Faculty Profiles - INAGAKI Tetsuya

Papers - INAGAKI Tetsuya

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Determination of true optical absorption and scattering coefficient of wooden cell wall substance by time-of-flight near infrared spectroscopy Reviewed

Ryunosuke Kitamura, Tetsuya Inagaki and Satoru Tsuchikawa

Optic Express Vol. 24 page： 3999-4009 2016

Prediction of oven-dry density of wood by time-domain terahertz spectroscopy Reviewed

Tetsuya Inagaki, Ian D. Hartley, Satoru Tsuchikawa Matthew Reid

Holzforschung 2013

Difference of Cellulosic Crystalline Structure in Wood between Hydrothermal and Ageing Degradation Observed by NIRs and XRD Reviewed

Tetsuya Inagaki, Heinz W. Siesler, Katsuya Mitsui and Satoru Tsuchikawa

Biomacromolecules Vol. 11 page： 2300 2010

Design and development of a portable Vis-NIR spatially resolved spectroscopic device for nondestructive and rapid evaluation of growth stress in standing trees

Te Ma, Hiroyuki Yamamoto, Takusu Kajimura, Tetsuya Inagaki, Satoru Tsuchikawa

Computers and Electronics in Agriculture Vol. 231 page： 110014 - 110014 2025.4

Publishing type：Research paper (scientific journal) Publisher：Elsevier BV

Growth stress (growth strain) is caused by internal stresses that develop within the wood during expansive growth and maturation. Although growth stress evaluations are critical for predicting and mitigating problems such as warping, cracking, and deformation during processing and use, conventional methods have several disadvantages, including notably high operational costs, time-consuming, and relatively destructive. This study aimed to develop a nondestructive, portable, and rapid technique that can evaluate local growth stress in standing trees. A multifiber-based visible-near-infrared (Vis-NIR) spatially resolved spectroscopic (SRS) device was, therefore, designed and used to collect light scattering and absorption information from standing trees. Principal component analysis revealed that the collected Vis-NIR SRS spectra were highly correlated with anatomical features related to growth stress, such as the difference in light scattering (particularly at approximately 846 nm) and moisture content (approximately 970 nm) inside the wood, as well as the wood surface color (approximately 660 nm). The determination coefficient for the cross-validation set was found to be 0.84 with a root mean square error of 333 με using partial least squares regression analysis. In addition to the high prediction accuracy achieved by machine learning algorithms, the results of Monte Carlo modeling of photon migration in 3D wood structure models also demonstrated that the Vis-NIR SRS approach has great potential for on-site applications, offering a new and cost-effective method for evaluating growth stress in green trees.

DOI： 10.1016/j.compag.2025.110014

Intelligent monitoring of post-processing characteristics in 3D-printed food products: A focus on fermentation process of starch-gluten mixture using NIR and multivariate analysis

Qian Jiang, Yanru Bao, Te Ma, Satoru Tsuchikawa, Tetsuya Inagaki, Han Wang, Hao Jiang

Journal of Food Engineering Vol. 388 2025.3

Publishing type：Research paper (scientific journal)

The production of three-dimensional (3D)-printed food products requires not only optimal 3D-printing adaptability but also appropriate post-processing characteristics. This study aimed to use near infrared (NIR) spectroscopy to predict the rheological properties of 3D-printed dough, enabling intelligent monitoring of the dough's fermentation process. Utilizing support vector machine (SVM) classification model, the fermentation stages can be classified as under-fermentation, complete fermentation, and over-fermentation. Employing preprocessing methods with Synergy Interval Partial Least Square-Competitive Adaptive Reweighted Sampling (SIPLS-CARS) algorithm, 27, 39, 23, and 27 key wavelengths were filtered from the raw NIR spectral data, corresponding to the prediction of storage modulus (G′), loss modulus (G″), complex viscosity (η∗), and loss factor (tan δ), respectively. Quantitatively, SVM (Support Vector Machine) regression outperformed Partial Least Squares (PLS) with Rc2 values (0.95, 0.94, 0.94) and Rp2 values (0.93, 0.93, 0.94) for G′, G″, and η∗. NIR spectra-based predictive models demonstrated superior performance compared to rheo-fermentation properties models. In summary, these findings show the potential of NIR spectroscopy as a rapid tool for predicting the fermentation progress of 3D-printed doughs.

