Patent Publication Number: US-2022225644-A1

Title: A method for reducing an amount of microorganisms in brewers spent grains

Description:
TECHNICAL FIELD 
     The invention relates to a method for reducing an amount of microorganisms in brewers spent grains. 
     BACKGROUND ART 
     Brewers spent grains (BSG) is a by-product from the brewing industry. The BSG comprises starch sources such as barley grains used to brew beer. A produced amount of the BSG for each 100 liter beer may be about 15 Kg. The BSG contains proteins, fibers, and carbohydrates. Although the BSG is a nutritious source, it is microbiologically unstable as it is typically contaminated with pathogenic microorganisms such as  Bacillus cereus  and Enterobacteriaceae. Therefore, the BSG rapidly degrades and spoils within about 24 hours which makes it difficult to trade or use at all. Today, breweries pay a fee to waste treatment for each kilogram of the BSG that they produce and the BSG is mainly used as animal feed or in biogas installations. 
     Therefore there is a need to preserve nutrients of the BSG and to make it a nutrition, instead of a costly undesired waste product. In particular, there is a need to make the BSG a human nutrition. 
     SUMMARY 
     It is an object of the invention to at least partly overcome one or more of the above-identified limitations of the prior art. In particular, it is an object to provide a method to reduce an amount of microorganisms in the BSG. 
     According to an aspect of the present inventive concept there is provided a method for reducing an amount of microorganisms in the BSG. The method comprises feeding a liquid and the BSG into a mixing arrangement, mixing, by means of the mixing arrangement, the liquid and the BSG to form a mixture, feeding the mixture into a heat exchanger, and heating, by means of the heat exchanger, the mixture for a predetermined period of time at a predetermined temperature such that the amount of microorganisms in the BSG is reduced. 
     The method is advantageous in that it allows reducing the amount of microorganisms such as  Bacillus cereus  and Enterobacteriaceae in the BSG and thereby allows it to be used as human nutrition i.e. an ingredient in the food industry. The method in turn allows to reduce waste products of the beer brewing by making the BSG into a human nutrition instead of the costly waste product. Thereby the method is economically and environmentally advantageous. 
     The BSG is a rather dry product which is not suitable for feeding into the heat exchanger. The mixing, by means of the mixing arrangement, of the BSG and the liquid allows to disperse the BSG to be able to feed that into the heat exchanger. The mixing, by means of the mixing arrangement, of the BSG and the liquid further allows to form an even mixture i.e. a homogeneous mixture. The method is also advantageous in that it allows a continuous process and does not require any chemical agent. The heating of the mixture may be performed using conventional Ultra High Temperature (UHT) processing techniques, including allowing a heat recovery. The heating of the mixture may be performed using an indirect heating process such that the BSG is not directly exposed to the heating media. For instance, the heating of the mixture may be performed using a tubular heat exchanger. The tubular heat exchanger may provide optimal performance, long production time and low maintenance costs. 
     By reducing the amount of microorganisms in the BSG is hereby meant removing, killing or deactivating at least 90%, or at least 99%, of living microorganisms in the BSG. 
     By the mixing arrangement is hereby meant any unit that is capable of dispersing BSG in water. 
     The predetermined temperature may be in a range of 127 to 140° C. The predetermined temperature may preferably be in a range of 133 to 138° C. The optimal predetermined temperature may be 137° C. 
     The predetermined period of time may be in a range of 30 to 90 seconds. The predetermined period of time may preferably be in a range of 40 to 80 seconds. The predetermined period of time may more preferably be in a range of 55 to 65 seconds. The optimal predetermined period of time may be 60 seconds. 
     The above predetermined time and temperature ranges may provide sufficient heating to reduce the amount of microorganisms in the BSG. The predetermined temperature may scale inversely with the predetermined time such the heating at a higher temperature may require a shorter time. 
