WO2021195226A1

WO2021195226A1 - Corn products useful in beer fermentation

Info

Publication number: WO2021195226A1
Application number: PCT/US2021/023909
Authority: WO
Inventors: Yifang Zhang
Original assignee: Cargill, Incorporated
Priority date: 2020-03-25
Filing date: 2021-03-24
Publication date: 2021-09-30
Also published as: BR112022019359A2

Abstract

This disclosure provides a corn protein concentrate (CPC) product and beer, and methods for their preparation and use. The corn protein concentrate product comprises protein of about 42-72wt% on a dry weight basis (dwb), and lactic acid of about 5-20wt% (dwb). The protein comprises α-amino nitrogen of about 1.1-4wt% (dwb), and the mass ratio of the lactic acid to the α-amino nitrogen is ≤ 6. The corn protein concentrate product can be obtained from a corn steep liquor (CSL), and can be applied to the production of beer. The CPC has been found to improve beer flavor, enhance its foam stability and reduce fermentation time.

Description

CORN PRODUCTS USEFUL IN BEER FERMENTATION

CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application claims the benefit of Chinese Application No. 202010219996.0, filed 25 March 2020 and entitled

U.S.

Provisional Patent Application No. 63/026,795, filed 19 May 2020 and entitled “CORN PRODUCTS USEFUL IN BEER FERMENTATION”, Chinese Application No. 202010779647.4, filed 05 August 2020 and entitled

n¾, MΊ&7:

'/i; ¹ -jT'U IJ", and U.S. Provisional Patent Application No. 63/140,545, filed 22 January 2021 and entitled “CORN PRODUCTS USEFUL IN BEER FERMENTATION”, the entirety of each of which is hereby incorporated by reference.

FIELD OF THE INVENTION

[0002] The present disclosure relates to the field of com processing and application.

Particularly, it relates to a corn protein concentrate (CPC) product, beer, and methods of preparation and use thereof.

BACKGROUND

[0003] In the corn processing industry, there are primarily three types of resources for obtaining corn protein: com steep liquor (CSL), corn gluten powder (also known as com yellow powder or corn protein powder), and corn germ. Among them, corn steep liquor is a by-product of wet com milling, in which com is soaked in sulfur dioxide for a period of time until they are separated into starch (insoluble component) and corn steep liquor (containing soluble component). The solid content of com steep liquor is generally in a range of 8%-10%. Typically, more than 40% of the solid content is protein and the solid content contains a large amount of lactic acid. [0004] At present, com steep liquor is consumed industrially (concentrated as feed or pharmaceutical culture medium), but in some countries as much as half of the corn steep liquor is wasted. Concentrated corn steep liquor (a product obtained by concentrating corn steep liquor at a certain level), also known as heavy steep liquor, has been sold commercially. Some commercially available concentrated com steep liquor products, such as CORNSTEEP (Tate & Lyle, London, UK), are sold for animal feed and can contain high levels of lactic acid. Com steep liquor has also been sold as a reagent for specialty lab-scale fermentation purposes; Sigma Aldrich (St. Louis, Missouri, US), for example, indicates that its com steep liquor may be used in broth to act as an indicator for starch utilization; for simultaneous saccharification and co-fermentation (SSCF) testing; or as a peptone substitute in a “high-density culture of S. cerevisiae”.

[0005] Alternative methods of using and processing corn steep liquor can expand the market for CSL and achieve a better market value.

SUMMARY OF THE INVENTION

[0006] The present disclosure provides a corn protein concentrate (CPC) product, a beer, and methods of preparation and use thereof. The com protein concentrate can be obtained from corn steep liquor (CSL), and can be applied to the production of beer. This CPC can improve the flavor of beer, increase the foam stability, and reduce fermentation time. The CPC of the present disclosure has an enormous market potential and value.

[0007] In a first aspect, a corn protein concentrate (CPC) product contains protein and lactic acid (LA), the protein contains a-amino nitrogen (a-N), and the mass ratio of lactic acid and a-amino nitrogen is < about 6. One such product comprises: a) protein of about 42-72 wt%, based on dry weight of the product (i.e., dry weight basis, dwb); and b) lactic acid of about 5-20 wt% (dwb); wherein said protein comprises a-amino nitrogen of about 1.1-4 wt% (dwb), and wherein the mass ratio of the lactic acid to the a-amino nitrogen is < about 6.

[0008] Normally, the mass ratio of the lactic acid to the a-amino nitrogen in the CPC product is < about 6, < about 5.5, < about 4.5, < about 4, < about 3.5, < about 3, < about 2.5, and even < about 2.

[0009] Such a CPC Such a product includes a relatively large amount of a-amino nitrogen and a relatively small amount of lactic acid. When the product is applied to beer production, the a-amino nitrogen in the product can promote fermentation, while the lactic acid will not affect the beer flavor due to its low amount, and could otherwise adjust the pH value during the saccharification and thus promote fermentation.

[00010] The content of lysine (LYS) in the a-amino nitrogen may be about 2.1 times or more the content of methionine (MET), preferably about 2.2 times or more, more preferably about 2.3 times or more. [00011] Lysine has been found to promote the metabolism of free amino acids by yeasts during the beer fermentation and thus shortens the fermentation time, while Methionine has been found to have opposite effect, which inhibits the metabolism of free amino acids by yeasts and prolongs the fermentation period. A LYS content in the a-amino nitrogen of a CPC product can be about 2 times or more in comparison to that of MET, and can even reach about 2.3 times or more, meaning that the product contains a far greater amount of LYS than MET. As a result, when the product is applied to beer fermentation, it can promote the metabolism of free amino acids by yeasts, and thus promotes the fermentation and shortens the fermentation time.

[00012] In one aspect, the CPC product has a solid content of about 8-96wt%, preferably about 10-70wt%, more preferably about 42-50wt%. Particularly, the solid content of the product can be about 8wt%, about 12wt%, about 16wt%, about 20wt%, about 24wt%, about 28wt%, about 32wt%, about 36wt%, about 40wt%, about 44wt%, about 48wt%, about 52wt%, about 56wt%, about 60wt%, about 64wt%, about 68wt%, about 72wt%, about 76wt%, about 80wt%, about 84wt%, about 88wt%, about 92wt%, or about 96wt%.

