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1.
A method using Raman spectroscopy was recently developed for the determination of the degree of substitution of succinate in waxy maize starch. In this paper it is demonstrated that the method can be generalized to a wide range of starches of different amylose contents and botanical origins. Raman calibration sets were used to form regression equations for five types of succinylated starches, that is, waxy, regular, and two high-amylose maize samples (47 and 66% amylose, respectively) and wheat. The derived calibration curves can be used to find the degree of substitution in samples with unknown levels of succinylation. The Raman calibration lines had linear correlation coefficients of 0.995 or better and enable the fast and nondestructive determination of the degree of substitution of succinate for different types of starches with minimal sample preparation. Also discussed is the potential utility of Raman spectroscopy to simultaneously determine the degree of substitution of succinate and amylose content, using previously determined calibration curves developed for the amylose content of maize starches.  相似文献   

2.
Waxy maize starch was chemically modified to varying benzylation levels and the degree of benzylation substitution was measured using a nuclear magnetic resonance (NMR) method. Fourier Transform (FT) Raman spectra of the chemically modified starches were acquired and aromatic C=C stretch Raman bands characteristic of the benzylation modification were used to derive a calibration curve for the Raman intensity of these marker bands versus the degree of benzylation substitution. The best‐fit linear regression to the plotted data gave a linear correlation coefficient of 0.997. The FT‐Raman technique provides a fast, nondestructive method for the measurement of the degree of benzylation substitution of modified waxy maize starches and should be applicable for use with benzylated starches from other botanical sources.  相似文献   

3.
A method using Raman spectroscopy was recently developed for the determination of the degree of acetylation in modified wheat starch. In this article, we show that the method can be generalized to a wide range of starches of different botanical origin and amylose content. Calibration sets were used to develop regression equations for 11 types of acetylated starches, including cereal (rice, maize, wheat) and noncereal (potato and sweetpotato) sources. The calibration lines were then used to predict the level of acetylation of starch samples with unknown level of acetylation using their Raman spectra. In each case, R2 > 0.98 for linear regression of Raman vs. titrimetric determination of acetylation. The Raman-based calibration curves allow fast and nondestructive determination of the degree of acetylation for different types of starches.  相似文献   

4.
An analytical method using Raman spectroscopy was developed for the determination of amylose concentration in maize starches. FT-Raman spectra of four maize starches with amylose content varying from 3.3 to 66% were obtained. A Raman band at ≈1657 cm-1 correlated linearly with amylose concentration in the four maize starches, and a calibration curve for Raman band intensity versus amylose content was developed. The linear correlation of the I1657/I900 integrated areas with amylose content was r = 0.997. The Raman-based calibration curve allows fast and nondestructive determination of the amylose content in maize starches with minimal sample preparation.  相似文献   

5.
A novel, fast, and straightforward procedure is presented for the characterization of starch (the largest energy component in food) and modified starches (such as octenyl succinic anhydride (OSA)-modified starches used as a dispersing agent in the food industry). The method uses (1)H NMR to measure the degree of branching and also, for modified starches, the degree of chemical substitution. The substrate is dissolved in dimethyl-d(6) sulfoxide; addition of a very low amount of deuterated trifluoroacetic acid (d(1)-TFA) to the medium gives rise to a shift to high frequency of the exchangeable protons of the starch hydroxyl groups, leading to a clear and well-defined (1)H NMR spectrum, which provides an improved way to determine the degrees of both branching and chemical substitution. Measurements of the size and molecular weight distributions by multiple-detector size exclusion chromatography show that degradation by TFA does not affect the accuracy of the method.  相似文献   

6.
We present a brief introduction to FT‐Raman spectroscopy and examples of its use in cereal science for readers not familiar with Raman spectroscopy. We illustrate the use of FT‐Raman spectroscopy as an analytical tool to measure the degree of chemical modification of chemically modified starches and as a technique to determine conformational and structural changes in plant proteins under different environmental conditions. We briefly describe other applications of Raman spectroscopy in cereal science.  相似文献   

7.
A new starch acetate‐maleate mixed ester with different degrees of substitution (DS) for each ester group was prepared. High‐amylose (70%) corn starch was first reacted at 123°C with ≈4.5 equivalents of acetic anhydride for different times, and then the intermediate products were further reacted at 80°C with 0.27–1.1 equivalents of maleic anhydride for a fixed time. 1H NMR and alkaline saponification were used to determine DS values of acetyl and maleate groups. Increasing the reaction time from 60 to 120 min for starch and acetic anhydride increased DS of the acetyl group, while DS of the maleate group increased with increasing amounts of maleic anhydride. There was a good agreement between the two methods for DS determination. The reaction efficiency of acetylation increased from ≈30 to 50% with reaction time, and maleation decreased from ≈30 to 20% with increasing amounts of maleic anhydride. The mixed esters were characterized by 1H NMR, 13C NMR, FTIR, DSC, and TGA. Characteristic peaks in 1H NMR, 13C NMR, and FTIR spectra indicated the presence of acetyl and maleate groups in starch molecules. The exothermic peak in the DSC curve and the increase in thermal stability from the TGA curve were attributed to thermal cross‐linking of the double bond of the maleate group.  相似文献   