     A solid content of the BSG may be in a range of 20% to 40% by weight of the BSG. The solid content of the BSG may preferably be in a range of 20% to 30% by weight of the BSG. The solid content of the BSG may more preferably be in a range of 20% to 25% by weight of the BSG. The range may depend on the starch source used for brewing beer and may therefore depend on the starch source material. 
     The feeding may comprise feeding the liquid and the BSG such that a solid content of the mixture may be in a range of 10% to 20% by weight of the mixture. The solid content of the mixture may preferably be in a range of 11% to 17% by weight of the mixture. The optimal solid content of the mixture may be 17% by weight of the mixture. This range may provide a sufficient fluidity and concentration to feed the mixture into the heat exchanger. Thereby this range may result into processing a highest amount of the solid BSG which may be reduced according to the above mentioned method. 
     The mixing of the liquid and the BSG may comprise agitating, by means of an agitator, the liquid and the BSG. Thereby the agitating, by means of the agitator, may improve the homogeneity of the mixture. This may in turn facilitate the feeding of the mixture into the heat exchanger and heating of the mixture to reduce the amount of the microorganisms therein. 
     The mixing of the liquid and the BSG may comprise circulating, by means of a circulating loop, the mixture out of and into the mixing arrangement, such that the formation of the mixture is facilitated. The circulating of the mixture out of the mixing arrangement may be performed from a bottom portion of the mixing arrangement into a top portion of the mixing arrangement. This may in turn reduce a risk of sedimentation. The circulating, by means of the circulation loop, may further improve the homogeneity of the mixture. The circulating may be performed initially to speed up the formation of the homogeneous mixture and to facilitate stabilizing of the mixture. 
     The circulating may comprise pumping, by means of a screw pump, the mixture. An advantage brought by the screw pump is that the screw pump may facilitate the pumping of the mixture. The screw pump may pump the mixture out of the mixing arrangement via a slit arranged at the bottom of the mixing arrangement. The pumped mixture may be circulated into the mixing arrangement via the circulation loop to facilitate the formation of the homogeneous mixture. 
     The method may further comprise introducing a viscosity increasing agent into the liquid and the BSG, such that a viscosity of the mixture is increased. Increased viscosity facilitates more even dispersion of the BSG in the liquid as well as reduces the risk of BSG sedimentation. 
     The liquid may be water. The liquid may be water only. The liquid may comprise at least 99% water. 
     The feeding of the mixture into the heat exchanger may comprise pumping the mixture by means of a screw pump. The same screw pump that may be used for pumping the mixture out of the mixing arrangement into the circulation loop may be used to feed the mixture into the heat exchanger. The pumping of the mixture into the heat exchanger may be performed subsequent to the circulating of the mixture. 
     The feeding of the BSG and the liquid into the mixing arrangement may further comprise determining a weight of the BSG being fed into the mixing arrangement and feeding an amount of the liquid based on the determined weight of the BSG. Thereby, the weight of the BSG being fed into the mixing arrangement may be determined, as the BSG weight may depend e.g. types of grains used in the brewing industry. The determining of the weight of the BSG may hence facilitate adjusting the solid content of the mixture i.e. the BSG to the liquid ratio. 
     The method may further comprise, subsequent to the heating of the mixture, drying the mixture to form a dried BSG product and grinding the dried BSG product to form a flour. Thereby, the flour may be used as human nutrition i.e. an ingredient in the food industry. The drying of the mixture may be performed using any conventional drying techniques including e.g. belt pressing and evaporation. The grinding of the BSG product may be performed using any conventional grinding techniques. 
     By drying is hereby meant removal or separation of the major part of liquid in the mixture, allowing the BSG to be grinded to flour. The dried BSG and thus also grinded BSG still have a minor liquid content. 
     The BSG is originated from seeds or grains chosen from a group consisting of barley, wheat, rye, corn, rice, oats and combinations thereof. The BSG may comprise any other grains used in the brewing industry. In case of forming the flour, by drying and grinding of the dried BSG product, the formed flour may have various nutrients depending on the grains used in the brewing industry and may hence provide various flours i.e. various ingredients to the food industry. 
