NIR‐FT/Raman Spectroscopy for Nutritional Classification of Cereal Foods

The classification of cereals using near‐infrared Fourier transform Raman (NIR‐FT/Raman) spectroscopy was accomplished. Cereal‐based food samples (n = 120) were utilized in the study. Ground samples were scanned in low‐iron NMR tubes with a 1064 nm (NIR) excitation laser using 500 mW of power. Raman scatter was collected using a Ge (LN₂) detector over the Raman shift range of 202.45~3399.89 cm^‐1. Samples were classified based on their primary nutritional components (total dietary fiber [TDF], fat, protein, and sugar) using principle component analysis (PCA) to extract the main information. Samples were classified according to high and low content of each component using the spectral variables. Both soft independent modeling of class analogy (SIMCA) and partial least squares (PLS) regression based classification were investigated to determine which technique was the most appropriate. PCA results suggested that the classification of a target component is subject to interference by other components in cereal. The Raman shifts that were most responsible for classification of each component were 1600~1630 cm^‐1 for TDF, 1440 and 2853 cm^‐1 for fat, 2910 and 1660 cm^‐1 for protein, and 401 and 848 cm^‐1 for sugar. The use of the selected spectral region (frequency region) for each component produced better results than the use of the entire region in both SIMCA and PLS‐based classifications. PLS‐based classification performed better than SIMCA for all four components, resulting in correct classification of samples 85~95% of the time. NIR‐FT/Raman spectroscopy represents a rapid and reliable method by which to classify cereal foods based on their nutritional components.     

Scanning Probe Microscopes—Applications in Cereal Science

Scanning probe microscopes (SPMs) are a family of related instruments which can produce high-resolution images of structures at the molecular and atomic levels. Their main impact so far has been in surface science, but they also have tremendous potential for the study of biomolecules. In this article we will briefly introduce the properties and principles of these instruments, and then discuss a range of preliminary studies from our laboratories in relation to future applications in cereal science.     

FT‐Raman Spectra of Unsoaked and NaOH‐Soaked Wheat Kernels,Bran, and Ferulic Acid

The sodium hydroxide (NaOH) test for determining wheat color class depends on the observation that on soaking in NaOH, red wheat turns a darker red and white wheat turns straw yellow. To understand the mechanism of this test, Raman spectra of wheat bran, wheat starch, ferulic acid, and whole kernels of wheat, before and after NaOH soak, were studied. The major observable components in the whole kernel were that of starch, protein, and ferulic acid, perhaps esterified to arabinoxylan and sterols. When kernels are soaked in NaOH, spectral bands due to ferulic acid shift to lower energy and show a slightly reduced intensity that is consistent with deprotonation of the phenolic group and extraction of a portion of the ferulic acid into solution. Other phenolic acids, alkyl resorcinols, and flavonoids observed in the NaOH extracts of wheat by HPLC were not observed in the Raman spectra. Wheat bran accounts for most of the ferulic acid in the whole kernel, as indicated by the increased intensity of the doublet at 1,631 and 1,600 cm^‐1 in the bran. The intense starch band at 480 cm^‐1 in whole kernel wheat was nearly absent in the wheat bran.     

Description of Chemical Changes Implied During Bread Dough Mixing by FT‐ATR Mid‐Infrared Spectroscopy

The aim of the present study was to investigate the ability of mid‐infrared (MIR) spectroscopy to identify physicochemical changes in the French bread dough mixing process. An ATR FT‐MIR spectrometer at 4000–800 cm^–1 was used. The MIR spectra collections recorded during mixing were analyzed after standard normal variate using principal component analysis (PCA) and after second‐derivative treatment. The results were interpreted in terms of chemical changes involved in dough development and more particularly in terms of secondary structural protein changes (amide III). The loading spectrum associated with principal component 1 (PC1) allows three MIR wave number regions of variations (3500–3000, 1700–1200, and 1200–800 cm^–1) to be identified. The loading spectrum associated with PC1 describes an increase in the relative protein band intensities and a decrease in relative water and starch band intensities. The variation during bread dough mixing time of the different amide III bands identified after the second‐derivative show that α‐helical, β‐turn, and β‐sheet structures increase while random coil structure decreases, suggesting that the gluten structure is becoming a more ordered structure. The MIR mixing time identified as being the maximum scores value on the PC1 scores plots was associated with the time at which the dough apparent torque begin to collapse, suggesting that the MIR spectroscopy could monitor bread dough development.     

