Multivariate Spectral Analyses Research Articles

Interconnection between protein-related chemical functional group spectral features of prairie oat (Avena sativa L.) varieties and ruminant relevant nutrition-Degradation, intestinal digestionand true nutrient supply to dairy cows.

To our knowledge, the study interconnection between inherent chemical functional group spectral features and nutrient utilisation is still limited. The objective of this study was to test the adequacy of vibrational Fourier transform infrared attenuated total reflectance (ATR-FTIR) spectroscopy as a fast tool to assess the interactive relationship between the nutritive value of the Prairie cool-season oat (Avena sativa L.) varieties in dairy cows and inherent chemical functional group spectral features. The chemical functional group spectral features of the Prairie cool-season oat varieties in western Canada were determined by Fourier transform infrared attenuated total reflectancespectroscopy. The protein-related spectral parameters of chemical functional groups included peak height and peak area intensity of Amide I, Amid II, protein structural α-helix and β-sheet, and their ratios. The rumen degradation kinetics were determined using in situ techniques with four rumen-canulated lactating dairy cows. The intestinal digestion was evaluated using a three-step in vitro technique with 12 h preincubation. The experiment was an randomized complete block design. The data were analysed using the mixed-model procedure of the Statistical Analysis System. The results showed that the interconnection between rumen degradation kinetics, intestinal digestionand true nutrient supply to dairy cows and protein-related chemical functional group spectral features could be revealed by ATR-FTIR with univariate and multi-variate spectral analyses. These findings indicate that ruminant relevant nutritive value of cool-season oats could be rapidly evaluated and predicted using oat-specific functional group spectral characteristics which could be obtained by a non-distractive bioanalytical tool of ATR-FTIR spectroscopy.

Tilted Two-Dimensional Array Multifocus Confocal Raman Microspectroscopy.

A simple and efficient two-dimensional multifocus confocal Raman microspectroscopy featuring the tilted-array technique is demonstrated. Raman scattering from a 4 × 4 square foci array passing through a 4 × 4 confocal pinhole array is tilted with a periscope. The tilted array of Raman scattering signals is dispersed by an imaging spectrograph onto a CCD detector, giving 16 independent Raman spectra formed as 16 bands with different heights on the sensor. Use of a state-of-the-art imaging spectrograph enables high-precision wavenumber duplicability of the 16 spectra. This high duplicability makes the simultaneously obtained spectra endurable for multivariate spectral analyses, which is demonstrated by a singular value decomposition analysis for Raman spectra of liquid indene. Although the present implementation attains only 16 measurement points, the number of points can be extended to larger than 100 without any technical leaps. Limit of parallelization depends on the interval of measurement points as well as the performance of the optical system. Criteria for finding the maximum feasible number are discussed.

On a molecular basis pelleting-induced changes on carbohydrate structure of co-products from bio-oil production revealed with vibrational molecular spectroscopy plus chemometrics: Sensitivity and response to conditioning temperature and time

Molecular structure changes are closely related to nutrient utilization and availability. However, so far little research was found to determine the processing induced changes on carbohydrate structure in co-products from bio-oil processing. The objectives of this study were to investigate synergistic effects of conditioning temperature (70, 80 and 90°C) and time (50 and 75 s) during the pelleting process on carbohydrate structure profile of the co-products from bio-oil processing (canola meal). The vibrational molecular spectroscopy (ATR-VMS) with chemometrics was used to determine the impact of pelleting at different conditions on the inherent molecular structure changes. The molecular spectral analyses, Univariate and Multivariate spectral analyses, were used in this study. Multivariate spectral analyses included cluster analysis and principal analysis. The chemical functional groups mainly associated with carbohydrate structure profile in this lipid-free co-products (or with very little lipid) included cellulosic compounds (CEL, ranged at ca. 1302-1186 cm −1 ), structural CHO (SCHO, ranged at ca. 1488- 1186 cm −1 ) and total CHO (TCHO, ranged at ca. 1193-879 cm −1 ). The results showed that the pelleting process was able to alter inherent structures of CHO functional groups in the co-products from bio-oil processing. The univariate molecular analysis indicated that spectral intensities of CHO functional groups in the co-products were significantly affected by the pelleting process in the current study ( P< 0.05). Altering processing conditions resulted changes in molecular structure features of CHO functional groups except TCHO. The results of multivariate spectral analysis of CHO indicated that inherent CHO structural characteristics of all functional groups were not fully distinguished. This study demonstrated that the pelleting process under the conditions investigated caused partial changes in carbohydrate structures in terms of the spectral features of specific functional groups. These changes were not sufficient enough to make the entire spectral region of CHO functional groups become fully distinguishable. Future research is needed to investigate the interactive relationships between the absorption intensities of carbohydrate functional groups (TCHO, SCHO, CEL) and biodegradation and digestion of the co-products in order to reveal how carbohydrate molecular structure changes induced by processing affect nutritive availability.

