JP2010008342A - Moisturizing force measuring method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for easily measuring a moisturizing force of an object material to be measured, such as hair of which water content changes with the change of a surrounding environment, namely a force to keep the water content of the object material. <P>SOLUTION: The method for measuring a moisturizing force includes the steps of determining reference moisture data at, at least, two levels of absolute temperatures T (K) for a material to be measured and determining the slope of a line on which 1/T (K<SP>-1</SP>) is plotted with logarithmic values lnw (mol/kg) of moisture contents w (mol/kg) of each determined reference moisture data. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a moisturizing power measuring method, and more particularly to a moisturizing power measuring method capable of non-destructively measuring moisturizing power using near infrared spectroscopy.

  Substances that change the amount of water that can be contained due to changes in the surrounding environment, such as skin, hair, fiber, paper, etc., depend on the amount of water contained in the substance for properties such as surface flexibility and elasticity. However, it is regulated by the water retention capacity.

  For example, hair is called a cuticle region (5 to 10 μm) containing a cuticle and a cell membrane complex (CMC), a cortex region (40 to 140 μm) containing cortex and CMC, and a medura (0 to 8 μm). Divided into layers. The cuticle is a combination of 4 to 8 colorless and transparent urine-like thin cells composed mainly of keratin. The CMC in the cuticle region adheres the cuticles and protects the cuticle from physical and chemical stimuli from the outside to prevent the hair components from flowing out.

  Of these, the cortex has a cigar shape, which is connected in the vertical direction and is relatively regularly arranged. The main component is keratin. Cortexes are bonded to each other by CMC in the cortex region, and CMC retains moisture and serves as a path for water and drugs. This cortex region occupies 85 to 90% of the whole hair, retains moisture, and determines the strength and hair color of the hair (depending on the melanin pigment in the cortex). It is said that the preferable property of hair “moisturizing” is that the cortex region contains moderate moisture (10 to 15%).

  It is important to analyze the properties of substances such as skin, hair, fiber, paper, and the like that change the amount of water that can be contained by changes in the surrounding environment by measuring their water content. As the measurement method, after measuring the mass of the substance to be measured under a certain environment, the mass of the substance dried at a high temperature (100 ° C. or higher) is measured, and the mass of the water mass to the dry substance is calculated. The method (mass method) has been widely adopted.

  In addition, near infrared rays in the wavelength range of 0.8 μm to 2.5 μm use electromagnetic waves with low energy, so that the sample is hardly damaged. That is, the present invention can be applied to samples in various states such as solid, powder, fiber, film, paste, liquid, solution, and gas that can be measured non-destructively and non-invasively. Near-infrared light has the advantage that water absorption intensity is considerably weaker than infrared light, making it easier to study and analyze in aqueous solution.

  Therefore, the reference moisture data is obtained for a plurality of sample skins using a skin moisture measuring device, and then the near infrared rays are irradiated to the same plurality of sample skins to detect the reflection spectrum, and the detected reflection spectrum is obtained. Separated into a calibration set and a verification set by an arbitrary extraction method, multivariate regression analysis of the reflectance spectrum and reference moisture data of the calibration set is performed to obtain a standard calibration formula, and this standard calibration formula is corrected using the verification set and stored in memory To do. Thereafter, the reflection spectrum is detected by irradiating the subject's skin with near infrared rays, and the detected spectrum is substituted into the already stored standard calibration formula to measure the skin moisture concentration of the subject (see Patent Document 1). ) A method has been proposed.

Alternatively, a calibration curve creating step of creating a calibration curve for the moisture content of the hair by irradiating a plurality of hair samples with known moisture amounts to obtain a plurality of diffuse reflection or transmission reflection spectrum data, and a subject's hair A moisture content measuring step comprising: directly irradiating near-infrared rays to obtain diffuse reflection or transmission reflection spectrum data and measuring the moisture content of the hair using the calibration curve. The method (refer patent document 2) etc. are proposed.
JP 2002-90298 A JP 2003-344279 A

  By the conventional method for measuring the amount of water as described above, the amount of water of the substance to be measured can be practically measured in the environment such as the temperature and humidity where it is placed. Attempts have also been made to capture the amount of moisture as a moisturizing power by individually measuring the amount of moisture of a substance to be measured according to environmental changes.

