Alcohol analyzing device

Abstract

An alcohol analyzing device (1) is provided with: a light source (2) that emits excitation light; a spectrometer (4); an optical system (3) that irradiates an alcoholic beverage (7) with the excitation light and guides Raman scattered light radiated from the alcoholic beverage (7) to the spectrometer (4); a photodetector (5) that detects the spectrum of the Raman scattered light spectrally diffracted by the spectrometer (4); and a processing unit (6) that obtains the alcohol concentration of the alcoholic beverage (7) from the spectrum of the Raman scattered light detected by the photodetector (5).

Description

Alcohol analyzer

[0001] The present invention relates to an alcohol analyzer.

[0002] Gas chromatography-mass spectrometry (GC-MS) and high-performance liquid chromatography (HPLC) are used to measure the alcohol content of liquids. However, spectroscopic techniques can be used to measure the alcohol content of liquids more easily than chromatographic techniques. An example of such a commercially available alcohol measurement device is the Alcolyzer manufactured by Anton Paar. The Alcolyzer uses near-infrared spectroscopy to measure the alcohol content of liquids by measuring light absorption in the near-infrared region.

[0003] Regarding the measurement of the alcohol content of a liquid using near-infrared spectroscopy, for example, Patent Document 1 discloses that the absorption of light transmitted through a sample to be tested at a wavelength in the range of 1100 to 1300 nm, preferably in the range of 1150 to 1250 nm, is measured, and the alcohol concentration is determined from the absorption of the tested light using a calibration, and the alcohol concentration is calculated from the determined absorption of the light using a calibration.

[0004] Special Publication No. 2002-538432

[0005] The Liquor Tax Act requires that alcohol concentrations of alcoholic beverages be measured. There are multiple types of alcoholic beverages, including beer, sake, shochu, and whiskey. The alcohol concentrations vary greatly depending on the type, ranging from low to high. The components contained in each type also vary. Even within the same type of alcoholic beverage, the alcohol concentration may differ between products. However, near-infrared spectroscopy makes it difficult to accurately evaluate signals containing multiple component types. Furthermore, because near-infrared spectroscopy is an absorption spectroscopy method, accurate measurements become impossible as the concentration increases. Therefore, it is not possible to universally measure the alcohol concentration of multiple types of alcoholic beverages.

[0006] The present invention has been made in view of the above circumstances, and has as its object to determine the alcohol concentration of a variety of alcoholic beverages in a general manner.

[0007] The alcohol analysis device according to the present invention comprises: a light source that emits excitation light; a spectroscope; an optical system that irradiates an alcoholic beverage with the excitation light and guides Raman scattered light emitted from the alcoholic beverage to the spectroscope; a photodetector that detects the spectrum of the Raman scattered light dispersed by the spectroscope; and a processing unit that determines the alcohol concentration of the alcoholic beverage from the spectrum of the Raman scattered light detected by the photodetector.

[0008] According to the present invention, the alcohol concentration is determined from the spectrum of Raman scattered light emitted from an alcoholic beverage, so that the alcohol concentration can be determined universally for a variety of alcoholic beverages.

[0009] 1 is a diagram illustrating the configuration of an alcohol analyzer according to an embodiment of the present invention; 2 is a diagram illustrating a Raman spectrum of beer measured by the alcohol analyzer according to an embodiment of the present invention; 3 is a graph of a calibration curve showing the alcohol concentration and Raman intensity for each type of beer; 4 is a diagram illustrating the Raman spectrum of beer when excitation light with a wavelength of 785 nm is used; 5 is a diagram illustrating the Raman spectrum for each type of alcoholic beverage; and 6 is a graph of a calibration curve showing the alcohol concentration and Raman intensity for each type of alcoholic beverage.

[0010] 1 is a diagram showing the configuration of an alcohol analyzer 1 according to an embodiment of the present invention. The alcohol analyzer 1 analyzes the alcohol concentration and other information contained in an alcoholic beverage 7 based on Raman scattered light emitted from the alcoholic beverage 7 when irradiated with excitation light. The alcohol analyzer 1 includes a light source 2, an optical system 3, a spectroscope 4, a photodetector 5, and a processing unit 6, and performs spectral measurement of the alcoholic beverage 7, which is the object of analysis, to obtain the alcohol concentration.

