Faculty Profiles - INAGAKI Tetsuya

Papers - INAGAKI Tetsuya

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Near infrared estimation of concentration of ginsenosides in Asian ginseng Reviewed

Tetsuya Inagaki, Norihisa Katayama, Rae-Kwang Cho, Xijun Chen, Satoru Tsuchikawa

JOURNAL OF NEAR INFRARED SPECTROSCOPY Vol. 27 ( 2 ) page： 115 - 122 2019.4

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal) Publisher：SAGE PUBLICATIONS LTD

In this study, the feasibility of near infrared reflectance spectroscopy for the quality evaluation of the main bioactive compounds, ginsenosides, in Panax ginseng was examined. Second derivative NIR spectra of standard reagents of ginsenoside Rg(1), Re, Rb-1, Rc, Rb-2 and Rd were used for analysis. Characteristic bands were observed at around 5250 cm(-1) in the spectra of ginsenoside Rg(1) group (including Rg(1) and Re); however, this was not to be observed on the spectra of ginsenoside Rb-1 group (including Rb-1, Rc, Rb-2 and Rd). PLS regression models were constructed of air-dry ginseng powder samples and ginsenoside content in ginsengs was determined by HPLC methods. The calibration models covered various types of ginseng (white ginseng, red ginseng and bleached ginseng) from various cultivated areas (Japan, China and Korea) and were well established for each kind of ginsenoside. It was shown that NIR spectroscopy can be used for the accurate prediction of ginsenoside.

DOI： 10.1177/0967033518814851

Rapid identification of wood species by near-infrared spatially resolved spectroscopy (NIR-SRS) based on hyperspectral imaging (HSI) Reviewed

Te Ma, Tetsuya Inagaki, Mayuka Ban, Satoru Tsuchikawa

HOLZFORSCHUNG Vol. 73 ( 4 ) page： 323 - 330 2019.4

Language：English Publishing type：Research paper (scientific journal) Publisher：WALTER DE GRUYTER GMBH

Conventional near-infrared (NIR) spectroscopy has shown its potential to separate wood species nonde-structively based on the aggregate effect of light absorption and scattering values. However, wood has an aligned microstructure, and there is a large refractive index (RI) mismatch between the wood cell wall substance (n approximate to 1.55) and the cell lumen (air approximate to 1.0, water approximate to 1.33). Light scattering is dominant over absorption (mu(s)' >> mu(a)) in wood, and this fact can be utilized for complex classification purposes. In this study, an NIR hyperspectral imaging (HSI) camera combined with one focused halogen light source (empty set 1 mm) was designed to evaluate the light scattering patterns of five softwood (SW) and 10 hardwood (HW) species in the wavelength range from 1002 to 2130 nm. Several parameters were combined to improve the data quality, such as image histogram plots of defined spaced bins (associated with diffuse reflectance values of light), variance calculation on the frequency (the number of pixels in each bin) of each histogram and the principal component analysis (PCA) of all the variance values at each wavelength. The identification accuracy of the quadratic discriminant analysis (QUA) under the five-fold cross-validation method was 94.1%, based on the first three principal component (PC) scores.

DOI： 10.1515/hf-2018-0128

DETERMINATION OF CAROTENOIDS AND DOBI CONTENT IN CRUDE PALM OIL BY SPECTROSCOPY TECHNIQUES: COMPARISON OF RAMAN AND FT-NIR SPECTROSCOPY Reviewed

Rayakorn Nokkaew, Vittaya Punsuvon, Tetsuya Inagaki, Satoru Tsuchikawa

INTERNATIONAL JOURNAL OF GEOMATE Vol. 16 ( 55 ) page： 92 - 98 2019.3

Language：English Publishing type：Research paper (scientific journal) Publisher：GEOMATE INT SOC