  However, in the above conventional method for measuring the amount of moisture, the amount of moisture in the environment is regarded as the moisturizing power at that time of the measurement target substance from each measurement, and the moisture retention power that each measurement target substance has as a characteristic is quantitatively determined. It was not something to express.

  Therefore, the present inventors have focused on the possibility that the amount of moisture of the measurement target substance that changes with temperature has a certain relationship with the property that it is difficult to lose moisture due to changes in the environment, and have reached the present invention. The purpose is to make it possible to quantitatively measure the moisturizing power unique to the substance to be measured.

In order to achieve the above object, the method of measuring the moisturizing power of the present invention is a step of obtaining reference moisture data at at least two levels of absolute temperature T (K) for a substance to be measured, and each obtained reference moisture data. The logarithm lnw (mol / kg) of the water content w (mol / kg) of 1 / T
The inclination of the straight line plotted against (K ⁻¹ ) is obtained. The unit (K ⁻¹ ) represents the reciprocal of the absolute temperature T (K).

Here, the moisturizing power measuring method of the present invention is a step of obtaining reference moisture data at at least two levels of absolute temperature T (K) for a measurement target substance using near infrared spectroscopy, and each of the above reference moisture data. To perform pre-processing calculations consisting of smoothing, Kubelka-Munk transformation, and normalization, to create a calibration curve using multiple regression analysis from each pre-processed reference moisture spectrum data, The step of irradiating near infrared rays to obtain reference moisture spectrum data at at least two levels of absolute temperature T (K) and calculating the moisture content of the substance to be measured using the calibration curve, and the moisture content of each obtained reference moisture data It includes determining the slope of a straight line in which the logarithm lnw (mol / kg) of the quantity w (mol / kg) is plotted against 1 / T (K ⁻¹ ).

As described above, the step of obtaining the reference moisture data at at least two levels of the absolute temperature T (K) for the measurement target substance of the present invention, the moisture amount w of each obtained reference moisture data
Quantitatively measure the moisturizing power specific to the substance to be measured by determining the slope of a straight line plotting the logarithm lnw (mol / kg) of (mol / kg) against 1 / T (K ⁻¹ ) Can do.

In addition, using near-infrared spectroscopy, a step of obtaining reference moisture data at at least two levels of absolute temperature T (K) for the measurement target substance, smoothing, Kubelka-Munk conversion, A step of performing pre-processing calculation consisting of normal standardization, a step of creating a calibration curve using multiple regression analysis from each reference moisture spectrum data subjected to the above pre-processing, and irradiating the measurement target substance with near infrared rays to at least two levels Calculating the moisture content of the substance to be measured using the above calibration curve, and calculating the logarithm lnw of the moisture content w (mol / kg) of each of the obtained reference moisture data By calculating the slope of the straight line (mol / kg) plotted against 1 / T (K ⁻¹ ), the external size such as temperature and humidity can be measured by a small portable near infrared spectrometer. It is stable and reproducible in the environment, and it is possible to measure moisture retention quickly and easily anywhere.

  Examples of substances to be measured to which the present invention can be applied include substances that can maintain desirable properties depending on the amount of water, such as hair, skin, paper, fibers, and foods. In particular, the method for measuring moisturizing power by near infrared spectroscopy can be used nondestructively, so it can be applied to substances that make up living organisms such as hair and skin, and food in packaging that is transparent to near infrared rays. It can be preferably applied.

  The absolute temperature T (K) of at least two levels in the present invention can usually be selected from the range of 273 K (0 ° C.) to 373 K (100 ° C.), preferably 293 K (20 ° C.) to 353 K (80 ° C.).

  In the present invention, the method for obtaining the reference moisture data may be any method that can measure the moisture content at the two levels of absolute temperature T (K), such as mass method, electrical conduction method, impedance method, color analysis method, near red color. An external spectroscopic method or the like can be used, and a near infrared spectroscopic method can be used particularly preferably.

In the present invention, the reference moisture data is expressed as a moisture content, and the moisture content is obtained by measuring the mass A (g) in a wet state and the mass B (g) in an absolute dry state at an absolute temperature T (K), and obtaining the following formula. .
(Equation 1)
Water content w (mol / kg) = ((A−B) ÷ molecular weight of water) ÷ (B ÷ 1000)
The unit (mol / kg) represents the weight of all hair components (keratin, oil, etc.) other than water, that is, the number of moles of water in the matrix.

