CN115078665A

CN115078665A - Method for judging quality of refined beer

Info

Publication number: CN115078665A
Application number: CN202210786992.XA
Authority: CN
Inventors: 邵文尧; 杨炳文; 侯逸雪; 卢英华
Original assignee: Xiamen University
Current assignee: Xiamen University
Priority date: 2022-07-04
Filing date: 2022-07-04
Publication date: 2022-09-20

Abstract

A quality evaluation method for refined beer belongs to the field of quality evaluation of refined beer. The method comprises the following steps: 1) determining the physicochemical properties of the beer, including: diacetylProtein, bitterness and total sugar content, and taking the four physical and chemical property indexes as factors influencing the quality of the brewed beer to obtain the physical and chemical property detection result of the beer; 2) evaluation of beer flavor: performing grade evaluation according to the grade table and the grade standard to obtain a flavor grade evaluation result of the beer; 3) combining the flavor evaluation result of the beer with the physicochemical property detection result to evaluate the quality of the beer, establishing a relationship between the flavor index of the beer and the quality of the beer, and establishing a multivariate linear equation correlation coefficient R between the four indexes and the score of the beer ² 0.7995, the quality judgment equation has good fitting degree, and can accurately judge the quality of the brewed beer. The method is suitable for quality judgment of the brewed beer of various non-turbid types and fruit flavor-enhancing types.

Description

Method for judging quality of refined beer

Technical Field

The invention belongs to the field of quality judgment of refined beer, and particularly relates to a quality judgment method of refined beer by utilizing the rationalized property detection judgment of flavor evaluation.

Background

The refined beer has a plurality of types, and is popular among consumers due to the mellow wine body and the complex taste and smell experience compared with the industrial beer, and the development prospect is wide. The physical and chemical properties of the refined beer are complex, hundreds of flavor substances are contained, the research on the physical and chemical properties of the refined beer at present focuses on the aspects of alcohol ester ratio, aroma substances, protein, diacetyl, saccharides, bitterness and the like, the physical and chemical properties have large influence on the flavor, but the flavor of the refined beer is the result of the comprehensive influence of various flavor substances, and the quality of the beer is not accurate only by detecting the physical and chemical properties. The flavor evaluation of the brewed beer is to evaluate the appearance, foam performance, aroma and wine body taste of the beer through the vision, taste and smell of people, but the flavor preference of different people is different, the feeling of the brewed beer is also different, and the quality of the brewed beer is difficult to objectively evaluate only through the evaluation. Therefore, finding a method for objectively, accurately and effectively judging the quality of the brewed beer becomes an important development target. The physical and chemical property detection method is not accurate enough, the flavor evaluation is not objective enough, the physical and chemical properties of the beer and the flavor are combined to find the relation between the physical and chemical properties of the beer and the flavor, and the quality of the brewed beer can be objectively and accurately judged by adopting the method.

Chinese patent CN201110383280.5 discloses a series of reagents for evaluating and detecting beer solid flavor, which are white solid powder particles in appearance and are formed by mixing maltose crystals and flavor substances, wherein the content of each flavor substance is below 0.1 percent, and the series of solid reagents overcome the defects that liquid is easy to volatilize and not easy to quantify, the concentration change in use is too large and not easy to control and transport, the solid reagents are easy to damage and crush, the safety inspection in air transportation is not easy to pass, and the like. Through the use of the beer sensory evaluation personnel, the technical personnel can be helped to carry out sensory quality control on the beer.

Disclosure of Invention

The invention aims to provide a method for judging the quality of the refined beer by combining flavor evaluation and physicochemical properties aiming at the problems that the prior judging method is difficult to accurately and objectively judge the quality of the refined beer, and the like.