8.
The physical properties of octenyl succinic anhydride (OSA) starches prepared from rice, wheat, and potato starches were studied. Rice and wheat OSA starches had significantly higher peak viscosity (PV), hot paste viscosity (HPV), and cool paste viscosity (CPV), but potato OSA starch had only significantly higher CPV, relative to the native starch. The gel hardness was higher with lower degree of substitution (DS) but lower with higher DS OSA compared to native starch. The swelling volumes (SV) of rice and wheat OSA starches were significantly higher compared to native starch, but the SV of potato OSA starch was slightly lower at high DS. The gelatinization temperature (GT) of rice OSA starches was sharply lower at low DS; for wheat OSA starch it was slightly lower even at high DS, but potato OSA starches had higher GT than the native starch. The enthalpy of all the OSA starches decreased gradually with increased DS. This study showed that the magnitude of changes in physical properties of OSA-modified starches depends not only on their DS but also on the botanical origin of the native starches.  相似文献   

9.
The soybean industry requires rapid, accurate, and precise technologies for the analyses of seed/grain constituents. While the current gold standard for nondestructive quantification of economically and nutritionally important soybean components is near-infrared spectroscopy (NIRS), emerging technology may provide viable alternatives and lead to next generation instrumentation for grain compositional analysis. In principle, Raman spectroscopy provides the necessary chemical information to generate models for predicting the concentration of soybean constituents. In this communication, we explore the use of transmission Raman spectroscopy (TRS) for nondestructive soybean measurements. We show that TRS uses the light scattering properties of soybeans to effectively homogenize the heterogeneous bulk of a soybean for representative sampling. Working with over 1000 individual intact soybean seeds, we developed a simple partial least-squares model for predicting oil and protein content nondestructively. We find TRS to have a root-mean-standard error of prediction (RMSEP) of 0.89% for oil measurements and 0.92% for protein measurements. In both calibration and validation sets, the predicative capabilities of the model were similar to the error in the reference methods.  相似文献   

10.
Fourier‐transform Raman (FT‐Raman) spectroscopy and near‐infrared (NIR) reflectance spectroscopy were used to compare calibration models for determining rice cooking quality parameters such as apparent amylose and protein. Samples from two seasons were used in each calibration set. The laboratory values ranged from 4.89 to 12.48% for protein and from 0.2 to 25.7% for amylose. The data for both FT‐Raman and NIR were preprocessed with orthogonal signal correction (OSC) for standardization. For both spectroscopic methods, five models were optimized by partial least squares regression (PLSR) and by Martens' uncertainty regression (MUR), including no processing, smoothing, normalization, first derivative (D1), and second derivative (D2). Based solely on standard error of cross‐validation (SECV), the FT‐Raman method was superior to the NIR method for protein. For amylose, the FT‐Raman and NIR methods resulted in similar calibration statistics with a high precision, with the FT‐Raman requiring fewer factors. The best FT‐Raman models were generated from OSC preprocessing with MUR for protein (SECV 0.15%, five factors) and from OSC without MUR for amylose (SECV 0.70%, seven factors). The best NIR models were obtained with D2 transform of OSC spectra for protein (SECV 0.22%, four factors) and with OSC spectra for amylose (SECV 0.57%, 11 factors).  相似文献   

11.
摘要：为探讨近红外光谱技术在鉴定种子硬实特性上的普遍性,该文采用近红外光谱法结合偏最小二乘法建立了大豆、苦豆子和决明子单粒种子硬实特性的定性分析模型,每种种子均选择120粒种子进行近红外定性分析,种子分为建模集、检验集2组,建模集80粒,检验集40粒,各组中硬实与非硬实种子的比例为1:1,比较了光谱重复次数、光谱范围以及不同建模样品的建模效果。结果表明：采用二次平均光谱所建模型的鉴别率优于单次光谱;大豆采用4 000～5 000 cm-1光谱范围,矢量校正预处理,主成分为8时,建模集与检验集鉴别率均在85%以上;决明子采用4 000～8 000 cm-1光谱范围,一阶导数预处理,主成分为4时,模型建模集与检验集鉴别率均在90%左右;苦豆子采用4 000～8 000 cm-1光谱范围,二阶导数预处理,主成分为8时,模型的建模集与检验集鉴别率均在95%以上。以上结果表明近红外光谱技术可以很好地应用于单粒种子硬实特性的判断,有助于硬实机理的深入研究。  相似文献   