Crude palm oil (CPO) is a rich source of carotenoids which are a precursor of vitamin A as an important antioxidant. Carotenoids and Deterioration Of Bleachability Index (DOBI) are important factors to indicated quality of CPO. The conventional method for DOBI and carotenoids determination use UV-Vis spectrophotometry and HPLC, respectively which methods use solvents and spend time for analysis. This research interests Raman and FT-NIR spectroscopy for carotenoids and DOBI determination due to those techniques are an alternative technique for rapid measurement, non-destruction of material, and environmental suitability. The results indicated that Raman is better for determination than FT-NIR spectrometry. In Raman analysis, multiplicative scatter correction (MSC) and standard normal variate (SNV) treated methods were the best models for carotenoids and DOBI, respectively. The bands of carotenoids were at 1,100 and 1,500 cm(-1) wavenumber. Validation on carotenoids produced 0.94 of correlation coefficient (R), 0.88 of coefficient of determination (R-2), 40.65 ppm of root mean square error of prediction (RMSEP) and 3.25 of the ratio of standard error of prediction to standard deviation (RPD). The validation of DOBI produced 0.76 of R, 0.57 of R-2, 0.31 of RMSEP, 1.92 of RPD of 1.92. The limitation of carotenoids and DOBI determination using FT-NIR is having sufficient concentration of carotenoids for analysis. In addition, data for various samples regarding location, season, and oil palm species are important to build models for precise prediction.

DOI： 10.21660/2019.55.4813

Effect of knots and holes on the modulus of elasticity prediction and mapping of sugi (Cryptomeria japonica) veneer using near-infrared hyperspectral imaging (NIR-HSI) Reviewed

Imran Arra'd Sofianto, Tetsuya Inagaki, Te Ma, Satoru Tsuchikawa

HOLZFORSCHUNG Vol. 73 ( 3 ) page： 259 - 268 2019.3

Language：English Publishing type：Research paper (scientific journal) Publisher：WALTER DE GRUYTER GMBH

Naturally occurring knots reduce the mechanical strength of wood. Veneers from sugi (Cryptomeria japonica) served as research material to study the effect of knots and holes. Veneer samples were first subjected to a three-point bending test to obtain measured modulus of elasticity (MOE) values. Then, near-infrared (NIR) hyperspectral imaging (HSI) was used to construct a prediction model and map the predicted MOE values. This is the first attempt for MOE prediction from the entire veneer surface based on NIR-HSI technology, while the mathematical part relies on chemometrics and cross-validation partial least squares regression (CV-PLSR). Maps of MOE prediction values could distinguish between latewood (LW) and earlywood (EW), as well as between a sound knot and a dead knot.

DOI： 10.1515/hf-2018-0060

Non-destructive evaluation of wood stiffness and fiber coarseness, derived from SilviScan data, via near infrared hyperspectral imaging Reviewed

Te Ma, Tetsuya Inagaki, Satoru Tsuchikawa

JOURNAL OF NEAR INFRARED SPECTROSCOPY Vol. 26 ( 6 ) page： 398 - 405 2018.12

Language：English Publishing type：Research paper (scientific journal) Publisher：SAGE PUBLICATIONS LTD

Near infrared hyperspectral imaging combined with partial least squares regression analysis was used to evaluate wood stiffness (modulus of elasticity) and fiber coarseness. Five samples with normal wood and compression wood collected from two Japanese Cedar (Cryptomeria japonica) trees were analyzed. To achieve high reliability of the prediction values, a SilviScan system (X-ray densitometry, X-ray diffractometry, and optical microscopy) with the high spatial resolution was used for measuring reference data. The measurement interval for modulus of elasticity and fiber coarseness was 1 mm and 25 mu m, respectively. After spectral pre-treatment and key wavelengths selection, partial least squares analysis was applied to calibrate near infrared data to reference values. The determination coefficient (R-CV(2)) of modulus of elasticity was 0.66 with a root mean square error of cross validation (RMSECV) of 1.80 GPa. For the constructed fiber coarseness calibration model, R-CV(2) and RMSECV were 0.62 and 35.02 mu m/g, respectively. Finally, modulus of elasticity and fiber coarseness mapping results show detailed information (156 mu m/pixel) at the grown ring level. The differences among earlywood, latewood, and compression wood were all well identifiable.