The invention comprises the following steps:

1) determining the physicochemical properties of the beer, including: the four physicochemical property indexes are used as factors influencing the quality of the brewed beer to obtain the physicochemical property detection result of the beer;

2) evaluation of beer flavor: in order to comprehensively evaluate the actual flavor characteristics of the refined beer, a plurality of tasters comprehensively analyze the flavor characteristics of the refined beer through the matching of the flavor evaluation of the sample refined beer to obtain the flavor evaluation result of the beer;

in the step 2), the specific method for evaluating the beer flavor is as follows:

numbering and sequencing beer samples, recording corresponding cup numbers on a rating table, then taking out the beer which is placed in a refrigerator for refrigeration at 4 ℃ and a fermentation tank, and pouring the beer into a special wine cup for wine tasting from a height of 3cm according to the numbers;

the professional taster scores according to a rating table and a rating standard, wherein the rating items comprise appearance, foam performance, beer aroma, wine body taste and the like;

thirdly, collecting the evaluation table, carrying out statistical analysis, and averaging the final results.

3) And calculating the relationship between the physicochemical property of the beer and the flavor evaluation result through multivariate regression analysis to obtain a fitting equation for quality evaluation of the brewed beer.

In step 3), the step of combining the flavor evaluation result of the beer with the physicochemical property detection result to evaluate the quality of the beer may be: after the flavor evaluation, according to the scores of professional tasters on various flavor characteristics of the beer samples, the effective scores of all the tasters are counted and averaged, the average score of each beer sample is calculated, and the relation between the diacetyl, the protein, the bitterness and the total sugar content and the beer evaluation score Y is calculated through multiple regression analysis, and then the relation is obtained by fitting an equation:

Y＝0.5133B+0.2872D-0.6002A-0.0373C+50.3459，R ² ＝0.7995；

wherein A is diacetyl content, B is protein content, C is bitterness, D is total sugar content, and R is total sugar content ² The fitness shows that the fitness of the relation between the contents of the four indexes and the beer score Y is good; if the content of the diacetyl and the bitterness value are larger, the score of the beer is relatively smaller; if the protein and total sugar content is greater, the score for beer is relatively greater.

The method takes the corresponding relation between four indexes of the diacetyl, the protein, the total sugar and the bitterness of the beer and the grade score of the beer as a link, determines the specific corresponding relation between the four indexes and the grade score of the beer, and ensures that the diacetyl content and the bitterness and the grade score of the beer are in a reverse relation, namely when the diacetyl content and the bitterness are higher, the grade score of the beer is relatively lower; whereas the protein and total sugar content are greater, the beer score is relatively greater. The four indexes selected by the invention all have influence on the quality of the beer, wherein the diacetyl content and the bitterness value are the factory-bound detection indexes of the refined beer, the total sugar and the protein are non-essential detection indexes, but the total sugar is related to the characteristics of the refined beer, such as mellow wine body, sweet return and the like, the protein content directly influences the foam performance of the refined beer and is an important component in the grading of the refined beer, and the four indexes are simultaneously detected, so that the quality of the refined beer can be comprehensively evaluated.

Compared with the prior art, the invention provides an objective and effective beer quality evaluation method, a relation is established between beer flavor indexes and beer quality, and a multivariate linear equation correlation coefficient R between the four indexes and beer scores ² 0.7995, the quality assessment equation has better fitting degree, and can be better standardThe quality of the refined beer is judged. The method can be applied to the quality judgment of the brewed beer of various non-turbid types (namely, the wine body is required to be clear) and fruit flavor-enhancing types.

Drawings

FIG. 1 is a schematic view of an apparatus for home brewing beer according to an embodiment of the present invention.

FIG. 2 is a bar graph of diacetyl content in different beer samples.

FIG. 3 is a bar graph of total sugar content in different beer samples.

FIG. 4 is a bar graph of protein content in different beer samples.

FIG. 5 is a bar graph of bitterness values for different beer samples.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the following embodiments will be further described with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. On the contrary, the invention is intended to cover alternatives, modifications, equivalents and alternatives which may be included within the spirit and scope of the invention as defined by the appended claims.