DOI： 10.1016/j.jfoodeng.2024.112357

Development of a time-resolved laser-induced fluorescence fingerprinting method for detecting low-level adulteration in extra virgin olive oil

Te Ma, Hao Jiang, Satoru Tsuchikawa, Tetsuya Inagaki

Food Chemistry Vol. 465 page： 142125 - 142125 2025.2

Authorship：Last author,　Corresponding author Publishing type：Research paper (scientific journal) Publisher：Elsevier BV

Adulteration identification in extra virgin olive oil (EVOO) is a significant concern in the olive oil industry. This study aimed to detect low-level adulteration of EVOO with other edible oils by using a novel time-resolved laser-induced fluorescence (TRLIF) fingerprinting method. Five EVOO brands were first analyzed to assess its potential for classification based on their differing fluorophore content. The developed method effectively reduces the effects associated with the optical path length and excitation light intensity. Subsequently, three sets of binary mixtures were tested: EVOO adulterated with refined olive oil, soybean oil, and sunflower oil. Quantitative analysis was performed using parallel factor analysis, which achieved a cross-validation coefficient of determination (R2) exceeding 0.90, with a prediction error < 1.40 %. These findings demonstrate that this method has the potential to determine the purity and quality of EVOO.

DOI： 10.1016/j.foodchem.2024.142125

Examination of SWIR hyperspectral imaging for estimating corewood – outerwood transition age for Douglas-fir grown at different planting densities

Ighoyivwi Onakpoma, Te Ma, Laurence R. Schimleck, Tetsuya Inagaki, Satoru Tsuchikawa

Holzforschung 2025.1

Publishing type：Research paper (scientific journal) Publisher：Walter de Gruyter GmbH

Abstract

Silvicultural practices, particularly planting density (PD), significantly affect the wood quality of plantation-grown trees by influencing the age of transition from corewood to outerwood. Determining transition age (TA) is challenging. Near infrared hyperspectral imaging was used to assess the age of transition from corewood to outerwood in Douglas-fir (Pseudotsuga menziesii) grown under different PD. Wood samples were taken from permanent research plots with six PD ranging from 2,990 to 248 stems/hectare. Twenty trees were destructively sampled at age 25, and wood discs were collected at 10 % of total tree height. Pith-to-bark radial strips obtained from each disc were scanned using a compovision hyperspectral imaging system (1,002–2,350 nm). Partial least square discriminant analysis (PLS-DA) models were fitted to approximate TA using hyperspectral data representative of corewood and outerwood. PD influenced TA and the duration over which it occurred. Average age of transition was estimated to vary from 10 (closest spacing) to 14 years (widest). Closely spaced trees exhibited an abrupt transition, while widely spaced trees had a more gradual transition. However, PLS-DA likely underestimated the transition duration for widely spaced trees, as their average ring densities did not yet match those typical of outerwood based on X-ray densitometry data.

DOI： 10.1515/hf-2024-0058

Other Link： https://www.degruyter.com/document/doi/10.1515/hf-2024-0058/pdf

Enhanced detection of early bruises in apples using near-infrared hyperspectral imaging with geometrical influence correction for universal size adaptation