Estimation of the Deoxynivalenol and Moisture Contents of Bulk Wheat Grain Samples by FT‐NIR Spectroscopy

Deoxynivalenol (DON) levels in harvested grain samples are used to evaluate the Fusarium head blight (FHB) resistance of wheat cultivars and breeding lines. Fourier transform near‐infrared (FT‐NIR) calibrations were developed to estimate the DON level and moisture content (MC) of bulk wheat grain samples harvested from FHB screening trials. Grains in a rotating glass petri dish were scanned in the 10,000–4,000 cm⁻¹ (1,000–2,500 nm) spectral range using a Perkin Elmer Spectrum 400 FT‐IR/FT‐NIR spectrometer. The DON calibration predicted the DON levels in test samples with R ² = 0.62 and root mean square error of prediction (RMSEP) = 8.01 ppm. When 5–25 ppm of DON was used as the cut‐off to classify samples into low‐ and high‐DON groups, 60.8–82.3% of the low‐DON samples were correctly classified, whereas the classification accuracy of the high‐DON group was 82.3–94.0%. The MC calibration predicted the MC in grain samples with R ² = 0.98 and RMSEP = 0.19%. Therefore, these FT‐NIR calibrations can be used to rapidly prescreen wheat lines to identify low‐DON lines for further evaluation using standard laboratory methods, thereby reducing the time and costs of analyzing samples from FHB screening trials.     

分形及其在土壤科学中的应用

介绍了分形这一新兴的数学分支,并讨论了分形理论在土壤科学中的价值和应用。结合相应的模型论述了分形理论在土壤水分特征曲线及在土壤大孔隙流研究中的应用。     

Protein and Apparent Amylose Contents of Milled Rice by NIR‐FT/Raman Spectroscopy

The chemometric calibration of near‐infrared Fourier‐transform Raman (NIR‐FT/Raman) spectroscopy was investigated for the purpose of providing a rigorous spectroscopic technique to analyze rice flour for protein and apparent amylose content. Ninety rice samples from a 1996 collection of short, medium, and long grain rice grown in four states of the United States, as well as Taiwan, Korea, and Australia were investigated. Milled rice flour samples were scanned in rotating cups with a 1,064 nm (NIR) excitation laser using 500 mW of power. Raman scatter was collected using a liquid N₂ cooled Ge detector over the Raman shift range of 175–3,600 cm^‐1. The spectral data was preprocessed using baseline correction with and without derivatives or with derivatives alone and normalization. Nearly equivalent results were obtained using all of the preprocessing methods with partial least squares (PLS) models. However, models using baseline correction and normalization of the entire spectrum, without derivatives, showed slightly better performance based on the criteria of highest r² and the lowest SEP with low bias. Calibration samples (n = 57) and validation samples (n = 33) were chosen to have similar respective distributions for protein and apparent amylose. The best model for protein was obtained using six factors giving r² = 0.992, SEP = 0.138%, and bias = ‐0.009%. The best model for apparent amylose was obtained using eight factors giving r² = 0.985, SEP = 1.05%, and bias = ‐0.006%.     