Example 1

The embodiment of the invention comprises the following steps:

randomly selecting 9 kinds of fine-brewed beer from the market, adding 3 kinds of beer from brewing, totaling 12 kinds of fine-brewed beer samples, and measuring the diacetyl, protein, total sugar content and bitterness value:

the No. 1 self-brewing beer, the No. 2 self-brewing beer and the No. 3 self-brewing beer are respectively marked as No. 1-No. 3 samples;

the random selection of 9 types of refined beer from the market comprises the following steps: sedrin ice beer, super chariot douglang, finely-brewed dog punk, Fujia white beer, lost coast double IPA, finely-brewed dog Jane, Rossfu No. 6, Barcelsi flat promontory light color Aier and Budweiser, which are respectively marked as sample No. 4-12;

the self-brewing 3-style beer is brewed by adopting the following method:

1. the refined beer can be fermented in a fermentation tank

(1) Crushing malt: weighing appropriate amount of fructus Hordei Germinatus, pouring into stainless steel basin, adding appropriate amount of water to moisten fructus Hordei Germinatus, and making fructus Hordei Germinatus be kneaded into dough with hand, but loose. Then, the gap between the millstones of the grinder is adjusted to grind the malt into particles with the size of a pen point.

(2) Calculating the water consumption for saccharification: the amount of water used for saccharification is generally calculated according to formula 1.

W ═ A (100-B)/B (formula 1)

In the formula, W is the water consumption for saccharification of 100kg of malt flour; a is the percentage of the leaching rate of the malt; b is the wort concentration at the beginning of filtration.

(3) Saccharification: using the single-stage extraction mashing method, the malt-water mixture was heated directly from room temperature to 67 ℃ and incubated for 60 min.

(4) And (3) filtering the wort: after the filter sieve plate is lifted up and filtered, the filter layer is washed by a small amount of water, and the washing liquid is poured back to the saccharification pot.

(5) Boiling wort: heating filtered wort to boil, adding bitter flower granule immediately before boiling, and adding fragrant flower granule 10min before boiling.

(6) Pre-cooling the wort: and starting a cooling circulating water machine, cooling the wort to about 20 ℃, and pumping the cooled wort into the fermentation tank through a wort pump.

(7) Measuring the sugar degree of the wort: placing 100mL of wort in a 100mL measuring cylinder, slowly placing into a brix meter, reading scale lines after the brix meter is stable, recording sugar degree and wort temperature, and calibrating the sugar degree value when the temperature is lower than or higher than 20 ℃.

(8) Beer main fermentation: pouring the yeast dry powder into a clean and sterilized beaker, adding a small amount of sterilized drinking water at about 30 ℃, and activating in a constant-temperature water bath at 30 ℃ for 20 min. Inoculating yeast into the wort, and oxygenating. Sampling every 12h to determine the sugar degree of the beer until the sugar degree is reduced to about 5-7BX, and sealing the can. After the sugar degree is reduced to 2-3BX, carrying out gradient cooling, reducing the temperature by 2 ℃ every 12h, reducing the temperature to 12 ℃, keeping for 4 days, then carrying out gradient cooling to 4 ℃, and keeping for more than 7 days to obtain the finished product of the refined beer.

FIG. 1 is a schematic view of an apparatus for home brewing beer according to an embodiment of the present invention. In the saccharification and wort boiling stage, a saccharification and boiling integrated pot can be adopted; the beer main fermentation can adopt an RGB15/10 conical beer fermentation tank; the strain used for fermentation is Saccharomyces cerevisiae S-189, and the dosage proportion of malt, hops and yeast is shown in Table 1; the early saccharification parameters are that the temperature is 67 ℃ and the temperature is kept for 1h, and the boiling period parameters are as follows: keeping the temperature at 100 deg.C for 1h, adding bitter flower immediately before boiling, and adding fragrant flower 10min before boiling; the fermentation period parameters are as follows: inoculating yeast when the temperature of the wort is reduced to 30 ℃, fermenting at 20 ℃, sealing the tank when the sugar degree is reduced to 6BX, cooling for 12h to 2 ℃, performing gradient cooling to 4 ℃, and performing after-ripening for 14 days to obtain the finished product of the refined beer;

TABLE 1 Table for home-brewed beer

The method for measuring the physical and chemical properties of the beer comprises the following specific steps:

1. determination of beer diacetyl content:

(1) derivatization of beer samples: taking 25mL of beer in a blue-cap bottle, and carrying out ultrasonic treatment for 10 min. Then 12.5mg of o-phenylenediamine is added, after uniform mixing, the pH is adjusted to 8.0, and the mixture is placed in a water bath at 60 ℃ for reaction for 3 h. After the reaction is finished, the sample is directly injected and measured after being filtered by a filter membrane of 0.2 mu m.

