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1.
Adulteration of honey with sugars is the most crucial quality assurance concern to the honey industry. The application of Fourier transform infrared spectroscopy as a screening tool for the determination of the type of sugar adulterant in honey was investigated. Spectra of honey adulterated with simple and complex sugars were recorded in the mid-infrared range using the attenuated total reflectance accessory of a Fourier transform infrared spectrometer. Adulterants considered were sugars (glucose, fructose and sucrose) and invert sugars (cane invert and beet invert). Predictive models were developed to classify the adulterated honey samples using discriminant analysis. Spectral data were compressed using principal component analysis and partial least-square methods. Linear discriminant analysis was used to discriminate the type of adulterant in three different honey varieties. An optimum classification of 100% was achieved for honey samples adulterated with glucose, fructose, sucrose and beet and cane invert sugars. Results demonstrated that discriminant analysis of the spectra of adulterated honey samples could be used for rapid detection of adulteration in honey.  相似文献   

2.
    
A combination of Fourier transform infrared (FTIR) spectroscopy and multivariate statistics as a screening tool for the determination of beet medium invert sugar adulteration in three different varieties of honey is discussed. Honey samples with different concentrations of beet invert sugar were scanned using the attenuated total reflectance (ATR) accessory of the Bio‐Rad FTS‐6000 Fourier transform spectrometer. The spectral wavenumber region between 950 and 1500 cm?1 was selected for partial least squares (PLS) regression to develop calibration models for beet invert sugar determination in honey samples. Results from the PLS (first derivative) models were slightly better than those obtained with other calibration models. Predictive models were also developed to classify beet sugar invert in three different varieties of honey samples using discriminant analysis. Spectral data were compressed using the principal component method, and linear discriminant and canonical variate analyses were used to detect the level of beet invert sugar in honey samples. The best predictive model for adulterated honey samples was achieved with canonical variate analysis, which successfully classified 88–94 per cent of the validation set. The present study demonstrated that Fourier transform infrared spectroscopy could be used for rapid detection of beet invert sugar adulteration in different varieties of honey. © 2001 Society of Chemical Industry  相似文献   

3.
  总被引:1,自引:0,他引:1  
Crude phenol‐phase extracts containing bacterial lipopolysaccharides (LPS) from 5 strains of Escherichia coli were investigated to differentiate the strains using Fourier transform infrared (FTIR) spectroscopy and multivariate statistical analysis. The strains used were E. coli K12, E. coli DH5α, E. coli O157:H7, E. coli O157:H12, and E. coli O157:H19. LPS‐containing extracts were isolated from each E. coli strain using a hot phenol‐water extraction procedure. The extracts were 1st analyzed by deoxycholic acid‐polyacrylamide gel electrophoresis and visualized by silver‐staining. Analysis of the extracts from E. coli K12 and E. coli DH5α showed rough‐type LPS on the lower half of the gel, whereas E. coli O157:H7, E. coli O157:H12, and E. coli O157:H19 yielded abundant smooth LPS (high‐molecular‐weight LPS that include the O‐polysaccharides). Spectra (4000 cm‐1 to 700 cm‐1) of crude E. coli LPS extracts and intact cells were collected using a FTIR spectrometer. Spectral data were compressed by principle component analysis and analyzed using canonical variate analysis (CVA) of 4000 cm‐1 to 700 cm‐1 or 1200 cm‐1 to 900 cm‐1 spectral regions. CVA showed better separation between strains using LPS extracts than intact cells in the 1200 cm‐1 to 900 cm‐1 spectral region. The same separation trend was found using Mahalanobis distances that quantified spectral differences between the E. coli strains, providing 80% and >95% correct classifications of intact cells and LPS extracts, respectively. This article is the first to report the successful differentiation of E. coli strains at a serotype level using FTIR spectra of bacterial phenol‐phase extracts (crude LPS preparations).  相似文献   

4.
Fourier-transform infrared spectroscopy, followed by linear discriminant analysis of the spectral data, was used to classify Italian Pecorino cheeses according to their ripening time and manufacturing technique. The Fourier transform infrared spectra of the cheeses were divided into 18 regions and the normalized absorbance peak areas within these regions were used as predictors. Linear discriminant analysis models were constructed to classify Pecorino cheeses according to different ripening stages (hard and semi-hard) or according to their manufacturing technique (fossa and nonfossa cheeses). An excellent resolution was achieved according to both ripening time and manufacturing technique. Also, a final linear discriminant analysis model considering the 3 categories (hard nonfossa, hard fossa, and semi-hard nonfossa) was constructed. A good resolution among the 3 categories was obtained.  相似文献   

5.
    