Bin Li, Te Ma, Tetsuya Inagaki, Satoru Tsuchikawa

Postharvest Biology and Technology Vol. 219 page： 113282 - 113282 2025.1

Publishing type：Research paper (scientific journal) Publisher：Elsevier BV

Near-infrared (NIR) imaging is effective in monitoring the optical property changes of fruit arising from mechanical damage. However, differences in fruit geometry and size severely limit the application of bruise detection solutions. By integrating NIR hyperspectral imaging (NIR-HSI) with geometrical influence correction (GIC), this paper presents a universal bruise enhancement and detection method for early-stage bruises inspection across apple cultivars with large size variations. HSI and shape data were collected via 360° rotational scanning of Sun Fuji, Shinano Sweet, and Esopus Spitzenburg apples before and during the first 24 h post-bruising. GIC was applied as a pretreatment method. For comparison, we applied whiteboard reflectance calibration (WRC) and WRC combined with the standard normal variate (SNV) approach. Using principal component analysis (PCA), a set of effective wavelength-loading coefficients for bruise enhancement was extracted across pooled datasets of average sound and bruise spectra from different samples. The optimal coefficients, determined using logistic regression, were applied uniformly across all HSI datasets for bruise enhancement. Finally, the local Otsu method combined with connected-domain screening was applied for bruise identification. Based on spectral analysis, PCA successfully extracted bruise-related wavelength coefficients with consistent trends across cultivars, facilitating universal bruise enhancement. GIC reduced shape-related interference, improving the use of the light scattering-related PC for bruise identification. GIC coupled with the universal enhancement emerged as the most effective method, consistently achieving the highest classification accuracy, superior identification accuracies for both central and edge bruises, and the earliest peak accuracy.

DOI： 10.1016/j.postharvbio.2024.113282

The Detection of Pest Contaminants in Chocolate Using Visible-Near-Infrared Single-Pixel Imaging Technology

Hidemasa Taketoshi, Tetsuya Inagaki, Satoru Tsuchikawa, Te Ma

Foods Vol. 14 ( 2 ) 2025.1

Publishing type：Research paper (scientific journal)

Food safety is gaining increasing attention worldwide. Currently, low-density organic foreign objects such as insects are extremely challenging to detect using conventional metal detectors and X-ray inspection systems. This study aimed to develop a visible-near-infrared single-pixel imaging (Vis-NIR-SPI) method to detect small insects inside food. The advantages of Vis-NIR light include its ability to analyze samples non-destructively and measure multiple components simultaneously and quickly, while SPI is robust against dark noise, high scattering, and high equipment costs. The experimental results demonstrated that (1) the newly designed system effectively reduces scattering effects from the highly scattering sample (intralipid 20%), allowing for the capture of information beyond the capabilities of a charge-coupled-device camera; (2) insects positioned behind ham and bread were readily detectable using the imaging reconstruction algorithm; and (3) even for chocolate samples with very high light absorption, only 1 uncontaminated sample out of 100 was mistakenly classified as contaminated, yielding an overall accuracy of 99%. This high level of accuracy underscores the potential of the Vis-NIR-SPI method to provide reliable detection while maintaining sample integrity. Furthermore, this method is cost-effective, offering a practical and efficient solution to improve quality control processes and consumer trust in the food industry.

DOI： 10.3390/foods14020206

The effects of growth rate on the age dependent variation of wood properties evaluated by differential geometry Reviewed

Takaaki Fujimoto, Te Ma, Tetsuya Inagaki, Satoru Tsuchikawa

Industrial Crops and Products Vol. 222 2024.12

Publishing type：Research paper (scientific journal)

A correct understanding of the variations seen in wood properties with tree age is of great importance for both the forestry and timber industries. However, this phenomenon is complex because of the differences between individuals and the variations associated with multiple wood properties. In this study, we have identified age-dependent changes in the state of wood as a surface that contains comprehensive information on the coupled variation of multiple properties in many individuals. By comparing the geometric quantities of the surface between sample groups with different growth rates caused by silvicultural treatments, we have discussed the ideal forest management in terms of wood quality and forest ecosystems. The slow-growing group showed larger Gaussian curvatures of the surface and a more tortuous and longer geodesic than the fast-growing group, resulting in less energy loss during tree growth. Assuming that processes with high symmetry are more sustainable, the characteristic class representing the global structure of the growth process indicates that the slow-growing group follows a more sustainable process than the fast-growing group. These results indicate that it is ideal for trees to grow slowly, in terms of variation of wood properties and forest ecosystem. Because the geometric quantities are invariant under coordinate transformations, the proposed methods provide us with the intrinsic behavior of the tree growth process independent of a specific coordinate system, that is, a concrete space spanned by the measured wood properties.

