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The condensation of glycerol and adipic acid was studied by 2D correlation spectroscopy in combination with MCR to identify spectral changes associated with this polymerization reaction and to describe the development of structure in the polymer. This biobased polymer is being evaluated for use as a controlled release matrix where the extent of reaction is a key performance parameter. A spectroscopic technique was sought to estimate the extent of reaction and guide product development. FT-IR spectra were collected as the reaction was performed on a temperature programmable ATR assembly fitted to a Bruker Tensor 27 spectrophotometer. The resulting time series was analyzed by 2D correlation spectroscopy. Correlation maps were used to identify bands related to the formation of the polymer and multivariate curve resolution (MCR) was applied to develop a model in terms of pure components. This combined technique offers a rapid method for sample analysis and facilitates the preparation of materials to a specified extent of reaction.

During harvest, a variety of plant based contaminants are collected along with cotton lint. The USDA previously created a mid-infrared, attenuated total reflection (ATR), Fourier transform infrared (FT-IR) spectral library of cotton contaminants for contaminant identification as the contaminants have negative impacts on yarn quality. This library has shown impressive identification rates for extremely similar cellulose based contaminants in cases where the library was representative of the samples searched. When spectra of contaminant samples from crops grown in different geographic locations, seasons, and conditions and measured with a different spectrometer and accessories were searched, identification rates for standard search algorithms decreased significantly. Six standard algorithms were examined: dot product, correlation, sum of absolute values of differences, sum of the square root of the absolute values of differences, sum of absolute values of differences of derivatives, and sum of squared differences of derivatives. Four categories of contaminants derived from cotton plants were considered: leaf, stem, seed coat, and hull. Experiments revealed that the performance of the standard search algorithms depended upon the category of sample being searched and that different algorithms provided complementary information about sample identity. These results indicated that choosing a single standard algorithm to search the library was not possible. Three voting scheme algorithms based on result frequency, result rank, category frequency, or a combination of these factors for the results returned by the standard algorithms were developed and tested for their capability to overcome the unpredictability of the standard algorithms' performances. The group voting scheme search was based on the number of spectra from each category of samples represented in the library returned in the top ten results of the standard algorithms. This group algorithm was able to identify correctly as many test spectra as the best standard algorithm without relying on human choice to select a standard algorithm to perform the searches.

Interesterified plastic fats were produced with trans-free substrates of fully hydrogenated soybean oil, extra virgin olive oil, and palm stearin in a weight ratio of 10:20:70, 10:40:50, and 10:50:40, respectively, by lipase catalysis. The major fatty acids of the products were palmitic (32.2-47.4%), stearic (12.0-12.4%), and oleic acid (33.6-49.5%). After storage at 5 degrees C (refrigerator temperature) or 24 degrees C (room temperature) for 16 h, the physical properties were evaluated for solid fat content, texture, melting, and crystallization behavior, viscoelastic properties, crystal polymorphism, and crystal microstructure. The interesterified fats contained desirable crystal polymorphs (beta' form) as determined by X-ray diffraction spectroscopy. They exhibited a wide plastic range of solid fat content of 52-58% at 10 degrees C and 15% at 40 degrees C. The physical properties were influenced by the ratio of palm stearin and olive oil. Harder and more brittle texture, crystallization and melting at higher temperature, higher solid fat contents, and more elastic (G') or viscous (G') characteristics were observed in the produced fats containing a higher content of palm stearin and lower content of olive oil. The produced fats stored at 5 degrees C consisted mostly of beta' form crystal together with a small content of beta form, while those at 24 degrees C had only beta' form. The produced fat with a higher amount of palm stearin appeared to have more beta' form crystal and small size crystal clusters. Thus, the physical properties of the produced plastic fats may be desirable for use in a bakery product.

Rapid visco analysis (RVA) and differential scannning calorimetry (DSC) provided overall assessments of the effects of variable temperature soaking at 30, 50, 70, and 90°C and steaming at 4, 8, and 12 min. Calculation of the relative parboiling index (RPI) and percent gelatinization provided good metrics for determining the overall effects of partial parboiling. FT-Raman and solid-state 13C CP-MAS NMR spectroscopies provided insight to conformational changes in protein and starch of paddy rice under various parboiling conditions. RVA showed lower pasting curves and DSC showed lower ΔH with increased temperature and steaming times. A large decrease in viscosity occurred with only the 30-4 treatment as opposed to raw rice. This observation was consistent with FT-Raman results that indicated substantial conversion of the protein from α-helix to other conformations. DSC indicated incomplete gelatinization of starch, even with 90°C soaking and 12 min of steaming. Solid-state 13C CP-MAS NMR spectroscop...

This study was conducted to develop calibration models for determining quality parameters of whole kernel barley using a rapid and nondestructive near-infrared (NIR) spectroscopic method. Two hundred and five samples of whole barley grains of three winter-habit types (hulled, malt, and hull-less) produced over three growing seasons and from various locations in the United States were used in this study. Among these samples, 137 were used for calibration and 68 for validation. Three NIR instruments with different resolutions, one Fourier transform instrument (4 cm−1 resolution), and two dispersive instruments (8 nm and 10 nm bandpass) were utilized to develop calibration models for six components (moisture, starch, β-glucan, protein, oil, and ash) and the results were compared. Partial least squares regression was used to build models, and various methods for preprocessing of spectral data were used to find the best model. Our results reveal that the coefficient of determination for calibration models (NIR predicted versus reference values) ranged from 0.96 for moisture to 0.79 for β-glucan. The level of precision of the model developed for each component was sufficient for screening or classification of whole kernel barley, except for β-glucan. The higher resolution Fourier transform instrument gave better results than the lower resolution instrument for starch and β-glucan analysis. The starch model was most improved by the increased resolution. There was no advantage of using a higher resolution instrument over a lower resolution instrument for other components. Most of the components were best predicted using first-derivative processing, except for β-glucan, where second-derivative processing was more informative and precise.

