JPH07929Y2 - Beer bitterness analyzer by flow injection - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Background of the Invention] <Technical Analysis> The present invention relates to an apparatus for analyzing a bitterness value of beer by so-called flow injection.

The bitterness that characterizes beer is due to hop-derived isohumulones, but it is indispensable for quality control of beer to know the bitterness content in beer accurately.

<Related technology> Several methods have been proposed for analyzing the bitterness content in beer, that is, the bitterness value. However, flow injection (hereinafter referred to as FIA) has been proposed because analysis can be performed continuously and quickly. Is the point of interest.

FIA falls into the category of liquid-liquid extraction, but if this is applied to beer bitterness value analysis, an acid aqueous solution (for example, 0.1NH _{2) is} used as a carry liquid for precipitating a dissolved bitter substance and feeding a sample. SO ₄ ) is used, and a water-insoluble extractant for bitterness (eg, isooctane) is added to transfer the bitterness to the organic phase, the organic phase is separated from the aqueous phase, and the separated organic phase It consists of measuring the absorbance at a specific wavelength (for example, 275 nm) and knowing the bitterness value from the absorbance value by a calibration curve.

FIA is preferable because it can automatically perform the reaction from the sample to the measurement, but this method also has a problem due to the fact that the analysis target is beer bitterness. That is, the bitterness that is precipitated by acidifying the sample beer adheres to the tube of the flow path and the inner surface of the switching valve, and the accuracy of analysis decreases. For example, the reproducibility CV value is as high as 2% (the reproducibility CV value means the ratio of the standard deviation to the average value when the same sample is repeatedly analyzed).

This problem can be solved to some extent by using an aqueous surfactant solution as the carrier liquid. However, according to the knowledge of the present inventor, this alone does not provide a sufficient solution. That is, using an existing FIA device, a beer degassed with an aqueous solution of a surfactant as a carrier liquid (for example, 0.1% Brij aqueous solution: an aqueous solution of brand name Brij35 manufactured by Atlas Powder Co. in the United States) is injected into the device. Acid (for example, 0.3N HCl) is added to carry out acidification in the mixing zone consisting of the coil of the flow channel tube, and then isooctane is injected and similarly passed through the mixing / extracting zone consisting of the coil of the flow channel tube. According to the law
When UV analysis was performed, the reproducible CV value declined to 0.95%, but it is still not sufficient, and the correlation coefficient with manual analysis (Kaoru Ishikawa, Toshimi Fujimori, Hitoshi Kume "Chemist and Chemistry" Statistical method for engineers "(Tokyo Kagaku Doujin (1964),
According to formula (1A.9) on page 12. However, when n beers with different bitterness contents were analyzed by hand analysis and FIA analysis,
The hand analysis value obtained for the i-th beer is y _i , and the FIA analysis value is x.
_{Let i} be the average of manual analysis values and the average of FIA analysis values. ) Is as low as 0.93, and in any case sufficient analysis accuracy cannot be obtained.

[Outline of device]

<Summary> The object of the present invention is to provide a solution to the above point, and to achieve this object by further improvement of the above-mentioned improved technique in which the injection positions of the aqueous acid solution and the organic solvent are specified.

That is, the beer bitterness value analyzer by flow injection according to the present invention includes (1) a pipeline through which the beer to be analyzed should be distributed, and (2) the beer through the pipeline using an aqueous surfactant solution as a carrier liquid. An inlet for injecting the aqueous surfactant solution and the beer into the pipeline, and a downstream side of the inlet of the pipeline (3)
An acid aqueous solution injection port, (4) a non-water-soluble organic solvent injection port for bitterness extraction, and (5) a downstream side of the organic solvent injection port, which gives the beer the time required for bitterness extraction And a water phase / organic phase separation device provided on the downstream side of the extension, the organic solvent inlet being the acid aqueous solution inlet. It is characterized in that it is provided at a position not on the downstream side.

<Effect> According to the device of the present invention, since the sample beer is acidified in the device substantially in the presence of the organic solvent, the bitterness precipitated by the acidification is rapidly dissolved in the organic solvent. It is virtually unrecognized that it adheres to the inner surface of the tube after deposition.

[Specific explanation of the invention]

<Basics of FIA analyzer> This FIA analyzer is essentially the same as the conventional one except that the injection of the organic solvent as the extractant is not performed downstream of the injection of the acid solution.