DOI： 10.1016/j.indcrop.2024.119596

Enhanced quantification of chlorophyll a and its degradation products in olive oil using time-resolved laser-induced fluorescence fingerprint analysis Invited Reviewed

Te Ma, Hao Jiang, Satoru Tsuchikawa, Tetsuya Inagaki

Food Chemistry Vol. 460 2024.12

Authorship：Last author,　Corresponding author Publishing type：Research paper (scientific journal)

Potential errors in the fluorescence analysis of chlorophylls and their degradation products, primarily due to spectral overlap and inner filter, are widely acknowledged. This study aimed to devise a sensitivity-enhanced technique for the concurrent quantification of chlorophyll a and its degradation products while minimizing effects from type-B chlorophylls. Initially, a time-resolved laser-induced fluorescence spectroscopic system was designed and tested on stardard chlorophyll samples. The origins, implications, and mitigation strategies of spectral overlap and the inner filter effect on the measured fluorescence intensity were thoroughly examined. Then, this methodology was proved to be efficacious within complex liquid matrices derived from olive oil. The experimental outcomes not only shed additional light on the mechanisms of chlorophyll fluorescence overlap and the inner filter effect, but also establish a general framework for developing spectrally and timely resolved fluorescence fingerprint analysis for the simultaneous quantification of chlorophylls and their degradation products at high concentrations.

DOI： 10.1016/j.foodchem.2024.140656

Three-dimensional modeling of moisture transport in wood using near-infrared hyperspectral imaging and X-ray computed tomography in conjunction with finite element analysis Reviewed

Wenpeng Zeng, Takaaki Fujimoto, Tetsuya Inagaki, Satoru Tsuchikawa, Te Ma

Journal of Wood Science Vol. 70 ( 1 ) 2024.12

Authorship：Corresponding author Publishing type：Research paper (scientific journal)

In past studies, finite element analysis (FEA) methods have been used to simulate the thermal and moisture coupling of wood. However, challenges remain in achieving high-quality three-dimensional (3D) simulations, mainly because of the heterogeneous and complex structure of wood and its difficult-to-detect internal structure, which makes modeling challenging, in addition to the lack of robust experimental techniques to validate simulation results. In this study, the FEA simulation model was refined by combining X-ray computed tomography (CT) and near-infrared hyperspectral imaging (NIR-HSI). CT was used to probe the 3D density of wood, and a novel FEA tetrahedral mesh was constructed based on the results. The NIR-HSI method visualizes the moisture distribution during adsorption and desorption inside the wood. This result is then used to adjust the parameters of the FEA simulation model and as a reference value to evaluate the simulation results. The visualization and simulation results fit well with the theoretical properties. The simulation results can more accurately reflect the spatial distribution and transfer trend of wood moisture at different points in time. Therefore, the CT and NIR-HSI-based 3D heat and moisture-coupled FEA model of wood proposed in this study can be used as a basis for optimizing drying parameters to provide high-quality wood.

DOI： 10.1186/s10086-023-02120-2

Evaluating Soluble Solids in White Strawberries: A Comparative Analysis of Vis-NIR and NIR Spectroscopy Reviewed

Hayato Seki, Haruko Murakami, Te Ma, Satoru Tsuchikawa, Tetsuya Inagaki

Foods Vol. 13 ( 14 ) 2024.7

Authorship：Last author,　Corresponding author Publishing type：Research paper (scientific journal)