The reason why the moisturizing power of the substance to be measured can be specified by the moisturizing power measuring method of the present invention is considered as follows when taking hair as an example. Considering the enthalpy of evaporation ΔH (kJ / mol) as the moisturizing power based on the fact that the moisture in the hair and the moisture evaporated from the hair reach equilibrium at a constant temperature,
(Equation 2)
∂ (ln [w]) / ∂ (1 / T) = ΔH / R
From the above formula, the logarithm lnw of the concentration w (mol / kg) of water present in the hair
(Mol / kg) is plotted against 1 / T (K ⁻¹ ), and the slope is R
By multiplying (= 0.0083145 kJ / (K · mol)), ΔH (kJ / mol) can be obtained.

∂ (lnw (mol / kg)) / ∂ (1 / T (K ⁻¹ )), that is, lnw (mol /
kg) vs. The slope of the 1 / T (K ⁻¹ ) plot corresponds to the evaporation enthalpy. Therefore, it is considered that the obtained slope ΔH (kJ / mol) can discuss the magnitude of the moisturizing power as compared with the evaporation enthalpy value of pure water (43.991 kJ / mol) at room temperature.

Moreover, conversion from the generally used water content w (%) to w (mol / kg) is obtained by the following formula.
(Equation 3)
Water content w (%) = ((A−B) ÷ A) × 100
(Equation 4)
Water content w (mol / kg) = (w (%) × 10) ÷ water molecular weight In the near-infrared spectroscopy, the water content w (%) is calculated by multiple regression analysis, and w (mol / kg) Evaporation enthalpy ΔH (kJ / mol) is determined in terms of.

  In the present invention, near-infrared spectroscopic analysis uses a light source that emits near-infrared light, divides this light and irradiates the sample, detects transmitted light or reflected light, and transmits light and reflectivity. It is an analysis method that converts to

  As a procedure for performing smoothing on each of the above-mentioned reference moisture data obtained by the near-infrared spectroscopy in the present invention, the near-infrared spectrum is observed by overlapping peaks due to many overtones and combined sounds. It becomes a peak and band assignment is not easy. By performing the second derivative on the original spectrum, a sharp peak is obtained, and peak assignment and quantification are possible. However, there are cases where no meaningful peak appears even if the original spectrum is subjected to second-order differentiation. This is because the secondary differential processing emphasizes small noise, and physical influences such as sample alignment and density affect diffuse reflection. In order to remove such influence, first, smoothing was performed using a moving average to remove noise.

Next, in the present invention, the linear approximation of the nonlinearity of absorbance in the diffuse reflection method is performed.
The absorbance of the original spectrum was converted by the formula derived from the Kubelka-Munk formula.
(Equation 5)
K (λ) / S (λ) = coshA (λ) −1
Here, K (λ) represents the absorption coefficient of the scattering material, S (λ) represents the scattering coefficient, and A (λ) represents the absorbance.

Further, in the present invention, it is necessary to perform normal standardization after the conversion. This is a processing method in which the influence of additive and multiplicative scattering factors is removed, and the absorbance values in the entire spectrum range are average 0 and standard deviation 1.
(Equation 6)
Normalized absorbance = (Absorbance An−Absorbance average) / Absorbance standard deviation

  The spectrum obtained by pre-processing the original spectrum as described above showed that peaks could be separated and assigned.

Hereinafter, with respect to the method for measuring the moisturizing power of the present invention, the hair is taken as an example, examples relating to measurement using the mass method, FIGS. 1 to 4, and examples relating to measurement using near infrared spectroscopy, 5
This will be described in detail with reference to FIG.

FIG. 1 is a flow chart showing the procedure of a method for measuring moisture retention by a mass method to which the present invention is applied, and FIG. 2 shows the amount of water w (g) in hair at a constant temperature with respect to the drying time (h). FIG. 3 is a graph in which the relationship between the drying temperature (° C.) and the moisture content (g) is individually graphed for each of the measurement objects A to J, and FIG. 4 is the moisture content w (mol / kg). ) Logarithm lnw (mol /
kg) is a table showing a straight line plotted with respect to 1 / T (K ⁻¹ ), and an evaporation enthalpy value and a vaporization enthalpy value of pure water calculated from the slope.