(2) Liquid chromatography measurement conditions:

agilent C18 column (3.9 mm. times.150 mm, 4 μm);

mobile phase: methanol (A) -30 mmol/L ammonium acetate aqueous solution (B);

and (3) sample introduction mode: automatic sample introduction;

flow rate: 0.9 mL/min;

sample introduction amount: 10 mu L of the solution;

column temperature: 30 ℃;

measuring wavelength: 237 nm;

2. determination of total sugar concentration in beer

The content of total sugar in beer is determined by adopting a phenol-sulfuric acid method, polysaccharide in the beer can be firstly hydrolyzed into monosaccharide under the action of sulfuric acid, and then the monosaccharide and phenol react to generate an orange substance, the substance has maximum absorption at 490nm, and the light absorption value is in direct proportion to the content of the total sugar in a certain concentration range, so that the content of the total sugar can be determined.

3. Determination of beer protein concentration

The protein content of wort is determined by Coomassie brilliant blue staining method, wherein Coomassie brilliant blue G-250 is red in free state, and cyan after being combined with protein, and the maximum absorption wavelength of protein-pigment combination is 595 nm. Within a certain concentration range, the light absorption value is proportional to the protein content, so that the protein content can be determined.

4. Determination of bitterness in beer

(1) Preparation of blank control solution: a drop of octanol was added dropwise to 20mL of isooctane, and the absorbance at 275nm was measured using a 10mm cuvette as a blank zero point.

(2) Using a pipette with a tip carrying a drop of octanol, 10mL of an unaerated beer sample was pipetted into a 50mL centrifuge tube, followed by addition of 1mL of hydrochloric acid solution and 20mL of isooctane, screwing the cap, shaking for 15min (creaming), centrifugation at 4000r/min for 10min, and taking the supernatant and determining its absorbance OD275nm at 275nm in a 10mm cuvette. Bitterness (BU) was calculated according to equation 1:

X＝OD _275nm x50 (BU) (formula 1)

In the formula: x-beer bitterness value, BU.

The results of the physical and chemical property tests of the 12 types of the home-brewed beer samples are shown in Table 2.

TABLE 2

Sample (I)	Diacetyl (mg/L)	Protein (mg/L)	Bitterness (BU)	Total sugar (g/L)	Score of
						1	4.81	40.28	34	25.00	69
2	4.11	35.92	29	9.66	66
						3	16.95	28.13	102	44.22	65
4	0.53	25.70	7	20.69	65
						5	1.19	36.79	11	19.35	79
6	1.84	49.21	35	21.35	85
						7	0.73	53.98	13	31.21	89
8	2.79	73.28	80	16.48	86
						9	1.27	57.74	37	22.93	86
10	1.41	74.73	28	19.91	91
						11	1.27	45.97	15	44.22	82
12	0.49	30.71	8	23.11	73

Secondly, evaluating the flavor of the beer: as different people have different thresholds for different substances, in order to comprehensively evaluate the actual flavor characteristics of the refined beer, a taster scores the total score of 100 according to a rating table and a rating standard, wherein the total score comprises 10 scores of appearance, 15 scores of foam performance, 20 scores of beer aroma and 55 scores of wine body taste (the rating table and the rating standard can refer to table 3), and the scoring result is the quality embodiment of the corresponding refined beer.

TABLE 3

The beer samples are numbered and sorted, the corresponding cup numbers are marked on a rating table, the beer which is placed in a refrigerator for refrigeration at 4 ℃ and a fermentation tank is taken out, and the beer is poured into a special wine cup for wine tasting from a height of 3cm according to the numbers. In this example, 15 tasters were invited to evaluate the 12 beer samples and the sensory experience of different beers. And (4) evaluating the beer by a taster and grading correspondingly, collecting a rating table, performing statistical analysis, and taking average scores, wherein the rating results of 12 types of beer samples are averagely graded in a table 4.