Implication of modified molecular structure of lipid through heat-related process to fatty acids supply in Brassica carinata seed

This study was conducted to explore the effect of different autoclave heating times (30, 60 and 90min) on fatty acids supply and molecular stability in Brassica carinata seed. Multivariate spectral analyses and correlation analyses were also carried out in our study. The results showed that autoclaving treatments significantly decreased the total fatty acids content in a linear fashion in B. carinata seed as heating time increased. Reduced concentrations were also observed in C18:3n3, C20:1, C22:1n9, monounsaturated fatty acids (MUFA), polyunsaturated fatty acids (PUFA), omega 3 (ω-3) and 9 (ω-9) fatty acids. Correspondingly, the heated seeds showed dramatic reductions in all the peak intensities within lipid-related spectral regions. Results from agglomerative hierarchical cluster analysis (AHCA) and principal component analysis (PCA) indicated that the raw oilseed had completely different structural make-up from the autoclaved seeds in both CH3 and CH2 asymmetric and symmetric stretching region (ca. 2999–2800cm−1) and lipid ester CO carbonyl region (ca. 1787–1706cm−1). However, the oilseeds heated for 30, 60 and 90min were not grouped into separate classes or ellipses in all the lipid-related regions, indicating that there still exhibited similarities in lipid biopolymer conformations among autoclaved B. carinata seeds. Moreover, strong correlations between spectral information and fatty acid compositions observed in our study could imply that lipid-related spectral parameters might have a potential to predict some fatty acids content in oilseed samples, i.e. B. carinata. However, more data from large sample size and diverse range would be necessary and helpful to draw up a final conclusion.

Characterization of protein and carbohydrate mid-IR spectral features in crop residues

To the best of our knowledge, a few studies have been conducted on inherent structure spectral traits related to biopolymers of crop residues. The objective of this study was to characterize protein and carbohydrate structure spectral features of three field crop residues (rice straw, wheat straw and millet straw) in comparison with two crop vines (peanut vine and pea vine) by using Fourier transform infrared spectroscopy (FTIR) technique with attenuated total reflectance (ATR). Also, multivariate analyses were performed on spectral data sets within the regions mainly related to protein and carbohydrate in this study. The results showed that spectral differences existed in mid-IR peak intensities that are mainly related to protein and carbohydrate among these crop residue samples. With regard to protein spectral profile, peanut vine showed the greatest mid-IR band intensities that are related to protein amide and protein secondary structures, followed by pea vine and the rest three field crop straws. The crop vines had 48–134% higher spectral band intensity than the grain straws in spectral features associated with protein. Similar trends were also found in the bands that are mainly related to structural carbohydrates (such as cellulosic compounds). However, the field crop residues had higher peak intensity in total carbohydrates region than the crop vines. Furthermore, spectral ratios varied among the residue samples, indicating that these five crop residues had different internal structural conformation. However, multivariate spectral analyses showed that structural similarities still exhibited among crop residues in the regions associated with protein biopolymers and carbohydrate. Further study is needed to find out whether there is any relationship between spectroscopic information and nutrition supply in various kinds of crop residue when fed to animals.