[00013] In such a CPC, the product could have a wide range of solid content. Namely, the product can be in various forms, ranging from a very dilute solution with a solid content as low as the solid content of the CSL (which is used as the starting material), to a dry powder product with a relatively high solid content.

[00014] In another aspect, the CPC product comprises protein of about 48-68wt% based on the dry weight of the product (dwb), preferably about 50-65wt% (dwb), and more preferably about 51-59wt% (dwb). The content of protein in the product can be, on a dry weight basis, about 40wt%, about 41wt%, about 42wt%, about 43wt%, about 44wt%, about 45wt%, about 46wt%, about 47wt%, about 48wt%, about 49wt%, about 50wt%, about 51wt%, about 52wt%, about 53wt%, about 54wt%, about 55wt%, about 56wt%, about 57wt%, about 58wt%, about 59wt%, about 60wt%, about 61wt%, about 62wt%, about 63wt%, about 64wt%, about 65wt%, about 66wt%, about 67wt%, about 68wt%, about 69wt%, about 70wt%, about 71wt%, about 72wt%, about 73wt%, about 74wt%, or about 75wt%.

[00015] The content of protein in such a product is relatively high. If an even higher content of protein is desired, the process of preparation would be more complicated with a remarkable increase of cost. An inevitable protein loss may occur accordingly.

[00016] In one aspect, the CPC product comprises lactic acid of about 9-17wt% based on dry weight of the product (dwb), preferably about ll-15wt% (dwb), and more preferably about 12-14wt% (dwb).The content of the lactic acid can be, on a dry weight basis, about 4wt%, about 5wt%, about 6wt%, about 7wt%, about 8wt%, about 9wt%, about 10wt%, about llwt%, about 12wt%, about 13wt%, about 14wt%, about 15wt%, about 16wt%, about 17wt%, about 18wt%, about 19wt%, about 20wt%, about 21wt%, or about 22wt%.

[00017] The content of lactic acid in such a product is relatively low. If the content of lactic acid is too high, it will affect the beer flavor at the time of being applied to the production of beer. If the content of lactic acid is too low, it may not function well when being applied to the production of beer. Therefore, the lactic acid content is preferably kept in a relatively stable range, which is helpful for improving the beer flavor.

[00018] The protein may comprise a-amino nitrogen of about 1.5-3.5wt% based on dry weight of the product (dwb), preferably about 1.8-3.2wt% (dwb), and more preferably about 2.3- 3.1wt% (dwb).The content of a-amino nitrogen can be, on a dry weight basis, about lwt%, about l.lwt%, about 1.2wt%, about 1.3wt%, about 1.4wt%, about 1.5wt%, about 1.6wt%, about

1.7wt%, about 1.8wt%, about 1.9wt%, about 2.0wt%, about 2.1wt%, about 2.2wt%, about

2.3wt%, about 2.4wt%, about 2.5wt%, about 2.6wt%, about 2.7wt%, about 2.8wt%, about

2.9wt%, about 3.0wt%, about 3.1wt%, about 3.2wt%, about 3.3wt%, about 3.4wt%, about

3.5wt%, about 3.6wt%, about 3.7wt%, about 3.8wt%, about 3.9wt%, about 4.0wt%, about

4.1wt%, about 4.2wt%, about 4.3wt%, about 4.4wt%, or about 4.5wt%.

[00019] In one aspect, more than about 70wt% of the protein in the product has a molecular weight of 1000D or less, and preferably more than about 80 wt% of the protein has a molecular weight of 1000D or less. Further, more than about 60 wt% of the protein in the product can have a molecular weight of 500D or less, and preferably more than about 70 wt% of the protein has a molecular weight of 500D or less.

[00020] In such a CPC product, most of the protein in the product has a molecular weight of 1000D or less. The proteins having such molecular weight range are capable of promoting fermentation.

[00021] In another aspect, about 30-60wt% of the protein in the product has a molecular weight of 180D or less, preferably about 40-50wt% of the protein has a molecular weight of 180D or less. About 30%, about 32wt%, about 34wt%, about 36wt%, about 38wt%, about 40wt%, about 42wt%, about 44wt%, about 46wt%, about 48wt%, about 50wt%, about 52wt%, about 54wt%, about 56wt%, about 58wt%, or about 60wt% of the protein in the product can have a molecular weight of 180D or less. [00022] As can be seen, in such a CPC product, a large portion of the proteins have a molecular weight of 180D or less, indicating that a large portion of the proteins is in the form of a-amino nitrogen (a-N) in the product, which is helpful in promoting the beer fermentation. In the context of this product, a-N content can be considered as generally equivalent to the free amino acid content. Since the amount of free amino acids can be determined by measuring the amount of nitrogen elements on the free amino acids, free amino acid is therefore also called free amino nitrogen (FAN). a-N is one of the nitrogen sources for yeasts. A high level of FAN content plays a significant part in the beer fermentation. Therefore, the products containing a large amount of FAN would be favorable for beer fermentation.

[00023] In a second aspect, the present disclosure provides a method of preparing a corn protein concentrate (CPC) product from a corn steep liquor (CSL). Such a method may comprise the steps of:

(1) performing a first filtration on the corn steep liquor to remove insoluble materials and soluble materials having a molecular weight of > lOOkD, to obtain a filtrate;

(2) performing a second filtration on the filtrate to remove part of materials having a molecular weight of < 150D to obtain a retentate; and optionally repeating step (1), step (2), or step (1) and (2); wherein the step (1) and/or step (2) can be optionally repeated one time or more times; and preferably the step (1) and/or step (2) can be repeated two times, three times, four times, or more than four times; wherein the mass ratio of the lactic acid to the a-amino nitrogen in the retentate finally obtained is < 6.

[00024] In such a method, insoluble materials and soluble materials having a molecular weight of > lOOkD are removed by a first filtration on the corn steep liquor, and part of materials having a molecular weight of < 150D (most being lactic acid in the CSL, and some amino acids and small molecule organic acids) are removed by a second filtration. The filtrations simultaneously exert a function of preliminary concentration, until the mass ratio of lactic acid and a-N is < 6. CSL is used as starting material, from which a com protein concentrate (CPC) is obtained, through specific preparation methods, by removing the components that will affect the beer fermentation or produce bad flavor, while retaining components that promote the beer fermentation. The resultant CPC product can be applied to beer production, so as to improve the flavor of beer, enhance the stability of foams, and reduce fermentation time, and has a huge market potential and value. [00025] In one aspect, the preparation method comprises a step of repeating the second filtration until the mass ratio of lactic acid and a- amino nitrogen in the retentate reaches < about 6.