DOI： 10.1177/0967033518808053

Inspection of Microfibril Angle of Sugi Wood by THz-TDS Reviewed

H. Wang, S. Tsuchikawa, T. Inagaki

International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz Vol. 2018-September 2018.10

Authorship：Last author,　Corresponding author Publishing type：Research paper (international conference proceedings)

Wood as a biological material has large differences in individual properties, and terahertz time-domain spectroscopy (THz-TDS) provide a new possibility for the wood products industry since THz exhibits high transparency to wood with big birefringence and diattenuation. By using the complex refractive index and absorption coefficient, THz is excepted to estimate important properties such as fiber orientation, microfibril angle (MFA) etc. simultaneously. In this study, sugi was used as sample because of its simple structure. Density and moisture content were predicted by using the real part of complex refractive index combined with absorption coefficient and showed a high correlation between measured and predicted values, prediction of MFA is still an ongoing mission.

DOI： 10.1109/IRMMW-THz.2018.8510303

Optical characteristics of Douglas fir at various densities, grain directions and thicknesses investigated by near-infrared spatially resolved spectroscopy (NIR-SRS) Reviewed

Te Ma, Gary Schajer, Tetsuya Inagaki, Zarin Pirouz, Satoru Tsuchikawa

HOLZFORSCHUNG Vol. 72 ( 9 ) page： 789 - 796 2018.9

Language：English Publishing type：Research paper (scientific journal) Publisher：WALTER DE GRUYTER GMBH

A near-infrared spatially resolved spectroscopy (NIR-SRS) system, also called the hyperspectral imaging system, was applied in a line scanning model combined with a concentrated halogen light source (empty set 1 mm), and spatially resolved reflectance images of Douglas fir [Pseudotsuga menziesii (Mirb.) Franco] wood were obtained. The samples with various densities, grain directions and thicknesses were observed in the NIR range of 1000-1600 nm. Then, a nonlinear curve-fitting algorithm was applied based on the steady-state diffusion theory model to estimate the absorption coefficient (mu'(s)), and reduced scattering coefficients (mu(a)),( )both parallel and perpendicular to the grain direction at each measurement position. The absorption scattering coefficients at 1457 nm and two kinds of reduced scattering coefficients at 1002 nm were highly correlated with wood densities measured by an X-ray densitometer. The correlation coefficients were 0.953 and 0.987 for 3 mm and 5 mm samples, respectively, while three optical profiles were combined. It can be concluded that NIR-SRS is a fast and simple method for measuring the optical characteristics of softwood, although it has a non-homogeneous cellular structure. Sub-surface density and grain direction could be predicted with satisfactory accuracy based on a few key wavelengths without relying on multivariate statistical analysis.

DOI： 10.1515/hf-2017-0213

Determination of physical and chemical properties and degradation of archeological Japanese cypress wood from the Tohyamago area using near-infrared spectroscopy Reviewed

Tetsuya Inagaki, Hitoshi Yonenobu, Yuuki Asanuma, Satoru Tsuchikawa

JOURNAL OF WOOD SCIENCE Vol. 64 ( 4 ) page： 347 - 355 2018.8

Authorship：Lead author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：SPRINGER JAPAN KK

