JP4267119B2 - Evaluation method of beer degradation - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for evaluating the degree of deterioration of beer using analysis of the isohumulone isomer of beer.
[0002]
[Prior art]
Fresh beer is exhilarating and delicious, but over time, it produces a deodorizing odor and a taste that deteriorates the taste when fresh. Accurate evaluation of the degree of beer flavor degradation is very important in elucidating the mechanism of beer flavor degradation and developing beer that is fragile and does not easily deteriorate.
[0003]
Conventionally, sensory evaluation by a trained person (panel) is known as a method of evaluating the degree of flavor deterioration of beer.
However, the sensory evaluation method requires a great deal of labor to evaluate a large number of samples, and is greatly influenced by differences in threshold values between panels and differences in flavors between samples other than deterioration. For this reason, it is not sufficient in terms of quantitativeness and objectivity, and is not necessarily an objective evaluation method.
[0004]
In order to compensate for this, attempts have been made to find an indicator of the deterioration intensity of beer flavor. For example, the TBA (2-Thiobarbituric Acid) method, the chemiluminescence method, the ESR (Electron spin resonance) method, and the like. ) Analytical values by the method, carbonyl compounds and glutamine contents, and correlations with sensory evaluation have been reported.
[0005]
These methods are very effective methods for clarifying the deteriorated flavor main body, but complicated operations and advanced techniques associated with extraction and analysis are indispensable, which is a major obstacle.
In addition, research on these flavor-degrading components was overwhelmingly related to deteriorated odors and hardly related to deteriorated tastes.
[0006]
In light of the above situation, the present inventors have conducted extensive studies to find a method for objectively and simply evaluating the degree of deterioration of beer, and as a result, one of the bitter components in beer is a bitter beer. Focusing on isohumulone, which is directly related to the characteristic taste and contained in a large amount in beer and is easy to measure, and using its oxidative degradation as an index, it is a simple and objective degree of beer degradation. The present invention was reached based on this finding.
[0007]
[Problems to be solved by the invention]
That is, the present invention requires a great deal of effort to evaluate a large number of samples, and is greatly influenced by differences in threshold values between panels and differences in flavors between samples other than deterioration. It aims at providing the objective and simple evaluation method of the flavor deterioration of beer which replaces the conventional sensory evaluation method which is not enough at points, such as property.
[0008]
[Means for Solving the Problems]
That is, the present invention according to claim 1 (hereinafter simply referred to as the present invention) provides a method for evaluating the degree of deterioration of beer characterized by measuring the component ratio of isohumulone isomers in beer. .
[0009]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described in detail below.
The present invention is characterized by measuring the component ratio of normal isohumulone (hereinafter referred to as “isohumulone”) isomers in beer when evaluating the degree of deterioration of beer.
[0010]
Isohumulone is one of the components in beer and causes beer bitterness. This isohumulone is derived from humulone contained in hops, which are beer raw materials, and is produced by isomerizing humulone during the wort boiling process during the beer manufacturing process. This isohumulone is contained in a large amount in the beer at the time of manufacture, and is contained about 20 to 30 ppm.
[0011]
Isohumulone includes isomers having different conformations with respect to the prenyl group and the isohexenoyl group, cis form and trans form. Among these, the cis body has a stronger bitter taste than the trans body. The component ratio of both isomers is almost constant regardless of the type of beer.
[0012]
The deterioration of beer is mainly due to oxidation. A very small amount of oxygen is mixed in the beer bottle during production. This slightly mixed oxygen generates free radicals (active oxygen) by reaction with iron, copper ions, etc. during the storage process. This free radical reacts with a bitter component such as isohumulone and a fragrance component such as alcohol to cause a deteriorated odor and a deteriorated taste.
On the other hand, beer contains antioxidant components (polyphenol, sulfite, etc.) that stop this radical reaction and prevent oxidation, and it is also known that these have a function of suppressing oxidation.
[0013]
Isohumulone is subject to oxidative degradation by this radical, and is reduced by being oxidized during storage. This isohumulone changes into various substances when it is oxidatively decomposed. For example, a pyran ring or a furan ring is formed by adding an OH group to a double bond in a side chain of a five-membered ring.
[0014]
The inventor paid attention to such isohumulone and examined the degree of reduction of isohumulone during beer storage.
That is, when beer is stored for a predetermined period (production-3 months) in an environment equivalent to the environment in the normal distribution process (temperature 20-30 ° C), the degree of decrease in isohumulone during that period is examined. It was found that it decomposes quickly.
[0015]
FIG. 1 is a graph in which beer was stored at 20 ° C. for 0 to 6 months, and the degree of decrease in isohumulone during that period was examined with the content in beer before storage being 100.
According to FIG. 1, the trans isomer is structurally unstable and easily decomposed, whereas the cis isomer is relatively stable and has a low decomposition rate, so that it does not decrease so much during storage of beer.
[0016]
Therefore, in the beer during storage, the component ratio of the trans isomer in the isohumulone isomer decreases, and the component ratio of the cis isomer increases with time.
