of cellular protein fragments .; In one embodiment, the microbial mass will be separated, for example by centrifugation, from the obtained reaction product. ; and In a further or different embodiment, the obtained microbial mass will be sterilized, for example by heat treatment, freeze drying or spray drying, thereby killing living cells in the mass. In this way it is guaranteed that the microbial mass has no harmful effects during storage and for possible application in food and feed. In one embodiment, the microbial mass can be used as a semi-liquid such as a slurry. In another embodiment, the mass can be further dried to remove residual moisture. The obtained (sterilized) microbial mass can be used as fish feed, animal feed, pet food or in food for human consumption.

In one embodiment, for the first and anaerobic fermentation, the naturally active microorganism culture is used from the starchy (residual) stream itself. These natural microorganisms present, in this case originating from potato steam peels, can be applied to other starchy sources. In another embodiment, a predefined culture of microorganisms is used that is known to be capable of converting starchy residues. The term "microorganisms" refers to both bacteria and yeasts. In a preferred form, the cultures used are a mixture of at least two or more different types of microorganisms.

In one embodiment, the second culture of microorganisms will be predetermined or defined to be suitable for converting the reaction product of the first and anaerobic fermentation. In a preferred form, the second culture will be able to convert this reaction product to a protein concentrate of 50-80% protein by dry matter in this second, aerobic fermentation.

In one embodiment, the reaction product of the first and anaerobic fermentation with formed products such as (fatty) acids, sugars and oligosaccharides can be separated into dissolved parts that go further in the conversion process and undissolved parts such as shells that are separated. The separation can be done by conventional means known in the market. Non-limiting examples of this are one or more filters, or centrifuges, or sieves, or settlers, or cyclones. These undissolved parts can optionally be further washed to separate the remaining starch parts from the undissolved parts. In this way washed potato skins are obtained.

In one embodiment, the dissolved parts will be briefly heated in a pasteurization step. This allows the mass of living microbial cells to be reduced. In one embodiment, the reduction may be at least 4 to 6 log values, preferably for example from log 10-15 per liter to log 6-11 per liter, or for example from log 10-15 to log 4-9 per liter. Subsequently, the pasteurized microbial mass can be fed to a single cell protein reactor (SCPR) or fermenter, in which an aerobic fermentation is carried out using a culture of microorganisms suitable for converting the reaction product of the first and anaerobic fermentation. to single cell protein or other value added products such as exopolysaccharides, PHA,… by means of the second but now aerobic fermentation in the SCPR.

In one embodiment, inorganic and / or organic nitrogen, with or without phosphate, and / or micronutrients, and / or other nutrients (Ca, Mg, Fe, ...) can be added to the reaction mixture of the aerobic fermentation without their maximum useful limit to exceed.

Defining a culture of microorganisms suitable for converting the reaction product of the first and anaerobic fermentation is done according to a specific method with the following steps:

- defining the microbiome by means of an aerobic fermentation on the starting substrate; - the cultivation of the microbiome by scaling up batches, in which the strains are first cultivated in small volumes and are completely added to a larger volume at sufficient cell density, optical density or OD value, in several steps until a sufficiently large volume is representative for a industrial inoculation or more is achieved, (e.g., between 0.1 and 10% of the reactor volume, or, for example, 400 ml may be representative), suitable for batch and preferably a laboratory scale CSTR process or Continuous Stirred Tank Reactor; - gradually adding the starting substrate, whereby the same amount of mass is also gradually removed from the reactor, so that the mass in the reactor acquires the same composition as the outgoing mass; - plating the obtained culture on selective growth media after the adaptation and achieving a protein content of 50-80% of the dry matter; - identifying the isolated strains by DNA sequencing; - quantifying the defined strains; - elimination of the identified strains known to be harmful to the defined culture of microorganisms, modifying the mixed culture as little as possible in order to best retain the previously obtained functionality and stability.