Wang J  Yue T  Yuan Y  Lu X  Shin JH  Rasco B 《Journal of food science》2011,76(2):M137-M142
Alicyclobacillus spp. are thermoacidophilic, spore-forming bacteria, some of which cause spoilage in pasteurized and heat-treated apple juice products through the production of guaiacol. It would be helpful if a rapid method to detect and discriminate Alicyclobacillus strains was available. A simple and rapid sample preparation method using nitrocellulose membrane filter (NMF) and a single reflection horizontal attenuated total reflection (HATR) accessory with Fourier transform infrared (FT-IR) was developed here. Fourier transform infrared (FT-IR) spectroscopy was used and tested on 8 Alicyclobacillus strains (KF, WAC, NWN-13501, NWN-12697, NWN-12654, NWN-10682, 1016, 1101). A linear discriminant analysis (LDA) was established to discriminate Alicyclobacillus strains. The sample preparation method could successfully separated strains into different groups by principal component analysis (PCA). High identification accuracy (95%) was achieved with the LDA model. PRACTICAL APPLICATION: The method developed in the paper can be used to discriminate different Alicyclobacillus strains from each other making it possible to easily determine whether the strain of Alicyclobacillus present is associated with juice spoilage.  相似文献   

6.
刘嘉  李建超  陈嘉  赵国华 《食品科学》2011,32(8):226-230
以葛粉及葛粉中分别掺假红薯粉和马铃薯粉作为研究对象,采集400~4000cm-1波数范围内的红外傅里叶变换光谱,结合主成分分析对样品的进行聚类划分。并通过Fisher判别,建立葛粉真伪的判别方程。分别以样本回判及外部验证考察模型可靠性。结果表明:葛粉、红薯粉与马铃薯粉及三者不同比例混合样品的二维主成分分布位于不同区域,且葛粉与掺假葛粉之间无重叠。判别方程经样本回判及外部验证表明,葛粉中掺假红薯粉和葛粉中掺假马铃薯粉的自身验证准确率分别为93.3%和100%;交互验证准确率分别为86.7%和92.0%。此方法具有很好的鉴别作用,可作为葛粉中掺假红薯粉和马铃薯粉的一种鉴别方法。  相似文献   

7.
    
It is not known if peats derived from different areas of Scotland have distinctive chemical constituents that could impact on malt whisky in discernible organoleptic ways. Fourier transform‐infrared (FT‐IR) spectroscopy was used as a high throughput screening method to investigate discrimination of a large number of peat samples from six different geographical origins around Scotland. The data were analysed statistically (using principal component‐discriminant function analysis) and the results showed a difference between peat samples from different geographical origins. Therefore, we have shown that FT‐IR spectroscopy provides a quick and simple method for differentiating peat types.  相似文献   

8.
The potential of FTIR combined with chemometrics was studied to classify five Moroccan varieties of olives by analysis on the endocarps. Attenuated total reflectance (ATR) enabled the samples to be examined directly in the solid state. The spectral data were subjected to a preliminary derivative elaboration based on the Norris gap algorithm to reduce the noise and extract larger analytical information. Linear discriminant analysis (LDA) was adopted as classification method, and Principle component analysis (PCA) was employed to compress the original data set into a reduced new set of variables before LDA. The calibration set was built by using the IR data from seventy‐five samples scanned in reflectance mode, and the ranges 3000–2400 and 2300–600 cm?1 were selected because furnishing the most useful analytical information. PCA allowed clustering the samples in five classes by using the first two principal components with an explained variance of 98.16%. Application of LDA on an external test set of twenty‐five samples enabled to classify them into five variety groups with a correct classification of 92.0%.  相似文献   