[0011] The light source 2 is a light source that emits excitation light, and irradiates the alcoholic beverage 7 with the excitation light. Because the Raman scattered light generated in the alcoholic beverage 7 by irradiation with excitation light tends to be weak, it is preferable that the light source 2 be a light source that emits high-intensity excitation light. Furthermore, because the concentration of alcohol contained in the alcoholic beverage 7 is calculated based on the wavelength of the excitation light, it is preferable that the light source 2 be a light source that emits excitation light of a single wavelength. Examples of such light sources include semiconductor lasers and solid-state lasers. Furthermore, instead of a laser, an LED (light emitting diode) may be used.

[0012] The optical system 3 irradiates the alcoholic beverage 7 with excitation light emitted from the light source 2, and guides Raman scattered light from the alcoholic beverage 7 to the spectrometer 4. In detail, the optical system 3 comprises an irradiation optical system composed of a collimator lens 31, a bandpass filter 32, a reflecting mirror 33, a dichroic mirror 34, a reflecting mirror 35, and an objective lens 36, which guides the excitation light in a direction in which it is irradiated onto the alcoholic beverage 7, and an imaging optical system composed of the objective lens 36, the reflecting mirror 35, the dichroic mirror 34, an edge filter 37, and a condenser lens 38, which guides the Raman scattered light generated from the alcoholic beverage 7 to the spectrometer 4.

[0013] The collimating lens 31 converts the excitation light emitted from the light source 2 into a parallel beam. The bandpass filter 32 attenuates wavelength components excluding the peak wavelength among the wavelength components contained in the excitation light that has passed through the collimating lens 31. The reflecting mirror 33 reflects the excitation light that has passed through the bandpass filter 32 and guides it to the dichroic mirror 34. The dichroic mirror 34 reflects the excitation light and guides it to the reflecting mirror 35, while transmitting Raman scattered light having a wavelength different from that of the excitation light and directing it to the edge filter 37.

[0014] The reflecting mirror 35 reflects the excitation light reflected by the dichroic mirror 34 and guides it to the objective lens 36 , and also reflects the Raman scattered light emitted from the alcoholic beverage 7 and guides it to the dichroic mirror 34 .

[0015] The objective lens 36 focuses the excitation light reflected by the reflecting mirror 35 onto the alcoholic beverage 7 , and also focuses the Raman scattered light emitted from the alcoholic beverage 7 .

[0016] The edge filter 37 reflects or transmits light depending on the wavelength, reflecting light depending on the wavelength of the excitation light emitted from the light source 2 and transmitting light with a wavelength longer or shorter than that of the excitation light. Therefore, the edge filter 37 transmits Raman scattered light with a wavelength shifted from the wavelength of the excitation light emitted from the alcoholic beverage 7 due to irradiation with the excitation light, and guides it toward the spectrometer 4. The condenser lens 38 converts the Raman scattered light that has passed through the edge filter 37 into a convergent beam of light and guides it to the spectrometer 4.

[0017] The spectrometer 4 is, for example, a Fourier transform spectrometer that utilizes the coherence of light and disperses the Raman scattered light that has passed through the edge filter 37. The Fourier transform spectrometer includes an interferometer and measures the interference waveform of the light using the interferometer. The interferometer forms interference light from the Raman scattered light generated in the alcoholic beverage 7. The formed interference light is received by the photodetector 5 and output as an electrical signal. The interference waveform output from the photodetector 5 is Fourier transformed to measure the light intensity distribution (spectrum) for each wavelength.

[0018] The photodetector 5 has a plurality of light-receiving elements on its light-receiving surface. Raman scattered light is incident on the light-receiving surface of the photodetector 5. When the photodetector 5 receives the Raman scattered light from the spectroscopic element, the light-receiving elements convert the light of each wavelength into an electrical signal. For example, a photodiode, a CCD (Charge Coupled Device), or a CMOS (Complementary Metal Oxide Semiconductor) may be used as the photodetector 5. The signal output from the photodetector 5 is Fourier transformed to generate a spectrum showing the intensity distribution for each wavelength.

[0019] The photodetector 5 is connected to a processing unit 6, and the spectrum generated by the photodetector 5 is input to an analytical device. The processing unit 6 is a computer such as a personal computer, and includes a processor that processes data according to a control program, a main memory that functions as a work area for the processor, an auxiliary memory for storing data for a long period of time, a display that displays the calculation results, etc. The processing unit 6 determines the alcohol concentration contained in the alcoholic beverage 7 based on the spectrum input from the photodetector 5.

