JP3390695B2 - Microanalysis of 3-methyl-2-butene-1-thiol, a trace sun odor component in beer - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a trace analysis method for 3-methyl-2-butene-1-thiol, which is a sunlight odor component in beer. In addition, the beer in the present invention is a general term for those obtained by alcohol-fermenting a raw material whose main component is added hop wort obtained by using malt, and is not limited to beer defined by JAS and includes so-called Happoshu. Is a concept to do.

[0002]

2. Description of the Related Art The sunlight odor of beer is also called the photo-deterioration odor
It is an offensive odor that occurs when the bottle is exposed to sunlight. It may also occur when placed near a fluorescent lamp for a long time. The causative agent of sunlight odor is generated by the decomposition of the side chain portion of the isoalpha acid molecule, which is a bitter ingredient of beer, at a wavelength of 520 nm or less, and the binding of nascent hydrogen sulfide formed from sulfur-containing amino acids in beer. Thiol compound 3
-Methyl-2-butene-1-thiol (hereinafter referred to as MBT). This sunlight-causing substance MBT
Is a substance that contributes significantly to the commercial value of beer, but its sensory threshold concentration is extremely low.
ers Digest, May, 18-25, 199
In 5), it is described as 4.4 to 35 ppt in beer and 0.2 to 0.4 ppt in water. Therefore, it is difficult to analyze MBT below the sensory threshold concentration by instrumental analysis.

For example, as a method for analyzing MBT in beer, Proceedings of the 6t
h Convention of the Insti
toute of Brewing Central a
nd Southern African Secti
on, Durban, 123-128 (1997). This method is used for purging and trapping (pur
ge and trap) followed by Sieve
rs sulfur specific Chemi
Luminescence detector (SCP
355, Burke & Measure, 1995).
And the gas chromatograph method (GC) are combined, and although the detection sensitivity of MBT is better than that of the conventional analysis method, the detection limit is 3 ppt, and analysis below the sensory threshold concentration is performed. The reality is that the detection sensitivity has not reached sufficient level.

On the other hand, researchers at Kirin Brewery Co., Ltd. have found that American Society of Bre
wing Chemists Journal, vo
l. 49, No. 4, P162-165 (1991), followed by purging and trapping MBT in beer, followed by gas chromatography and FlameP.
Although an analysis method in combination with a photometric detector (FPD) is adopted, the detection sensitivity below the sensory threshold concentration has not been reached, and the presence or absence of a trace amount of MBT cannot be determined.

[0005]

Therefore, an object of the present invention is to provide a novel analytical method which enables sufficient analysis of MBT which is a causative agent of sunlight odor even in a region lower than the sensory threshold concentration. is there.

[0006]

SUMMARY OF THE INVENTION The present invention is a purge and trap method and a gas chromatograph-mass spectrometric method (GC / GC).
It was developed by investigating the conditions of analysis using MS) and detecting MBT, which is the causative agent of sunlight odor, with high sensitivity below the sensory threshold concentration.

That is, according to the present invention, an inert gas is blown into beer as a test substance to expel a trace amount of volatile components contained in the beer from the beer, and the beer is collected by a collecting agent and then collected. In the microanalytical method for trace amount of 3-methyl-2-butene-1-thiol, which is a trace sunlight odor component detected by a mass spectrometer, after passing a heat desorption device and a capillary gas chromatograph column, a specific collecting agent It relates to an analytical method characterized in that the beer temperature using the composition or blowing an inert gas is low.

According to the present invention, in the above method, (1) 10 to 50% by weight, preferably 20 to 40% by weight, of graphite carbon as the scavenger and poly (2,6-diphenyl-p-phenylene oxide) 90 are used. ˜50% by weight, preferably 80-60% by weight, and / or (2) the beer temperature when blowing an inert gas into beer is −5 ° C. to 10 ° C., preferably −2. It is to be ℃ ~ 5 ℃. The method of the present invention is particularly effective when the concentration of 3-methyl-2-butene-1-thiol in the sample beer is below the sensory threshold.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The purge & trap device used in the present invention can be used without any problem as long as it is a commercially available device.
As for the GC / MS, any commercially available GC / MS device can be used.

In purging and trapping,
Also in the present invention, it is preferable to add an internal standard substance to beer. As the internal standard substance, a substance having physicochemical properties similar to MBT can be used, and examples thereof include 1-hexanethiol. The amount of the internal standard substance added is adjusted according to the content of MBT.