[00026] In such a method, the second filtration is repeated multiple times to remove much of the K⁺ that exits in a large amount in the CSL, and an adequate amount of Na⁺, and corresponding monovalent anions. The reduction of these components could minimize their impact on the beer fermentation.

[00027] In another aspect, the method does not include any steps of adding enzymes for hydrolysis. Specifically, one such method of preparing a com protein concentrate (CPC) product according to the present disclosure does not include any steps of adding enzymes (amylase, protease, cellulase) to hydrolyze the material. Desirably, the method mainly uses physical methods, rather than biochemical methods such as enzymatic hydrolysis, to prepare the CPC product. As a result, the present disclosure enables considerable improvement in the maneuverability of the process, can simplify the technology and can save unnecessary enzymatic hydrolysis steps and costs thereof.

[00028] Membrane filtration technology may be used for the first and/or the second filtration.

[00029] In another aspect, the first filtration intends to remove substances having a large molecular weight, and the material of the filtration membrane materials for the first filtration optionally comprises inorganic membrane or organic membrane. If an inorganic membrane is used for the first filtration, the material of the inorganic membrane includes but is not limited to, for example, ceramic membrane having a pore size in a range of about 4-200nm; or metal membrane having a pore size in a range of about 100-200 nm. If an organic membrane is used for the first filtration, the material of the organic membrane includes but is not limited to, for example, cellulose acetate (CA), polysulfone (PSO), polyvinylidene fluoride (PVDF), or the like, which can be made into filtration membranes that block substances having a molecular weight of 50-100,000 kDa. The forms of the filter membrane above could be readily modified by those skilled in the art as needed, and may include but is not limited to hollow fiber membrane, spiral membrane (spiral- wound membrane), tubular membrane, plate membrane (flat membrane) or any other forms. [00030] The conditions for the first filtration are optionally as follows: (1) the pressure is controlled at 0.1-0.4 Mpa, preferably 0.12-0.35 MPa; (2) the flow rate is controlled at 2-5 m³/hr, preferably 2.5-4.8 m³/hr; (3) the temperature is set as 20-60°C, preferably 22-55°C; and (4) the filtration rate is maintained at 5-30 L/hr, preferably 6-25 L/hr. It should be noted that the “flow rate” in the present disclosure refers to the flow of the liquid outside the filter membrane; and the “filtration rate” refers to the flow of the liquid at the time of passing through the filter membrane. [00031] The second filtration intends to remove substances having smaller molecular weight. The material of the filtration membrane for the second filtration are primarily organic membranes, which include but not limited to, for example, cellulose acetate (CA), polysulfone (PSO), polyvinylidene fluoride ( PVDF) or the like, which can be made into filtration membranes that block substances having a molecular weight of lower than 300 Dalton. The form of the filter membrane above could be readily modifited by those skilled in the art as needed, which includes but not limited to a hollow fiber membrane, spiral membrane, tubular membrane, plate membrane or any other forms.

[00032] The conditions for the second filtration are optionally as follows: (1) the pressure is controlled at 1-3.5 Mpa, preferably 1.5-3 MPa; (2) the flow rate is controlled at 1-2 m³/hr, preferably 1.2-1.8 m³/hr; (3) the temperature is set at 15-40°C, Preferably 16-38°C; and (4) the filtration rate is maintained at 600-100 ml/15s (i.e., 24-144L/hr), preferably 30-140 L/hr.

[00033] One useful preparation method does not include a step of lactic acid extraction and separation. Preferably, the method does not include a step of lactic acid separation other than filtration itself. Such a method of preparing CPC product does not include a separate step of extraction or isolation of lactic acid, such as lactic acid separation adsorption tower. As a result, the preparation method is a simple and straightforward process, and excludes unnecessary steps. [00034] The preparation method may further include a step of sterilizing the retentate and/or a step of concentrating the retentate. Preferably, the sterilization occurs at a temperature of about 120-150°C.

[00035] In one such a method, the concentrated solution through the second filtration is sterilized at 120-150°C, in which white solid containing calcium and magnesium may be precipitated. The precipitate could be filtered and removed, and the retentate is concentrated in vacuum to obtain a CPC product.

[00036] The present disclosure also provides a CSL comprising: a) protein of about 40-50wt% based on dry weight of the CSL (i.e., dry weight basis, dwb); and b) lactic acid of about 27-38wt% (dwb); wherein said protein comprises a-amino nitrogen of about l-2.5wt% (dwb), and wherein the mass ratio of the lactic acid to the a-amino nitrogen is >12. Normally, the mass ratio of the lactic acid to the a-amino nitrogen in the CSL is at least about 12, at least about 12.5, at least about 13, at least about 13.5, at least about 14, at least about 14.5, at least about 15, at least about 15.5, or even at least about 16.

[00037] CSL contains many impurities, with a high level of lactic acid and a low level of a-amino nitrogen. After the CSL is treated and utilized by methods in accordance with aspects of this disclosure, the content of lactic acid decreases, while the content of a-amino nitrogen increases, and the market value of the product significantly increases.

[00038] The present disclosure provides a CPC product, which is obtained by the preparation method of CPC product according to the preceding discussion.

[00039] The present disclosure also proposes a use of a CPC product described above in beer fermentation. In this use, the CPC product contains an adequate amount of a-amino nitrogen, which is suitable for the growth of beer yeast. The product further contains an adequate amount of protein and lactic acid, which are helpful in the beer production, for improving the flavor of beer, increasing the stability of foam, and considerably reducing the fermentation time.

[00040] In another respect, the present disclosure provides a method for preparing a beer. The CPC product described previously is added into a fermentation source, and then the fermentation is performed when the content of a-amino nitrogen reaches about 160 ppm or more, preferably reaches about 170 ppm or more, more preferably reaches about 180 ppm or more. [00041 ] In one implementation, the fermentation source comprises syrup, wherein the syrup comprises sugar that accounts for about 10-90wt% of the total amount of sugar in the fermentation source, and preferably the syrup comprises sugar that accounts for about 20-60wt% of the total amount of sugar in the fermentation source, and more preferably the syrup comprises sugar that accounts for about 30-50wt% of the total amount of sugar in the fermentation source, and most preferably the syrup comprises sugar that accounts for about 40wt% of the total amount of sugar in the fermentation source.