FIG. 5 is a flow chart showing the procedure of the method for measuring the moisturizing power by the near infrared spectroscopy, and FIG. 6 is a product made by IFS Japan Co., Ltd. which is a near infrared spectroscopic device of the moisturizing power measuring apparatus to which the present invention is applied. FIG. 7 is a block diagram schematically showing the configuration of PlaScan-W, FIG. 7 is an original hair spectrum for measurement objects A to J, and FIG. 8 is a graph showing smoothing, Kubelka-Munk conversion, normal standardization, It is a normal standardization 2nd derivative spectrum of the hair which gave the 2nd derivative treatment.

FIG. 9 shows the correlation between the prediction formula for obtaining the moisture content w (%) in hair and the selected wavelength, the actual measurement value (%) and the NIR prediction value (%) by applying multiple regression analysis to the normal standardized second derivative spectrum. FIG. 10 is a graph in which the logarithm lnw (mol / kg) of the water content w (mol / kg) obtained from the NIR spectrum is plotted against 1 / T (K ⁻¹ ), and the slope. 11 is a table showing the evaporation enthalpy value for each measurement object calculated from FIG. 11. FIG. 11 shows an actual measurement value (kJ / mol) of ΔH obtained from the mass method and a predicted NIR value (kJ / mol) obtained from the near infrared spectroscopy. mol).

  As shown in FIG. 1, the moisture content of the hair was first measured by the so-called mass method according to the procedures shown in (a) to (f) below. (Measurement by this mass method becomes basic data and may be referred to as an actual measurement value. In addition, a measurement value by near infrared spectroscopy may be referred to as a predicted value for this actual measurement value.) Ten or more pieces were cut and collected. The measurement targets were 21 to 23 year old men A to E5 and women F to J5 (including hair colors, permanents, and objects B and F without wave history).

Next, a) the moisture content of the hair was measured by washing it lightly with pure water and drying it, then placing it on a slide glass, and b) allowing it to stand at a constant temperature for 1 hour and measuring the mass. The standing was carried out by placing it in a constant temperature drier having an internal size of 30 cm long × 30 cm wide × 30 cm high. The standing temperature for one hour was increased from 20 ° C. (room temperature) by 10 ° C. and measured to 100 ° C. The reason why the maximum temperature was set to 100 ° C. was that no change in mass was observed at 100 to 130 ° C. At this time, the room temperature remains unchanged at 18 ° C. and 60% RH, and the relative humidity in the cabinet is 56.4% RH at 20 ° C., 37.5% RH at 30 ° C., 20.6% RH at 40 ° C., 50 ° C. And 13.4% RH. Also, the drying time was set to one hour, as shown in FIG. 2, the amount of water in the hair being dried at a constant temperature w.
This is because the time when (g) is constant, that is, the drying time (h) at which the evaporated moisture and the moisture in the hair reach equilibrium is one hour.

C) Obtain the weight at a temperature of two or more levels by weighing. Here, after measuring both the mass and the near-infrared spectrum, the sample allowed to stand for 1 hour was immediately left at the next temperature for 1 hour to perform the next measurement. The hair was allowed to stand at room temperature until it returned to its original state (even if the temperature was raised to 100 ° C., the hair changed its mass only by the evaporation of water, and when it was returned to room temperature, it absorbed water and returned to its original mass). The amount of water at that temperature was 0 g at 100 ° C., and the difference from the measured mass at that temperature. The moisture content of the hair is measured, and the gender (age), (one hour standing) measurement temperature (° C.), and moisture content (g) are shown in FIG.

In the procedure shown in FIG. 1 d), the molar molar concentration (mol / kg) is obtained from the water content w (g) shown in FIG. 3 by the equation shown in (Equation 1) and shown in FIG. In the procedure, taking the logarithm lnw (mol / kg) and taking these as the vertical axis, taking the reciprocal 1 / T (K ⁻¹ ) of the measured temperature converted to the absolute temperature T (K) as the horizontal axis, This is shown in FIG. As shown in FIG. 4, straight lines having different slopes can be drawn depending on the measurement objects A to J.

In the procedure shown in FIG. 1), the slope of this straight line is expressed as R by the equation shown in (Expression 2).
Multiplying (= 0.0083145 kJ / (K · mol)) to calculate ΔH (kJ / mol), it was distributed between 25 to 48 kJ / mol with respect to measurement objects A to J. These ΔH (kJ / mol) are calculated from the enthalpy value of pure water at room temperature (43.991 kJ / mol).
mol), the magnitude of the moisturizing power can be discussed. In other words, it can be said that the greater the amount of water at room temperature, the more moisturized the hair is.