Here, we evaluated the application of near-infrared (NIR) spectroscopy for estimating the degradation level of archeological wood samples from the Tohyamago area, the dendrochronological ages of which were also determined. The wood samples were radially cut from three logs obtained from the Tohyamago area. NIR reflectance spectra were measured from the tangential faces of air- and oven-dried wood samples using a Fourier transform NIR spectrophotometer. The second derivative spectra within the wavenumber range of 6400-5200 cm(-1), in which the effect of moisture content in wood is suspected to be insignificant, showed a characteristic behavior with age. By comparing the second derivative spectral change in our wood samples with that in wood degraded by aging, thermal treatment, fungal attack, and lightning reported in the literature, we found that the second derivative spectra of wood samples from one log was similar to those of wood degraded by hygro-thermal treatment, whereas those of wood samples from another log was similar to those of wood degraded by brown-rot fungi. The physical and chemical properties of archeological wood were well predicted using a combination of partial least square regression analysis and NIR spectroscopy.

DOI： 10.1007/s10086-018-1718-8

Noncontact evaluation of soluble solids content in apples by near-infrared hyperspectral imaging Reviewed

Te Ma, Xinze Li, Tetsuya Inagaki, Haoyu Yang, Satoru Tsuchikawa

JOURNAL OF FOOD ENGINEERING Vol. 224 page： 53 - 61 2018.5

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCI LTD

Near-infrared (NIR) hyperspectral imaging was used to evaluate soluble solids content (SSC) in 'Fuji' apples [Malus sylvestris (L.) Mill. var. domestica (Borkh. Mansf.)]. Eighty 'Fuji' apples were analyzed by collecting four small block samples from each one (approximately 2.0 cm x 2.0 cm x 1.5 cm). Partial least squares (PLS) regression analysis was performed to determine the relation between SSC reference data and NIR spectral data measured from each sample. The cross-validation coefficient of determination (r(2)) between predicted and measured SSC values is 0.89 with a root mean squared error of cross-validation (RMSECV) of 0.55%. Then, we successfully mapped SSC at a high spatial resolution (375 mu m per pixel). In addition, the absorption and reduced scattering coefficients of the measured samples were determined based on a diffusion theory model. The absorption coefficients are positively correlated to the SSC values (chemical information), whereas water cored tissue content (physical information) causes a characteristic change in light scattering coefficients. The fitting results were validated by Monte Carlo simulation, and the light penetration depth in 'Fuji' apples was estimated to be around 033 cm at 1198 nm and 0.17 cm at 1450 nm, respectively. (C) 2017 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.jfoodeng.2017.12.028

Selective assessment of duplex heat-treated wood by near-infrared spectroscopy with principal component and kinetic analyses Reviewed

Tetsuya Inagaki, Yuuki Asanuma, Satoru Tsuchikawa

JOURNAL OF WOOD SCIENCE Vol. 64 ( 1 ) page： 6 - 15 2018.2

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal) Publisher：SPRINGER JAPAN KK

We selectively assessed the thermal and hygrothermal treatment times of duplex heat-treated samples from the softwood hinoki cypress (Chamaecyparis obtusa) and the hardwood Japanese zelkova (Zelkova serrata) using near-infrared (NIR) spectroscopy with principal component analysis (PCA) and spectral-kinetic analysis. Wood samples from each species were thermally or hygrothermally treated at 120, 130, 150, and 180 A degrees C, and the second-derivative spectra of these samples in the 6300-5450 cm(-1) range, where moisture content has the smallest effect, were then subjected to PCA. The master curve that was calculated by kinetic analysis successfully explained changes in the first principal component (PC1) scores with thermal treatment time for all temperatures. The angles between the PC1 loadings that explained the spectral variation due to thermal and hygrothermal treatment were 79A degrees for hinoki and 80A degrees for zelkova. Thus, calculation of the inner product between the second-derivative spectra of duplex heat-treated wood and a loading vector that explained the spectral variation due to thermal or hygrothermal treatment allowed us to selectively assess the thermal and hygrothermal treatment times.