[0020] Next, a case where the alcohol concentration contained in the alcoholic beverage 7 is determined by the alcohol analyzer 1 will be described.

[0021] The excitation light emitted from the light source 2 is converted into a parallel beam by a collimating lens 31, and after unnecessary wavelength components are removed by a bandpass filter 32, is reflected by a reflecting mirror 33 and enters a dichroic mirror 34. The excitation light is reflected by the dichroic mirror 34 and enters a reflecting mirror 35. The excitation light reflected by the reflecting mirror 35 is collected by an objective lens 36 and irradiated onto the alcoholic beverage 7.

[0022] When excitation light is incident on the alcoholic beverage 7, components contained in the alcoholic beverage 7 generate Raman scattered light having a wavelength different from that of the excitation light, as well as Rayleigh scattered light having the same wavelength as the excitation light. The Raman scattered light and Rayleigh scattered light generated in the alcoholic beverage 7 are incident on the reflecting mirror 35 via the objective lens 36. The Raman scattered light and Rayleigh scattered light incident on the reflecting mirror 35 are reflected and incident on the dichroic mirror 34. The dichroic mirror 34 reflects Rayleigh scattered light having the same wavelength as the excitation light and transmits Raman scattered light having a wavelength different from that of the excitation light. Furthermore, the scattered light transmitted through the dichroic mirror 34 is incident on the edge filter 37, where the Rayleigh scattered light is removed. The Raman scattered light that passes through the edge filter 37 is collected by the collecting lens 38 and input to the spectrometer 4. The spectrometer 4 separates the input Raman scattered light and inputs it to the photodetector 5. The photodetector 5 detects the spectrum of the dispersed Raman scattered light and inputs the detection signal to the processing unit 6. The processing unit 6 analyzes the detected spectrum and determines the intensity of the spectrum indicating the alcohol component, thereby determining the alcohol concentration contained in the alcoholic beverage 7.

[0023] FIG. 2 shows the results of alcohol analysis of beer performed using the alcohol analyzer of FIG. 1. Several types of beer with different alcohol concentrations were analyzed. Specifically, six types of beer, A, B, C, D, E, and F, with alcohol concentrations of 6%, 6.9%, 7.7%, 8.8%, 9.8%, and 10.8%, were analyzed. The conditions were excitation light with a wavelength of 830 nm and an intensity of 300 mW, and an exposure time of 5 seconds. FIG. 2A shows the Raman spectra of each type of beer, with the horizontal axis representing the Raman shift (cm －１ 2B shows the alcohol concentration and Raman intensity for each of the above types of beer, with the horizontal axis representing the alcohol concentration (%) and the vertical axis representing the Raman intensity (Counts).

[0024] In FIG. 2A, the Raman shift is 880 cm －１ The Raman intensity increases around 880 cm. －１The spectrum around this point indicates an alcohol component. The Raman shift is 880 cm －１ The Raman intensity of the spectral peaks around this range varies from beer to beer, with the higher the alcohol concentration, the greater the Raman intensity of the peak. As shown in the figure, the vibrational mode of the measured Raman scattered light is fundamental, resulting in a distinctive peak that is less likely to interfere with the peaks of other components. In contrast, with near-infrared spectroscopy, the vibrational mode of the measured absorption is not fundamental, but overtones or combination vibrations, resulting in a broad absorption peak that may overlap with the peaks of other components. Thus, compared to near-infrared spectroscopy, it is easier to measure alcoholic components in alcoholic beverages 7 containing multiple component types.

[0025] FIG. 2B shows the Raman shift of 880 cm for beers A to F, which indicates the known alcohol concentration and alcohol components, based on FIG. 2A. －１ 2B is a graph of a calibration curve showing the relationship between alcohol concentration and Raman intensity, plotting the Raman intensity of the spectrum around

[0049] . As shown by the dotted line in FIG. 2B, the Raman intensity of the spectrum increases in proportion to the alcohol concentration. Therefore, the alcohol concentration can be determined by linear approximation. As mentioned above, the spectrum of Raman scattered light is less likely to interfere with peaks of other components than near-infrared spectroscopy, and therefore has high linearity. According to this calibration curve, the alcohol concentration of an alcoholic beverage 7, whose concentration is unknown, can be determined by applying the Raman intensity of the spectrum of the alcohol component to the alcoholic beverage 7. Since the alcohol concentration can be determined according to a calibration curve showing high linearity, compared to near-infrared spectroscopy, which has strong water absorption and can only measure relatively low concentrations, the alcohol concentration can be accurately measured over a wide dynamic range from low to high concentrations due to weak water absorption. Furthermore, since the alcohol concentration can be evaluated simply by plotting a single spectral peak corresponding to the alcohol component, a complex calibration curve is not required, as is the case with near-infrared spectroscopy.