To assess the variation in quality of chicken breast fillets available from retail supermarkets, six brands of boneless, skinless fillets without additives were obtained from the fresh counter at grocery stores in Athens, GA, and the surrounding area during fall of 2005. The samples were stored at −20C and subsequently cooked using a Henny Penny MCS-6 combi oven (Henny Penny Corp., Eaton, OH). Quality parameters of the fillets were measured on the cooked chicken breast fillets including cook yield, descriptive sensory flavor and texture profiling, and Warner–Bratzler (WB) shear force. Our results show that the average cook yield ranged from 78.1 to 80.9%, the average intensity of individual descriptive sensory characteristics was less than 5.4 in a 0–15 universal scale, and WB shear force values were less than 5.2 kg. There were no significant differences in the intensity among brands of all flavor attributes and the texture characteristics associated with moisture. However, significant differences were found among the brands for cook yield, mechanical properties of texture (including springiness, cohesiveness, hardness and chewiness) and WB shear force values. The variation of WB shear force measurements (coefficient of variation) depended on brand. These results indicate that differences exist in the quality and shear force consistency among market brands of boneless, skinless chicken breast fillets available in Athens, GA, and the surrounding area. PRACTICAL APPLICATIONS This study is the first survey reported to evaluate the quality of boneless, skinless chicken breast products without additives in U.S. retail market. This study supplies the evidence that the intensity of sensory quality is mild of cooked boneless, skinless chicken breast products and there are the differences in the quality among the different retail brands obtained by consumers.

Xylan, cellulose and lignin are the three major components of secondary walls in wood, and elucidation of the biosynthetic pathway of xylan is of importance for potential modification of secondary wall composition to produce wood with improved properties. So far, three Arabidopsis glycosyltransferases, FRAGILE FIBER8, IRREGULAR XYLEM8 and IRREGULAR XYLEM9, have been implicated in glucuronoxylan (GX) biosynthesis. In this study, we demonstrate that PARVUS, which is a member of family GT8, is required for the biosynthesis of the tetrasaccharide primer sequence, beta-D-Xyl-(1 --> 3)-alpha-l-Rha-(1 --> 2)-alpha-D-GalA-(1 --> 4)-D-Xyl, located at the reducing end of GX. The PARVUS gene is expressed during secondary wall biosynthesis in fibers and vessels, and its encoded protein is predominantly localized in the endoplasmic reticulum. Mutation of the PARVUS gene leads to a drastic reduction in secondary wall thickening and GX content. Structural analysis of GX using (1)H-nuclear magnetic resonance (NMR) spectroscopy revealed that the parvus mutation causes a loss of the tetrasaccharide primer sequence at the reducing end of GX and an absence of glucuronic acid side chains in GX. Activity assay showed that the xylan xylosyltransferase and glucuronyltransferase activities were not affected in the parvus mutant. Together, these findings implicate a possible role for PARVUS in the initiation of biosynthesis of the GX tetrasaccharide primer sequence and provide novel insights into the mechanisms of GX biosynthesis.

Fourier transform mid-infrared (FT-IR) spectroscopy was investigated as a method of analysis for trans fatty acid content of cereal products without the need for prior oil extraction. Spectra were obtained, with an FT-IR spectrometer equipped with an attenuated total reflectance (ATR) device, of ground samples pressed onto the diamond ATR surface, and trans fatty acids were measured by a modification of AOAC Method 996.01. Partial least-squares (PLS) models were developed for the prediction of trans fatty acids in ground samples using several wavenumber selections on the basis of bands related to lipids. The models (n = 79) predicted trans fatty acids in ground samples with standard error of cross-validation (SECV) of 1.10-1.25 (range 0-12.4) % and R2 of 0.85-0.88 and in validation samples (n = 26) with standard error of performance (SEP) of 0.96-1.12 (range 0-12.2) % and r2 of 0.89-0.92, indicating sufficient accuracy for screening. Sample trans fatty acid % was predicted as accurately with the fingerprint region (1500-900 cm(-1)) as with the entire range (4000-650 cm(-1)) indicating, in concert with the regression coefficients, the importance of the isolated trans double bonds at 966 cm(-1) in development of the model. Data is also presented on prediction of trans fatty acids using the spectra of residual oil films on the ATR surface after removing the solid portion of the sample.

Flax fibers may be blended with cotton to provide an aesthetic property, improve performance and tailor fabric properties. The quality and cost of the woven fabric blends are affected by the amount of linen in the blend. Microscopic and chemical analyses are currently used to determine linen content in fabrics. This study describes a method to predict the linen percentage in linen/cotton blends using Fourier transform near-infrared (FT-NIR) spectroscopy, rapidly and non-invasively. A calibration model using partial least squares regression analysis was developed with gravimetrically measured ground flax-cotton fiber mixtures as reference samples versus NIR spectra. The best model occurred with a combination of multiplicative scatter correction and first derivative processing of the spectral data gave a standard error of validation of 2.20%, and only one factor was used for the model performance. Using this model, flax content was predicted in specific mixtures of flax and cotton fibers, blended flax-cotton yarns, and various non-scoured flax-cotton fabrics, giving standard errors of prediction less than 3%. Application of the calibration model to the scoured fabric, however, resulted in a higher error value. This result seemed to be due to loss in wax components and substantial changes in the NIR absorbance values of the fabric resulting from the scouring process. An alternative calibration model for scoured and dyed fabrics was developed, and using the model it was possible to predict flax contents in dyed fabrics with an error of 4–6%.

The objective of the review is to provide fundamental knowledge on the chemical composition and structural characteristics of flax fibres. These are long and multinucleate cells without septum or partition (average length 2–5 cm) and have a secondary wall of very large thickness (5–15 μm). Fibres are gathered in bundles of one to three dozen cells that encircle the vascular cylinder. The bundle cohesion is insured by pectins, accumulating in the primary wall and cell junctions. In contrast, lignin, which is present in very low amount, does not seem to play a major role in bundle cohesion. At maturity, secondary wall is characterised by (i) a high level of cellulose with microfibrils locked into an almost axial direction and (ii) 5–15% non-cellulosic polysaccharides (NCPs). The chemical composition of NCPs depends on growth stage, indicating important cell wall remodelling, fibre position and variety. Despite the large disparity of the results reported in the literature, galactose appears to be the predominant sugar of NCPs, and β-1-4-galactan together with rhamnogalacturonan of type I (RG-I) and polygalacturonic acid (PGA) become, with fibre maturity, the most abundant tightly bound NCPs. Glycine-rich proteins (GRPs) and arabinogalactan-proteins (AGPs), also present in flax fibres, are both characterised by appreciable levels of glycine and acidic amino acid and are deficient in hydroxyproline, and may contribute to the cross-linking of pectins. (Galacto)glucomanans/glucans rather than xylans consist of cross-linking polymers in fibre secondary wall. A model is proposed where cellulose microfibrils, tethered by cross-linking (galacto)glucomanans/glucans, are embedded in a pectic matrix.