In recent years, due to breeding improvements, strawberries with low anthocyanin content and a white rind are now available, and they are highly valued in the market. Strawberries with white skin color do not turn red when ripe, making it difficult to judge ripeness. The soluble solids content (SSC) is an indicator of fruit quality and is closely related to ripeness. In this study, visible–near-infrared (Vis-NIR) spectroscopy and near-infrared (NIR) spectroscopy are used for non-destructive evaluation of the SSC. Vis-NIR (500–978 nm) and NIR (908–1676 nm) data collected from 180 samples of “Tochigi iW1 go” white strawberries and 150 samples of “Tochigi i27 go” red strawberries are investigated. The white strawberry SSC model developed by partial least squares regression (PLSR) in Vis-NIR had a determination coefficient R2p of 0.89 and a root mean square error prediction (RMSEP) of 0.40%; the model developed in NIR showed satisfactory estimation accuracy with an R2p of 0.85 and an RMSEP of 0.43%. These estimation accuracies were comparable to the results of the red strawberry model. Absorption derived from anthocyanin and chlorophyll pigments in white strawberries was observed in the Vis-NIR region. In addition, a dataset consisting of red and white strawberries can be used to predict the pigment-independent SSC. These results contribute to the development of methods for a rapid fruit sorting system and the development of an on-site ripeness determination system.

DOI： 10.3390/foods13142274

Effect of dielectric barrier discharge (DBD) plasma treatment on physicochemical and 3D printing properties of wheat starch Reviewed International coauthorship

Shu Ma, Te Ma, Satoru Tsuchikawa, Tetsuya Inagaki, Han Wang, Hao Jiang

International Journal of Biological Macromolecules Vol. 269 2024.6

Publishing type：Research paper (scientific journal)

In recent years, the focus has shifted towards carbohydrate-based hydrogels and their eco-friendly preparation methods. This study involved an investigation into the treatment of wheat starch using dielectric barrier discharge (DBD) plasma technology over varying time gradients (0, 2, 5, 10, 15, and 20 min). The objective was to systematically examine the impact of different treatment durations on the physicochemical properties of wheat starch and the suitability of its gels for 3D printing. Morphology of wheat starch remained intact after DBD treatment. However, it led to a reduction in the amylose content, molecular weight, and crystallinity. This subsequently resulted in a decrease in the pasting temperature and viscosity. Moreover, the gels of the DBD-treated starch exhibited superior 3D printing performance. After a 2-min DBD treatment, the 3D printed samples of the wheat starch gel showed no significant improvements, as broken bars were evident on the surface of the 3D printed graphic, whereas DBD-20 showed better printing accuracy and surface structure, compared to the original starch without slumping. These results suggested that DBD technology holds potential for developing new starch-based gels with impressive 3D printing properties.

DOI： 10.1016/j.ijbiomac.2024.132159

Cellulose crystalline structure and thermal properties under heat treatment: An investigation by two-dimensional correlation of near infrared spectroscopy and differential scanning calorimetry Reviewed International coauthorship

Siti Hanifah Mahdiyanti, Masaki Asaoka, Tetsuya Inagaki, Satoru Tsuchikawa

Journal of Near Infrared Spectroscopy Vol. 32 ( 3 ) page： 113 - 124 2024.6

Publishing type：Research paper (scientific journal)

This study investigated the thermal behavior and crystallinity of microcrystalline cellulose (MCC) under heat treatment using near infrared (NIR) spectroscopy and differential scanning calorimetry (DSC). The results showed that heat treatment reduced the crystallinity and thermal stability of MCC at a certain point, and that the changes in the chemical components and structure of MCC were correlated with the heat flow measured by DSC. The analysis was performed using two-dimensional correlation spectroscopy (2DCOS), which revealed the simultaneous changes in the NIR second-derivative spectra and the DSC thermograms of heat-treated MCC. Linear regression analysis showed a high r2 value of 0.90 between the DSC enthalpy change at 270 °C–400°C and the PC1 score of NIR second-derivative spectra at 7500–4100 cm−1. The 2DCOS synchronous map showed a positive correlation at 6656–6229 cm−1 with a r value of 0.70–0.98 for the endothermic reaction, and a negative correlation at 6229; 5620; 5401; 4844; 4535 cm−1 with a r value of −0.90 to −0.99 for the exothermic reaction. This study extended the knowledge on the thermal behavior and decomposition mechanisms of heat-treated MCC, and provided a useful method for cellulose characterization and identification.