TABLE 4

As can be seen from table 4, the 12 beers scored the highest score of 91 parts for rossofu No. 6 (sample No. 10), followed by 91 parts for fujia white beer (sample No. 7), twice IPA on lost coast (sample No. 8), refined dog jian (sample No. 9), refined dog punk (sample No. 6), and pale ale on the headland of balanci (sample No. 11), and the scores were 87 parts, 86 parts, 84 parts, and 81 parts, respectively. The scores of the self-brewed 3 types of beer (samples No. 1-3) are all in the range of 60-70 points, and the overall taste is far different from that of the rest beer.

Rossfu No. 6 (sample No. 10) performed well overall, but the disadvantage was that the duration of the foam was slightly short, and had a slightly rancid smell, with certain taste defects. The other wines with the scores of more than 80 and less than 90 have the main defect that the foam durability is poorer and is below 2 min. The wine has more or less defects in the aspects of the taste of the wine body and the aroma of the hop. But the overall feel is good.

The beer with the score of 70-80 points is three types, namely, Sedrin ice beer (sample No. 4), super-combat tank Bimaterial Lag (sample No. 5) and carbofuran (sample No. 12), and the three types of beer belong to Lag beer, and the Lag beer has more materials, so that the performances of all aspects are greatly reduced.

The performance of the self-brewed three types of wine (sample No. 1-3) is the worst, and the wine is turbid and has more appearance marks due to the fact that larger pressure still exists during fermentation and the beer is not filtered after being taken out. In the aspect of foam performance, the three types of wine have the problems of weak soaking and poor cup hanging performance. And all have some defects in the aspect of hop aroma, which has a certain relation with the hop quality, the taste defects of the three types of wine are obvious, the rancid taste and the unripe green taste are obvious, and the drinkability of the beer is greatly reduced.

And fitting the relationship between the four factor indexes and the beer score to obtain the corresponding sample predicted evaluation score, wherein the actual evaluation score is slightly different from the predicted evaluation score, but the difference is not large, so that the quality of the brewed beer can be objectively and accurately judged overall, and the table 5 shows.

TABLE 5

Sample (I)	Actual evaluation score	Predictive assessment score
			1	69	74
2	66	68
			3	65	63
4	65	68
			5	79	73
6	85	79
			7	89	86
8	86	88
			9	86	84
10	91	92
			11	82	85
12	73	72

Performing multiple regression linear fitting on the four factors of the physical and chemical properties of the beer and the scores of the 12 kinds of beer to obtain an equation as follows:

Y＝0.5133B+0.2872D-0.6002A-0.0373C+50.3459，R ² ＝0.7995。

wherein A is diacetyl content, B is protein content, C is bitterness, D is total sugar content, and R is total sugar content ² The fitness shows that the fitness of the relation between the contents of the four indexes and the beer score Y is good;if the content of the diacetyl and the bitterness value are larger, the score of the beer is relatively smaller; if the protein and total sugar content is greater, the score for beer is relatively greater.

Example 2

In this example, the diacetyl content of 12 beers was measured and the relationship between diacetyl content and the defective beer taste "rancid" was analyzed for different beers.

The method comprises the following steps:

taking 25mL of beer in a blue-cap bottle, and carrying out ultrasonic treatment for 10 min. Then 12.5mg of o-phenylenediamine is added, after uniform mixing, the pH is adjusted to 8.0, and the mixture is placed in a water bath at 60 ℃ for reaction for 3 hours. After the reaction, the sample was directly injected after being filtered by a 0.2 μm filter membrane, and the result of the HPLC assay was shown in FIG. 2.