Preliminary studies by atomization test the application of various kinds of enzymes as a means of tailoring dew-retted flax fibers in a low moisture atmosphere. A series of chemical and physical tests determines the effect of enzymes on fibers and blended yarns (50:50 flax : cotton). GLC analysis of post-treatment fiber washes shows that lipase and cellulase release the most sugars, likely due to structural disorganization of the fiber matrix. Glucose is the sugar most released by enzyme treatment. Mid-infrared spectros copy of fibers indicates the loss of carbohydrates and the presence of absorbed proteins following all enzyme treatments. All treatments reduce fiber strength and elongation compared to untreated fibers, with cellulase reducing fiber strength the most at 56% of the untreated control. Treatments reduce the occurrence of thick and thin places but reduce yarn strength as well. In general, lipase and arabinanase treatments influence yarn properties the most by increasing strength over the buffer-only treatment, increasing elongation over untreated and buffer-treated yams, and reducing neps and thick/thin places. These preliminary results suggest strategies to optimize enzyme treatments for improved textile properties.

Fourier-transform mid-infrared mapping and histochemical staining are used to reveal the location and relative importance of chemical components involved with the base of cotton fibers and their associated seed coat. These two complementary techniques are focused on the nature of the chemical components that hold cotton fibers at their bases to the seed coat and with other portions of seed coat fragments that are often found as part of the trash component of ginned cotton. Infrared results reveal waxes or long-chain alcohols adjacent to the shank of cotton fiber bases in the outer epidermal tissue in all regions of the cotton seed; uronate anions in the outer epidermis and pigment layers surrounding the bases of the fibers and strongly present in the upper palisade layer tissue of all seed regions; compounds containing carbonyl functionality, acids, and bases, at the juncture of the upper palisade and colorless layers; tannin or pretannin-type aromatic structures in the outer pigment layer and interior to the cells in the epidermal layer of all seed coat regions; and lignin-type aromatics in the "colorless" layer of all regions of the seed coat. The infrared results are complemented by staining with Oil Red O for waxes, Ruthenium Red for pectins, acid phloroglucinol for lignins, and vanillin-HCl for tannins. The results provide a better understanding of fiber-seed interactions that are important to the development of methods for improving the separation of cotton fibers from seed coats. In turn, this will help to avoid breaking fibers and pulling out seed coat fragments with the fibers during ginning.

The use of atomization or an aerosol formation is investigated as a vehicle for enzyme treatment of dew-retted flax fibers. A cellulase/endoglucanase from Trichoderma reesei is applied by atomization to dew-retted fibers at concentrations of 0. 50, and 100 U. Enzyme activity post-atomization is verified by GLC analyses of sugars hydrolyzed from the treated fibers. Cellulase treatment results in the release of glucose and galactose moieties in a dose response manner. Fiber strength determination also demonstrates a dose response effect in relation to treatment with 50 and 100 U of enzyme, yielding strength decreases of 17 and 56%, respectively. Visualization of treated flax fibers by polarized light microscopy reveal the presence of structural aberrations previously identified as nodes, and treatment with the atomized enzyme coincides with fiber disruption at these regions. Mid-IR attenuated total reflectance spectra of fiber mats show a reduction in bound water and loss of acetylated components at the fiber surface resulting from enzyme treatment. Collectively. these results demonstrate the effectiveness of atomization as a means of applying enzymes for fiber modification, and the results also have implications for the flax fiber structure.

Fourier transform infrared (FT-IR) microspectroscopic mapping was investigated as a tool to study the effects of enzymatic retting of flax stems. The FT-IR technique permitted the elucidation of the relative loss or changes in the distribution of key chemical components after treatment with enzymes or enzyme/chelator mixtures in association with visible changes in structure. Cross-sections of Ariane flax stems were treated with SP 249 (a pectinase-rich enzyme mixture from Novo Nordisk) at 0.5, 0.7 or 1.0 ml l -1 concentration in pH 5 acetate buffer for 6h at 40°C. Flax stems treated with 0.5 or 0.7 ml l -1 SP 249 and 50 mM oxalic acid as a chelator were also investigated by the technique. The results indicated that treatment with 0.5 ml l -1 SP 249 alone was ineffective in releasing the fibre bundles from the surrounding tissue, but the release was increased by the addition of 50mM oxalic acid as a likely chelator for the cations of pectate salts. However, the IR spectra of the bundles indicated that an insoluble oxalate salt remained on the tissue after this treatment. Increasing the concentration of SP 249 to 0.7 ml l -1 plus 50 mM oxalic acid was effective in releasing the fibre bundles and generating some ultimate fibres with no detectable oxalate expectate salt residues. Increasing the SP 249 concentration to 1.0 ml l -1 without using oxalic acid was effective in separating the fibre bundles into ultimate (individual) fibres, leaving no pectate salt residue and only a trace of pectic esters and/or acids. The use of infrared mapping, or so-called chemical imaging, is shown to have advantages over visible imaging alone in that it can detect and locate the chemical species present after each treatment in relation to the anatomical features of the flax stem. This analytical tool shows promise as a technique by which to study the effects of enzymatic treatment of natural fibre materials. Le rouissage, qui permet la liberation des fibres de plantes comme le lin (Linum usitatissimum L) n'est pas uniforme et constitue un probleme economique pour ce secteur. Cette etude utilise la microspectrosocopie infra rouge a transformee de Fourier pour examiner les effets du procede de rouissage enzymatique. Cette technique permet d'evaluer les changements relatifs dans la distribution des composants chimiques cles apres traitement par des enzymes ou des melanges enzyme/chelateur en association avec les changements physiques de la structure.