A schematic of the apparatus for performing the purge and trap of the present invention is shown in FIG. 1 in flask 2
The test substance (beer) and the internal standard substance of 0 to 600 ml are put, and the flask 2 is immersed in the bath 1. Put a liquid (usually water, glycol water, etc.) in the bath -5 ° C-10
The temperature of the beer in the flask 2 is controlled to that temperature. An inert gas such as nitrogen gas was blown into the flask 2 through the line 3 to remove MBT or 1 in the beer.
-Remove hexanethiol, etc. (purging). Usually, purging is performed for about 10 to 30 minutes. The inert gas for purging is usually 50-200 ml / min,
The gas flow rate is preferably 100 to 180 ml / min. The component containing the purged MBT is the capacitor 4
And is collected (trapped) by the collecting pipe 5 filled with the collecting agent attached to the upper part of the apparatus.

When the purge and trap is completed,
Remove the collection tube 5. Capillary gas chromatograph-mass spectrometer (GC / M equipped with thermal desorption cold trap injector (TCT)
The collecting tube 5 is attached to the aluminum heat block 11 in S).
Set the aluminum heat block 11 to 180-22
It is heated to about 0 ° C. for 5 to 10 minutes (see FIGS. 1 and 2).
On the other hand, the cryofocus trap (see FIG. 2) is precooled in advance, and the temperature of the cryofocus portion is −200 ° C. to 0 ° C., preferably −50 ° C. to −180 ° C.
Keep it in. The MBT, 1-hexanethiol, and the like collected in the collecting agent 5 are removed from the aluminum heat block 11
Is desorbed by heating to 180-220 ℃,
The carrier gas (ex, He) is sent to the cryofocus unit 12, where it is cooled and concentrated. Then, the temperature of the cryofocus unit 12 was raised to 180 to 230 ° C., and the MB which had been cooled and concentrated in the cryofocus unit was used.
A component to be detected such as T is injected into the capillary column.
As a device for this TCT portion, a commercially available CP4020 manufactured by Chrompack can be used.

The object gasified in the TCT portion is
It is injected into the capillary column of the gas chromatograph by the carrier gas. As this device, for example, a commercially available HEWLETT PACKARD GC device H
P6890 or manufactured by Shimadzu Corporation can be used. This capillary column has a length of 30 m, an outer diameter of 0.25 mm, and a film thickness of 0.25 μm, and the analysis temperature of the oven that houses this capillary column is raised from 40 ° C. to 10 ° C. per minute, and finally 240 ° C. To be set.

The mass spectrometer of the present invention is a commercially available H
HP5973 manufactured by EWLETT PACKARD or manufactured by Shimadzu Corporation can be used.

[0015]

EXAMPLES The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited thereto.

Example 1 200 ml of ice-cooled product beer was placed in a 200 ml eggplant-shaped flask, MBT was added to a concentration of 10 ppt, and 40 μm of 1-octanol was added as a defoaming agent.
1 was added. The prepared sample was subjected to purge and trap and GC / MS, and the S /
I checked N. The conditions under which the measurement with the highest sensitivity was possible were examined.
In the examination, (A) bath temperature in the device of FIG. 1,
(B) Collection time of components purged from the flask 2,
The experiment was conducted by changing the flow rate of the purge gas (C) and the type of the collector (D). These conditions are shown in Table 1.

[0017]

[Table 1] * (A) is poly (2,6-diphenyl-p-phenylene oxide) 100%. 20/3 particles
It is of 5 mesh. (B) is a composition of 70% by weight of poly (2,6-diphenyl-p-phenylene oxide) and 30% by weight of graphite carbon. The particles are of 20/35 mesh. ** S / N represents the ratio of the height of the signal peak of MBT to the width of noise.

In the above examination, the conditions of purge and trap, TCT, and GC / MS are uniformly as follows. <Purge and trap> Condenser temperature: 40 ° C <TCT> Cryofocusing: -150 ° C Precooling time: 2 minutes Desorption temperature: 200 ° C Desorption time: 6 minutes Carrier gas injection temperature into GC: 200 ° C Carrier gas Injection time: 1 minute <GC / MS> Capillary column: trade name DB-FFAP (length 30 m, outer diameter 0.25 mm, membrane pressure 0.25 μm) Oven temperature: 40 ° C. (5 minutes) −10 ° C./min→240 ° C (8 minutes) Carrier gas: He, 72 kPa Transfer line temperature: 250 ° C MS ion source temperature: 230 ° C MS Q pole temperature: 106 ° C Monitoring ion: MBT m / z = 102 Internal standard m / z = 118 Table 1 As you can see from the result, the best S / N (ratio of signal to noise) is obtained in experiment number 2. I understood it. When the beer containing 1.06 ng / L of MBT was analyzed again under the same conditions, the S / N was 15.5. If the detection limit is a concentration that gives S / N = 3, 1.
It was found that 06 / (15.5 / 3) = 0.21, that is, the detection limit of MBT under this condition was 0.21 ppt, and good results far below the sensory threshold concentration were obtained. Therefore, the subsequent Examples 2 and 3 were performed under the experimental conditions of Experiment No. 2.