In a preferred form, the stability will be maintained over the production period of preferably several days to months and this by imposing selective process conditions such as pH, temperature, dilution rate, nutrient limitation, etc. Stability is understood to mean that the product delivered is always within the normal bandwidth of the stated composition and functionality falls;

- composing a defined culture unique for each substrate that is suitable for the second and aerobic fermentation of the starchy (residual) product concerned; 5 - any yeasts present are only eliminated if they are harmful to the defined culture. A culture suitable for the second and aerobic fermentation of potato skins may have, for example, the following composition: Castellaniella (denitrificans / defragrans / daejeonensis) Lactobacillus (casei / paracasei) Lactobacillus fermentum Xenophilus (unident / azovorans) Paracoccus (denitrophusifiedhusomonca / thermomonca (pantotrificans) / haemolytica / koreensis) Acinetobacter venetianus Pigmentiphaga (kullae / daeguensis) Stenotrophomonas (unidentified / nitritireducens / acidaminiphila) Hydrogenophaga (unidentified / temperata) Pseudoxanthomonas (jiangsuensis / uncultiiii) Pseudavensisanthomonasensis also kulamevriii (helyzianii) that also speaks kalamevrihi / wuyzanthomonasens. cultures may be suitable for this purpose. Once a suitably defined culture is known, it can of course be used over and over again for the same starchy (residual) stream, without having to make a new selection. The defined culture will adapt further over time to the substrate, whereby the incorporated strains are not lost but become more robust against unfavorable influences. For a new type of starchy (residual) stream, a new selection can be made according to the same method.

In addition to the valorisation of the microbial product, the remaining relatively pure peels can also be used as covering material in plant cultivation and as covering material in stables. The reduced presence of starch also makes it easier to recover functional potato pectin from the skins.

By selecting the microbiome openly, the composition of the culture can still be directed in the direction of desired by-products in addition to the protein obtained. Desired by-products can be vitamins belonging to the B group, for example and certain (fatty) acids, but can also be a desired amino acid profile. For example, certain strains make amino acids and other strains consume these amino acids and convert them into cellular protein fragments, increasing the protein content.

On the one hand, the stability of the entire process is guaranteed by the CSTR or continuous stirred reactor set-up that is continuously stirred and fed. The same amount of influent is fed in as the amount of effluent that is discharged, whereby the residence time for each process must be sufficient to keep the composition in the reactor and of the effluent equal, with a positive effect of the buffering microbial mass, the mixed culture that resilience , synergy, natural adaptation and plasmid expression. On the other hand, the two-stage fermentation promotes the synergy between the two fermenters.

With the insight to better demonstrate the characteristics of the invention, a preferred application of the method for converting starch-containing (residual) streams into high-value proteins according to the invention is described below, by way of example without any limiting character, with reference to the accompanying drawings, in which: figure 1 schematically shows an apparatus for applying the method according to the invention described in claim 1.

Figure 1 shows an apparatus for applying the method described in claim 1 for converting starchy (residual) streams into high-quality proteins. This device comprises a storage tank 1, in which in this case a (residual) flow 2 of potato peelings and other potato residues is collected via a supply line 3. From the storage tank 1, the (residual) stream 2 is fed by means of a pump 4 and a supply line 5 to a first fermentor 6 for anaerobic fermentation, which is provided with an agitator 7.

After the anaerobic fermentation, the fermentation product 8 is fed by means of a pump 9 through the discharge line 10 to a filter 11 which separates the undissolved parts 12 and shells from the dissolved parts 13. The undissolved parts 12 are discharged via a transport system for further processing. The dissolved parts 13 are passed through pasteurization unit 14 where they are briefly heated to lower the living microbial mass, for example from log 10-15 per liter to log 6-11 per liter, or for example from log 10-15 per liter to log 4-9 per liter. Subsequently, the pasteurized microbial mass 15 is fed to a second fermentor 16, provided with an agitator 17, but now for an aerobic fermentation. To this end, a defined culture of microorganisms 18 is added to the aerobic fermentation mixture 20 via a supply line 19.

The aerobic fermentation converts the pasteurized microbial mass 15 of the dissolved parts 13 of the fermentation product 8 from the first and anaerobic fermentation into single cell protein 21 which is fed via feed line 22 to a centrifugation unit 23, thereby allowing centrifugation or other separation means known in the art. technique a protein concentrate 24 of 50-80% dry matter is separated. The protein concentrate 24 is sterilized by heat treatment and dried before being used in fish feed, animal feed, pet food or in food for human consumption.

The remaining liquid in the centrifugation unit 23 is returned through a return line 25 to the first anaerobic fermenter 6 for recycling.

The operation of the device shown in Figure 1 is very simple and as follows.

A starch-containing (residual) product is supplied to a first fermentor, in which a first and anaerobic fermentation is carried out which converts the insoluble and soluble starch components into intermediates such as (fatty) acids, sugars, alcohols and oligomers such as oligosaccharides. The naturally active microorganisms from the starchy (residual) stream are used for this.