Rice samples were taken from a study of rice milling properties that affect quality. The spectra of milled and cooked samples were taken in the near-infrared, mid-infrared, and Raman region. These spectra, two regions at a time, were regressed by a two-dimensional technique to develop contour maps that indicated the correlation of two spectral regions. These relationships demonstrate that it is possible to recognize the hydration effects caused by gelatinization (cooked samples vs. milled rice). Three water (O-H stretch) spectral bands (960, 1445, 1,930 nm) in the near-infrared (NIR) show marked differences between milled and cooked rice. The difference spectra indicated that there were additional phenomena occurring besides the addition of water. These differences are apparent in both C-O-H and N-H bands, which indicate that water is interacting with both starch and protein. The two-dimensional technique developed in this laboratory was used to get a better interpretation of what occurs during c...

Lignin, a complex phenylpropanoid compound, is polymerized from the monolignols p-coumaryl alcohol, coniferyl alcohol and sinapyl alcohol. These three monolignols differ only by the 3- and 5-methoxyl groups. Therefore, enzymatic reactions controlling the methylations of the 3- and 5-hydroxyls of monolignol precursors are critical to determine the lignin composition. Recent biochemical and transgenic studies have indicated that the methylation pathways in monolignol biosynthesis are much more complicated than we have previously envisioned. It has been demonstrated that caffeoyl CoA O-methyltransferase plays an essential role in the synthesis of guaiacyl lignin units as well as in the supply of substrates for the synthesis of syringyl lignin units. Caffeic acid O-methyltransferase has been found to essentially control the biosynthesis of syringyl lignin units. These new findings have greatly enriched our knowledge on the methylation pathways in monolignol biosynthesis.

Three types of spectroscopy were used to examine rice quality: near infrared (NIR), Raman, and proton nuclear magnetic resonance (1H NMR). Samples from 96 rice cultivars were tested. Protein, amylose, transparency, alkali spreading values, whiteness, and degree of milling were measured by standard techniques and the values were regressed against NIR and Raman spectra data. The NMR spectra were used for a qualitative or semiquantitative assessment of the amylose/amylopectin ratio by determining the 1–4 to 1–6 ratio for glucans. Protein can be measured by almost any instrument in any configuration because of the strong relationship between the spectral response and the precision of the reference method. Amylose has an equally strong relationship to the vibrational spectra, but its determination by any reference method is far less precise, resulting in a 10× increase in the standard error of cross-validation (SECv) or standard error of performance (SEP) with R 2 values equal to that of the protein m...

Flax (Linum ustitatissimum L.) is the source of natural fibers that provides biobased products for a variety of existing markets, but considerable processing and cleaning is required. Flax fibers, and bast fibers generally, are produced in the outer regions of the stem between bark and inner core tissues and require retting, which is the microbial separation of fiber from nonfiber tissues, as the first and most limiting stage of processing. Enzyme retting offers a method to overcome disadvantages of the current method, i.e., dew-retting, for high- and consistent-quality fibers with tailored properties for specific applications. Using chemical analyses, microscopy, and microspectroscopy, sites of carbohydrates, aromatics, and waxes plus cutins were identified in flax stems and their relationship to effective enzyme retting determined. Aromatics occur mostly in the inner, core tissues, with the fibers containing only small amounts located sporadically in cell corners of fiber bundles. Therefore, effective retting using enzymes to separate the aromatic-containing tissues from the fibers, but not to degrade aromatic compounds per se, is required. Waxes and cutin in the epidermal regions are effective barriers to enzyme penetration, and mechanical disruption facilitates enzyme penetration into the stems. Pectinases, with chelators to remove Ca++ and destabilize pectin molecules, remove matrix compounds holding fibers within the stem and have been used in effective formulations to ret flax stems.

A series of flax fibre and yarn samples that had been commercially graded low, medium, and high quality were analysed by light microscopy, wet chemical analysis, Raman spectroscopy, and nuclear magnetic resonance (NMR) spectroscopy to determine characteristics which could be related to quality ratings for each sample type. Light microscopy revealed fragments of cuticular and epidermal material bound to the fibres. As the quality ratings improved, fewer of these fragments were found and greater separation of the fibre bundles to smaller bundles and, in some cases, elementary fibres occurred indicating more efficient retting. Chemical evaluation showed that, as quality of the yarns increased, amounts of fatty acid and long-chain alcohols as well as dihydroxy fatty acids decreased. Chemical data on fibre did not show consistent trends with quality. Raman spectroscopy showed increasing amounts of cellulose and decreasing amounts of aromatics and hydrocarbons with increasing quality, which paralleled the chemical data. NMR analysis showed nearly equal amounts of crystalline cellulose regardless of quality for both fibre and yarn samples. The strengths and weaknesses of each analytical method are discussed. This initial study suggested that chemical constituents characteristic of cutin and waxes could be used as an initial marker of quality. © 1999 Society of Chemical Industry

Samples of flax (Linum usitatissimum L.) stem and its anatomical parts were studied by near-infrared Fourier transform Raman (NIR-FT-Raman) spectroscopy to determine if the major chemical component...

Partial least-squares regression (PLSR) was used to generate three Raman and three near-infrared reflectance (NIRR) models for the spectroscopic determination of total dietary fiber (TDF) of a wide variety of cereal foods. To allow comparison of the spectral techniques, both analyses used the same sets of samples ( ncal = 63, nval = 63). Six models were optimized by full leave-one-out cross-validation (CV), including a smoothed, a first-, and a second-derivative model for each spectral technique. Both kinds of raw spectral data required correction of interfering baseline and amplitude variations. Derivative preprocessing generally reduced the number of latent variables (LVs) for both spectral types and significantly reduced the CV error of the Raman models. The derivative treatments enhanced the influence of select vibrational-bandwidth-sized features in the Raman data (64–84 cm−1). The Savitzky–Golay derivative calculation method was better for the NIRR data, while the gap-difference method was better for the Raman data, which had a higher level of baseline noise. Raman models required 6 to 9 latent variables while NIRR models required 10 to 14 LVs. The root-mean-squared CV model errors were 2–2.3% TDF for all six models, and the three Raman models had root-mean-squared prediction errors (RMSEPs) in the range 2.8–3.2% TDF, with the best model being generated from second-derivative data. First-derivative data provided the best NIRR model, and for all three NIRR models the RMSEP spanned 2.4–2.9%. For some types of samples, it is suggested that the Raman method is limited by its sampling technique and could be improved with more densely packed, larger-area specimens. The regression vectors of the Raman models seem more easily interpretable than NIRR models. Either spectral method appears capable of acheiving an acceptable level of error; TDF reference method precision was 0.68% TDF, while the product label information had an error of 2.8% TDF relative to the reference.