Example 2 200 ml of ice-cooled product beer was placed in a 200 ml eggplant-shaped flask, and the concentration of M was adjusted to 0 to 20 ng / L.
The BT standard stock solution was added to prepare a standard solution for calibration curve.
Further, 100 μl of hexanethiol was added as an internal standard, and 40 μl of 1-octanol was further added as an antifoaming agent. The prepared sample was subjected to purge and trap and GC / MS under the conditions shown in Example 1, and a calibration curve was prepared from the obtained peak area ratio of MBT and internal standard. The results are shown below. MBT added concentration (ng / L) Internal standard ratio 0 0.012 2.5 0.054 5.0 0.122 10.0 0.212 20.0 0.530 From the above, r = 0.993, and thus the present method Was confirmed to be a method with excellent quantification. The repeatability is 5.
It was a good value of 5%.

Example 3 For 20 beer bottles (standard size) in a plastic case, MBT was quantified for two beers at the positions shown in FIG. The sample beer was prepared on a sunny day in November in the sun for 5 hours. 200 ml of ice-cooled sample beer was placed in a 200 ml eggplant-shaped flask, and hexanethiol 1 was used as an internal standard substance.
00 μl and 40 μl of 1-octanol as a defoaming agent were added to obtain an analytical sample. The prepared analytical sample was purged and trapped under the conditions shown in Example 1, GC /
It was subjected to MS. As a result, 8.6 ppt of MBT was detected from the beer placed on the outside indicated by, and 1.9 ppt was detected from the beer placed on the inside indicated by.

[0021]

[Effect] According to the method of the present invention, it becomes possible to analyze 3-methyl-2-butene-1-thiol, which is a trace sunlight odor component in beer, with a sensitivity of 1/10 of the functional threshold concentration. This method can contribute to more precise quality control of beer, and is useful for the development of a new container that does not easily generate the odor of sunlight.

[Brief description of drawings]

FIG. 1 is a schematic view of an apparatus used in the present invention.

FIG. 2 is a diagram showing details of a cryofocus portion and a connection relationship between a capillary column of a gas chromatograph.

FIG. 3 is a plan view showing the positions of two beer bottles used in the test among 20 beer bottles contained in a plastic case.

[Explanation of symbols]

1 bus 2 flasks 3 Inert gas introduction line for purging 4 capacitors 5 Collection tube filled with collection agent 11 Aluminum heat block 12 Cryofocus section 13 lines 14 Capillary columns

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI G01N 30/08 G01N 30/08 G 30/72 30/72 A 33/14 33/14 (56) References JP-A-3- 142337 (JP, A) ASBC Journal, 1993, vol. 51, no. 2, p. 70-74 ASBC Journal, 1991, vol. 49, no. 4, p. 162-165 (58) Fields investigated (Int.Cl. ⁷ , DB name) G01N 30/88 G01N 1/22 G01N 27/62 G01N 30/04 G01N 30/08 G01N 30/72 G01N 33/14

Claims (2)

(57) [Claims] 1. A small amount of volatile components contained in beer are blown out from the beer by injecting an inert gas into the beer, which is a sample, and the collected volatile components are collected by a collecting agent, and then the collected components are heated. In a microanalysis method of 3-methyl-2-butene-1-thiol, which is a trace sunlight odor component in beer, which is detected by a mass spectrometer after passing through a desorption device and a capillary gas chromatographic column, (1) The collection As an agent, graphite carbon 10
A composition comprising 50% by weight and 90 to 50% by weight of poly (2,6-diphenyl-p-phenylene oxide) is used. (2) The beer temperature when an inert gas is blown into the beer is from -5 ° C. It is carried out under the condition of either one or both of 10 ° C., and 3-methyl- which is a trace sunlight odor component in beer.
Microanalysis of 2-butene-1-thiol. 2. 3-Methyl-2-butene-1-in a sample
3-Methyl, which is a trace amount of sunlight odor component in beer according to claim 1, wherein the concentration of thiol is not more than the sensory threshold concentration.
Microanalysis of 2-butene-1-thiol.