The fermentation product formed is separated by means of a filter into a dissolved fraction and an insoluble residual fraction. The dissolved fraction is pasteurized by a short heating and is then added to a second fermenter, in which a second but now aerobic fermentation is carried out.

To this end, a (predefined) culture of microorganisms is added to the fermenter, which has been selected to give an optimal second and aerobic fermentation for converting the reaction product from the first and anaerobic fermentation into single cell protein with the formation of high-quality proteins. in the second and aerobic fermentation. In addition to bacterial strains, this culture can also contain yeasts.

By using CSTR reactors, the supply of substrate and discharge of product are slowly optimized to the intended residence times. This means that the predefined culture does not have to be administered over and over again.

From the fermentation product of the second and aerobic fermentation, a protein concentrate 24 with a protein content of 50 to 80% dry matter and a dry matter content of 7 to 30% dry matter is separated by centrifugation, which protein concentrate 24 is further sterilized by freeze-drying, spray drying or heat treatment and dried before being used in protein rich fish feed, livestock feed, pet food or in food for human consumption.

The present invention also relates to a microbial mass comprising at least 60% protein, and further characterized by a digestibility of at least 80% and an amino acid pattern containing at least the following essential amino acids expressed on crude protein: methionine> 1.5%, threonine> 4 , 5%, tryptophan> 1.5%, valine> 5%, alanine> 7% and glycine> 5%.

The protein content and amino acid composition can be determined by known methods in the art.

In a preferred form, this microbial mass is obtained by a method as discussed above.

The microbial mass obtained has a high nutritional value and is suitable for use in the food industry and the feed industry. The microbial mass is particularly suitable for use as fish feed, animal feed, pet food or in food for human consumption. To this end, the microbial mass can be processed in a feed or food additive, at a concentration of 0.5 to 99.9% in the additive. The microbial mass can be added in liquid or semi-liquid, as well as in dry form. Accordingly, the present invention also provides a method for providing a protein-rich component to feed such as fish feed, livestock feed, pet food or food for human consumption; the method comprising producing a microbial mass according to a method as described above and dosing the microbial mass or a component comprising the microbial mass into feed and / or food.

The present invention also relates to a device for converting starch-containing (residual) streams into high-quality proteins, characterized in that the device contains at least two serially connected fermenters, the first of which serves for an anaerobic fermentation, the fermentation product of which in the second fermenter is a undergoes aerobic fermentation to produce high-quality protein, the equipment is suitable for a continuous or semi-continuous process. The present invention is by no means limited to the embodiment described by way of example and shown in the figures, but such a method and device for converting starch-containing (residual) streams into high-quality proteins can be realized according to different variants without departing from the scope of the invention. as defined in the following claims.

Claims (18)