[00042] When the CPC product is applied in the process of beer production, it can supplement a-amino nitrogen and thus promote beer fermentation. Particularly for the industrial beer in some countries, in order to reduce the production cost, syrup or starch may be used in place of part of wort as a fermentation source. This will lead to a deficiency of a-amino nitrogen, thus resulting in yeast malnutrition and a low efficiency of fermentation, and both quality and flavor of beer will be affected. Addition of CPC product disclosed herein can supplement a-amino nitrogen, and therefore solves the problems of beer quality and flavor. In the fermentation source, wort usually provides about 90wt%, about 80wt%, about 70wt%, about 60wt%, about 50wt%, about 40wt%, about 30wt%, about 20wt%, or about 10wt% of sugar, while syrup can provide the rest of about 10wt%, about 20wt%, about 30wt%, about 40wt%, about 50wt%, about 60wt%, about 70wt%, about 80wt%, or about 90wt% of the sugar. Theoretically, cereal-derived sugars such as those in wort in fermentation resource can be completely replaced by syrup. That is, syrup can contribute about 100% of sugar content in the fermentation source.

[00043] Such fermentation may last about 3-12 days; preferably about 5-10 days; and more preferably about 8 days.

[00044] Another aspect of the disclosure provides a beer obtained by the preceding method of preparing a beer. The beer may have an alcohol to ester ratio of about 3 to about 5, optionally about 3.5 to about 4.5, further optionally about 3.5 to about 4.4. Specifically, the beer can have an alcohol to ester ratio of about 3, about 3.5, about 4, about 4.1, about 4.2, about 4.3, about 4.5 or about 5.

[00045] The beer may have a foam stability of about 255S or more, preferably about 260S or more, and more preferably about 263S or more.

[00046] The beer may contain diacetyl in an amount of < about 50ppm, preferably < about 45ppm, and more preferably < about 40ppm.

[00047] The term “about” or “approximately” must be determined in the context of the variable concerned. For example, in some respects “about” or “approximately” may refer to plus or minus 10% of the recited value. For example, “about 100°C” as might mean any temperature between 90-110°C.

[00048] The term “based on the dry weight” or “dry weight basis” used in the present disclosure means a calculation based on the weight of the anhydrous solid retained after the moisture is removed (typically by subtracting the water weight rather than physically drying the product to 0% moisture), which is commonly abbreviated as dwb (dry weight basis). For example, “based on dry weight of the product” means calculation of weight based on the product in which the moisture has been removed/subtracted from the product.

DETAILED DESCRIPTION OF THE INVENTION [00049] Aspects of the CPC product and processes mentioned above are clarified and described more completely below. If specific conditions are not indicated in the description or examples, it means it is carried out according to the regular conditions or the conditions recommended by the manufacturers. If reagents or instruments used are not indicated with the manufacturers, they are conventional products that are commercially available.

[00050] The com protein concentrate (CPC) product and beer, their preparation method and use thereof are described in detail below.

[00051] A CPC product of the present disclosure is primarily prepared from corn steep liquor (CSL) as starting material, which is a product usually used in the corn wet milling industry. In some special cases, CSL can also be the product obtained when the heavy steep liquor is diluted. The corn steep liquor comprises a solid substance content (solid content) of about 3wt%-20wt%, normally about 6wt%-10wt%. In normal circumstances, the corn steep liquor (CSL) comprises: protein of about 40-50 wt% based on dry weight of the CSL (dwb), and lactic acid of about 27- 38wt% (dwb), preferably about 30-38wt% (dwb); wherein the protein comprises a-amino nitrogen of about l-2.5wt% (dwb), preferably about 1.8-2.2wt%, and wherein the mass ratio of the lactic acid to the a-amino nitrogen is >12.

[00052] Percentage (%) in the present disclosure refers to the weight percentage (wt%) unless stated otherwise. The dry weight refers to the solid content unless stated otherwise. [00053] Accordingly, the present disclosure provides a method of preparing a corn protein concentrate (CPC) product from a com steep liquor (CSL), comprising steps of:

(1) Performing a first filtration on the com steep liquor to remove insoluble materials and soluble materials having a molecular weight of > lOOkD to obtain a filtrate. The first filtration may be performed by using a membrane filtration technology.

(2) Performing a second filtration on the filtrate to remove part of materials having a molecular weight of < 150D. Generally, slightly more than about half of the original lactic acid and slightly more than about half of the original amino acids may be removed, and a retentate is obtained. The second filtration can be performed by using a membrane filtration technology.

Step (1), step (2), or step (1) and (2) are optionally repeated. Preferably, step (2) is repeated until the mass ratio of the lactic acid to the a-amino nitrogen in the retentate obtained is < 6.

(3) Optionally, the retentate may be sterilized and/or concentrated. Preferably, the sterilization takes place at a temperature of about 120-150 °C, for example, 120°C, 130°C, 140°C, 150°C or any intermediate value between any two of those temperature values.

[00054] Preferably, the first filtration is performed before the second filtration. If the second filtration is performed first, the efficiency of filtration may be affected and the filtration device may also be spoiled. Therefore, it is preferable to start with the first filtration before the second filtration.

[00055] Surprisingly, it is not necessary to add any hydrolytic enzyme in the preparation method from the CSL to the CPC product. Also, a separate step of extracting and separating lactic acid typically is unnecessary. In other words, steps of lactic acid separation other than filtration can be excluded from the preparation method.

[00056] The present disclosure provides a corn protein concentrate product, which can be prepared by the above-mentioned preparation method of CPC product. In general, the percentage of protein containing a-amino nitrogen in the product is at least twice, at least three times or at least four times the percentage of protein containing a-amino nitrogen in the CSL.