DOI： 10.1177/09670335241257649

Terahertz time-domain spectroscopy as a novel tool for crystallographic analysis in cellulose: tracking lattice changes following physical treatments Reviewed

Han Wang, Dan Aoki, Yoshikuni Teramoto, Satoru Tsuchikawa, Tetsuya Inagaki

Cellulose Vol. 31 ( 7 ) page： 4085 - 4098 2024.5

Authorship：Last author,　Corresponding author Publishing type：Research paper (scientific journal)

The authors’ series of studies aimed to explore the potential of terahertz time-domain spectroscopy (THz-TDS) in cellulose crystallographic studies, since THz radiation can detect most intermolecular vibrations and respond to lattice phonons. In this study, we tracked changes in four types of cellulose after ball milling. As the planetary ball milling time increases, it is observed through electron microscopy that the four types of cellulose particles are gradually destroyed into finer particles, while gel permeation chromatography can prove that the molecular weight gradually decreases after ball milling and the dispersity gradually approaches one, which indicates that the dispersion of the material was reduced. The most fascinating observation was made by THz-TDS, that is we have confirmed that after ball milling, the absorption characteristics of cellulose I and II in cellulose I treated with 10% NaOH (crystalline partial transition from cellulose I to II) exhibited an opposite trend. Specifically, the absorption of cellulose II at 2.40THz and 2.77THz increased, while the absorption of cellulose I at 2.11THz and 3.04THz decreased after ball milling, which suggests an increased conversion rate of cellulose I to cellulose II post-milling. Cellulose with different crystalline allomorphs shows different characteristic absorption in the THz region, and the peak position will not change even after the ball milling, only the absorption intensity changes. Although it can be observed through the most traditional X-ray diffraction method that the crystallinity index of all cellulose samples gradually decreases after ball milling. However, different from the THz results, the change after ball milling of cellulose I treated with 10% NaOH is only reflected in very subtle pattern changes, that is, the peak close to the 200 crystalline plane position is slightly shifted after ball milling.

DOI： 10.1007/s10570-024-05834-8

Development of a sensitivity-enhanced fluorescence lifetime spectroscopic method for nondestructive quality monitoring of mature tomatoes during storage Reviewed

Te Ma, Tetsuya Inagaki, Satoru Tsuchikawa

Scientia Horticulturae Vol. 330 2024.4

Publishing type：Research paper (scientific journal)

The decay of fluorescence lifetime (FLT) is an absolute indication for observing the environment surrounding the fluorescent molecules. This study presents the characterization of fluorescence intensity and the FLT in tomatoes, spanning from the green to the red stage, using a novel time-resolved and laser-induced fluorescence (TRLIF) spectroscopic system. Furthermore, the applicability of this method was assessed for evaluating the postharvest quality of commercially acquired red tomatoes. The results collectively indicate a progressive decrease in the FLT of the red tomatoes throughout shelf-life storage. The average FLT loss decreased by approximately 17, 26, 32, and 38% after 1, 2, 3, and 4 d, respectively. Furthermore, the first principal component scores of the time-resolved spectra were confirmed to be stable for early quality degradation monitoring purposes. This investigation highlights that the devised TRLIF spectroscopic technique is a non-destructive and robust method for studying the degradation of fluorescent compounds. It facilitates an in-depth exploration of the underlying mechanisms behind the fluorescent phenomena in postharvest research.

DOI： 10.1016/j.scienta.2024.113059

Three-dimensional visualization and detection of early bruise in apple based on near-infrared hyperspectral imaging coupled with geometrical influence correction Reviewed

Bin Li, Te Ma, Leshang Bai, Tetsuya Inagaki, Hayato Seki, Satoru Tsuchikawa

Postharvest Biology and Technology Vol. 210 2024.4

Publishing type：Research paper (scientific journal)