Studies on Brassica carinata Seed. 1. Protein Molecular Structure in Relation to Protein Nutritive Values and Metabolic Characteristics

The objectives of this study were to investigate (1) the protein chemical profile, (2) the protein subfractions partitioned by the Cornell Net Carbohydrate and Protein System (CNCPS), (3) the rumen crude protein (CP) degradation kinetics, (4) the protein supply predicted by the DVE/OEB system, (5) the protein structural features using a Fourier transform infrared (FTIR) spectroscopic technique with attenuated total reflectance (ATR), and (6) the correlations between protein intrinsic structural features and nutritional profiles in three strains of Brassica carinata in yellow and brown seed coats, with comparison to canola seed as a reference. The results showed that carinata seed strains were different in both nutritional values and IR absorbance within the protein spectral region (ca. 1720-1482 cm(-1)). The comparison between yellow and brown B. carinata seeds indicated that the former was lower in acid detergent insoluble crude protein (ADICP; P = 0.002) and undegradable protein fraction (PC; P = 0.002) and greater in the degradable (D) fraction (P = 0.004) and true absorbed protein in the small intestine (DVE; P = 0.02) as well as feed milk value (FMV; P = 0.02) than the latter. The brown canola seed (Brassica napus L.) was also not in full accordance with B. carinata seed on these parameters. The FTIR studies showed significant differences in protein amide II peak height, amide I peak area, and β-sheet height among different B. carinata strains. However, multivariate spectral analyses indicated a similarity in protein structural makeup in these four kinds of oilseed. The not very strong correlations shown in this study implied that the limited sample size and narrow range in biological and spectral variation might be responses for the weak relationships between chemical profile and mid-IR spectral data. Further studies using sufficient samples with wide and diverse range in nutritional properties are needed to illustrate the actual relationship between spectroscopic data and nutritional profiles in oilseeds.

Application of multivariate spectral analyses in micro-Raman imaging to unveil structural/chemical features of the adhesive/dentin interface.

This study presents the application of multivariate analyses to analyze micro-Raman spectral imaging data in reference to the adhesive/dentin interface as well as comparison with univariate analysis. The univariate statistical methods, such as mapping of specific functional group peak intensities, do not always detect functional group positions and quantities due to peak overlapping. A comprehensive chemical analysis of the adhesive/dentin interface, along with the multivariate statistical methods, principal component analysis, and fuzzy c-means clustering, is studied. Compared to univariate analysis, multivariate methods present the entire hyperspectral information from the specimen in a concise and uncorrelated way. Apart from the ease with which information can be extracted and presented, multivariate methods also highlight minute and often important variations in the spectra that are difficult to observe using univariate methods. The results show for the first time the clear chemical and structural classifications in the adhesive/dentin interface at successively greater resolutions.

Seasonal variation in platelet [3H]paroxetine binding in healthy volunteers: Relationship to climatic variables

Recently, our laboratory has reported significant seasonal differences in [3H]paroxetine binding to platelets in depressed subjects. This study aimed to examine the seasonal variation in [3H]paroxetine binding to platelets and the relationships between [3H]paroxetine binding and climatic variables in healthy volunteers. We took monthly blood samples during one calendar year from 26 healthy volunteers for assay of [3H]paroxetine binding and analyzed the data by means of univariate and multivariate spectral and cosinor analyses. There was a statistically highly significant seasonal pattern in [3H]paroxetine binding to platelets with significant annual, 4-monthly, and bimonthly rhythms, which were expressed as a group phenomenon. [3H]Paroxetine binding to platelets was significantly lower in fall and summer than in winter and spring; lows occurred in summer and peaks in spring. The peak-trough difference in this yearly variation, expressed as a percentage of the mean, was as large as 83.7%. A large part of the variance, that is, 32.5%, in [3H]paroxetine binding could be explained by weather variables, such as ambient temperature, relative humidity, and air pressure. Highly significant common annual rhythms were expressed in [3H]paroxetine binding and ambient temperature or humidity (both inversely related) and changes in temperature the 2 weeks preceding blood samplings (positively related).