[00057] The present com protein concentrate (CPC) product can have: a) protein of about 42-72wt% based on dry weight of the product (dwb), preferably about 48-68wt% (dwb), more preferably about 50-65wt% (dwb), for example about 42wt%, 45wt%, 48wt%, 50wt%, 51wt%, 53wt%, 57wt%, 59wt%, 65wt%, 68wt%, 72wt% or a weight percentage of protein corresponding to any intermediate value between any two of those point values; and b) lactic acid of about 5wt%- 20wt% (dwb), preferably about 9-17wt% (dwb), more preferably about 1 l-15wt% (dwb), and still more preferably about 12-14wt% (dwb), for example 5wt%, 7wt%, 9wt%, llwt%, 12wt%, 14wt%, 15wt%, 17wt%, 20wt% (dwb) or a weight percentage of lactic acid corresponding to any intermediate value between any two of those point values. The protein may comprise a-amino nitrogen of about 1.1-4 wt% (dwb), preferably about 1.5-3.5wt% (dwb), more preferably about 1.8-3.2wt% (dwb), and still more preferably about 2.3-3. lwt% (dwb). The mass ratio of the lactic acid to the a-amino nitrogen is desirably < 6, preferably the mass ratio is about 3-5, for example, 2, 2.5, 3, 3.5, 4, 4.5, 4.8, 5, 5.5 or any intermediate value between any two of those point values. Moreover, the product may have an ash content of about 17wt%-18wt% (dwb) and may also include carbohydrates or fats.

[00058] It is to be noted that there is no special limit on the solid content of the product. Generally, though, the solid content of the product is about 8wt%-96wt% based on weight of the product, preferably about 10wt%-70wt%, and more preferably about 42wt%-50wt%.

[00059] In one particular aspect, more than about 70wt% of the protein may have a molecular weight of 1000D or less in the CPC product, and preferably more than about 80wt% of the protein has an average molecular weight of 1000D or less. In addition, about 40-60wt% of the protein can have a molecular weight of 180D or less, and preferably about 40-50wt% of the protein has a molecular weight of 180D or less. Moreover, the content of lysine (LYS) in the a-amino nitrogen is desirably more than about 2.1 times to the content of methionine (MET) in the a-amino nitrogen, preferably more than about 2.2 times, more preferably more than about 2.3 times, for example, about 2.1, 2.2, 2.3, 2.4, 2.5 and the like.

[00060] The present disclosure provides a use of the corn protein concentrate (CPC) product in beer fermentation.

[00061] It is to be noted that the “beer” herein refers not only to conventional beer beverages, which are specifically defined in “ GB/T 4927-2008 beer” according to the Chinese national standard, but also refers to any similar fermented product that can be used as distillation sources to further make high-alcohol drinks, such as distilled spirits.

[00062] The present disclosure provides a method of preparing beer in which a corn protein concentrate (CPC) product as mentioned above is added into a fermentation source, until the content of a-amino nitrogen therein reaches about at least about 160 ppm, preferably at least about 180 ppm, and fermentation is performed. The fermentation usually lasts for about 3-12 days, preferably lasts for about 5-10 days, and more preferably lasts for about 8 days. The fermentation time can be adjusted according to the actual conditions. It can be 3 days, 4 days, 5 days, 6 days, 7 days, 8 days, 9 days, 10 days, 11 days or 12 days.

[00063] For beer fermentation industry, wort is usually used as the fermentation source in beer preparation, as it can guarantee a beer with high quality in flavor and foam. In order to reduce cost in some countries, though, the fermentation source is usually added with syrup, such as beer syrup or maltose syrup, e.g., a syrup that meets the requirement set forth in Chinese national standard “QB/T 2687-2005 Syrup for beer”. The syrup added can include sugars that account for about 10-90wt% of the total amount of sugars in the fermentation source. In some special cases, the cereal derived sugars such as wort in the fermentation source can be completely replaced by syrup, that is, syrup can contribute about 100% sugars in the fermentation source. Preferably, syrup can provide about 20-60wt% of sugars in the fermentation source, more preferably about 30-50wt%, and still more preferably about 40wt% of sugars in the fermentation source.

[00064] By using the above-mentioned method for preparing the beer, even a large replacement of wort by syrup can result in a high quality beer. For example, in a preferable embodiment, the total sugar content (brix) in the fermentation source before beer fermentation is 12°, wherein the brix provided by wort is 7.2° (about 60% of the total brix), and the brix provided by syrup is 4.8° (about 40% of the total brix). (The brix value in this field can be considered approximately the same as the solid content in this field, that is, the solid content is around 12%.) The resulting beer prepared by the above-mentioned preparation method is a high quality beer. [00065] The present disclosure also provides a beer, which is obtained by the above- mentioned preparation method. The inventor is surprised in finding that the preparation method of this disclosure, especially for the instances where syrup is used in place of wort, can produce beer with the following properties:

(1) the beer has an alcohol to ester ratio of about 3-5, preferably about 3-4.5, and more preferably about 3.5-4.4;

(2) the beer has a foam stability of about 255 S or more, preferably about 260S or more, and more preferably about 263S or more. Specifically, it could be any value between about 255-265S;

(3) the beer contains diacetyl in an amount of < about 50ppm, preferably < about 45ppm, and more preferably < about 40ppm. Specifically, it could be any value between about 35-45ppm.

[00066] The features, properties and performances of the present CPC and its preparation and use will be further illustrated in the following examples.

Example 1

[00067] The example provides a CPC product, which was prepared from the CSL. The CSL was measured and the result showed that it comprises: a solid content of 8%; protein content of 43.15% based on dry weight of the CSL (dwb), a-N content of 2.01% (dwb), lactic acid content of 32.77% (dwb), wherein the mass ratio of the lactic acid to the a-amino nitrogen was 16.3. The test results of amino acids and free amino acids (FAN) can be found in Table 1, and the test was conducted by SGS-CSTC standard technical service (Qingdao) Co., Ltd. It is to be noted that the protein content was measured by Kjeldahl method in this test, and the detailed measurement can be found in Chinese national standard “QB/T 2687-2005 Syrup for Beer”. Lactic acid content was measured by the method for determining lactic acid according to the Chinese national standard “GB 1886.173-2016 national food safety standard, food additive, lactic acid”. a-N content was measured by the method for determining a-N as set forth in the Chinese national standard “QB/T 2687-2005 Syrup for beer”.

[00068] The specific preparation method is as follows: Firstly, the com steep liquor underwent a first filtration to remove insoluble materials and soluble materials having a molecular weight of > lOOkD to obtain a first filtrate. [00069] The detailed process of the first filtration is as follows: Com steep liquor (CSL, 67.67 kg) underwent the first filtration, where a ceramic membrane having a pore size of 50 nm and a filtration area of 0.1m² was used. The pressure for the first filtration was controlled at 0.25- 0.3 Mpa. The flow rate was controlled at 4.5 m³/hr. The temperature was kept at 30-48°C. The filtration rate was maintained at 12-20 L/hr. A filtrate of 57.68kg was obtained therefrom.