[0026] The above analysis used laser light with a wavelength of 830 nm as excitation light, which is longer than the visible light region (400 nm to 700 nm). Next, Raman spectra measured when the wavelength of the excitation light was changed are shown in Figure 3. Here, the Raman spectrum was measured for Beer A with a beer concentration of 6%, and shown is when the wavelength of the excitation light was set to 785 nm, which is longer than the visible light region and closer to the visible light region than 830 nm.

[0027] In FIG. 3, the peaks surrounded by circles represent the Raman spectrum of the alcohol component. Here, the Raman intensity of the peak in the Raman spectrum representing the alcohol component is 1000 counts. In contrast, in FIG. 2A, which shows the Raman spectrum when the wavelength of the excitation light is 830 nm, the Raman intensity of the peak in the Raman spectrum representing the alcohol component is 4000 counts. Therefore, the Raman intensity of the peak in the Raman spectrum representing the alcohol component is greater when the wavelength of the excitation light is 830 nm, which is longer in the near-infrared region, than when the wavelength of the excitation light is 785 nm. For this reason, it is easier to determine the alcohol concentration when the wavelength is 830 nm, which is longer than 785 nm.

[0028] Alcoholic beverages 7 contain components that can become autofluorescent, and colored alcoholic beverages 7 such as beer and whiskey contain many components that can become autofluorescent. When determining the alcohol concentration based on the detection of Raman scattered light, the detected Raman scattered light is a weak signal and is therefore susceptible to the influence of autofluorescence. Colored alcoholic beverages 7 such as beer and whiskey, which contain many components that can become autofluorescent, are particularly susceptible to the influence of autofluorescence. In this case, as described above, by using a long wavelength excitation light, the alcohol concentration can be determined without being influenced by autofluorescence.

[0029] Next, the results of alcohol analysis of beer and other types of alcoholic beverages 7 other than beer are shown in Figure 4. Here, the results of analysis of beer G, highball H, gin I, and whiskey J as alcoholic beverages 7, as well as anhydrous alcohol K, are shown.

[0030] The conditions were the same as in Figure 2, with excitation light having a wavelength of 830 nm and an intensity of 300 mW, and the exposure time was 5 seconds. Figure 4A shows the Raman spectra for each type of alcoholic beverage 7, with the horizontal axis representing the Raman shift (cm －１ 4B is a graph of a calibration curve showing the relationship between the known alcohol concentration of each type of alcoholic beverage 7 and the Raman intensity peak of the spectrum showing the alcohol component, with the horizontal axis representing the alcohol concentration (%) and the vertical axis representing the Raman intensity (Counts).

[0031] In FIG. 4A, the Raman shift is 880 cm －１ The Raman intensity increases around 880 cm. －１ The spectrum around this point indicates the alcohol component. Here, the Raman shift is 880 cm －１ The intensity of the spectrum around this peak varies for each type of alcoholic beverage 7. As in Figure 2A, the peak of the measured Raman scattered light spectrum is distinctive and is unlikely to interfere with the peaks of other components. Therefore, it is possible to measure the alcohol components of multiple types of alcoholic beverages 7, each containing different types of components.