     The BSG may comprise particles having a dimension in a range from 100-4000 μm. The dimension of the particles may vary depending on the grains used in the brewing industry. 
     According to another aspect of the present inventive concept there is provided a method for brewing beer. The method comprises malting raw grains, mashing the malted grains such that wort and BSG are formed, lautering the wort and the BSG such that the wort and the BSG are separated, processing the wort to produce beer, and reducing an amount of microorganisms in the BSG by using the method according to the first aspect. 
     The raw grains may comprise seeds chosen from a group consisting of barley, wheat, rye, corn, rice, and oats and combinations thereof. The malting, mashing, lautering and processing of the wort may be performed in manners which per se are known in the beer brewing industry. 
     The method, according to the second aspect, allows producing the beer and reducing the amount of the microorganisms in the BSG in the same method. The above mentioned features of the first method according to the first aspect, when applicable, apply to this second aspect as well. In order to avoid undue repetition, reference is made to the above. 
     Still other objectives, features, aspects and advantages of the invention will appear from the following detailed description as well as from the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the invention will now be described, by way of example, with reference to the accompanying schematic drawings, in which 
         FIG. 1  is an schematic illustration of an arrangement capable of reducing an amount of microorganisms in BSG. 
         FIG. 2  is a block scheme of a method for reducing an amount of microorganisms in BSG. 
         FIG. 3  is a block scheme of a method for brewing beer. 
     
    
    
     DETAILED DESCRIPTION 
     With reference to  FIG. 1  an arrangement  100  is illustrated. The arrangement  100  may be used to reduce an amount of microorganisms in BSG  110 . The arrangement  100  may be installed next to a brewing facility such that the produced BSG  110  from beer brewing may directly be fed into the arrangement  100 . 
     In the following the BSG  110  and the arrangement  100  in relation to reducing an amount of microorganisms in the BSG  110  will be described. 
     The BSG  110  may originate from any grains or seeds used in brewing industry. The BSG  110  may originate from barley, wheat, rye, corn, rice, oats and combinations thereof. The BSG  110  may be in a form of ground malt. The BSG  110  may comprise water. The BSG  110  may have a pH of 6.7-6.9. The BSG  110  may be comprise particles a dimension in a range from 100-4000 μm. As an example, the dimension of the BSG particles may be distributed, as follows: below 160 μm (d 10 ), between 950 to 1650 μm (d 50 ), 2900 μm (d 90 ) and 4000 μm (d max ). A solid content (SC) of the BSG  110  may be in a range from 20% to 40% by weight of the BSG  110 . The BSG  110  may have a water content of 73-82%. Still, the BSG  110  may be rather solid i.e. show no pronounced flowability, no bridging, and no free water. A bulk density of the BSG  110  may be 0.4-0.5 g/ml. 
     The arrangement  100  may comprise a mixing arrangement  130  and a heat exchanger  140 . The general function of the mixing arrangement  130  is mixing and the general function of the heater exchanger  140  is heating. 
     The mixing arrangement  130  may be a dispersion tank. A volume of the dispersion tank may as an example be 1500 liter.  FIG. 1  shows that the mixing arrangement  130  has two inlets. One inlet may be used to feed a liquid  120  and one inlet may be used to feed the BSG  110  into the mixing arrangement  130 . The liquid  120  may be water. 
     The mixing arrangement  130  may have more than two inlets. For instance, mixing arrangement  130  may have a third inlet to feed a viscosity increasing agent into the liquid  120 . Alternatively, the viscosity increasing agent may be introduced into the liquid  120 . The viscosity increasing agent may increase a viscosity of the mixture. 
     A weight of the BSG  110  being fed into the mixing arrangement  130  may be determined, by means of a sensor  190 . The sensor  190  may be any suitable conventional sensor arranged such that the weight of the BSG  110  may be determined while feeding the BSG  110  into the mixing arrangement  130 , i.e. continuous in-line determination. Alternatively, the BSG  110  may be weighted prior to feeding the BSG  110  into the mixing arrangement  130 . An amount of the liquid  120 , based on the determined weight of the BSG  110 , may be fed into the mixing arrangement  130 . The feeding of the liquid  120  and the BSG  110  may be performed such that a solid content of the mixture may be in a range of 10% to 20% by weight of the mixture. The mixing arrangement  130  may mix the BSG  110  and the liquid  120  to form an even and a homogeneous mixture. 