[00070] Then the first filtrate underwent a second filtration so that part of materials having a molecular weight of < 150D were removed and resulted in a retentate. The second filtration was repeated several times until the mass ratio of the lactic acid to the a- amino nitrogen in the retentate reached about 5. The retentate was further sterilized and concentrated to obtain a CPC product. [00071] The detailed process of the second filtration is as follows. The filtrate above (57.4 kg) underwent a second filtration (first time), where a DK2540 spiral-wound membrane having a filtration area of 2.2 m² and blocking substances having molecular weight of 150D was used. The pressure for the second filtration (first time) was controlled at 2.6 Mpa. The flow rate was controlled at 1.5-1.6 m³/hr. The temperature was kept at 18-29°C, and the filtration rate was maintained at 272-104 ml/15s (i.e., 24.96-65.28 L/hr ). A first retentate of 23.6 kg was obtained therefrom. Deionized water of equivalent volume was added to the first retentate, and a second filtration was performed (second time) by using the same filtration membrane. The pressure for the second filtration (second time) was controlled at 2.6-2.8 Mpa. The flow rate was controlled at 1.4- 1.5 m³/hr. The temperature was kept at 26-32°C, and the filtration rate was maintained at 306- 142 ml/15s (i.e., 34.08-73.44 L /hr). A second retentate of 24 kg was obtained therefrom. Deionized water of equivalent volume was added to the second retentate, and the second filtration was repeated for a third time. The pressure for the second filtration (third time) was controlled at 2.6 Mpa. The flow rate was controlled at 1.4-1.5 m³/hr. The temperature was kept at 27-34°C, and the filtration rate was maintained at 358-154 ml/15s (i.e., 36.96-85.92 L/hr). A third retentate of 13.2 kg was obtained therefrom.

[00072] The third retentate (13.2 kg) above was sterilized at 135°C, and the precipitate was filtered out. The retentate was concentrated in vacuum, and a CPC product (4.2 kg) was obtained. [00073] The composition of different samples in the preparation process above are shown in Table 4.

[00074] The CPC product was measured and the result showed that it comprises: a solid content of 42.52%, protein of 53.25% based on dry weight of the CPC product (dwb), a-N of 2.35% (dwb), and lactic acid of 13.17% (dwb). The mass ratio of the lactic acid to the a-amino nitrogen is about 5.59. The test results of amino acids and free amino acids (FAN) can be found in Table 2, and the testing was conducted by SGS-CSTC standard technical service (Qingdao) Co., Ltd. It is to be noted that the testing methods for protein content, a-N content and amino acids content were the same as that of CSL, which were determined according to the Chinese national standards.

[00075] The molecular weight distribution of protein in the CPC product was also tested and shown in Table 3. The testing was conducted by SGS-CSTC Standard Technical Service Co., Ltd.

Table 1. Test Results of Amino Acids in CSL

Table 2. Test Results of Amino Acids in CPC product

Table 3. Distribution of Proteins in CPC products Based on Molecular Weight

Table 4. Results of composition of samples at different stages in Example 1

[00076] The results in Table 1 and Table 2 showed that: the total protein (total amino acids) in the CSL is 2.68%, while the total protein (total amino acids) in the CPC product is 20.58%. This was mainly because a large amount of water and ashes as well as lactic acid were removed from the CSL in the process of preparing the CPC product.

[00077] In comparison between the CSL and the CPC product, the distribution of each amino acid and each free amino acid in the protein has changed substantially, especially the distribution of free amino acid, as shown in the total amino acids (mg/g protein) in column 2 and free amino acids (mg/g protein) in column 4 in Tables 1 and 2,

[00078] Interestingly, as shown in the results of free amino acids (mg/g protein) in column 4 of Tables 1 and 2, the lysine (LYS) content in the free amino acids in the CSL is about 2.0 times to that of methionine (MET), while the lysine (LYS) content in the free amino acids in the CPC product is about 2.34 times that of methionine (MET). That is a remarkable increase of 17%. Presumably, the result occurred partially because of the inherent property of lysine which is relatively insoluble, and thus lysine was hardly removed in the process of preparing the CPC products from the CSL. As a result, the lysine retained in the protein was relatively large. A high lysine content and a low methionine content are both beneficial to yeast metabolism.

[00079] As can be seen from Table 3, most of the proteins in the CPC product had a molecular weight of less than 1000D, which accounted for about 84.16% of the total protein. Especially, 46.31% of the total protein had a molecular weight of less than 180D, which indicated that there was a high amount of small molecule proteins in the CPC products. Considering that most free amino acids have a molecular weight of less than 180D, thus it was assumed that the content of free amino acids was quite high.

[00080] As can be seen from Table 4, CPC products have been changed remarkably from CSL in terms of the a-amino nitrogen content, the protein content, the lactic acid content, and the mass ratio of lactic acid toa-amino nitrogen, indicating that the method of preparation according to the present example can make ideal CPC products from the CSL where the CPC products can be readily used in beer brewing.

Example 2

[00081] The present example provides a CPC product, where the preparation method thereof is substantially the same as the preparation method described in Example 1 , except for that in the present example.

[00082] The corn steep liquor (CSL, 40 kg) underwent the first filtration through a ceramic membrane having a pore size of 200 nm and a filtration area of 0.1 m². The pressure for the first filtration was controlled at 0.14-0.3 Mpa. The flow rate was controlled at 3 m³/hr. The temperature was kept at 24-54 °C, and the filtration rate was maintained at 8-14 L/hr. A filtrate of 33.1 kg was obtained therefrom.