FIG. 2 is a graph showing changes in isohumulone isomer component ratio (trans / cis) when beer is stored at 20 ° C. or 30 ° C. for 0 to 6 months.
According to FIG. 2, it can be seen that the component ratio (trans / cis) of isohumulone isomers decreases with storage, and the decrease rate increases as the storage temperature increases.
[0017]
Thus, although the component ratio (trans / cis) of isohumulone isomers decreased with the passage of time immediately after the production of beer, it was found that this has a correlation with the degree of deterioration of beer.
[0018]
FIG. 3 is a graph showing the correlation between the isohumulone isomer component ratio (trans / cis) and the sensory evaluation results when beer is stored at 20 ° C. or 30 ° C. for 0 to 6 months.
According to FIG. 3, as the component ratio (trans / cis) of isohumulone isomers decreased, a high correlation was observed that the result of sensory evaluation deteriorated. Since the same correlation is observed even when the storage temperature is changed, it can be seen that if the component ratio (trans / cis) of isohumulone isomers is the same, the degree of deterioration is the same.
[0019]
Therefore, the decrease in the component ratio (trans / cis) of isohumulone isomers is considered to reflect the progress of the deterioration reaction of the flavor component in beer, and is useful as an index of the oxidation of the flavor component in beer. I understood that.
The present invention has been made based on such findings, and evaluates the degree of deterioration of beer by measuring the component ratio (trans / cis) of isohumulone isomers.
[0020]
The component ratio (trans / cis) of isohumulone isomers contained in beer can be determined based on quantitative determination of isohumulone isomers by a conventional method. Quantification of isohumulone isomers is described in, for example, Ono, M., Kakudo, Y., Yamamoto, Y., Nagami, K., Kumada, J.,: J. American Society of Brewing Chemists, 45, 70 (1987). According to the method, it can be carried out by a high-performance liquid chromatograph apparatus with a pretreatment column (with a UV detector) or the like.
[0021]
Prior to the measurement, it is desirable to separate the other components as much as possible in order to increase the accuracy of the component ratio of the isohumulone isomer obtained. For this purpose, various types of chromatography can be used alone or in combination, and among them, high performance liquid chromatography is preferred.
In the present invention, such a series of operations can be easily performed, and therefore, a high-performance liquid chromatograph apparatus with a pretreatment column (Hop Bitter Analysis System, Shimadzu Corporation) and the like can be suitably used.
[0022]
The component ratio of the isohumulone isomer has a high correlation with the sensory evaluation as described above. This correlation is the same when the storage temperature is different.
Therefore, the evaluation method of the present invention using the component ratio of isohumulone isomers as an index is useful as an objective beer deterioration evaluation method.
[0023]
In addition, in order to see whether the difference in hop varieties affects the component ratio of isohumulone isomers, we investigated the component ratio of isohumulone isomers for beer using three types of hops: fine aroma, aroma and bitter hop. As a result, it was confirmed that there was almost no difference between the three.
This result shows that the evaluation method of the present invention can be evaluated by objective numerical values without considering the difference of hop varieties.
[0024]
Moreover, the component ratio of isohumulone isomers can be used as an index for suppressing the deterioration of beer.
That is, by suppressing the decrease in the component ratio of isohumulone isomers, the deterioration rate of beer can be slowed and the storage stability can be improved.
For example, the ratio of isohumulone isomers after storage for a certain period of beer with added catechins, phenols, sulfites, etc., which are antioxidant components contained in beer, is higher than when no additives are added. became.
From this, it is possible to know the effect of improving the antioxidant ability of beer containing a large amount of antioxidant components such as catechin by the method of the present invention.
[0025]
Although the present invention is intended for beer, it is also possible to target Happoshu made from the same raw material as beer and containing isohumulone as a component, and the degree of deterioration can also be measured. is there.
[0026]
Thus, according to the present invention, the flavor deterioration degree of beer can be easily and objectively evaluated.
Moreover, in the present invention, since the degree of deterioration of beer can be known from the component ratio of isohumulone isomers, there is an advantage that the degree of deterioration can be estimated even if analysis before storage is not obtained.
[0027]
【Example】
EXAMPLES Next, although an Example demonstrates this invention in detail, this invention is not limited by these.
[0028]
Example 1 (Change with time of component ratio of isohumulone isomer)
Fresh beer immediately after production was stored at 20 ° C. and 30 ° C. for 0 to 3 months for deterioration, and the change over time in the component ratio of isohumulone isomers in the beer was examined.
The measurement was performed according to the method described in Ono, M., Kakudo, Y., Yamamoto, Y., Nagami, K., Kumada, J.,: J. American Society of Brewing Chemists, 45, 70 (1987). Using an isohumulone isomer analysis system shown in No. 4 (high-performance liquid chromatograph with pretreatment column, hop bitterness analysis system, manufactured by Shimadzu Corporation), quantification was performed using reverse phase HPLC.
[0029]
In this system, an operation consisting of two steps of Step 1 and Step 2 can be automatically performed.