The proliferation of applications for near infrared (NIR) spectroscopy has been fostered by advances in instrumentation and statistics. NIR analytical instrumentation is becoming more stable and reliable. Chemometrics is playing an important role in qualitative and quantitative NIR spectra analysis. The objective of this study was to evaluate the performances of four commonly used calibration models: (1) stepwise multiple linear regression (SMLR); (2) classical least-squares (CLS); (3) principal component regression (PCR); and (4) partial least-squares (PLS) in NIR spectroscopy analysis when random noise is present in the optical data. A conceptually simple procedure for comparing the performance of the four calibration methods in the presence of different levels of random noise in spectra data has been introduced here. This procedure, using the computer simulation data and real spectra of tobacco, has provided useful information for understanding the effects of random noise on the performance of multivariate calibration methods. Both numerical and graphical results will be shown.

This work evaluates the complementarity in the predictive ability of three Raman and three near-infrared reflectance (NIRR) partial least-squares regression (PLSR) models for total dietary fiber (TDF) determinations of a diverse set of ground cereal food products. For each spectral type (R or N), models had previously been developed from smoothed (D0), first-derivative (D1), or second-derivative (D2) spectral data. The NIRR and Raman models tend to have very different sets of outliers and uncorrelated errors in TDF determination. For a single spectral type, the prediction errors of various preprocessing methods are partially complementary. The samples are very diverse in terms of composition, but the main problem groups were narrowed to high-fat, high-bran, and high-germ samples, as well as and those containing synthetic fiber additives. Raman models perform better on the high-fat samples, while NIRR models perform better with high-bran and high-synthetic samples. Raman models were better able to accommodate a wheat germ sample, even though this sample type was poorly represented by the calibration set. Two methods are presented for utilizing the complementarity of the spectral and processing techniques: one involves simple averaging of predictions and the other involves avoidance of outliers by using statistics generated from the sample spectrum to choose the best model(s) for determination of the TDF value. The single best model (N-D1) has a root-mean-squared prediction error of 2.4% TDF. The best model of prediction averages yields an error of 1.9% (combining N-D0, N-D1, N-D2, R-D0, and R-D1). An error of 1.9% was also obtained by choosing a single prediction from the six models by using statistics to avoid outliers. With the selection of the best three models and averaging their predictions, an error of 1.5% was achieved.

Crystalline sugar has unique spectral characteristics that influence the near-infrared (NIR) region of the spectrum often used to assess product composition. The current study investigated the potential of expanding an existing NIR spectroscopic calibration for the prediction of total dietary fiber in cereal products to include products with high sugar and crystalline sugar content. Using AOAC Procedure 991.43 as the reference method, an NIRSystems monochromator and ISI software for scanning and data analysis, and a selection algorithm to select representative high-sugar samples, a sugar-expanded partial least-squares model (n = 100) was developed for prediction of dietary fiber. The standard error of cross-validation, R2, standard error of performance (n = 45 independent validation samples), and r2 were 1.88%, 0.98, 1.40%, and 0.99, respectively. The NIR model for prediction of total dietary fiber in cereal products was, thus, expanded to include samples with high sugar and crystalline sugar content. Key...

Two-dimensional correlation spectroscopy across the near infrared (NIR) and mid-infrared (MIR) regions have been used to explain the NIR spectra of hard red winter and spring wheat and provide additional confidence in analytical models developed with empirical data. Recent studies have shown that the major C–H stretching vibrations and some of the aromatic C–H and ring stretching vibrations and the minor vibrations in the “fingerprint” region are correlated also. The technique has been expanded to include Raman spectra. The Raman spectra were enhanced with Maximum Likelihood methods to improve signal-to-noise (S/N) while maintaining resolution. This was necessary to eliminate the effects of fluorescence which degrades S/N. The use of NIR lasers at 1.1 μm generally eliminates fluorescence as a problem, but it is still quite prevalent in agricultural materials. The original study did not show any significant correlations to aromatic functionality. However, the band at 1552 nm correlates to the Raman and not to the MIR. This band has shown up in NIR spectroscopy models for the determination of lignin, but is not readily observed in the MIR. Thus it correlates to a Raman active rather than a MIR active band. The same phenomena are observed for the amide I, II and III bands for wheat. The interesting features from NIR and MIR are that there are correlations that distinguish winter from spring wheat. These, and the Raman spectra of wheat, will be shown. These studies show that multiple regions of the electromagnetic spectrum can be, and in deed need to be, used to interpret adequately the spectral and statistical results we have traditionally obtained in the NIR.

The determination of the structure of {[5-O-(E)-feruloyl] [O-β-D -xylopyranosyl-(1 2)]-O-α-L arabinofuranosyl-(1 3)}-O-β-D-xylopyranosyl-(1 4)-D-xylopyranose, a compound isolated from the cell walls of Gramineae, is presented. Use is made of 1D HOHAHA and 2D 1H, 13C 1H-detected HMQC to assign the 1H and 13C NMR spectra of the individual residues. The 2D 1H, 13C 1H-detected HMBC and 1H, 1H ROESY, in comparison with 1H, 1H COSY, experiments are used to establish the inter-residue linkages. This is the first report of a feruloylated arabinoxylan that contains the β-D-Xylp-(1 rarr; 2)-α-L-Araf element.