[00083] The filtrate above (33.1 kg) underwent a second filtration (first time) through a DL2540 spiral-wound membrane which has a filtration area of 2.2 m² and blocks substances having molecular weight of 300D. The pressure for the second filtration (first time) was controlled at 2.3/1.7 Mpa (i.e., the pressure for entering the membrane (pressure before membrane) was 2.3 Mpa, and the pressure for coming out of the membrane (pressure after membrane) was 1.7 Mpa). The flow rate was controlled at 1.5-1.6 m³/hr. The temperature was kept at 21-31°C, and the filtration rate was maintained at 44-50 L/hr. A first retentate of 22 kg was obtained therefrom. Deionized water of equivalent volume was added to the first retentate, and the second filtration was repeated for the second time. The pressure for the second filtration (second time) was controlled at 2.3/1.7 Mpa. The flow rate was controlled at 1.5 m³/hr. The temperature was kept at 22-30°C, and the filtration rate was maintained at 50-76 L/hr. A second retentate of 20.8 kg was obtained therefrom. Deionized water of equivalent volume was added to the second retentate, and the second filtration was repeated for the third time. The pressure for the second filtration (third time) was controlled at 2.3/1.7 Mpa. The flow rate was controlled at 1.5 m³/hr. The temperature was kept at 21-36°C, and the filtration rate was maintained at 40-130 L/hr (normally, the filtration rate at the beginning of the filtration was relatively large - e.g., 130 L/hr, but the filtration rate gradually decreased as the filter membrane would be gradually clogged or contaminated over the filtration progresses). A third retentate of 19.52 kg was obtained therefrom.

[00084] The third retentate (19.52 kg) was sterilized at 125°C, and the precipitate was filtered out. The retentate was concentrated in vacuum, and a CPC product of 4.2 kg was obtained. [00085] The composition of different samples in the preparation process above are shown in Table 5.

Table 5. Results of composition of samples at different stages in Example 2

Comparative Example 1

[00086] The comparative Example provided a nitrogen source supplement agent, which was obtained from com protein powder via enzymatic hydrolysis by neutral protease and papain. The detailed method was shown below. 150g corn protein powder was mixed with 850mL water. The mixture was stirred until it was uniform. Then the mixture was sterilized for 30 minutes at 121°C, and cooled down to 45°C. 0.075g neutral protease (50000u/g) was added and stirred evenly. The mixture was hydrolyzed under a heat-preserved condition for 5 hours, and then the pH was adjusted to 4.8-5.2. 0.3g papain (2000000u/g) was added, and the mixture was increased to 60°C and kept at a heat-preserved condition for 8-hour hydrolysis. After the hydrolysis was done, the mixture underwent an enzyme deactivation and sterilization for 30 minutes under a condition of 121 °C with heat and moisture. 4 grams of activated carbon was then added and kept at 60°C for decolorization for 45 minutes. Filtration was then performed. After filtration, the filtrate was further condensed to 45Bx and dried by spray to form a solid powder.

[00087] The mass ratio of lysine (LYS) to methionine (MET) in the free amino acids of corn protein powder (as starting materials) was about 0.91. In the solid powder product obtained by enzymolysis, the ratio of LYS to MET in the free amino acids was about 0.90, which was almost unchanged compared to the starting material. Moreover, the solid powder product obtained by enzymolysis of com protein powder did not contain any lactic acid.

Example 3

[00088] A beer was prepared by fermentation in a 300L beer fermentation tank. The fermentation source in the fermentation tank consist of 60% of sugar provided by wort and 40% of sugar provided by syrup (i.e., 40% of the sugar that would ordinarily be provided by the wort was replaced by syrup). The a-N content in the fermentation source was measured to be about 152mg/L, and the CPC product from Example 1 was added into the fermentation source until the a-N content reached about 184mg/L, then the fermentation was performed. After being fermented for 8 days, the beer was obtained and its properties and parameters were tested according to the Chinese national standards, specifically the parameters set forth in “GB/T 4927-2008 Beer”. The beer was shown to meet the requirement of Chinese national standard.

Comparative Example 2

[00089] The comparative example provides a beer. The preparation method of the beer was substantially identical to that of Example 3. The only difference was that no CPC product was added and the fermentation was performed under the same conditions for 14 days instead of just 8 days. The beer obtained was tested and was shown to meet the requirement of the Chinese national standard.

[00090] The beers from Example 3 and Comparative Example 2 were tested and compared. It is to be noted that all of the parameters of beers in this disclosure were tested and analyzed in accordance with the Chinese national standards of “ GB/T 4928-2008 Beer Analysis Method ”.

1. Foam stability of beer

[00091] Testing method: The foam stability is measured in accordance with GB/T 4928- 2008 Beer Analysis Method, Section 7.2 stopwatch method. The result is shown in Table 6 below:

Table 6. Experimental Data on Foam Stability of Beer

2. Flavor of beer

[00092] Both beers were analyzed for the components that affect beer flavor below by Yanjing Beer. All of the test methods were obtained by conventional methods in the beer brewing field, and the results are shown in Table 7: Table 7. Results of Beer Flavor

[00093] As shown in the results of Table 6 and Table 7 above, the beer of Example 3 is better than that of comparative Example 2 in terms of foam and flavor. Specifically, the foam stability of the beer in Example 3 is higher than that of comparative Example 2. Moreover, the alcohol to ester ratio in Example 3 is 4.3, within the alcohol to ester ratio of regular beers. That is lower than the alcohol to ester ratio of 6.5 in the Comparative example 2, which does not achieve the alcohol to ester ratio of regular beers. Use of the CPC achieved this result in just 8 days of fermentation, but the control without the CPC didn’t achieve this standard given 14 days to ferment.

[00094] In addition, the beer in Example 3 contains diacetyl in an amount of 40ppm, which is remarkably lower than 200ppm of the beer in the Comparative example 2. The Chinese national standard requires that the diacetyl in the beer shall be below lOOppm. However the diacetyl content in the Comparative example 2 is higher than the Chinese national standard because parts of the wort were replaced by the syrup, which we surmise to be due to a lack of a-N. On the other hand, the diacetyl in the beer of example 3 was reduced to 40ppm, because the added CPC product sufficiently supplemented the a-N, and also simultaneously supplemented other components that can promote fermentation.

[00095] It is to be noted that alcohol to ester ratio is a parameter which has been used to quantify the beer flavor. Conventional beer commonly has an alcohol to ester ratio in a range of 2-5. Within this range, the lower the alcohol to ester ratio, the better the flavor a beer has. A relatively high level of alcohol and a relatively low level of ester will typically give the beer a bad flavor. In comparison with the beer of Comparative example 2, the beer in Example 3 has a remarkably improved flavor profile. The CPC product was added in Example 3 during the process, especially provided a-N to the yeasts, which allowed the yeasts to obtain more nutrition and become more active and robust. As a result, the fermentation time could be decreased from 14 days as in the Comparative example 2 to 8 days in Example 2, and the diacetyl content was decreased from 200ppm to 40ppm.