     The mixing arrangement  130  may further comprise an agitator  150 . The agitator  150  may include a propeller, a screw or similar. The mixing arrangement  130  may comprise more than one agitator  150 . The agitator  150  may agitate the BSG  110  and the liquid  120 .  FIG. 1  shows that the agitator  150  is arranged at a bottom portion of the mixing arrangement  130 . The agitator  150  may be arranged anywhere in the mixing arrangement  130  e.g. at a middle portion.  FIG. 1  shows that the agitator  150  is connected to a motor  180   a .  FIG. 1  shows that the motor  180   a , connected to the agitator  150 , is arranged above the mixing arrangement  130 . The motor  180   a  may provide mechanical energy to agitate the agitator  150 . 
     The mixing arrangement  130  may further comprise a circulation loop  160 , shown in  FIG. 1 . The mixing arrangement  130  may comprise more than one circulation loop  160 . The mixture may be circulated by means of the circulation loop  160 . The circulation loop  160  may connect a bottom portion of the mixing arrangement  130  to a top portion of the mixing arrangement  130 . The circulation loop  160  may circulate the mixture out of the bottom portion of the mixing arrangement  130  into the top portion of the mixing arrangement  130 . The circulation loop  160  may facilitate the formation of the mixture. 
     The mixing arrangement  130  may further comprise a slit arranged at the bottom portion of the mixing arrangement  130 . The slit may have a circular cross section. The slit may be connected to a screw pump  170 . The slit may be connected to a feed screw  172  of the screw pump  170 . The feed screw  172  may have an opening facing the slit of the mixing arrangement  130 . The opening of the feed screw  172  may have the shape and same size as the slit. The mixture may exit the slit and enter feed screw  172  such that no mixture may remain at an interface between the slit and the feed screw  172 . The feed screw  172  may be connected to a motor  180   b , as shown in  FIG. 1 . The motor  180   b  may provide mechanical energy to the feed screw  172  to pump the mixture from the mixing arrangement  130  into the feed screw  172 . The screw pump  170  may further comprise a pump screw executer  174 . The feed screw  172  and the pump screw executer  174  may be arranged on the same shaft so as to co-rotate. The motor  180   b  may hence provide mechanical energy to the pump screw executer  174 . The mixture may flow from the feed screw  172  into the pump screw executer  174 . The pump screw executer  174  may be connected to the circulation loop  160 . The circulating of the mixture into the circulation loop  160  may comprise pumping, by means of the screw pump  170 , the mixture. The mixture may flow from the feed screw  172  into the pump screw executer  174  and then into the circulation loop  160 . The flow of the mixture from the pump screw executer  174  into the circulation loop  160  may be controlled by means of a valve  195   a . The valve  195   a  may be open initially to speed up the formation of the homogeneous mixture. The valve  195   a  may be closed after the stabilization of the mixture. A volume of the mixture after stabilization may as an example be 700 liters. 
       FIG. 1  also shows that the pump screw executer  174  of the screw pump  170  is connected to the heat exchanger  140 . The feeding of the mixture into the heat exchanger  140  may comprise pumping, by means of the screw pump  170 , the mixture into the heat exchanger  140 . The flow of the mixture from the pump screw executer  174  into the heat exchanger  140  may be controlled by means of another valve  195   b . The valve  195   b  of the heat exchanger  140  may be closed initially i.e. when the valve  195   a  of the circulation loop  160  is open. The valve  195   b  of the heat exchanger  140  may be open after the mixture has stabilized. The valve  195   b  of the heat exchanger  140  may be open when the valve  195   a  of the circulation loop  160  is closed. 