DOI： 10.1007/s10086-017-1670-z

Effect of cellular structure on the optical properties of wood Reviewed

Mayuka Ban, Tetsuya Inagaki, Te Ma, Satoru Tsuchikawa

JOURNAL OF NEAR INFRARED SPECTROSCOPY Vol. 26 ( 1 ) page： 53 - 60 2018.2

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal) Publisher：SAGE PUBLICATIONS LTD

To construct robust calibrations of wood properties by near infrared spectroscopy, one must independently evaluate the spectral contributions of light absorption and light scattering. However, the light propagation in wooden cellular structures is difficult to interpret because these structures are complex, heterogeneous, and anisotropic. This study investigates the reduced scattering coefficients of softwood and hardwood (with ring-porous or diffuse-porous vessels) at 846 nm by time-resolved spectroscopy. It also evaluates the effect of wooden cellular structure and air-dry density on the light propagation. After determining the reduced scattering coefficients, we observed cross-sectional microscopic images of the wood samples. Eighty-five percent of the variation in the reduced scattering coefficients was explainable by the air-dry density, area ratio of the cell wall, and the median pore area. Monte Carlo simulations of the light propagation through wood revealed that most of the photon transport occurs in the cell-wall substance.

DOI： 10.1177/0967033518757233

A novel combined application of capacitive method and near-infrared spectroscopy for predicting the density and moisture content of solid wood Reviewed

Vu Thi Hong Tham, Tetsuya Inagaki, Satoru Tsuchikawa

WOOD SCIENCE AND TECHNOLOGY Vol. 52 ( 1 ) page： 115 - 129 2018.1

Language：English Publishing type：Research paper (scientific journal) Publisher：SPRINGER

The use of a capacitive method and near-infrared (NIR) spectroscopy to simultaneously predict the density and moisture content (MC) of wood samples was investigated. Prediction accuracy of both methods was individually investigated by multivariate analyses. The capacity and absorbance at two wavelengths in the NIR range were combined to predict both the properties by the specific models. All wavelength combinations in the range of 908-1676 nm were tested, and the best combination yielding the highest coefficient of determination (R (2)) was chosen. This novel method showed a strong correlation between predicted and measured data, independent of sample thickness and wood species. The prediction accuracy of the wood samples, from green wood to oven-dried conditions, showed promising results for all thicknesses, with R (2) = 0.79, root-mean-square error of cross-validation (RMSECV) = 0.10 g/cm(3), and residual predictive deviation (RPD) = 2.22 for density and R (2) = 0.80, RMSECV = 25.70%, and RPD = 2.22 for MC. In the case of below fiber saturation point to oven-dried state, R (2) value was slightly decreased in the prediction of MC and slightly increased in the prediction of density, but RMSECV of MC declined significantly (maximum 5.46%) compared to the range of MC from saturated point (maximum 39.56%). These results were considerably better than those obtained by modeling the capacitive or NIR method individually, and improvement was particularly apparent in estimating density. The results suggest the possibility of a new device combining the capacitive method and NIR spectroscopy to predict density and MC more accurately.

DOI： 10.1007/s00226-017-0974-x

Near-infrared hyperspectral imaging for classification of mung bean seeds Reviewed

Kaewkarn Phuangsombut, Te Ma, Tetsuya Inagaki, Satoru Tsuchikawa, Anupun Terdwongworakul

INTERNATIONAL JOURNAL OF FOOD PROPERTIES Vol. 21 ( 1 ) page： 799 - 807 2018

Language：English Publishing type：Research paper (scientific journal) Publisher：TAYLOR & FRANCIS INC

Hard mung bean seeds pose a problem in the sprouting process as they develop mold and infect neighboring seeds. Near-infrared hyperspectral imaging combined with partial least squares discriminant analysis was applied to develop a classifying model to separate hard mung beans from normal ones. The orientation of the measured beans was found to affect the classification result. The optimal partial least squares discriminant analysis model based on all orientations resulted in a correlation coefficient (R) of 0.919 with a root mean squared error of prediction of 0.197. The non-germinative parts were mapped and were concentrated at one end of the bean. Finally, a germinability index was proposed according to the proportion of colored areas between the germinative and non-germinative parts from the hyperspectral imaging results.