[00096] In view of above, the present disclosure provides a com protein concentrate (CPC) product and beer, and their preparation method and use thereof. The CPC product is obtained from the com steep liquor, and the product can be used in beer production, so as to improve the beer flavor, increase the foam stability, and reduce the fermentation time. The product has a huge market potential and value.

[00097] The disclosure above is merely used as examples, and shall not be considered to limit the scope of the claims. Those skilled in the art would readily recognize that there are suitable alternatives or modifications to the examples described. Any modifications, substitution and improvements made within the spirit and principles of this disclosure shall be included in its scope.

Claims

1. A com protein concentrate (CPC) product, comprising: a) protein of about 42-72 wt%, based on dry weight of the product (dwb); and b) lactic acid of about 5-20 wt% (dwb); wherein said protein comprises a-amino nitrogen of about 1.1-4 wt% (dwb), and wherein the mass ratio of the lactic acid to the a-amino nitrogen is less than or equal to about 6.

2. The corn protein concentrate (CPC) product of claim 1, wherein the content of Lysine (LYS) in the a-amino nitrogen is more than about 2.1 times the content of Methionine (MET) in the a-amino nitrogen, preferably more than about 2.2 times, more preferably more than about 2.3 times.

3. The corn protein concentrate (CPC) product of claim 1, having a solid content of about 8- 96 wt%, preferably about 10-70 wt%, more preferably about 42-50 wt%.

4. The corn protein concentrate (CPC) product of any one of claims 1-3, comprising protein of about 48-68 wt% based on dry weight of the product (dwb), preferably about 50-65 wt% (dwb), and more preferably about 51-59 wt% (dwb).

5. The com protein concentrate (CPC) product of any one of claims 1-4, comprising lactic acid of about 9-17 wt% based on dry weight of the product (dwb), preferably about 11-15 wt% (dwb), and more preferably about 12-14 wt% (dwb).

6. The com protein concentrate (CPC) product of any one of claims 1-5, wherein said protein comprises a-amino nitrogen of about 1.5-3.5 wt% based on dry weight of the product (dwb), preferably about 1.8-3.2 wt% (dwb), and more preferably about 2.3-3.1 wt% (dwb).

7. The corn protein concentrate (CPC) product of any one of claims 1-6, wherein more than about 70 wt% of the protein has a molecular weight of 1000D or less, and preferably more than about 80 wt% of the protein has a molecular weight of 1000D or less.

8. The corn protein concentrate (CPC) product of any one of claims 1-7, wherein about 40- 60 wt% of the protein has a molecular weight of 180D or less, and preferably about 40-50 wt% of the protein has a molecular weight of 180D or less.

9. A method of preparing a com protein concentrate (CPC) product from a corn steep liquor (CSL), comprising steps of:

(1) performing a first filtration on the com steep liquor to remove insoluble materials and soluble materials having a molecular weight of > lOOkD, to obtain a first filtrate;

(2) performing a second filtration on the first filtrate to remove part of materials having a molecular weight of < 150D, to obtain a retentate; and optionally repeating step (1), step (2), or step (1) and (2); wherein the mass ratio of the lactic acid to the a- amino nitrogen in the retentate finally obtained is < 6.

10. The method of preparing a corn protein concentrate (CPC) product according to claim 9, further comprising: repeating the second filtration in step (2) until the mass ratio of the lactic acid to the a- amino nitrogen in the retentate is < 6.

11. The method of preparing a com protein concentrate (CPC) product according to claim 9 or 10, wherein the method does not include a step of adding enzyme for hydrolysis.

12. The method of preparing a com protein concentrate (CPC) product according to any one of claims 9-11, wherein one or both of the first filtration and the second filtration is performed via membrane filtration.

13. The method of preparing a com protein concentrate (CPC) product according to any one of claims 9-12, wherein the method does not include a step of lactic acid extraction; preferably, wherein the method does not include a step of lactic acid separation other than filtration.

14. The method of preparing a com protein concentrate (CPC) product according to any one of claims 9-13, further comprising step(s) of sterilizing the retentate and/or concentrating the retentate; preferably, the sterilization occurs at a temperature of about 120-150 °C.

15. The method of preparing a com protein concentrate (CPC) product according to any one of claims 9-14, wherein the corn steep liquor (CSL) comprises:

(a) protein of about 40-50 wt% based on dry weight of the CSL (dwb);

(b) lactic acid of about 27-38 wt% (dwb); wherein said protein comprises a-amino nitrogen of about 1-2.5 wt% (dwb), and wherein the mass ratio of the lactic acid to the a-amino nitrogen in the CSL is > 12.

16. A corn protein concentrate (CPC) product prepared by the method of any one of claims 9- 15.

17. Use of a corn protein concentrate (CPC) product according to any one of claims 1-8 or 16 in beer fermentation.

18. A method of preparing a beer, comprising: adding a com protein concentrate (CPC) product according to any one of claims 1-8 or 16 into a fermentation source, until the content of a-amino nitrogen therein reaches about 160 ppm or more, preferably reaches about 180 ppm or more, and then performing the fermentation.

19. The method of preparing a beer according to claim 18, wherein the fermentation source comprises syrup, wherein the syrup comprises sugar that accounts for about 10-90 wt% of the total amount of sugar in the fermentation source, and preferably the syrup comprises sugar that accounts for about 20-60 wt% of the total amount of sugar in the fermentation source, and more preferably the symp comprises sugar that accounts for about 30-50 wt% of the total amount of sugar in the fermentation source, and still more preferably the syrup comprises sugar that accounts for about 40 wt% of the total amount of sugar in the fermentation source.

20. The method of preparing a beer according to claim 18 or 19, wherein the fermentation lasts for about 3-12 days; preferably about 5-10 days, and more preferably about 8 days.

21. A beer prepared by a method of any one of claims 18-20.

22. The beer of claim 21 , wherein the beer has an alcohol to ester ratio of about 3 -5 , preferably about 3-4.5, and more preferably about 3.5-4.4.

23. The beer of claim 21 or 22, wherein the beer has a foam stability of about 255S or more, preferably about 260S or more, and more preferably about 263 S or more.

24. The beer of any one of claims 21-23, wherein the beer contains diacetyl in an amount of < about 50ppm, preferably < about 45ppm, and more preferably < about 40ppm.