Hideyuki Shinzawa

Non-destructive and rapid analysis of chemical compositions in Thai steamed pork sausages by near-infrared spectroscopy

The objective of the present study was to evaluate the ability of near-infrared (NIR) spectroscopy to predict chemical compositions of Thai steamed pork sausages in relation to different types of sample presentation forms of NIR measurements (with and without plastic casing). NIR spectra of sausages were scanned to predict the chemical compositions, protein, fat, ash and carbohydrate non-destructively. NIR spectrum features of the sausage samples were strongly influenced by physical properties of the samples, such as the presence of plastic casing and inhomogeneous physical structure inside the samples, yielding significant baseline fluctuations. Thus, regression models were developed using partial least squares (PLS) regressions with two pretreatment methods, namely multiplicative scatter correction (MSC) and second derivative, which overcame the baseline problems. The prediction results suggest that the contents for the protein, fat and moisture can be estimated well with the proper selection of the pretreatment method.

Parallel factor (PARAFAC) kernel analysis of temperature- and composition- dependent NMR spectra of poly(lactic acid) nanocomposites

The parallel factor (PARAFAC) kernel matrix to analyze a sample system stimulated by more than one type of perturbation is described. PARAFAC kernel is a quantitative representation of the synchronicity and asynchronicity observed within the PARAFAC score matrices generated by carrying out two-dimensional (2D) correlation analyses. Thus, kernel matrix representation provides more intuitively understandable interpretation to the conventional PARAFAC trilinear model. In this study, the utility of PARAFAC kernel is demonstrated by the study of poly(lactic acid)-nanocomposite undergoing a structural change depending on the temperature as well as the clay content in the sample. Seemingly complicated variation of nuclear magnetic resonance (NMR) spectra induced by the change in the temperature and clay content are readily analyzed by the multiple-perturbation 2D correlation spectroscopy and PARAFAC kernel. PARAFAC kernel revealed that crystalline and amorphous structures of the PLA substantially undergo thermal deformation, and these variations are also influenced by the presence of the clay.

Compression-induced morphological and molecular structural changes of cellulose tablets probed with near infrared imaging

An analytical technique based on band shift analysis to derive key information concerning molecular structural changes from near infrared (NIR) imaging data was demonstrated in the present study. Molecular structural changes induced by compression process of sets of cellulose tablets under varying pressure levels were monitored by NIR imaging. The detailed band position shift analysis of the spectral features has provided insight into the compression mechanism of cellulose tablets. It has been shown that fine features of the deformation of the crystalline structure can be readily captured by band shift analysis of specific peaks. Substantial band position shifts were observed when pressure was applied to cellulose samples, indicating the disintegration of crystalline structures and an increase in the amorphous component. Band shift analysis may be applicable to a wide range of NIR imaging data to derive an in-depth understanding of systems even if the NIR images exhibit unwanted baseline shifts due to morphological changes in the samples.

Compression effect on sustained-release and water absorption properties of cellulose tablets studied by heterospectral two-dimensional (2D) correlation analysis

Chemical and physical effects of the compression process on cellulose excipients are explored by near infrared (NIR) spectroscopy, X-ray diffraction (XRD), dissolution test and water absorption test. A set of pharmaceutical tablets including pentoxifylline (PTX) and cellulose are prepared under varying levels of compression. The compressive deformation of the tablets is probed by NIR spectroscopy and XRD. The interaction of tablet with water molecules is also analyzed with the dissolution and water absorption tests. The essential relationship between the two different classes of data, e.g. XRD and dissolution (or absorption) test, is effectively elucidated by heterospectral two-dimensional (2D) correlation analysis. It revealed that the compression produces a disordered amorphous component of cellulose. Such development of the mobile amorphous phase results in a more tightly packed matrix with less porosity. Thus, in turn, it prevents penetration of water molecules into the tablet and direct contact with PTX, which eventually brings the delay in the dissolution. Consequently, by carrying out the hetero-correlation analysis of the two datasets, it effectively provided a more detailed picture of the compression process.

The Effect of Microcrystalline Cellulose Crystallinity on the Hydrophilic Property of Tablets and the Hydrolysis of Acetylsalicylic Acid as Active Pharmaceutical Ingredient Inside Tablets

The crystal structures of active pharmaceutical ingredients and excipients should be strictly controlled because they influence pharmaceutical properties of products which cause the change in the quality or the bioavailability of the products. In this study, we investigated the effects of microcrystalline cellulose (MCC) crystallinity on the hydrophilic properties of tablets and the hydrolysis of active pharmaceutical ingredient, acetylsalicylic acid (ASA), inside tablets by using tablets containing 20% MCC as an excipient. Different levels of grinding were applied to MCC prior to tablet formulation, to intentionally cause structural variation in the MCC. The water penetration and moisture absorbability of the tablets increased with decreasing the crystallinity of MCC through higher level of grinding. More importantly, the hydrolysis of ASA inside tablets was also accelerated. These results indicate that the crystallinity of MCC has crucial effects on the pharmaceutical properties of tablets even when the tablets contain a relatively small amount of MCC. Therefore, controlling the crystal structure of excipients is important for controlling product qualities.

Partial least square discriminant analysis of mangosteen pericarp powder by near infrared spectroscopy

Partial least square discriminant analysis (PLS-DA) was applied to sort out the difference between mangosteen powder and fake samples measured by near infrared (NIR) spectroscopy. The main feature of the NIR diffuse reflectance spectra of the powder samples are overwhelmed by the baseline change due to the difference in the density and average particle size, making the discrimination difficult. The informative spectral feature was readily elucidated when the NIR spectra were subjected to the second derivative. The PLS-DA of the second derivative spectra revealed a substantial level of difference between the mangosteen powder and fake samples due to the resin and dietary fibre predominantly present in the mangosteen.