DOI： 10.1080/10942912.2018.1476378

Quality Evaluation of Engineered Wood by THz-TDS Reviewed

Moe Kashima, Satoru Tsuchikawa, Tetsuya Inagaki

2018 43RD INTERNATIONAL CONFERENCE ON INFRARED, MILLIMETER, AND TERAHERTZ WAVES (IRMMW-THZ) Vol. 2018-September 2018

Authorship：Last author,　Corresponding author Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

This study attempts simultaneous prediction of grain angle, density and moisture content by THz time domain spectroscopy (THz-TDS) which has sufficient spatial resolution and transparency for wood. Terahertz waves transmitted through wood contain information on moisture content, density, grain angle and crystallinity of the sample. In this study, we measured spectra of 14 kinds of wood (5 soft wood, 9 hard woods) at various moisture contents and air-dried douglas fir while rotating the sample against the polarization of the terahertz wave. It was shown that the fiber orientation, density and moisture content of wood can be predicted simultaneously from the calculated complex permittivity.

DOI： 10.1109/IRMMW-THz.2018.8510155

Dynamic behavior of wood chemical components under drying process measured by near infrared spectroscopy Reviewed

Shiho Sugii, Takaaki Fujimoto, Harusa Tsutsumi, Tetsuya Inagaki, Satoru Tsuchikawa

JOURNAL OF NEAR INFRARED SPECTROSCOPY Vol. 25 ( 6 ) page： 400 - 406 2017.12

Language：English Publishing type：Research paper (scientific journal) Publisher：SAGE PUBLICATIONS LTD

This study examined the dynamic behavior of wood chemical components during the drying process using near infrared spectroscopy. Principal component analysis and generalized two-dimensional correlation spectroscopy were applied to identify significant absorption bands from the heavily overlapping near infrared spectra. The near infrared spectra were successively acquired over the moisture content range of 60-11%. The principal component analysis scores indicated that the wood-water interaction in the moisture content range of 60-46% significantly differed from that in the range of 45-11%. The synchronous 2D correlation spectrum constructed from the spectra in the moisture content range of 60-46% revealed that the cell wall components and water molecules responded to the drying process even though the wood exceeded the fiber saturation point. In the moisture content range of 45-11%, the H-bonded OH groups in the crystalline region of cellulose clearly increased with the decrease in bound water. Moreover, the sequential order of events was also clarified from the asynchronous spectrum.

DOI： 10.1177/0967033517733379

High-Resolution and Non-destructive Evaluation of the Spatial Distribution of Nitrate and Its Dynamics in Spinach (Spinacia oleracea L.) Leaves by Near-Infrared Hyperspectral Imaging Reviewed

Hao-Yu Yang, Tetsuya Inagaki, Te Ma, Satoru Tsuchikawa

FRONTIERS IN PLANT SCIENCE Vol. 8 2017.11

Language：English Publishing type：Research paper (scientific journal) Publisher：FRONTIERS MEDIA SA

Nitrate is an important component of the nitrogen cycle and is therefore present in all plants. However, excessive nitrogen fertilization results in a high nitrate content in vegetables, which is unhealthy for humans. Understanding the spatial distribution of nitrate in leaves is beneficial for improving nitrogen assimilation efficiency and reducing its content in vegetables. In this study, near-infrared (NIR) hyperspectral imaging was used for the non-destructive and effective evaluation of nitrate content in spinach (Spinacia oleracea L.) leaves. Leaf samples with different nitrate contents were collected under various fertilization conditions, and reference data were obtained using reflectometer apparatus RQflex 10. Partial least squares regression analysis revealed that there was a high correlation between the reference data and NIR spectra (r(2) = 0.74, root mean squared error of cross-validation = 710.16 mg/kg). Furthermore, the nitrate content in spinach leaves was successfully mapped at a high spatial resolution, clearly displaying its distribution in the petiole, vein, and blade. Finally, the mapping results demonstrated dynamic changes in the nitrate content in intact leaf samples under different storage conditions, showing the value of this non-destructive tool for future analyses of the nitrate content in vegetables.