[0032] FIG. 4B shows the Raman shift of 880 cm , which indicates the known alcohol concentration and alcohol components for each type of alcoholic beverage 7 based on FIG. 4A . －１4B is a graph of a calibration curve showing the relationship between alcohol concentration and Raman intensity, plotting the Raman intensity of spectra around 400 nm. Here, the alcohol concentration of Beer G is 6%, the alcohol concentration of Highball H is 7%, the alcohol concentration of Gin I is 7%, the alcohol concentration of Whiskey J is 40%, and the alcohol concentration of Absolute Alcohol K is 100%. Each point in FIG. 4B represents the Raman intensity of the peak in the spectrum showing the alcohol concentration and alcohol components of each alcoholic beverage 7. As shown in the figure, Highball H and Gin I, which have the same alcohol concentration, have the same Raman intensity despite being different types. Furthermore, as shown by the dotted line, the Raman intensity increases in proportion to the alcohol concentration, regardless of the type of alcoholic beverage 7. Therefore, the alcohol concentration can be determined by linear approximation regardless of the type of alcoholic beverage 7. As mentioned above, the spectrum of Raman scattered light is less likely to interfere with peaks of other components than near-infrared spectroscopy, so high linearity can be achieved regardless of the type of alcoholic beverage 7, each of which has different component types. By applying the Raman intensity of the spectrum of the alcohol component of an alcoholic beverage 7 whose concentration is unknown according to this calibration curve, it is possible to determine the alcohol concentration universally for different types of alcoholic beverages 7. In this way, since the alcohol concentration can be determined according to a calibration curve that exhibits high linearity, it is possible to accurately measure the alcohol concentration universally for different types of alcoholic beverages 7 over a wide dynamic range from low to high concentrations compared to near-infrared spectroscopy. Furthermore, because the alcohol concentration can be evaluated simply by plotting a single spectral peak corresponding to the alcohol component, there is no need for a complex calibration curve for each different type of alcoholic beverage, as compared to near-infrared spectroscopy.

[0033] In this embodiment, alcohol analysis is performed by pouring an alcoholic beverage 7 into a container such as a vial and irradiating it with excitation light in the alcohol analyzer 1. Furthermore, if the container of the alcoholic beverage 7 is made of a material that allows light to pass through, it is also possible to analyze the alcoholic beverage 7 while it is contained in the container, without transferring it to a vial. Furthermore, the container does not have to be transparent, and it may be colored.

[0034] As described above, in this embodiment, by determining the alcohol concentration of an alcoholic beverage 7 using Raman scattered light, it is easier to distinguish the waveforms of multiple component types compared to near-infrared spectroscopy, which has difficulty accurately evaluating signals containing multiple component types, and alcohol analysis can be performed using a single device. Furthermore, alcohol concentration can be measured over a wide dynamic range, from low to high concentrations, which also makes it possible to perform alcohol analysis of multiple types of alcoholic beverages 7 using a single device. Furthermore, since the alcohol concentration can be evaluated simply by plotting a single peak, a complex calibration curve is not required. Furthermore, by changing the excitation wavelength to a higher wavelength, alcohol analysis can be performed across multiple types of alcoholic beverages 7 without being affected by autofluorescence.

[0035] It should be noted that the present invention is susceptible to various embodiments and modifications without departing from the broad spirit and scope of the present invention. Furthermore, the above-described embodiment is intended to illustrate one example of the present invention and does not limit the scope of the present invention. The above-described embodiments and modifications can be combined in any manner. Furthermore, even if some of the constituent elements of the embodiment are omitted as necessary, they will still fall within the scope of the technical idea of ​​the present invention.

[0036] The present invention can be widely applied to alcohol analyzers that determine the concentration of alcohol components contained in alcoholic beverages.

[0037] 1 Alcohol analyzer, 2 Light source, 3 Optical system, 4 Spectrometer, 5 Photodetector, 6 Processing unit, 7 Alcoholic beverage, 31 Collimating lens, 32 Bandpass filter, 33, 35 Reflecting mirror, 34 Dichroic mirror, 36 Objective lens, 37 Edge filter, 38 Condenser lens, A, B, C, D, E, F, G Beer, H Highball, I Gin, J Whiskey, K Absolute alcohol.

Claims

1. An alcohol analyzer comprising: a light source that emits excitation light; a spectroscope; an optical system that irradiates an alcoholic beverage with the excitation light and guides Raman scattered light emitted from the alcoholic beverage to the spectroscope; a photodetector that detects the spectrum of the Raman scattered light dispersed by the spectroscope; and a processing unit that determines the alcohol concentration of the alcoholic beverage from the spectrum of the Raman scattered light detected by the photodetector.

2. The alcohol analyzer according to claim 1, wherein the alcohol concentration is determined from the intensity of a Raman shift that indicates an alcohol component.

3. The alcohol analyzer according to claim 1 or 2, wherein the excitation light is light in a wavelength range longer than the visible light range.

4. The alcohol analyzer according to claim 3, wherein the wavelength of the excitation light is 830 nm.

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