According to experimental results, the diacetyl content of the three self-brewed wines (samples No. 1-3) is higher in the 12 beers, and is respectively 4.81, 4.11 and 16.95mg/L, which far exceeds the diacetyl threshold value, and the three self-brewed beers have a diacetyl rancid taste combined with the evaluation results in table 3. The measurement results of other nine types of beer show that the diacetyl content is higher, because the beer is produced for a longer time and the storage method is not proper, the diacetyl content exceeds the diacetyl content of the beer specified in the national standard. Except that the twice IPA on lost coast and the finely brewed dog punk have heavy rancid, the rest beer has only light punchid, but under the condition of relatively close content, the content of diacetyl in the beer cannot be judged only by evaluation.

Example 3

In this example, the total sugar content of 12 beers was measured, and the relationship between the total sugar content and the closing sweetness of beer among different beers was analyzed.

The method comprises the following steps:

taking 0.2mL of beer sample solution, using purified water to fix the volume to 100mL (diluting 500 times), then taking 200 μ L of diluent, sequentially adding 100 μ L of 6% phenol solution, then adding 500 μ L of concentrated sulfuric acid, reacting for 20min, measuring the absorbance of the solution at 490nm wavelength, and reading out the total sugar content according to a standard curve, wherein the result is shown in FIG. 3.

From the experimental results, the beer only has a sweet taste except that the sweet taste of the beer brewed in sample No. 3 (sample No. 3) and the pale ale in sample No. 11 from the cape of Balisin. When the total sugar content is greatly different, the thickness degree of the sweet taste of the beer has a certain positive correlation with the total sugar content. However, since the total sugar content of beer is mainly non-fermentable sugar, such as dextrin which is not sweet, in the case of a small difference in total sugar content, beer with a high total sugar content may have an insignificant sweetness.

Example 4

In this example, the protein content of 12 types of beer was measured, and the relationship between the protein content and the beer foam properties among different beers was analyzed.

The method comprises the following steps:

determining the separation gas speed to be 500mL/min, the liquid filling volume to be 100mL, the collection time to be 5min, and the natural pH value of the fermentation liquid to be 4.2. Initial enzyme concentrations were 0.25, 0.35, 0.45, 0.55, 0.65mg/mL, and the results of the foam separation experiments were shown in fig. 4.

The experimental results show that the foam performance of the beer has a certain correlation with the protein content. The protein content of the beer with Rossfu No. 6 and lost coast and double IPA reaches 74.73 and 73.28mg/L, and the evaluation results in Table 4 show that the performance of the foam is the best and the lasting time of the foam can reach 3 min. The foam properties of the rest of the beer deteriorate as the protein content decreases. However, the foam properties are also related to the polysaccharide, isohumulone content of the beer, and thus the foam properties of the beer with slightly different contents are slightly higher, for example, the protein content of the self-brewed No. 3 (sample No. 3) is slightly lower than that of the carbofuran (sample No. 12), but the foaming capacity is slightly higher. However, generally, the quality of beer foam is directly related to the protein content, especially the foam retention.

Example 5

This example is to determine the bitterness value of 12 beers and to analyze the relationship between the bitterness value and the real "bitterness" of the beers between different beers.

The method comprises the following steps:

(2) Using a pipette with a tip carrying a drop of octanol, 10mL of an unaerated beer sample was pipetted into a 50mL centrifuge tube, followed by addition of 1mL of hydrochloric acid solution and 20mL of isooctane, screwing the cap, shaking for 15min (creaming), centrifugation at 4000r/min for 10min, and taking the supernatant and determining its absorbance OD275nm at 275nm in a 10mm cuvette. Bitterness (BU) X ═ OD _275nm X 50(BU), the results are shown in FIG. 5.