12.
The time course and pattern of arabinoxylan deposition in the wheat (Triticum aestivum) endosperm during grain development were studied using Raman spectroscopy. The presence of arabinoxylans (AX) is detected at the beginning of grain filling. At this stage, AX appear more substituted than at the later stages. Feruloylation of AX increases during the grain-filling stage, especially in the case of the aleurone layer. Whatever the stage of grain development, four populations of cells could be defined according to Raman arabinoxylan signatures. In the walls of the aleurone cells, AX appeared to be little substituted and highly esterified with phenolic acids. In the walls of prismatic cells, AX were found to be highly substituted and poorly esterified. Apart from aleurone and prismatic cells, the substitution degree of AX in endosperm was in the same range. Cells in the crease region were distinguished from cells in the starchy endosperm by their lower amount of esterified phenolic compounds.  相似文献   

13.
Fourier transform infrared (FTIR) and Fourier transform Raman (FT-Raman) methods were used for rapid characterization and classification of selected irradiated starch samples. Biochemical changes due to irradiation were detected using the two vibrational spectroscopic techniques, and canonical variate analysis (CVA) was applied to the spectral data for discriminating starch samples based on the extent of irradiation. The O-H (3000-3600 cm(-1)) stretch, C-H (2800-3000 cm(-1)) stretch, the skeletal mode vibration of the glycosidic linkage (900-950 cm(-1)) in both Raman and infrared spectra, and the infrared band of water adsorbed in the amorphous parts of starches (1550-1750 cm(-1)) were employed in classification analysis of irradiated starches. Spectral data related to water adsorbed in the noncrystalline regions of starches provided a better classification of irradiated starches with 5 partial least-squares (PLS) factors in the multivariate model.  相似文献   

14.
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 measurement.  相似文献   

15.
The determination of conjugated linoleic acids (CLA) in cow milk fat was studied by using UV (210-250 nm) and Fourier transform (FT)-Raman (900-3400 cm (-1)) spectroscopy in order to determine the best spectrophotometric technique for routine analysis of milk fat. A collection of 57 milk fat samples was randomly divided into two sets, a calibration set and a validation set, representing two-thirds and one-third of the samples, respectively. All calculations were performed on the calibration set and then applied to the validation set. The CLA content ranged from 0.56 to 4.70%. A comparison of various spectral pretreatments and different multivariate calibration techniques, such as partial least-squares (PLS) and multiple linear regression (MLR), was done. This paper shows that UV spectroscopy is as reliable as FT-Raman spectroscopy to monitor CLA in cow milk fat. The best calibration for FT-Raman was given by a PLS model of seven factors with a standard error of prediction (SEP) of 0.246. For UV spectroscopy, PLS models were also better than MLR models. The most robust PLS model was constructed with only one factor and with SEP=0.288.  相似文献   

16.
The effect of starch crystallinity and phosphorus on starch gelatinization and retrogradation were studied using wide-angle X-ray powder diffraction, cross polarization/magic angle spinning (CP/MAS) 13C nuclear magnetic resonance (NMR) spectroscopy, 31P NMR spectroscopy, Rapid Visco Analyzer (RVA) and differential scanning calorimetry (DSC). Two starches differing significantly in peak viscosity (cv. Stephens, 283 BU; cv. Crew, 560 BU) were comparable in amylose content and starch crystallinity, while differing significantly in phospholipids content. Starch of lower peak viscosity had a higher phospholipids content and showed a slower rate of retrogradation. Starch from Stephens (0.098% phosphorus) had an enthalpy value of retrograded starch of 2.2 J/g after 14 days of storage, while starch from Crew (0.062% phosphorus) had an enthalpy value as high as 4.4 J/g. Defatting with a hot n-propanol and water (3:1) mixture caused substantial changes in peak viscosity. Peak viscosity for starch from Crew decreased by 75 RVU due to defatting, while starch from Stephens decreased by as much as 125 RVU. After defatting with the hot n-propanol water mixture, the rate and extent of starch retrogradation were comparable between the prime starches, which differed significantly in peak viscosity.  相似文献   