9.
目的 建立傅里叶变换红外光谱法分析评价红花药材质量的分析方法。方法 采用傅立叶变换红外光谱法(Fourier transform infrared spectrometry, FTIR)对采集自新疆不同产地的20批红花药材进行测量, 建立指纹图谱; 运用聚类分析与主成分分析等统计学及化学模式识别技术, 对不同来源的红花药材进行红外光谱数据比较分析。结果 筛选出12个波数段, 形成了红花药材FTIR红外光谱指纹图谱共有模式; 精密度、稳定性和重复性实验结果表明, 共有峰波数的相对标准偏差(relative standard deviation, RSD)分别为0.00%~0.1%、0.00%~4.56%、0.32%~7.5%, 符合指纹图谱的要求; 20批样品相似度均大于95%, 大致可以分为3大类, 区域间差异较为明显。结论 本研究建立的方法简单、易行、快速, 不污染、样品耗量低, 为不同来源红花药材的鉴定、内在质量评价与质量控制提供了依据、奠定了基础。  相似文献   

10.
目的 基于傅里叶变换衰减全反射红外光谱(attenuated total reflectance-Fourier transform infrared spectroscopy, ATR-FTIR)结合聚类判别分析等化学计量学方法, 建立山茶油、大豆油、玉米油、葵花籽油和花生油5种植物油的快速鉴别模型, 及山茶油掺假模型。方法 采集山茶油、大豆油、玉米油、葵花籽油和花生油5种植物油共99份样品, 并按照不同质量百分比(掺伪5%~95%)将大豆油、葵花籽油、玉米油、1:1玉米大豆油、花生油、棕榈油掺入到山茶油中, 获得掺假山茶油样品196份, 采集600~4000 cm-1波段的红外光谱信息, 建立偏最小二乘判别分析(partial least squares-discriminant analysis, PLS-DA)、主成分分析-判别分析(principal component analysis-linear discriminant analysis, PCA-LDA)、K最近邻分类算法(K-nearest neighbor, KNN)以及数据驱动型簇类独立软模式分类(data driven soft independent modelling of class analogy, DD-SIMCA)模型, 并比较各方法建模效果, 确定最优识别模型。结果 各样品组红外吸收光谱非常类似, 具有相似的特征峰数、峰位置和峰形。DD-SIMCA建立的鉴别模型能将山茶油和其他类别植物油样本完全分开; PLS-DA、PCA-LDA和KNN模型判别经分析比较, 发现利用PLS-DA和PCA-LDA模型在5种植物油的分类中校正集和预测集中的各样本的预测值与实际值很接近, 除了花生油以外其余种类植物油的校正集和预测集样本的识别率和预测正确率均为100.0%; ATR-FTIR结合PLS的计量学方法能够准确进行山茶油掺假定量分析, 可用于掺杂大豆油、玉米油、葵花籽油等的定性定量分析, 结果可靠, 最低检出限可达5%。结论 ATR-FTIR结合聚类判别分析等化学计量学方法实现对山茶油掺假的高效识别。  相似文献   

11.
The feasibility of measuring tetracycline at the ppb levels in milk was investigated by Fourier transform mid-infrared (FT-MIR) and Fourier transform near-infrared (FT-NIR) spectroscopic techniques. Milk samples spiked with different concentrations of tetracycline were scanned using FT-MIR and FT-NIR spectroscopy. Suitable spectral wave number regions were selected for principal least square (PLS) regression models development. Prediction errors were high when the calibration model was developed using the wide range of tetracycline concentrations (4 to 2000 ppb) in milk. Maximum correlation coefficient (R2) value of about 0.89 was obtained for the validation models developed using different concentration ranges. Prediction errors were high for FT-NIR method. Results indicated that FT-MIR spectroscopy could be used for rapid detection of tetracycline hydrochloride residues in milk.  相似文献   

12.
用傅里叶变换红外光谱对亚硫酸化结合型加脂剂合成过程中产生的酰胺化物、酯化物及亚硫酸化物的结构进行了表征 ,同时对亚硫酸化加脂剂乳液上的白色漂浮物的结构也进行了表征 ,还对影响亚硫酸化结合型加脂剂黏度的因素进行了研究  相似文献   

13.
    