     Still with reference to  FIG. 1 , in the following the heater exchanger  140  and the flow of the mixture in the heat exchanger  140  will be described.  FIG. 1  shows schematic illustration of a tube type heat exchanger  140 . The heating of the mixture may be performed using plate type heat exchanger or any other type of suitable heat exchanger. 
     The heat exchanger  140  may comprise several parts or portions serving different purposes or the same purposes. The heat exchanger  140  may comprise a preheater  142 . The heat exchanger  140  may comprise one or more final heaters  144 .  FIG. 1  shows only one final heater  144 . However, two or more number of final heaters  144  may be connected in series with the final heater  144 . The two or more number of the final heaters  144  may be arranged such that they may be connected to or disconnected from the mixture being feed into the heat exchanger  140 . The two or more number of the final heaters  144  may increase an area of the heat exchanger  140  and consequently increase an amount of heat transfer. 
     The heat exchanger  140  may comprise a holding tube  145 . The holding tube  145  may comprise corrugated or winding tubes. The holding tube  145  serves the purpose of maintain the mixture being feed into the heat exchanger  140  at a certain temperature for a certain time. The heat exchanger  140  may further comprise a regeneration cooler  146  and a final cooler  148 .  FIG. 1  shows one regeneration cooler  146  and one final cooler  148 . However, there may be more than one regeneration cooler  146  and more than one final cooler  148 . 
     As stated above, after the mixture has been stabilized, the valve  195   b  of the heat exchanger  140  connected to the pump screw executer  174  may be open. The mixture may hence flow from the pump screw executer  174  into the preheater  142 . The BSG  110  and the liquid  120  may continuously and proportionally be fed into mixing arrangement  130  to keep a continuous supply of the mixture. In other words, the BSG  110  and the liquid  120  may continuously be fed into the mixing arrangement  130  while the mixture is passing through the heater exchanger  140  i.e. being heated in the heater exchanger  140 , as this is a continuous process. The preheater  142  may preheat the mixture for to a temperature of 70° C. After the mixture has been preheated, by means of the preheater, the mixture may be sent to the final heater(s)  144 . The mixture may be heated at a predetermined temperature at the final heater  144 . The final heater  144  may be indirectly heated by a steam flow.  FIG. 1  shows the steam flow by the dashed-line arrow above the final heater  144 . The predetermined temperature may be in a range of 127 to 140° C. The optimal predetermined temperature may be 137° C. After heating of the mixture at the predetermined temperature, the mixture flows into the holding tube  145 . The mixture then passes the holding tube  145  which has a length that is chosen such that the passing takes a predetermined period of time. The predetermined period of time may be in a range of 30 to 90 seconds. The optimal predetermined period of time may be 60 seconds. The mixture may then be sent to the regeneration cooler  146 . The regeneration cooler  146  may decrease the temperature of the mixture. There may be a heat recovery between the preheater  142  and the regeneration cooler  146 . The heat recovery between the preheater  142  and the regeneration cooler  146  is shown by dashed-line in  FIG. 1 . The mixture may next be sent to the final cooler  148 . The final cooler  148  may further decrease the temperature of the mixture. The final cooler may be indirectly cooled by cooling water.  FIG. 1  shows the cooling water by the dashed-line arrow above the final cooler  144 . The mixture may then be sent out via an outlet  115 . The temperature of the mixture leaving the final cooler  148  may be 80° C. 
     Subsequent to heating of the mixture, by means of the heating exchanger  140 , the mixture may be dried. The mixture may be dried to form a dried BSG product. The drying may be done via a drier connected to the outlet  115  such that the heated mixture, the mixture exiting the outlet  115 , may be fed into the drier (not shown in  FIG. 1 ). The drier may be any type of conventional drier including e.g. a belt press drier. The drier reduces the amount of water or liquid from the heated mixture to form the dried BSG product. The dried BSG product may be ground to form a flour. The grinding of the dried BSG product may be performed using any conventional grinder or mill (not shown in  FIG. 1 ). The flour may be packed and provided to the food industry. The flour may be used as ingredient in the food industry. Depending on the type of raw grains used in the brewing industry, various flour types may be provided to the food industry. 