Therefore, in the FIA analyzer of the present invention, first, (1) a pipeline through which the beer to be analyzed is to be distributed, and (2) the beer so that the beer can be distributed through the pipeline by using an aqueous surfactant solution as a carrier liquid. An injection port for injecting the aqueous solution and the beer into the pipeline, (3) an acid aqueous solution injection port and (4) a water-insoluble material for extracting bitterness, which are provided on the downstream side of the injection port in the pipeline. An organic solvent inlet (all described below in detail), and (5) the pipe which is downstream from the organic solvent inlet and has a length sufficient to give the beer the time necessary for extracting the bitterness It consists of an extension of the channel and (6) a water / organic phase separator provided downstream of this extension.

(1) Pipeline The pipeline in the FIA analyzer is the skeleton of the flow injection device, and accepts the beer to be analyzed,
It is intended to provide a place for carrying out an analysis process until obtaining a solvent bitter substance extract.

This pipe is specifically, for example, polytetrafluoroethylene, polyethylene, poly (ethylene-propylene), other plastic materials, stainless steel, other metal materials, and an inner diameter of about 0.2 to 2 mm, preferably made of other materials. It consists of a tube of about 0.5 to 1 mm, and is provided with a valve or cock for injecting the beer to be analyzed, carrier liquid, acid solution, organic solvent solution and other necessary materials.

Also, in order to obtain the residence time required for the uniform mixing of the beer sample and the above-mentioned materials in the pipeline, it is necessary to give the pipeline a certain length, and for that purpose, the pipeline is coiled. It is common to place them in. According to this plan, it is necessary that at least such a coil is provided on the downstream side of the inlet of the organic solvent that is the extractant for bitterness. A suitable extraction coil length for the following operating conditions is, for example, 3 m.

(2) Injecting port for various materials The sample to be tested is usually circulated in the pipe together with the carrier liquid. However, the present invention uses an aqueous solution of a surfactant as the carrier liquid, and the inlet for this is also used in the device of the present invention. It is provided. The term "injection port for injecting the aqueous surfactant solution and the beer into the pipeline so that the beer flows through the pipeline using the aqueous surfactant solution as a carrier liquid" in the present proposal is purposeful. Means any arbitrary structure. One such structure has a sample beer inlet downstream of the carrier liquid inlet. The other one is a combination of both injection ports by a multi-necked cock, for example, a six-necked cock.

In conducting a bitterness analysis, it is necessary to know the sample amount of the sample beer accurately, and for this purpose, according to the conventional method, the cock is switched to specify the sample length, and thus the sample. It is usual to take up once in the volume of the conduit and push it downstream with the carrier liquid. Specifically, for example, when the sample beer and the carrier liquid are injected into the conduit by the hexagonal cock, the internal volume is, for example, 100 μ1 between the two mouths of the hexagonal cock.
A side conduit consisting of a loop will be provided so that samples can be collected quantitatively.

(3) Separation of water phase / organic phase The sample beer / carrier liquid that has been injected with the acid aqueous solution and the extractant (details described later) by the method according to the present invention stays in the pipeline for a predetermined time (for example, 0.5 minutes). After that, proceed to an aqueous phase / organic phase separator.

The water phase / organic phase separation device is also conventional, and specifically, for example, it is composed of a tube of a hydrophobic material such as tetrafluoroethylene, and the tube wall (for example, 1 μm in thickness) is microporous (pore size). Is, for example, 0.02 μ) and used as a permeable membrane as a separation element. When an aqueous / organic phase mixture is flown through a tube having such a structure, the organic phase passes through the fine pores and flows out of the tube, while the aqueous phase cannot pass through the hydrophobic fine pores. Separation of both phases is achieved.
This microporous tubular permeable membrane, which should pass through the micropores and go out of the tube to be collected and sent to the UV analyzer, is usually contained in another tube.

<UV Detector> In this way, the organic phase separated from the aqueous phase has bitterness dissolved therein. Therefore, this is sent to a conventional UV detector,
The absorbance at 275 nm is measured, and the bitterness value in the test beer is determined from the peak height according to the calibration curve previously obtained.