应用拉曼和中红外衰减全反射光谱测定溶液和土壤中的硝酸盐

为比较拉曼光谱和红外光谱在溶液和土壤中硝酸盐含量定量分析的适用性,采用两种光谱对溶液和土壤中的NO3–-N含量(0~200 mg/L)进行快速测定。结果表明,溶液中硝酸盐的拉曼特征峰在1 047 cm–1处,该特征峰强度与NO3–-N浓度成正比,对1 035~1 060 cm-1波段拉曼光谱峰面积和NO3–-N含量进行线性回归,决定系数R2为0.995 4;溶液中硝酸盐的中红外衰减全反射光谱特征吸收峰在1 350 cm–1,吸收峰与NO3–-N含量成正比,特征吸收区1 200~1 500 cm–1峰面积与NO3–-N含量的决定系数R2为0.991 1,表明两种光谱都可用于溶液中硝酸盐的测定。对于土壤样品,红外光谱在1 250~1 500 cm–1处有硝酸盐吸收峰,且吸收峰与NO3–-N含量成正比,峰面积与NO3–-N含量之间的决定系数R2为0.968 4;而对于拉曼光谱,硝酸盐的拉曼峰因受较强干扰导致吸收峰不明显,峰面积与NO3–-N含量之间的决定系数R2仅为0.000 9,表明中红外衰减全反射光谱可用于土壤中硝酸盐的测定,而拉曼光谱则很困难。因此,拉曼光谱和中红外衰减全反射光谱都可用于溶液中硝酸盐的测定,且前者灵敏度要高于后者;中红外衰减全反射光谱可用于土壤中硝酸盐的测定,而拉曼光谱难以用于土壤中硝酸盐定量分析,这为硝酸盐的快速测定提供理论依据和技术支持。     

Classification of Single‐ and Double‐Mutant Corn Endosperm Genotypes by Near‐Infrared Transmittance Spectroscopy

A total of 1,176 grain samples representing 10 different single‐ and double‐mutant genotypic classes of specialty starch corn were used for developing various classification models based on near‐infrared transmittance spectra. The genotypes used included amylose‐extender (ae), dull (du), sugary‐2 (su2), waxy (wx), ae wx, ae du, ae su2, du wx and du su2. Two‐class classification models (only two genotypes compared) were developed using partial least squares analysis (PLS) while three‐way and multiclass models were examined using principal component analysis (PCA). The effectiveness of the calibrations was evaluated by examining the percentage of unknown grain samples incorrectly classified. In general, two‐class models performed better than multiclass models. However, they did not show improvement when discriminating among genotypes with overlapping amylose contents such ae du vs. ae and ae su2 vs. ae. Three‐way models including double‐mutants and their corresponding single‐mutant counterparts had misclassification percentages typically <5% using 14 PCA factors but again, with the exception of models including genotypes with overlapping amylose contents such as ae du vs. ae vs. du. The best multiclass model using all 10 genotypic classes simultaneously revealed only two classes (ae su2 and du) with misclassification rates >10% based on 16 PCA factors. This study demonstrates that, depending on the material to be considered, near‐infrared transmittance spectroscopy could be useful when segregation of specialty starch hybrids grain from other grain types is necessary.     

Processing Affects the Physicochemical Properties of Fiber from Wheat and Flax in Ready‐to‐Eat (RTE) Flaked Cereal

Fiber from wheat and flax is mostly insoluble, making addition in high amounts to a food difficult without adversely affecting product attributes. One approach to increasing the level of these fibers in food is to hydrolyze fiber to more soluble forms through processing. This study was designed to evaluate the impact of a steam pressure cooking process on physicochemical properties of ready‐to‐eat (RTE) cereal with 17.7% added unhydrolyzed flax fiber (a combination of arabinoxylans, rhamnogalacturonans, and pectins) or 15.4% added hydrolyzed wheat fiber (a purified arabinoxylan extract). Peak molecular weights of unhydrolyzed and hydrolyzed fibers were ∼2.9 × 10⁶ and ∼800 g/mol, respectively, with a ∼400‐fold higher viscosity for unhydrolyzed fiber. Molecular weight of the unhydrolyzed fiber ingredient was reduced to approximately the molecular weight of the hydrolyzed fiber as a result of the low‐shear steam pressure cooking process used, and consistent with molecular weight results, there was only a twofold difference in viscosity of the cereal remaining. The low‐fiber control RTE cereal had the highest viscosity owing to starch content.     