     In the above, the arrangement  100  is described in relation to reducing an amount of microorganism in the BSG  110 . However, the arrangement  100  is not limited to reducing an amount of microorganism in the BSG  110  and may be used to reduce an amount of microorganism in other malted kernels as well. 
     With reference to  FIG. 2 , a block scheme of a method  300  for reducing an amount of microorganisms in BSG  110  is illustrated. The method comprises the following steps. 
     The method  300  may comprise determining S 300  a weight of the BSG  110  being fed into a mixing arrangement  130 . The mixing arrangement  130  may be configured, as described above. The determination of the BSG  110  weight may be performed using a sensor  190 , as described above. 
     The method  300  further comprises feeding S 305  a liquid  120  and the BSG  110  into a mixing arrangement  130 . The feeding S 305  of the liquid  120  may comprise feeding an amount of the liquid  120  based on the determined weight of the BSG  110  being fed into the mixing arrangement  130 . The liquid  120  may be as described above. 
     The method  300  further comprise mixing S 310 , by means of the mixing arrangement  130 , the liquid  120  and the BSG  110  to form a mixture. 
     The mixing S 310  may further comprise agitating S 315 , by means of an agitator  150 , the liquid  120  and the BSG  110 . The agitator  150  may be configured, as described above. 
     The method  300  may further comprise pumping S 320 , by means of a screw pump  170 , the mixture. The screw pump  170  may be configure, as described above. 
     The mixing S 310  may further comprise circulating S 325 , by means of a circulation loop  160 , the mixture out of and into the mixing arrangement  130 , such that the formation of the mixture is facilitated. The circulation loop  160  may be configured, as described above. The circulating S 325  may comprise pumping S 320 , by means of the screw pump  170 , the mixture. 
     The method  300  further comprises feeding S 330  the mixture into a heat exchanger  140 . The heat exchanger  140  may be configured as described above. The feeding S 330  of the mixture into the heat exchanger  140  may comprise pumping S 320 , by means of a screw pump  170 , the mixture. The screw pump  170  may be the same screw pump  170 , as described above. 
     The method  300  further comprises heating S 335 , by means of the heat exchanger  140 , the mixture for a predetermined time at a predetermined temperature such that the amount of microorganisms in the BSG  110  is reduced. The predetermined time and the predetermined temperature may be as described above. 
     The method  300  may further comprise, subsequent to heating S 335  of the mixture, drying S 340  the mixture to form a dried BSG product. The drying S 340  may be performed as described above. 
     The method  300  may further comprise grinding S 345  the dried BSG product to form a flour. The grinding S 345  may be performed as described above. 
     With reference to  FIG. 3 , a block scheme of a method  400  for brewing beer is illustrated. The method comprises the following steps. 
     The method  400  comprises malting S 400  raw grains  430 . The raw grains may originate from any of barley, wheat, rye, corn, rice, oats and combinations thereof. The malting S 400  may be performed in a manner which per se is known in the beer brewing industry. 
     The method  400  further comprises mashing S 405  the malted grains  430  such that wort  230  and BSG  110  are formed. The mashing S 405  may be performed in a manner which per se is known in the beer brewing industry. 
     The method  400  further comprises lautering S 410  the wort  230  and the BSG  110  such that the wort  230  and the BSG  110  are separated. The lautering S 410  may be performed in a manner which per se is known in the beer brewing industry. 
     The method  400  further comprises processing S 415  the wort  230  to produce beer  240 . The processing S 415  of the wort  230  may be performed in a manner which per se is known in the beer brewing industry. 
     The method  400  further comprises reducing S 420  an amount of microorganisms in the BSG  110  according to the method  300  described in connection with  FIG. 2 . 
     From the description above follows that, although various embodiments of the invention have been described and shown, the invention is not restricted thereto, but may also be embodied in other ways within the scope of the subject-matter defined in the following claims.