Misrecognition and toxic elements are two of several reasons responsible for food poisoning even death in the summer, a time when a great deal of edible mushrooms is celebrated in Southwestern China featured as complex environment conditions. It is highly important to identify the difference of chemical constituents in edible mushrooms at the regional‐scale. In this study, Fourier transform infrared (FT‐IR) spectroscopy and inductively coupled plasma mass spectrometry were applied to investigate organic matters and 18 mineral elements in porcini mushrooms of six species collected from 17 sampling sites in nine Yunnan cities. Classification models on the species, regions, and part levels were established using sparse partial least square‐discriminant analysis and principal component analysis. At the species level and region level accuracies of greater than 92.1% and 92.8% was achieved, respectively, whereas on the part level caps and stipes were classified with 96.7% accuracy. One of the most popular mushrooms is Boletus edulis characterized by polysaccharide, lipid, and ribonucleic acid as well as several phenolic compounds. Temperature and precipitation show possible influences on accumulations of polysaccharides and ribonucleic acid. Furthermore, the most important elements of caps contributed the difference between two parts are copper (Cu), zinc (Zn), and phosphorus (P), whereas stipes instead by manganese (Mn) and cobalt (Co). These results demonstrated that FT‐IR spectroscopy and elements contents provide information sufficient for classifying different porcini mushroom samples, which might be helpful for controlling food security and quality assessment of edible mushrooms.  相似文献   

14.
    
The objectives of this study were to determine if Fourier transform infrared (FT‐IR) spectroscopy and multivariate statistical analysis (chemometrics) could be used to rapidly differentiate epidemic clones (ECs) of Listeria monocytogenes, as well as their intact compared with heat‐killed populations. FT‐IR spectra were collected from dried thin smears on infrared slides prepared from aliquots of 10 μL of each L. monocytogenes ECs (ECIII: J1‐101 and R2‐499; ECIV: J1‐129 and J1‐220), and also from intact and heat‐killed cell populations of each EC strain using 250 scans at a resolution of 4 cm?1 in the mid‐infrared region in a reflectance mode. Chemometric analysis of spectra involved the application of the multivariate discriminant method for canonical variate analysis (CVA) and linear discriminant analysis (LDA). CVA of the spectra in the wavelength region 4000 to 600 cm?1 separated the EC strains while LDA resulted in a 100% accurate classification of all spectra in the data set. Further, CVA separated intact and heat‐killed cells of each EC strain and there was 100% accuracy in the classification of all spectra when LDA was applied. FT‐IR spectral wavenumbers 1650 to 1390 cm?1 were used to separate heat‐killed and intact populations of L. monocytogenes. The FT‐IR spectroscopy method allowed discrimination between strains that belong to the same EC. FT‐IR is a highly discriminatory and reproducible method that can be used for the rapid subtyping of L. monocytogenes, as well as for the detection of live compared with dead populations of the organism.  相似文献   

15.
The methods available for measuring organic P and bound Ca in cheese are either cumbersome or involve dilution of the cheese. Dilution of the cheese can lead to erroneous results, particularly in the case of bound Ca. Hence, the objective of this study was to evaluate the feasibility of Fourier transform infrared (FTIR) spectroscopy for direct measurement of organic P and bound Ca in Cheddar cheese. Two hundred sixteen samples of cheese were analyzed for protein-bound organic P, bound Ca using a water-extraction based method, and buffering curves. Additionally, the infrared spectra of the cheeses were collected between 4,000 and 650 cm−1, at a resolution of 4 cm−1, and 256 scans per sample. The spectral shifts in the infrared region from 1,050 to 900 cm−1, in addition to the measured concentrations of organic P, bound Ca, and buffering peak area at pH 5.1, were used to develop calibration models using partial least squares (PLS) regression analysis. The spectral region of 956 to 946 cm−1 correlated with the measured concentrations of organic P and the overall PLS model had a correlation (R2) of 0.76 between the predicted and measured concentrations. The spectral region at ∼980 cm−1 was correlated with the measured concentrations of bound Ca, and the overall PLS model had a correlation (R2) of 0.70 between the predicted and measured concentrations. A similar spectral region at ∼980 cm−1 was also correlated with the measured buffering peak areas and the overall PLS model had a correlation (R2) of 0.64 between the predicted and measured peak areas. A linear regression analysis between the bound Ca and buffering peak area demonstrated that bound Ca was correlated (R2 = 0.73) with buffering peak area. This study demonstrates that FTIR can be used to measure organic P in cheeses. It also has the potential to be used for measuring bound Ca in undiluted cheeses, and for prediction of the buffering capacity of cheese.  相似文献   