DOI： 10.3389/fpls.2017.01937

The effect of path length, light intensity and co-added time on the detection limit associated with NIR spectroscopy of potassium hydrogen phthalate in aqueous solution Reviewed

Tetsuya Inagaki, Tomoko Watanabe, Satoru Tsuchikawa

PLOS ONE Vol. 12 ( 5 ) page： e0176920 2017.5

Authorship：Lead author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：PUBLIC LIBRARY SCIENCE

Near infrared (NIR) spectroscopy is a common means of non-invasively determining the concentrations of organic compounds in relatively transparent aqueous solutions. Rigorous determination for limit of detection (LOD) is of importance for the application use of NIR spectroscopy. The work reported herein determined the LOD with the analysis of potassium hydrogen phthalate (KHP) in water with partial least square (PLS) calibration in the range of 6300 - 5800 cm (-1) between the two strong absorption bands of water, in which the C-H overtone bands of KHP are located. A comparison of the LOD estimated when using various condition (path length, aperture and co-added scan times) showed that the lowest LOD for KHP obtained with a fiber optic cable attachment equipped NIR spectrometer is approximately 150 ppm.

DOI： 10.1371/journal.pone.0176920

Calibration of SilviScan data of Cryptomeria japonica wood concerning density and microfibril angles with NIR hyperspectral imaging with high spatial resolution Reviewed

Te Ma, Tetsuya Inagaki, Satoru Tsuchikawa

HOLZFORSCHUNG Vol. 71 ( 4 ) page： 341 - 347 2017.4

Language：English Publishing type：Research paper (scientific journal) Publisher：WALTER DE GRUYTER GMBH

Wood density and microfibril angle (MFA) are strongly correlated with wood stiffness, swelling/shrinkage, and its anisotropy. Understanding the spatial distribution of these data is critical for solid timber applications. In this study, near-infrared (NIR) hyperspectral imaging has been calibrated for evaluation of wood density and MFA in an effective manner. Briefly, five wood samples collected from both normal wood (NW) and compression wood (CW) moieties of two different Cryptomeria japonica trees were analyzed. Partial least squares (PLS) regression analysis was performed to determine the relationship between X-ray densitometry data obtained by SilviScan and NIR spectra, and cross-validation (leave-one-out) approach served for prediction performances. The validation coefficient of determination (r(2)) between the predicted densities by the NIR technique and the X-ray data was 0.83 with a root mean squared error of cross-validation (RMSECV) of 105.2 kg m(-3). Regarding MFA, the r(2) was 0.77 and RMSECV 5.36 degrees. Wood density was successfully maped as well as the MFA at a high spatial resolution. As a result, the detection of annual growth ring features and evaluation of aspects of heterogeneous wood quality has been facilitated. The mapping results were visually checked by looking at the difference between earlywood (EW) and latewood (LW) for density and by means of the Maule color reaction indicating high lignin contents in CW in terms of MFA validation as CWs have high MFA values.

DOI： 10.1515/hf-2016-0153

Classification of mung bean seeds for sprout production using near-infrared spectroscopy and hyperspectral imaging Reviewed

K. Phuangsombut, A. Terdwongworakul, N. Suttiwijitpukdee, A. Phuangsombut, S. Tsuchikawa, T. Inagaki, T. Ma

Vol. 23 page： 23-29 2017

Stiffness and moisture content prediction model of wooden veneer using fast online near-infrared (NIR) spectroscopic system Reviewed

Forestry Research and Engineering: International Journal Vol. 1 page： 00006 2017

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