高耐铝红酵母RS1的红外光谱和拉曼光谱研究

微生物菌株RS1是从江西鹰潭油茶酸性土壤中筛选获得的一株高耐铝红酵母,能够忍耐高达200 mmol/L以上的铝浓度。前期研究表明RS1可以把铝固定在细胞表面,阻挡其进入细胞内部,但是细胞表面何种基团参与铝的固定并不清楚。本文综合采用傅里叶红外光谱和拉曼光谱技术研究了铝胁迫下红酵母RS1细胞表面官能团变化,以期从光谱学角度来探索RS1的高耐铝机制。研究发现,70 mmol/L铝处理24 h后RS1红外光谱中1 403 cm^-1处的吸收峰红移到1 397 cm^-1处,这可能是羧基峰;在1 706 cm^-1处出现新的吸收峰,这可能是羰基峰;酰胺I带吸收峰强度显著上升,且甘露聚糖的吸收峰消失。拉曼光谱在779、856 cm^-1处和1270cm^-1处出现新的吸收峰,可能分别为核糖核酸、酪氨酸和酰胺Ш带的吸收峰。综合结果表明,RS1细胞表面与铝吸附相关的物质主要是细胞壁多糖和蛋白质,主要涉及的官能团包括羧基、羰基和酰胺基。这些细胞表面官能团对铝的固定作用可能是红酵母RS1高耐铝的一个重要机...     

Review of Principles of Cereal Science and Technology, 3rd ed.

ABSTRACT

This study examines small ruminants produced by farmers in the Iseyin Local Government Area of Oyo State, Nigeria. A multistage sampling technique was used in selecting 125 respondents for the study. The majority of the respondents were between the ages of 21?40 years—male, married, and Muslim—with no formal education and a primary occupation of farming. Respondents kept an average stock size of 6–10 goats and 1–5 sheep on a free range. Farmers keep small ruminants as a source of income for spreading risks such as crop failure, for slaughter during social ceremonies, and as a measure of social status. Respondents had occasional contacts with extension agents. Constraints experienced by respondents include theft, lack of capital, drugs, and improved feed. Agricultural development programs should provide livestock extension services to small ruminant farmers and support local sanctions by government enforcement agents.     

Two‐Dimensional Vibration Spectroscopy of Rice Quality and Cooking

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 cooking. The Raman spectrum, which is relatively insensitive to water (O‐H stretch), revealed only changes in protein that could be associated with denaturization.     

Detecting and Segregating Black Tip‐Damaged Wheat Kernels Using Visible and Near‐Infrared Spectroscopy

Detection of individual wheat kernels with black tip symptom (BTS) and black tip damage (BTD) was demonstrated with near‐infrared reflectance spectroscopy (NIRS) and silicon light‐emitting‐diode (LED) based instruments. The two instruments tested, a single‐kernel NIRS instrument (SKNIRS) and a silicon LED‐based single‐kernel high‐speed sorter (SiLED‐SKS) were both developed by the Stored Product Insect and Engineering Research Unit, Center for Grain and Animal Health Research, USDA Agricultural Research Service. BTD was classified into four levels for the study ranging from sound, symptomatic (BTS) at two levels, and damaged (BTD). Discriminant analysis models for the SKNIRS instrument could distinguish sound undamaged kernels well, correctly classifying kernels 80% of the time. Damaged kernels were classified with 67% accuracy and symptomatic kernels at about 44%. Higher classification accuracy (81–87%) was obtained by creating only two groupings: 1) combined sound and lightly symptomatic kernels and 2) combined heavily symptomatic and damaged kernels. A linear regression model was developed from the SiLED‐SKS sorted fractions to predict the percentage of combined BTS and BTD kernels in a sample. The model had an R² of 0.64 and a standard error of prediction of 7.4%, showing it had some measurement ability for BTS and BTD. The SiLED‐SKS correctly classified and sorted out 90% of BTD and 66% of BTS for all 28 samples after three passes through the sorter. These instruments can serve as important tools for plant breeders and grading facilities of the wheat industry that require timely and objective determination and sorting of different levels of black tip present in wheat samples.     