  Next, the moisturizing power measuring method by the near-infrared spectroscopy of the present invention will be described in detail with reference to FIGS.

  FIG. 5 shows the measurement procedure by the near-infrared spectroscopic method. FIG. 6 is a block diagram schematically showing the configuration of a moisture retention measuring device by near infrared spectroscopy to which the present invention is applied. In the present invention, PlaScan-W manufactured by IFS Japan Co., Ltd. is used. The specifications are as follows.

Body dimensions: 220 length x 110 width x 40 thickness (unit: mm)
Mass: 0.6kg
Spectroscopy 1: Acousto-optic tunable filter (AOTF)
Wavelength range: 1200-2400 nm
Measurement time: 0.1 to 1 second Measurement method: Measurement by transmission reflection method or diffuse reflection method. Contact measurement on measurement object 2 (measurement is difficult for black objects with slight reflection, white ceramic plate is used as reflector 3 for transparent and translucent objects)

Spot diameter: 0.8-2mm
Light receiving element 4: light receiving grating is PbS
Light source 5: Tungsten / halogen lamp Resolution: 0.6 nm
Method: Bragg diffraction (one bundle of light for two bundles of Raman-Nath diffraction)
Crystal: Tellurium dioxide vibrator: Piezo element frequency: about 30-90 MHz

  In this Example 2, measurement was performed on the hairs of the same measurement objects A to J as in the measurement by the mass method of Example 1, but this near-infrared spectroscopic analysis method requires almost no pretreatment on the measurement object substance and is non-contact and near-by. Since it is a method of irradiating with infrared rays, it can be said to be a nondestructive analysis method. In Example 2, measurement can be performed according to the following procedure according to FIG.

A white ceramic plate (attached to PlaScan-W) was used as a reference material for transmission and reflection (blank). The measurement object 2 was placed on the ceramic reflector 3, and the ceramic reflector 3 and the PlaScan-W window were brought into close contact with each other for measurement.

  To measure the hair, lightly wash with pure water as shown in Fig. 5 (a) and dry it, then place it on a slide glass and leave it at a constant temperature for 1 hour using the above-mentioned electric drying cabinet in the procedure shown in (b). The near-infrared spectrum was measured simultaneously with the mass of Example 1.

  When measuring the near-infrared spectrum in the procedure shown in (c), a cover glass was placed from above. In addition, the measurement was performed in a state where 10 hairs were bundled so as not to overlap so as not to overlap and were stretched straight.

  FIG. 7 shows the original spectrum of the hairs related to the measurement objects A to J measured in the procedure of FIG. 1C), with the absorbance A on the vertical axis and the wavelength λ (nm) on the horizontal axis. As a procedure for performing smoothing on the original spectrum obtained by the near-infrared spectroscopy in the present invention, second derivative is performed on the original spectrum, but the second derivative process emphasizes small noise or Physical effects such as sample alignment and density may affect diffuse reflection. In order to remove such an influence, first, smoothing is performed using a moving average to remove noise.

In the procedure shown in d), smoothing the raw spectrum shown in FIG. 7, Kubelka-Munk conversion, normalization standardization, secondary differential processing is subjected to second derivative absorbance d ² A / dλ ² placed vertically, the wavelength lambda ( nm) on the horizontal axis, a normal standardized second derivative spectrum of hair as shown in FIG. 8 is obtained.

  Furthermore, the data processing of the multiple regression analysis is performed in the procedure indicated by the normal standardized second derivative spectrum as shown in e). However, in order to facilitate the analysis by Excel or the like, each of the 800 data points of PlaScan-W is a moving average (n = 4). And 200 data points were used. For the multiple regression analysis, free software multiple regression variable selection 1 (Tojigi Prefectural Agricultural Experiment Station, Seiji Mori) was downloaded and used.

FIG. 9 is a graph showing the correlation between the prediction formula for determining the moisture content w (%) in the hair thus obtained, its selected wavelength, the actual measurement value (%), and the NIR prediction value (%). The correlation between the ^two is r ² =
It was 0.96, and it was found that a good calibration curve was obtained by multiple regression analysis, and the moisture content w (%) of the hair could be predicted from the NIR spectrum.
The NIR predicted value w (%) for the actual value obtained by the mass method from the calibration curve is converted to w (mol / kg) by the formula shown in (Equation 4), and the logarithmic lnw (mol / kg) is calculated. FIG. 10 shows a straight line plotted against 1 / T (K ⁻¹ ). A straight line can be drawn for the measurement objects A to J. In the procedure shown in (g), R
Multiply (= 0.0083145 kJ / (K · mol)) to calculate ΔH (kJ / mol).