<Acid Aqueous Solution / Organic Solvent Inlet> In the FIA beer bitterness analyzer having the above-described configuration, the present invention provides an acid aqueous solution inlet and an organic solvent inlet for a bitterness extractant, the latter being Is not provided on the downstream side, that is, the organic solvent injection port is located substantially at the same position as the acid aqueous solution injection port or on the upstream side thereof.

In terms of simplicity of construction, it is preferable to combine both inlets into one by a suitable multi-neck so that both inlets exist at substantially the same position in the conduit.

In this way, in the configuration where both inlets are combined into one,
The “extension of the conduit of sufficient length to give the time required for extraction” provided on the downstream side is the aqueous acid solution and the beer to be tested /
Sufficient mixing time with the carrier liquid will be provided.

<Specific Example of Device> A specific example of the device of the present invention is as shown in the accompanying drawings.

<Operation of the device> The sample beer is degassed before being analyzed. An amount of about 100 μl is suitable for one analysis, and this is taken as a sample in the above-mentioned sample loop having an internal volume of 100 μl. An aqueous solution of a surfactant as a carrier liquid is a dilute aqueous solution of a suitable surfactant such as polyoxyethylene ether of a higher alcohol (eg Brij) (eg
0.2% concentration) at an appropriate flow rate, for example 0.2 ml /
The sample beer is fed into the pipeline through the sample loop described above.

It is preferable that the shape of a multi-port cock (particularly, a six-port cock) is preferable in order to perform a sample beer injection port (carrier liquid injection, and sample beer injection and quantitative determination (collection into a sample loop)). Immediately after), an aqueous acid solution such as dilute hydrochloric acid solution such as 0.6N HCl
The solution and organic solvent for the extractant, such as isooctane, are injected into the line. The injection amount of these liquids is, for example,
0.2 ml / min, the latter 1.0 ml / min. By increasing the isooctane flow rate to about 1: 2.5 with respect to the flow rate of the aqueous phase in this way, the calibration curve plotting the peak height and bitterness value in UV detection can be made to pass through 0 point. A calibration curve can be created with one beer with a bitterness value.

The peak height of isohumulone is measured by an integrator from the data from the UV detector and converted into the absorbance of isohumulone. From this absorbance, the isohumulone concentration is calculated.

According to the device of the present invention, the manual analysis and the correlation coefficient are 0.99.
It was 9 to 1.000, and the reproducible CV value was 0.5%. By the way, under the above conditions, after injecting 0.3N HCl at 0.5 ml / min and then injecting isooctane at 1.5 ml / min 3 m downstream,
The correlation coefficient with the manual analysis was 0.93, and the reproducible CV value was 0.95%.

It can be seen that the present invention has higher reproducibility and has a very high correlation with the hand analysis.

[Brief description of drawings]

The drawing schematically shows one specific example of the device of the present invention. 1 ... Surfactant container, 2 ... Sample beer container, 3 ...
Six-neck cock, 4 ... Sample loop, 5 ... HCl / isooctane inlet, 6 ... HCl container, 7 ... Isooctane container, 8 ... Extraction coil, 9 ... Water / organic phase separator,
10 ... UV detector, ... pump.

Claims (3)

[Scope of utility model registration request] 1. A pipeline through which beer to be analyzed should flow, and (2) the aqueous surfactant solution and the beer so that the beer flows through the pipeline using the aqueous surfactant solution as a carrier liquid. An injection port for injecting into the pipe, (3) an acid aqueous solution injection port, and (4) a non-water-soluble organic solvent injection port for bitterness extraction, which are provided on the downstream side of the injection port of the pipe. ,
(5) An extension portion of the conduit, which is downstream from the organic solvent injection port and has a length sufficient to give the beer a time required for extracting a bitter substance, and (6) the extension portion. And an aqueous phase / organic phase separation device provided on the downstream side of the beer by flow injection, wherein the organic solvent injection port is provided at a position that is not on the downstream side of the acid aqueous solution injection port. Bitterness value analyzer. 2. The beer bitterness value analyzer according to claim 1, wherein the organic solvent inlet is provided at substantially the same position as the acid aqueous solution inlet. 3. Beer bitterness value analysis according to claim 1 or 2, which is combined with a UV detector for measuring the absorbance of an organic phase obtained from an aqueous phase / organic phase separator. apparatus.