Long‐Term Storage Effect in Frozen Dough by Spectroscopy and Microscopy

Storage of dough at low temperatures (‐20°C) has a considerable effect on the final quality of baked bread; this is most obviously reflected in lowered specific volumes. In this study, a suite of structural characterization techniques is applied to examine the underlying mechanism of storage damage at the molecular, microstructural, and macroscopic level. By using infrared spectroscopy, the dehydration of the gluten component could be established at the molecular level, and its kinetics could be monitored in time. Time‐domain nuclear magnetic resonance (NMR) showed increased water mobility, which could be attributed to a release of water from the gluten matrix. At the microstructural level, the growth of ice crystals could be monitored by means of cryogenic scanning electron microscopy (cryo‐SEM). These ice crystals are preferably formed in gas cells with kinetics that are slower than those during infrared spectroscopy but similar to those in time‐domain NMR. At the macroscopic level, ice crystals are not evenly distributed over the molded dough, nor are the gas cells homogeneously distributed over the dough. This has implications for the macroscopic water distribution during frozen storage, which could be substantiated by magnetic resonance imaging (MRI) measurements.     

Vitamin D3: Preconcentration and Determination in Cereal Samples Using Ultrasonic‐Assisted Extraction and Microextraction Method

This research is the first analytical method to isolate and determine cholecalciferol (vitamin D₃) in cereal samples. Ultrasonic‐assisted extraction followed by dispersive liquid‐liquid microextraction as a fast, reliable, and highly sensitive method was employed for the preconcentration step. High‐performance liquid chromatography allowed an efficient and considerably faster analysis. Alcoholic KOH solution was employed for accomplishing the fast and easy release of vitamin D₃ from the wheat flour and bread matrix. Effective factors in the microextraction process were investigated and optimized with response surface methodology based on a central composite design. Under the best conditions, the calibration curves showed high levels of linearity (R ² > 0.999) for vitamin D₃ in the range of 2–500 ng/g. The relative standard deviation for the seven analyses was 6.2%. The relative recoveries of vitamin D₃ in spiked wheat flour and bread samples were 87–98%. The limit of detection and limit of quantitation were 0.7 and 2.1 ng/g, respectively. The method compared favorably with other methods for vitamin D₃ analysis of various foods.     

Effect of RS4 Resistant Starch on Extruded Ready‐to‐Eat (RTE) Breakfast Cereal Quality

A phosphorylated cross‐linked type 4 resistant wheat starch (RS4) containing 85.5% total dietary fiber (TDF) replaced 5–20% of the whole corn flour in an extruded ring‐shaped ready‐to‐eat breakfast cereal formulation. TDF content of the dry ingredient blend increased by roughly 3.6% for every 5% of added RS4. TDF loss during extrusion processing increased as RS4 level increased; however, a high percentage (78–89%) of the TDF content was retained in the final product. Product density increased as level of RS4 increased, but no effect on the specific mechanical energy was observed. X‐ray microtomography showed that RS4 addition did not affect internal air‐cell wall thickness, air‐cell size, or porosity. Moreover, addition of 5 or 10% RS4 did not affect expansion, physical appearance, initial crispness, or bowl life of the cereal rings. High levels of RS4 (15 and 20%) decreased cereal ring diameter but increased initial (dry) product crispness and extended bowl life. In general, RS4 addition level did not affect moisture content or moisture uptake of cereal rings during soaking in milk. Furthermore, moisture content and moisture uptake did not appear to influence the crispness of milk‐soaked cereal rings.     

Fourier Transform Infrared (FT‐IR) Microspectroscopic Genetic Expression of the Waxy Trait in Isogenic Durum and Common Wheat

The aim of recent breeding activity is to develop new wheat lines that incorporate desirable traits that are advantageous in baking and milling. Waxy wheats differ from wild‐type ones in functionality, end use, and biochemical contents (e.g., amylopectin/amylose ratios and lipid contents). Previous waxy wheat investigations focused only on differences in the carbohydrate and protein fractions. The goals of this work were to apply chemical imaging to discriminate between waxy and wild‐type wheats and to define contrasting lipid profiles that occur in the deliberate alteration of the carbohydrate fraction. Fourier transform infrared (IR) microspectroscopic in situ probing and imaging of kernel sections was applied with the use of high spatial resolution. Mid‐IR provided chemical manifestation of lipid genetic expression in isogenic samples. All waxy wheat specimens contained higher lipid content, mostly in the form of glycolipids. The relative lipid profiles differed among common, durum, and waxy wheats. Isogenic partial waxy cultivars and advanced breeding lines were also examined.