Baseline Correction of Diffuse Reflection Near-Infrared Spectra Using Searching Region Standard Normal Variate (SRSNV)

An alternative baseline correction method for diffuse reflection near-infrared (NIR) spectra, searching region standard normal variate (SRSNV), was proposed. Standard normal variate (SNV) is an effective pretreatment method for baseline correction of diffuse reflection NIR spectra of powder and granular samples; however, its baseline correction performance depends on the NIR region used for SNV calculation. To search for an optimal NIR region for baseline correction using SNV, SRSNV employs moving window partial least squares regression (MWPLSR), and an optimal NIR region is identified based on the root mean square error (RMSE) of cross-validation of the partial least squares regression (PLSR) models with the first latent variable (LV). The performance of SRSNV was evaluated using diffuse reflection NIR spectra of mixture samples consisting of wheat flour and granular glucose (0–100% glucose at 5% intervals). From the obtained NIR spectra of the mixture in the 10 000–4000 cm−1 region at 4 cm intervals (1501 spectral channels), a series of spectral windows consisting of 80 spectral channels was constructed, and then SNV spectra were calculated for each spectral window. Using these SNV spectra, a series of PLSR models with the first LV for glucose concentration was built. A plot of RMSE versus the spectral window position obtained using the PLSR models revealed that the 8680–8364 cm−1 region was optimal for baseline correction using SNV. In the SNV spectra calculated using the 8680–8364 cm−1 region (SRSNV spectra), a remarkable relative intensity change between a band due to wheat flour at 8500 cm−1 and that due to glucose at 8364 cm−1 was observed owing to successful baseline correction using SNV. A PLSR model with the first LV based on the SRSNV spectra yielded a determination coefficient (R2) of 0.999 and an RMSE of 0.70%, while a PLSR model with three LVs based on SNV spectra calculated in the full spectral region gave an R2 of 0.995 and an RMSE of 2.29%. Additional evaluation of SRSNV was carried out using diffuse reflection NIR spectra of marzipan and corn samples, and PLSR models based on SRSNV spectra showed good prediction results. These evaluation results indicate that SRSNV is effective in baseline correction of diffuse reflection NIR spectra and provides regression models with good prediction accuracy.

An Effect of Cellulose Crystallinity on the Moisture Absorbability of a Pharmaceutical Tablet Studied by Near-Infrared Spectroscopy

In this study, we investigated molecular-level variation of tablets caused by grinding and its effect on their actual moisture absorbability. Model tablets contained acetaminophen as an active pharmaceutical ingredient and microcrystalline cellulose (MCC) as an excipient. Different levels of grinding were applied during the tablet formulation to intentionally cause the structural variation of the MCC. The moisture absorbability of tablets showed obvious variation depending on the grinding time, and the corresponding change in near-infrared spectra was readily captured. The detailed analysis of the variation of the band frequencies (i.e., wavenumber) revealed that the grinding process substantially disintegrates the crystalline and generates a glassy amorphous structure of MCC, which is a requirement to absorb water molecules. Consequently, it is very likely that the change of the moisture absorbability of the tablets is closely related to the development of the amorphous structure. These results indicate that the pharmaceutical product performances can be influenced by the physical properties of the excipient, which in turn can be controlled by the grinding process.

Near-infrared (NIR) disrelation mapping analysis for poly(lactic) acid nanocomposite

Near infrared (NIR) imaging data of poly(lactic) acid (PLA) nanocomposite were analysed by disrelation mapping to prove the possible interaction between PLA matrix and montmorillonite-based nanoclay. The basic concept of disrelation mapping can be viewed as a spatial filter based on two-dimensional (2D) correlation function to elucidate specific areas where disrelated variation between intensities occurs. Correlation intensity develops on disrelation map only if spectral intensities at v1 and v2 within the local spatial area vary in a dissimilar manner. This feature is especially suitable for identifying the area where interaction between components occurs, which is not fully detected by the conventional visualizations based on a single wavenumber. Disrelation maps constructed with NIR bands arising from the crystalline and amorphous components of the PLA. The pattern appearing on the disrelation map indicated different distributions of the crystalline and amorphous components of the nanocomposite sample. In addition, the development of disrelation intensity becomes acute especially at the area adjacent to the clay, revealing that the clay essentially works as nucleating agent to cause the additional development of crystalline structure of PLA by lowering the surface energy barrier.

Monitoring of recrystallisation of microcrystalline cellulose inside pharmaceutical tablets during storage using near infrared diffuse reflectance spectroscopy

Changes in the crystallinity of microcrystalline cellulose (MCC) inside pharmaceutical tablets during storage were monitored by near infrared (NIR) diffuse reflectance spectroscopy to investigate transient variation at the molecular level. The MCC used in the tablets was ground before tablet formulation to intentionally cause a decrease in crystallinity. The variation in crystalline structure of MCC was evaluated from the intensity of NIR spectra peaks ascribed to OH groups in the crystalline region. The MCC exhibited clear signs of recrystallisation during 63 days of storage. In addition, the recrystallisation became even more pronounced when the MCC was stored under high-humidity conditions. Results also showed that the inclusion of anhydrous silicic acid induces a clear delay in recrystallisation by restricting the penetration of water molecules into the tablets. The findings derived from NIR spectra were substantiated by differential thermal analysis. The results from this study suggest that crystallinity of MCC inside tablets can be controlled by other excipients during storage, which has useful applications for controlling pharmaceutical product performance during storage.