Conclusions Method for converting starch-containing (residual) streams into high-quality proteins, characterized in that the method comprises the following steps: - converting the starch-containing (residual) products (2} by means of a first and anaerobic fermentation (6), which converts the insoluble and soluble starch components to intermediates; - converting the reaction product of the first and anaerobic fermentation (6) to a protein concentrate (24) by means of a second, but now aerobic fermentation (20), using a culture of microorganisms (18) which, in addition to bacterial strains, may also comprise yeasts, suitable for converting the reaction product of the first, anaerobic fermentation; - optionally separating the microbial mass (23) from the reaction product (21) obtained, which microbial mass contains a concentrate of cellular protein fragments (24); - optionally sterilizing the obtained microbial mass (23) by heat treatment, freeze-drying rye or spray drying process in which living cells are killed; Method according to claim 1, characterized in that for the first and anaerobic fermentation (6) the naturally active microorganism culture is used from the starchy (residual) stream (2). Method according to any one of the preceding claims, characterized in that the second culture of microorganisms used for the aerobic fermentation is predefined, wherein it is determined whether the culture is suitable for converting the reaction product of the first, anaerobic fermentation into a protein concentrate of 50 to 80% protein on a dry matter basis. Method according to any one of the preceding claims, characterized in that the reaction product of the first and anaerobic fermentation (6) is separated into dissolved parts (13) that go further into the conversion process and undissolved parts (15) that are separated. A method according to claim 4, characterized in that the undissolved parts (15) are further washed in order to separate the remaining starch parts from the undissolved parts (15). Method according to claim 4 or 5, characterized in that the dissolved parts (13) are briefly heated in a pasteurization (14) step to reduce the living microbial mass, preferably from log 10-15 per liter to log 6-11 per liter or from log 10-15 per liter to log 4-9 per liter. Method according to claim 6, characterized in that the dissolved parts (13) with the pasteurized microbial mass are transferred to a single cell protein reactor (SCPR), in which an aerobic fermentation is carried out using a defined culture of microorganisms ( 18), which is suitable for converting the reaction product (8) from the first and anaerobic fermentation (6) to single cell protein by means of the second but now aerobic fermentation in the SCPR or single cell protein reactor (20). Method according to claim 7, characterized in that inorganic and / or organic nitrogen and / or phosphate and / or (micro) nutrients are added to the reaction mixture of the aerobic fermentation (20) without exceeding their maximum useful limit. Method according to claim 3, characterized in that the definition of a culture of microorganisms (18) suitable for converting the reaction product (8) of the first and anaerobic fermentation (6) is done according to a specific method with the following steps: - defining the microbiome by means of an aerobic fermentation on the starting substrate; - the cultivation of the microbiome by upscaling batches in which the strains are first cultivated in small volumes and are completely added to a larger volume at sufficient cell density, optical density or OD value, in several steps until a sufficiently large volume is representative for an industrial inoculation or more is achieved, suitable for a batch and preferably a CSTR process or Continuous Stirred Tank Reactor on a laboratory scale; - gradually adding the starting substrate, whereby the same amount of mass is also gradually removed from the reactor, so that the mass in the reactor acquires the same composition as the outgoing mass; - plating the obtained culture on selective growth media after the adaptation and achieving a protein content of 50-80% protein on a dry matter basis; - identifying the isolated strains by DNA sequencing; - quantifying the defined strains; - eliminating the identified strains known to be harmful to the defined culture (18) of microorganisms, modifying the mixed culture as little as possible in order to best retain the previously obtained functionality and stability; - hereby assembling a defined culture (18) unique for each substrate suitable for the second and aerobic fermentation (20) of the starchy (residual) product (2) concerned; - the elimination of any yeasts present, only if they are harmful to the defined culture. Method according to any one of the preceding claims, characterized in that the culture (18) for the second and aerobic fermentation (20) of starchy (residual) streams has the following composition: Castellaniella (denitrificans / defragrans / daejeonensis) Lactobacillus (casei / paracasei) Lactobacillus fermentum Xenophilus (unidentified / azovorans) Paracoccus (denitrificans / pantotrophus) Thermomonas (fusca / haemolytica / koreensis) Acinetobacter venetianus Pigmentiphaga (kullae / daeguensis) Stenotrophomonas {unidentified / nitritireducens / acidaminiphila {Pseudanthanthian santhanis / unidentianthian / temperata kullae / daeguensis) Stenotrophomonas {unidentified / nitritireducens / acidaminiphila) {wizanthantiangsuanasomonas (heloxanthian santhanis. Pichia kudriavzevii. A method according to any one of the preceding claims, characterized in that the starch-containing (residual) flows are potatoes or potato by-products, such as potato peelings, process water, cutting water and potato chips. Device for converting starch-containing (residual) streams into high-quality proteins, characterized in that the device comprises at least two serially connected fermenters (6, 20), a first (6) of which is used for anaerobic fermentation, the fermentation product of which ( 8) undergoes an aerobic fermentation in the second fermentor (20) to produce high-quality protein (24). Device according to claim 12, characterized in that the device is suitable for a continuous or semi-continuous process. 14. Microbial mass comprising at least 60% protein, further characterized by a digestibility of at least 80% and an amino acid pattern containing at least the following essential amino acids expressed on crude protein: methionine> 1.5%, threonine> 4.5%, tryptophan> 1.5%, valine> 5%, alanine> 7% and glycine> 5%. Microbial mass according to the preceding claim, characterized in that the microbial mass is obtained by a method according to any one of claims 1 to 11. Use of a microbial mass according to any one of claims 14 or 15 as a fish feed, animal feed, pet food or in food for human consumption. A feed or food additive, provided with 0.5 to 99.9% of a microbial mass according to any one of claims 14 or 15. 18. A method for providing a protein-rich component to feed such as fish feed, cattle feed, pet food or to food for human consumption; the method comprising producing a microbial mass according to any one of claims 1 to 11 and dosing the microbial mass or a component comprising the microbial mass in feed and / or food.