Two-dimensional (2D) statistical correlation of mid- and near-infrared spectra was used as a means to assist with qualitative spectral interpretation of the lignin carbohydrate fractions from plant materials. Cross-correlation by least-squares is used to assess changes in both regions that result from changes in the set of sample spectra. The technique has been applied to a set of specially prepared “lignin” samples that differ in lignin content, species of origin, and method of preparation. Dispersive near-infrared (NIR) and Fourier transformed mid-infrared (FT-IR) diffuse reflectance spectra (DRIFTS) were obtained on each of the samples, and point-for-point 2D cross-correlation was obtained. The technique permits the correlation of the combination and overtone bands of the NIR region with the fundamental vibrations in the mid-infrared (MIR) region. The results show a broad correlation of aromatic C-H stretch at 3022 cm−1 in the MIR to 1666-nm location in the NIR region and other locations to a lesser extent all across the NIR from 1400 to 2500 nm. A narrower region of correlation was found for the phenolic O-H stretch in the MIR at 3663 cm−1 to 1428 nm and 1938 nm in the MIR. Multiple narrow correlations occur in the area of the summation bands from 1450 to 1650 cm−1, indicative of substitution patterns and correlated areas of C-H and O-H stretch in the NIR.

Maysin [2"-O-alpha-L-rhamnosyl-6-C-(6-deoxy-xylo-hexos-4-ulosyl) luteolin], the resistance factor of Zapalote Chico corn (Zea mays L.) silks to the corn earworm (Helicoverpa zea Boddie), was determined by HPLC in the silks of over 600 inbreds, populations, plant introductions (PI), and various unassigned collections. Maysin levels ranged from 0% to 0.9% fresh weight with approximately 19% of both the inbreds and populations containing maysin levels above 0.2%, a level considered to be necessary for resistance, as based on the laboratory bioassay determined level (for larval) of maysin toxicity. Over 25 lines yielded higher silk maysin than found in Zapalote Chico (0.347%). High levels of 2"-O-alpha-L-rhamnosyl-6-C-(6-deoxy-xylo-hexos-4-ulosyl) apigenin (apimysin) were found in inbred NC7, while Tx501 contained appreciable amounts of 2"-O-alpha-L-rhamnosyl-6-C (6-deoxy-xylo-hexos-4-ulosyl)-3'-methoxyluteolin (3'-methoxymaysin). Spectral data (13C NMR and FAB-MS) are given for the characterization of maysin, apimaysin, and 3'-methoxymaysin.

Techniques are needed to rapidly assess the location of phenotics within cell types. The objective of this work was to investigate by midinfrared microspectroscopy a series of intact cell types, which have a range of digestibilities, from normal (N) and brown midrib (bmr) pearl millet [Pennisetum glaucum (L) R. Br.]. Rind and parenchyma tissues were evaluated using a Nicolet System 740 spectrometer equipped with a Nicolet 0.25 mm MCT-A detector¹ interfaced to a microscope. Spectra of rind were similar for normal and bmr mutants and closely resembled lignin spectra. Spectra of pith tissue were similar among plant types and to that for carbohydrates, but differed from rind spectra. Preliminary results indicated that spectra were different for tissues of different digestibilities and showed promise for the use of microspectroscopy in evaluating forage quality of cell types.

Leaflets of alfalfa (Medicago sativa L) and leaf blade sections of orchardgrass (Dactylis glomerata L) were digested for three consecutive incubation periods of 3 days each with rumen bacteria. Residues were then analyzed by the following methods: (i) scanning electron and light microscopy to define the botanical structures; (ii) ultraviolet absorption microspectrophotometry to characterize phenolic constituents within specific regions; (iii) NMR and midinfrared spectroscopy to determine components, linkages, and functional groups; and (iv) gas-liquid chromatography for phenolic acids and lignin constituents after treatment with 1 M NaOH (25°C, 24 h) and 1 M NaOH followed by 4 M NaOH (170°C, 2h). Alfalfa residue consisted of extensive amounts of cuticular sheets, a network of vascular bundles, and smaller portions of cuticle overlying lignified structures associated with major vascular bundles. Orchardgrass residue consisted of large and small vascular bundles, usually without the mestome sheath surrounding phloem, and small portions of cuticle. Alfalfa lignin was more condensed but had similar proportion of ether-linked phenolic acids compared with that of orchardgrass, while the grass lignin had substantially higher concentrations of ester-linked p-coumaric and ferulic acids associated with a higher proportion of carbohydrates in the residue. Alfalfa had a higher fatty ester content, likely due to the large amount of cuticle in the residue, and protein, which likely was contained within the lignin. The results provide a detailed characterization of aromatics and linkages within the most recalcitrant tissues of plants and indicate variations between non-degradable residues of a legume and a grass.

4,4'-Dihydroxy-3,3'-dimethoxy-α-truxillic acid (II) and 4,4'-dihydroxy-3-methoxy-α-truxillic acid (III) were prepared and isolated for the first time in good yield from photodimerization of (E)-ferulic acid (F) alone and mixed with (E)-p-coumaric acid (P) (for III and II, respectively) using high-intensity fluorescent light. The rate of photodimerization of ferulic acid alone was much slower than the dimerization of P to 4,4'-dihydroxy-α-truxillic acid (I). When p-coumaric acid was added to ferulic acid, the rate of production of II was increased; the proportions of I-III formed varied with the ratio of P:F irradiated (.)

The ultrastructure and chemical composition of paper and pedicel from nests ofPolistes metricus that were constructed in the laboratory from known building material were compared to paper and pedicel from nests constructed in the field. Scanning electron micrographs showed the addition of a gluelike secretion from the wasp to the construction material. Solid-state [(13)C]NMR, elemental analyses, and amino acid analyses indicate that this secretion is a silklike protein with serine, glycine, alanine, and proline comprising 65-73% of the identified residues.