17.
Carboxymethyl rice starches (CMRS) were prepared from nine strains of native rice starches with amylose contents of 14.7–29.1%. The reaction was conducted at 50°C for 120 min using monochloroacetic acid as a reagent under alkaline conditions and 1-propanol as a solvent. After determining the degree of substitution (DS), the physicochemical properties including water solubility, pH, and viscosity of 1% (w/v) solution, scanning electron microscopy (SEM), and X-ray diffraction (XRD) analyses of the granules, as well as some pharmaceutical properties of CMRS powders and pastes were investigated. The DS range was 0.25–0.40. All CMRS dissolved in unheated water and formed viscous gel. A good positive correlation was observed between amylose content and DS (r = 0.9278) but not viscosity. SEM and XRD concurrently revealed significant physical alteration of CMRS granules compared with those of native starches, which reflected the changes in the properties of CMRS. At 3% (w/w), CMRS can function as tablet binder in the wet granulation of both water-soluble and water-insoluble diluents. The tablets compressed from these granules showed good hardness with fewer capping problems compared with those prepared using the pregelatinized native rice starch as a binder. In addition, most CMRS pastes formed clear films with varying film characteristics, depending upon the amylose content of the native starches. This type of modified rice starch can potentially be employed as a tablet binder and film-former for pharmaceutical dosage formulations.  相似文献   

18.
The collective term "conjugated linoleic acid" or "CLA" generally refers to a mixture of conjugated positional and geometric isomers of linoleic (cis-9,cis-12-octodecadienoic) acid. In nature, these isomers are mainly formed in the rumen by biohydrogenation of polyunsaturated fatty acids. This study concerns a first trial of CLA determination in cow's milk fat by Raman spectroscopy. The spectra of pure cis-9-oleic, cis-9,cis-12-linoleic, cis-9,trans-11-linoleic, and trans-10,cis-12-linoleic acids have been examined in comparison with the spectra of selected milk-fat samples containing between 0 and 3% of CLA. The trial of CLA determination by Raman spectroscopy on cow milk fat has reached its objective with the two following results. First, the examination of the Raman spectra allows to identify three specific Raman signals of the chemical bonds associated to the cis,trans conjugated C=C in the rumenic and trans-10,cis-12-octodecadienoic acids at 1652, 1438, and 3006 cm(-1). Second, the calibration of Raman spectrometer for the CLA determination has indicated that these three specific signals suit very well for the accurate and reliable measurement of CLA concentration in milk fat. To our knowledge, the present study is the first successful attempt to determine the CLA content of milk fat by a spectrophotometric method.  相似文献   

19.
We investigate the potential of near-infrared (NIR) spectroscopy to predict some heavy metals content (Zn, Cu, Pb, Cr and Ni) in several soil types in Stara Zagora Region, South Bulgaria, as affected by the size of calibration set using partial least squares (PLS) regression models. A total of 124 soil samples from the 0–20 and 20–40 cm layers were collected from fields with different cropping systems. Total Zn, Cu, Pb, Cr and Ni concentrations were determined by Atomic Absorption Spectrometry. Spectra of air dried soil samples were obtained using an FT-NIR Spectrometer (spectral range 700–2,500 nm). PLS calibration models were developed with full-cross-validation using calibration sets of 90 %, 80 %, 70 % and 60 % of the 124 samples. These models were validated with the same prediction set of 12 samples. The validation of the NIR models showed Cu to be best predicted with NIR spectroscopy. Less accurate prediction was observed for Zn, Pb and Ni, which was classified as possible to distinguish between high and low concentrations and as approximate quantitative. The worst model performance in cross-validation and prediction was for Cr. Results also showed that values of root mean square error in cross-validation (RMSEcv) increased with decreasing number of samples in calibration sets, which was particularly clear for Cu, Pb, Ni and Cr content. A similar tendency was observed in the prediction sets, where RMSEP values increased with a decrease in the number of samples, particularly for Pb, Ni and Cr content. This tendency was not clear for Zn, while even an increase in RMSEP for Cu with the sample size was observed. It can be concluded that NIR spectroscopy can be used to measure heavy metals in a sample set with different soil type, when sufficient number of soil samples (depending on variability) is used in the calibration set.  相似文献   

20.
《Cereal Chemistry》2017,94(3):554-559
The physicochemical properties of starches from cultivated Pueraria thomsonii Benth were examined and compared with those of P. lobata (Willd.) Ohwi and other root starches, and the effect of pueraria root starches on the improvement of buckwheat noodle quality was investigated. The total content of isoflavones in P. thomsonii root starches was higher than in P. lobata root starches, and the size and uniformity of those particles displayed a significant difference. The gel stabilities of pueraria root starches were similar and more favorable than those of potato starch and sweet potato starch. For the amylose molecular properties of pueraria root starches, the λmax and blue value index were higher than those of the potato starch and the sweet potato starch, whereas the amylose content and degree of polymerization were much lower in comparison. However, amylopectin branch lengths of pueraria root starches were shorter. Thus, pueraria root starches could improve the quality of buckwheat noodles and enhance their nutritional function. Therefore, pueraria root starches may be regarded as raw materials that influence the quality of buckwheat noodles.  相似文献   

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