Experiments show that the bitterness of the beer is used for measuring the drinkability of the beer. As shown in FIG. 5, the bitterness of the product from brewing No. 3 reaches 102BU, because excessive bitter flowers are added during boiling, the bitterness is higher and is too heavy to be accepted by people. The bitterness is within the range of 0-20 BU, the palatability for drinking is large, and the bitterness is only slight when the taste is evaluated. When the bitterness of the beer is increased to about 30-40 BU, the bitterness of the beer is improved a little. However, if the values are close, the bitterness of the beer and the BU value are not completely in a positive correlation, and when the bitter substances in the beer are extracted by using isooctane, some interfering substances are additionally extracted, so that the BU value is larger. The BU values of the beer brewed by the self-brewing beer 1 and the beer brewed by the self-brewing beer 2 are slightly smaller than those of the beer brewed by the fine-brewing beer dog, the bitterness is heavier, and the evaluation results in the table 3 show that the beer brewed by the self-brewing beer 1 and the beer brewed by the self-brewing beer 2 have relatively obvious after-bitterness, and the after-bitterness of the beer has relatively heavy bitterness instead of the beer with relatively small bitterness when the bitterness of the beer is close to that of the beer, and the after-bitterness of the beer cannot be judged according to the bitterness, so that the necessity of evaluation and detection is shown. When the BU values are different greatly, the bitter feeling obtained by evaluation is in positive correlation with the values.

In the embodiment of the invention, the contents and bitterness of diacetyl, protein and total sugar of 12 types of beer are respectively detected, and the evaluation results of all the beers are compared. The results show that: the degree of "sour taste" of beer is positively correlated with diacetyl content, and different beer with different "sour taste" has different diacetyl content. When the difference of the content of diacetyl is not large, the quality of beer cannot be identified by evaluation alone.

The protein content of the beer has strong positive correlation with the foam performance of the beer, particularly the foam retention and cup hanging performance, and the foaming capacity and the foam form have no correlation with the protein content. Only when the protein content is relatively close, the foam stability will be slightly different due to the influence of the contents of polysaccharide and isohumulone in the beer.

The bitterness value of the beer is positively correlated with the bitterness sensed by real evaluation. The bitter taste value is larger, the bitter taste of the beer is heavier, and the bitter taste of the beer is not in positive correlation with the bitter taste value only when the bitter taste value is not greatly different due to different bitter taste perception abilities of different people.

The total sugar content of the beer has a certain positive correlation with the sweet taste of the beer, and the sweet taste of the beer is slightly graded only when the total sugar content is similar because the total sugar of the beer is mostly dextrin.

The above description is only a preferred embodiment of the present invention and should not be taken as limiting the invention, and all changes, additions and modifications that fall within the spirit and scope of the invention are therefore intended to be embraced by the appended claims.

Claims

1. The method for judging the quality of the refined beer is characterized by comprising the following steps of:

1) measuring the physicochemical properties of the beer, including: the four physicochemical property indexes are used as factors influencing the quality of the brewed beer to obtain the physicochemical property detection result of the beer;

2) evaluation of beer flavor: grading the grade according to the grade table and the grade standard, and counting and calculating the average score to obtain the flavor grade result of the beer;

2. The method for judging the quality of the brewed beer according to claim 1, wherein in the step 2), the specific method for evaluating the flavor of the beer is as follows:

numbering and sequencing beer samples, recording corresponding cup numbers on a rating table, then taking out beer which is placed in a refrigerator for refrigeration at 4 ℃ and a fermentation tank, and pouring the beer into a wine-tasting cup from a height of 3cm according to the numbers;

a taster scores the quality according to a quality evaluation table and a quality evaluation standard, wherein the quality evaluation items comprise appearance, foam performance, beer aroma, wine body taste and the like;

3. The method for judging the quality of the brewed beer according to claim 1, wherein in the step 3), the specific step of calculating the relationship between the physicochemical property of the beer and the flavor evaluation result through multivariate regression analysis can be: after the flavor evaluation, according to the scores of tasters on various flavor characteristics of the beer samples, the effective scores of all the tasters are counted and averaged, the average score of each beer sample is calculated, and the relation between the diacetyl, the protein, the bitterness and the total sugar content and the beer evaluation score Y is calculated through multiple regression analysis, and then the relation is obtained by fitting an equation:

Y＝0.5133B+0.2872D-0.6002A-0.0373C+50.3459，R ² ＝0.7995；

wherein A is diacetyl content, B is protein content, C is bitterness, D is total sugar content, and R is total sugar content ² The degree of fit was determined.