That is, first, in step 1, beer, which is a sample, is injected into the apparatus together with a processing carrier liquid by a pump, and the first high performance liquid chromatography (HPLC) is performed.
In the next step 2, the carrier liquid for analysis is fed, and this and the sample that has passed through step 1 are mixed, and the second HPLC is performed.
Thereafter, the sample is sent to a UV detector to obtain a chromatogram of the sample, and the waveform area ratio between the trans isomer and cis isomer in the chromatogram is measured to obtain the component ratio of isohumulone isomers.
[0030]
As a result, it was found that the trans isomer in the isohumulone isomer decomposes faster than the cis isomer, similar to the result of FIG. 1 described above.
Therefore, it can be seen that the component ratio of isohumulone isomers decreases with time, similar to the result of FIG. 2 described above.
It can also be seen that the decrease rate increases as the storage temperature increases, similarly to the result of FIG. 2 described above.
From these facts, it is presumed that beer with a small isohumulone isomer component ratio is a beer that has been stored for a long period of time or until it has been examined, or has been stored at a high temperature, that is, a beer with a high degree of deterioration. .
[0031]
Example 2 (Correlation between component ratio of isohumulone isomer and sensory evaluation)
The sensory evaluation by 14 trained panelists evaluated the degree of deterioration of beer that had been deteriorated by storage for 0 to 3 months at 20 ° C. and 30 ° C. in Example 1 above, and determined the component ratio of isohumulone isomers. And the sensory evaluation were investigated.
[0032]
As a result, it was found that there was a very high correlation between the degree of deterioration (aging degree) by sensory evaluation and the component ratio of isohumulone isomers, similar to the result of FIG. 3 described above. From this, it can be seen that the smaller the component ratio of the isohumulone isomer, the greater the degree of deterioration, and the deterioration of the flavor component can be grasped by the change in the component ratio of the isomer.
That is, it was speculated that the change in the component ratio of isohumulone isomers reflected the progress of the flavor deterioration reaction of beer during storage.
[0033]
【The invention's effect】
In the evaluation method of the present invention, since the component ratio of isohumulone, which is a substance (substrate) that directly undergoes oxidative degradation, is directly evaluated in the components of beer, the progress of beer oxidation due to free radical generation must be accurately evaluated. Can do.
According to the evaluation method of the present invention, accurate evaluation is possible without being affected by the amount of precursor such as the amount of malt used, as in the case of evaluating with an oxidation product using carbonyls such as furfural as an index. Obtainable.
[0034]
That is, in the evaluation method of the present invention, the trans isomer of isohumulone isomers is structurally unstable and easily decomposed, whereas the cis isomer is relatively stable and has a slow decomposition rate, so that beer is being stored. Based on the knowledge that it is a component that does not decrease so much, depending on the degree of deterioration of beer, the component ratio (trans / cis) of isohumulone isomers decreases immediately after production, and the degree of deterioration of beer flavor is reduced. Can be evaluated.
Moreover, the component ratio (trans / cis) of this isohumulone isomer not only shows a high correlation with the result of sensory evaluation of beer, but the content of isohumulone isomer in beer is a high-performance liquid chromatograph equipped with a pretreatment column. It can be easily measured with a UV detector.
Therefore, according to the evaluation method of the present invention, as in the conventional sensory evaluation method, a great amount of labor is required to evaluate a large number of samples, and there is a difference in threshold between panels and flavors between samples other than deterioration. The degree of deterioration of the beer can be objectively, easily and accurately measured immediately from a small amount of beer without being greatly affected by the difference between the two.
[0035]
Further, in the evaluation method of the present invention, since the component ratio of isohumulone isomers is used instead of the content of isohumulone isomers, it is not necessary to consider the difference in detection conditions and the amount of hop usage between analyses.
Furthermore, the component ratio of isohumulone isomers is almost unaffected by precursors such as hop varieties, added amounts, and malt consumption, and takes almost the same value in beer immediately after production.
Thus, in the present invention, the degree of beer degradation can be known from the component ratio of isohumulone isomers, and the component ratio of isohumulone isomers takes almost the same value in beer immediately after production, so analysis before storage Even if the value is not obtained or the components of fresh beer are not known, there is an advantage that the approximate degree of deterioration can be estimated.
[Brief description of the drawings]
FIG. 1 is a graph in which beer is stored at 20 ° C. for 0 to 6 months, and the degree of reduction of isohumulone during that period is examined with the content in beer before storage being 100.
FIG. 2 is a graph showing changes in isohumulone isomer component ratio (trans / cis) when beer is stored at 20 ° C. or 30 ° C. for 0 to 6 months.
FIG. 3 is a graph showing the correlation between the isohumulone isomer component ratio (trans / cis) and the sensory evaluation results when beer is stored at 20 ° C. or 30 ° C. for 0 to 6 months.
FIG. 4 is an explanatory diagram showing an isohumulone isomer analysis system used in Examples.

Claims (1)

A method for evaluating the degree of deterioration of beer, comprising measuring the component ratio of isohumulone isomers in beer.

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