In FIG. 11, a graph showing the correlation between the actually measured value of ΔH obtained from the mass method (kJ / mol) and the predicted NIR value obtained from the near infrared spectroscopy (kJ / mol) is obtained. r ² = 0.99, and it was found that the evaporation enthalpy ΔH (kJ / mol) can be predicted from the NIR spectrum. Measured value w (%) and predicted value w of calibration curve obtained by multiple regression analysis
Since the correlation with (%) is good, the correlation with w (mol / kg) is also considered to be good. From this, it is considered that the moisture retention power specific to the substance to be measured can be quantitatively measured, and the moisture retention capacity can be measured using the NIR method suitable for nondestructive inspection.

As described above, the present invention obtains the reference moisture data at at least two levels of the absolute temperature T (K) for the substance to be measured, and the moisture content w of each obtained reference moisture data.
Since the moisturizing power measurement method is characterized in that the logarithm lnw (mol / kg) of (mol / kg) is obtained by calculating the slope of a straight line plotted against 1 / T (K ⁻¹ ), Moisturizing power of skin, fibers, paper or food can be quantitatively measured.

It is a flowchart which shows the procedure of the moisture retention measuring method by the mass method to which this invention was applied. It is the graph which plotted the moisture content w / g in the hair under fixed temperature with respect to drying time / h. The relationship between the drying temperature / ° C. and the amount of moisture / g is graphed individually for each of the measurement objects A to J. It is the table | surface of (DELTA) H / kJ / mol computed from the straight line which plotted the logarithm lnw / mol / kg of water content w / mol / kg with respect to 1 / T / K < ^-1 >, and each inclination. It is a flowchart which shows the procedure of the moisture retention measuring method by a near-infrared spectroscopy. The block diagram which showed schematically the structure of PlaScan-W by IFS Japan Co., Ltd. which is a near-infrared spectrometer of the moisture retention measuring apparatus to which this invention was applied. It is the original spectrum of the hair about measurement object AJ. It is a normal standardized second derivative spectrum of hair obtained by performing smoothing, Kubelka-Munk conversion, normal standardization, and second derivative processing on the original spectrum. It is the graph which showed the correlation of the prediction formula which applies the multiple regression analysis to a normal standardization secondary differential spectrum, and calculates | requires the moisture content w /% in hair, its selection wavelength, actual measurement value /%, and NIR prediction value /%. The water content w /% determined from the NIR spectrum was converted to w / mol / kg, and the logarithm lnw / mol / kg was calculated from the straight line plotted against 1 / T / K ⁻¹ and ΔH calculated from the respective slopes. It is a table of / kJ / mol. It is the graph which showed the correlation with the measured value kJ / mol of (DELTA) H calculated | required from the mass method, and the NIR prediction value kJ / mol calculated | required from the near-infrared spectroscopy.

Explanation of symbols

1: Acousto-optic tunable filter (AOTF)
2: Measurement object 3: Reflector (ceramic)
4: Light receiving element 5: Light source

Claims (2)

A step of obtaining reference moisture data at at least two levels of absolute temperature T (K) for the substance to be measured, a logarithm lnw of the moisture content w (mol / kg) of each obtained reference moisture data
A method for measuring moisture retention by determining the slope of a straight line in which (mol / kg) is plotted against 1 / T (K ⁻¹ ). A step of obtaining reference moisture data at an absolute temperature T (K) of at least two levels for a measurement target substance using near-infrared spectroscopy, smoothing the reference moisture data,
The stage of performing pre-processing calculations consisting of Kubelka-Munk conversion and normalization, the stage of creating a calibration curve using multiple regression analysis from each reference moisture spectrum data that has been subjected to the above pre-processing, Irradiating to obtain reference moisture spectrum data at at least two levels of absolute temperature T (K) and calculating the moisture content of the substance to be measured using the calibration curve, the moisture content w (mol / mol) of each obtained reference moisture data log) lnw (mol / kg) of 1 / T
A method for measuring a moisturizing power by a near infrared spectroscopic analysis method, wherein the slope of a straight line plotted against (K ⁻¹ ) is obtained.