This study deals with the rapid detection and differentiation of Escherichia coli, Salmonella, and Campylobacter, which are the most commonly identified commensal and pathogenic bacteria in foods, using fluorescence spectroscopy and multivariate analysis. Each bacterial sample cultured under controlled conditions was diluted in physiologic saline for analysis. Fluorescence spectra were collected over a range of 200–700 nm with 0.5 nm intervals on the PerkinElmer Fluorescence Spectrometer. The synchronous scan technique was employed to find the optimum excitation (λex) and emission (λem) wavelengths for individual bacteria with the wavelength interval (Δλ) being varied from 10 to 200 nm. The synchronous spectra and two-dimensional plots showed two maximum λex values at 225 nm and 280 nm and one maximum λem at 335–345 nm (λem=λex + Δλ), which correspond to the λex=225 nm, Δλ=110–120 nm, and λex=280 nm, Δλ=60–65 nm. For all three bacterial genera, the same synchronous scan results were obtained. The emission spectra from the three bacteria groups were very similar, creating difficulty in classification. However, the application of principal component analysis (PCA) to the fluorescence spectra resulted in successful classification of the bacteria by their genus as well as determining their concentration. The detection limit was approximately 103–104 cells/mL for each bacterial sample. These results demonstrated that fluorescence spectroscopy, when coupled with PCA processing, has the potential to detect and to classify bacterial pathogens in liquids. The methology is rapid (

The interaction of water with cellulose and its influence on the nuclear spin dynamics in Gossypium barbadense (Pima) cotton were investigated by 1H and 13C solid-state NMR techniques. 1H spin diffusion results from a Goldman-Shen experiment indicate that the water is multilayered. 1H MAS experiments provide evidence of a range of correlation times for the water, indicative of molecular motion ranging from restricted to relatively mobile. The 1H spin-lattice relaxation time varies with water content and is different for static and MAS conditions. By coupling the Goldman-Shen sequence with 13C CP/MAS, cross-polarization from the molecularly mobile water protons distributes magnetization throughout the cellulose (as opposed to enhancing 13C resonances from only the crystalline or the amorphous domains or from only the surface of the cellulose). However, spatial localization of the combined Goldman-Shen-13C CP/MAS experiment using both short mixing and contact times yields a spectrum consistent with predominantly the Iβ polymorph of cellulose. Longer mixing times and the same, short contact time yield a spectrum that is indicative of an increased Iα polymorph content in the crystallite interiors relative to the smaller values found with short mixing times.

Cell walls of Coastal Bermuda grass (Cynodon dactylon) were treated with polysaccharide hydrolases to release O-[5-O-(trans-p-coumaroyl)-alpha-L-arabinofuranosyl]-(1----3)-O-be ta-D- xylopyranosyl-(1----4)-D-xylopyranose (PAXX) which was isolated by liquid chromatography. The isolated PAXX was greater than 95% pure as determined by 1H NMR and was used as substrate for a sensitive assay of trans-p-coumaroyl esterase. PAXX was hydrolyzed by culture filtrates from the anaerobic fungus Neocallimastix MC-2. The trans-p-coumaric acid released by enzymatic hydrolysis was assayed by reverse-phase HPLC, and as little as 100 ng of acid could be determined. Steady-state velocities for the release of the acid obeyed Michaelis-Menten kinetics. Vmax was determined to be 1.17 mumol min-1 mg-1 and Km 13.2 microM at pH 7.5 and 30 degrees C.

The complete assignment of the proton and carbon chemical shifts of 6-O-acetyl-2,3,4-tri-O-(3S-methylpentanoyl)-α-D-glucopyranosyl-β-D-fructofuranoside, a naturally occurring flavor precursor of tobacco, is presented. These assignments were made by comparison of the spectra obtained from 1H-detected heteronuclear multiple quantum coherence and 1H-detected heteronuclear multiple-bond connectivity two-dimensional NMR experiments.

The walls of the major plant cell types, sclerenchyma and parenchyma, of the second (upper) and fifth (lower) internodes from the apex of bermudagrass (Cynodon dactylon L) stem have been examined by ultraviolet absorption microspectrophotometry and the results related to wall digestibility (measured in vitro with rumen liquor) and to histochemical reactions for ‘lignin’ and phenolics. Sclerenchyma walls from the lower internode gave high values of absorbance in the ultraviolet region of the spectrum equivalent to 109 mg trans-ferulic acid g−1 dry walls; similar walls from the upper internode also gave high values but these were lower than values from the lower internode. Histochemical examination showed that the sclerenchyma walls, which were indigestible to rumen microorganisms, gave positive tests with acid phloroglucinol reagent for lignin. Parenchyma walls, which were either digested or partially digested, gave much lower absorbance values in the ultraviolet region and negative tests with acid phloroglucinol but positive tests with diazotised sulphanilic acid (upper and lower internodes) and chlorine-sulphite (lower internode) reagents. Ultraviolet absorption microspectrophotometry is a useful technique for examining phenolics within individual cell walls that vary in biodegradability.

(...) The structures of fraction I SE contained one acetic acid group esterified to the fructose moiety in addition to three other aliphatic acids on the glucose portion of the sucrose, while fraction II SE only contained three aliphatic acids esterified to hydroxyl groups on the glucose moiety of the sucrose molecule

O-[5-O-((E)-p-coumaroyl)-α- l -arabinofuranosyl]-(1→3)-O-β- d -Xylopyranosyl-(1→4)- d -xylopyranose (PAXX) and O-[5-O-((E)-feruloyl)-α- L -arabinofuranosyl]-(1→3)-O-β- D -Xylopyranosyl-(1→4)- D -xylopyranose (FAXX) were isolated from cell walls of Cynodon dactylon by treatment with cell wall carbohydrases. The esters were exposed to light for several days. The p-coumaric acid (P) component of PAXX dimerized to 4,4′-dihydroxy-α-truxillic acid (Mr twice P, i.e. a `PP' type stereodimer) and to other PP type dimers esterified to oligosaccharide. FAXX behaved in a similar manner to PAXX; its ferulic acid (F) component dimerized to esterified 4,4′-dihydroxy-3,3′-dimethoxy-α- truxillic acid (Mr twice F, i.e. an `FF' type stereodimer) plus other esterified FF type dimers. A mixture of PAXX plus FAXX gave esterified 4,4′-dihydroxy-3-methoxy-α-truxillic acid (Mr P plus F, i.e. a `PF' type stereodimer) as the major product. It seems likely that similar dimerization reactions occur in the cell walls of the growing graminaceous plant. Such a mechanism could be involved in cross-linking adjacent p-coumaroyl and feruloyl groups in arabinoxylans leading to increased cell wall rigidity and decreased biodegradability of the wall polysaccharides.