Visible-near-infrared (Vis-NIR) spectral imaging holds great promise for the automatic detection of fruit defects. However, uneven brightness resulting from fruit geometry and the limitations of one-directional imaging significantly restrict the current detection to a limited area. This study presents a rotation measurement system that combines a line-scan NIR-hyperspectral imaging (HSI) camera with a laser profile. A total of 72 apple samples with bruises in the central and edge regions were prepared. A 360° scanning approach was employed to collect HSI and shape data from the entire surface of the samples over a 6-h post-bruising period. Height and angle corrections were applied to eliminate the surface geometric influences on the HSI data, resulting in improved reflectance spectrum uniformity. A two-step principal component analysis method was employed for image enhancement, followed by a straightforward bruise detection technique using global segmentation and connected-domain selection. The results demonstrated an overall improvement in bruise detection over time. Moreover, the correction significantly enhanced the detection accuracy. After 6 h of bruising, the corrected data achieved a classification accuracy of 90.3% and an identification rate of 83.3% for central bruises and 61.1% for edge bruises, whereas the uncorrected data yielded 70.8%, 58.3%, and 31.9%, respectively. Thus, this study successfully detected early bruising across the entire surface of apples and improved the detection in low-intensity edge areas. The proposed method has the potential to contribute to the comprehensive evaluation of agricultural products with irregular geometries.

DOI： 10.1016/j.postharvbio.2023.112753

Non-Destructive Near-Infrared Moisture Detection of Dried Goji (Lycium barbarum L.) Berry Reviewed

Rui Kang, Te Ma, Satoru Tsuchikawa, Tetsuya Inagaki, Jun Chen, Jian Zhao, Dongdong Li, Gongpei Cui

Horticulturae Vol. 10 ( 3 ) 2024.3

Publishing type：Research paper (scientific journal)

To detect the moisture of dried Goji (Lycium barbarum L.) berries nondestructively, a near-infrared (NIR) hyperspectral imager was used for experiments. NIR hyperspectral data were obtained and processed by standard normal variate (SNV) calculation using the MATLAB software v.R2016a. On the basis of the actual moisture of dried Goji berries, the predicted moisture was obtained based on the partial least squares (PLS) algorithm and a prediction model for the moisture of dried goji berries was established. It was found that the moisture of dried Goji berries was responsive to the NIR hyperspectral imager. The established prediction model could accurately predict the moisture of dried goji berries, and its R2-value was 0.9981. The results provide a theoretical basis for the design of non-destructive moisture-detecting equipment for dried Goji berries.

DOI： 10.3390/horticulturae10030302

Investigation of the effects of tableting parameters on reliable quantitative terahertz spectroscopy Reviewed

Yuan Su, Yang Xu, Han Wang, Te Ma, Satoru Tsuchikawa, Tetsuya Inagaki

Applied Physics A: Materials Science and Processing Vol. 130 ( 2 ) 2024.2

Authorship：Last author,　Corresponding author Publishing type：Research paper (scientific journal)

Particle size ratio, tablet thickness, and compaction pressure are three important tableting parameters that affect the obtained tablet spectrum. In this study, the single-factor test and response surface analysis (RSM) were adopted to examine how these three parameters and their interactions affect the analytical measurements performed over terahertz time-domain spectroscopy (THz-TDS). Tablet samples were composed of a different percent (wt-%) of acetylsalicylic acid within microcrystalline cellulose. Results indicate that change in absorption coefficient was found to be more obvious for a larger particle size ratio. Thinner tablets were sensitive to absorption coefficient effects created as the transmitted THz radiation propagates through the tablet interfaces. Compression pressure has a limited effect on the absorption coefficient. The particle size ratio had the largest effect on the coefficient of correlation of the quantitative regression model, followed by the compaction pressure, and the tablet thickness. In this study, the optimized tableting parameters were determined: tablet thickness of 0.48 mm, particle size ratio of about 1:1, and compaction pressure of 30 MPa. Under this condition, the R2 of the quantitative regression model of acetylsalicylic acid content was 0.971 and 0.998 at the range of acetylsalicylic acid mass fraction between 10 and 90 wt-%, 1 and 30 wt-%, respectively. This study provides a method to effectively reduce the scattering effect of spectral detection of tablets by improving the sample’s properties, to provide a reference for enhancing the reliability and accuracy of quantitative measurements.

DOI： 10.1007/s00339-024-07302-3

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