The objective of this study was to explore the potential of near-infrared spectroscopy for determining the compositional quality properties of barley as a feedstock for fuel ethanol production and to compare the prediction accuracy between calibration models obtained using a Fourier transform near-infrared system (FT-NIR) and a dispersive near-infrared system. The total sample set contained 206 samples of three types of barley, hull-less, malt, and hulled varieties, which were grown at various locations in the eastern U.S. from 2002 to 2005 years. A new hull-less barley variety, Doyce, which was specially bred for potential use in ethanol production, was included in the sample set. One hundred and thirty-eight barley samples were used for calibration and sixty-eight were used for validation. Ground barley samples were scanned on both a FT-NIR spectrometer (10000 to 4000 cm−1 at 4 cm−1 resolution) and a dispersive NIR spectrometer (400 to 2498 nm at 10 nm resolution), respectively. Six grain components, moisture, starch, β-glucan, protein, oil, and ash content, were analyzed as parameters of barley quality. Principal component analysis showed that barley samples could be classified by their types: hull-less, malt, and hulled. Partial least squares regression indicated that both FT-NIR and dispersive NIR spectroscopy have the potential to determine quality properties of barley with an acceptable accuracy, except for β-glucan content. There was no predictive advantage in using a high-resolution FT-NIR instrument over a dispersive system for most components of barley.

The transfer of a calibration model for determining fiber content in flax stem was accomplished between two near-infrared spectrometers, which are the same brand but which require a standardization. In this paper, three factors, including transfer sample set, spectral type, and standardization method, were investigated to obtain the best standardization result. Twelve standardization files were produced from two sets of the transfer sample (sealed reference standards and a subset of the prediction set), two types of the transfer sample spectra (raw and preprocessed spectra), and three standardization methods (direct standardization (DS), piecewise direct standardization (PDS), and double window piecewise direct standardization (DWPDS)). The efficacy of the model transfer was evaluated based on the root mean square error of prediction, calculated using the independent prediction samples. Results indicated that the standardization using the sealed reference standards was unacceptable, but the standardization using the prediction subset was adequate. The use of the preprocessed spectra of the transfer samples led to the calibration transfers that were successful, especially for the PDS and the DWPDS correction. Finally, standardization using the prediction subset and their preprocessed spectra with DWPDS correction proved to be the best method for transferring the model.

Dicot wood is mainly composed of cellulose, lignin and glucuronoxylan (GX). Although the biosynthetic genes for cellulose and lignin have been studied intensively, little is known about the genes involved in the biosynthesis of GX during wood formation. Here, we report the molecular characterization of two genes, PoGT8D and PoGT43B, which encode putative glycosyltransferases, in the hybrid poplar Populus alba x tremula. The predicted amino acid sequences of PoGT8D and PoGT43B exhibit 89 and 75% similarity to the Arabidopsis thaliana IRREGULAR XYLEM8 (IRX8) and IRX9, respectively, both of which have been shown to be required for GX biosynthesis. The PoGT8D and PoGT43B genes were found to be expressed in cells undergoing secondary wall thickening, including the primary xylem, secondary xylem and phloem fibers in stems, and the secondary xylem in roots. Both PoGT8D and PoGT43B are predicted to be type II membrane proteins and shown to be targeted to Golgi. Overexpression of PoGT43B in the irx9 mutant was able to rescue the defects in plant size and secondary wall thickness and partially restore the xylose content. Taken together, our results demonstrate that PoGT8D and PoGT43B are Golgi-localized, secondary wall-associated proteins, and PoGT43B is a functional ortholog of IRX9 involved in GX biosynthesis during wood formation.

The presence of foreign matter in cotton seriously affects the cotton grade and thus the price per bale paid by the spinner to the grower, the efficiency of the spinning and ginning operations, and the quality of the final woven product. Rapid identification of the nature of the extraneous matter in cotton at each stage of cleaning and processing is necessary to permit actions to eliminate or reduce its presence and improve efficiency and quality. Although several instruments are being successfully employed for the measurement of contamination in cotton fibers based on particle size/weight, no commercial instrument is capable of accurate qualitative identification of contaminants. To this end, ATR/FT-IR spectra of retrieved foreign matter were collected and subsequently rapidly matched to an authentic spectrum in a spectral database. The database includes contaminants typically classified as "trash", cotton plant parts (hull, shale, seed-coat fragments, bract, cacyx, leaf, bark, sticks, and stems) and grass plant parts (leaf and stem); "foreign objects and materials", synthetic materials (plastic bags, film, rubber, bale wrapping and strapping); organic materials (other fibers, yarns, paper, feathers, and leather); plus entomological and physiological sugars and inorganic materials (sand and rust). The spectral matching resulted in consistently high-score identification of the foreign matter based on chemical composition, irrespective of its particle size. The method is envisioned to be employed with stand-alone rugged infrared instrumentation to provide specific identification of extraneous materials in cotton as opposed to only general classification of the type by particle size or shape.

The quality of flax fiber in the textile industry is closely related to the wax content remaining on the fiber after the cleaning process. Extraction by organic solvents, which is currently used for determining wax content, is very time consuming and produces chemical waste. In this study, near-infrared (NIR) spectroscopy was used as a rapid analytical technique to develop models for wax content associated with flax fiber. Calibration samples ( n = 11) were prepared by manually mixing dewaxed fiber and isolated wax to provide a range of wax content from 0 to 5%. A total of fourteen flax fiber samples obtained after a cleaning process were used for prediction. Principal component analysis demonstrated that one principal component is enough to separate the flax fibers by their wax content. The most highly correlated wavelengths were 2312, 2352, 1732, and 1766 nm, in order of significance. Partial least squares models were developed with various chemometric preprocessing approaches to obtain the best model performance. Two models, one using the entire region (1100–2498 nm) and the other using the selected wavelengths, were developed and the accuracies compared. For the model using the entire region, the correlation coefficient ( R2) between actual and predicted values was 0.996 and the standard error of prediction (RMSEP) was 0.289%. For the selected-wavelengths model, the R2 was 0.997 and RMSEP was 0.272%. The results suggested that NIR spectroscopy can be used to determine wax content in very clean flax fiber and that development of a low-cost device, using few wavelengths, should be possible.