16.
Milk coagulation is based on a series of physicochemical changes at the casein micelle level, resulting in formation of a gel. Milk coagulation properties (MCP) are relevant for cheese quality and yield, important factors for the dairy industry. They are also evaluated in herd bulk milk to reward or penalize producers of Protected Designation of Origin cheeses. The economic importance of improving MCP justifies the need to account for this trait in the selection process. A pilot study was carried out to determine the feasibility of including MCP in the selection schemes of the Italian Holstein. The MCP were predicted in 1,055 individual milk samples collected in 16 herds (66 ± 24 cows per herd) located in Brescia province (northeastern Italy) by means of Fourier transform infrared (FTIR) spectroscopy. The coefficient of determination of prediction models indicated moderate predictions for milk rennet coagulation time (RCT = 0.65) and curd firmness (a30 = 0.68), and poor predictions for curd-firming time (k20 = 0.49), whereas the range error ratio (8.9, 6.9, and 9.5 for RCT, k20, and a30, respectively) indicated good practical utility of the predictive models for all parameters. Milk proteins were genotyped and casein haplotypes (αS1-, β-, αS2-, and κ-casein) were reconstructed. Data from 51 half-sib families (19.9 ± 16.4 daughters per sire) were analyzed by an animal model to estimate (1) the genetic parameters of predicted RCT, k20, and a30; (2) the breeding values for these predicted clotting variables; and (3) the effect of milk protein genotypes and casein haplotypes on predicted MCP (pMCP). This is the first study to estimate both genetic parameters and breeding values of pMCP, together with the effects of milk protein genotypes and casein haplotypes, that also considered k20, probably the most important parameter for the dairy industry (because it indicates the time for the beginning of curd-cutting). Heritability of predicted RCT (0.26) and k20 (0.31) were close to the average heritability described in literature, whereas the heritability of a30 was higher (0.52 vs. 0.27). The effects of milk proteins were statistically significant and similar to those obtained on measured MCP. In particular, haplotypes including uncommon variants showed positive (B-I-A-B) or negative (B-A1-A-E) effects. Based on these findings, FTIR spectroscopy-pMCP is proposed as a potential selection criterion for the Italian Holstein.  相似文献   

17.
以Nata为原料,通过冷冻干燥制备了密度为30 mg/cm-3的具有三维多孔结构和良好韧性的Nata气凝胶,并使用X射线衍射(XRD),傅立叶红外光谱(FT-IR),扫描电镜(SEM),热重分析法(TGA)对其形貌结构,超分子结构、晶体结构及热性质进行表征。XRD谱图表明Nata气凝胶中纤维素超分子结晶形态为纤维素I,具有比Nata和微晶纤维素更高的相对结晶度和更大晶粒尺寸;FT-IR光谱表明,没有新的官能团产生,计算出红外结晶指数比微晶纤维素大,结果与XRD一致;对FTIR光谱特征峰进行分峰拟合,3100~3600cm-1分峰拟合分子间氢键和分子内氢键变化,气凝胶中纤维素分子内氢键O(2)H...O(6)强度减弱,O(3)H...O(5)强度增大,分子间氢键O(6)H...O(3')强度增加;660~760 cm-1进行分峰拟合,纤维素Iα含量为92.18%;SEM显示该气凝胶中存在大量的孔隙;TGA显示:热分解温度为322.07℃,热稳定性优于Nata和MCC。  相似文献   

18.
The staling of bread has previously been studied by differential scanning calorimetry and by simple rheological measurements. In this collaborative study, two spectroscopic techniques (Fourier transform mid infrared spectroscopy and near infrared reflectance spectroscopy) have been used in addition to differential scanning calorimetry to follow the progress of bread staling. Using each technique, changes in measured properties were apparent which, when fitted by first order exponential equations, gave calculated rate constants of similar magnitude. It is postulated that each technique gives independent information about the crystallisation process in the amylopectin fraction of the bread crumb.  相似文献   

19.
The aim of this study was to assess the quality of different vegetable oils by applying common components and specific weights analysis as a tool for the evaluation and discrimination of chromatography, spectral and physicochemical data. This multiblock method of data analysis divided the data into three common components, corresponding to 56.44%, 34.74% and 8.77% of variance, and it was influenced mostly by chromatography, physicochemical and spectral data, respectively. Gas chromatography, which was used for discrimination of the botanical origin of oil and the groups of saturated, monounsaturated and polyunsaturated fatty acids, was situated in the first common dimension; physicochemical analysis, which was applied to evaluate quality parameters such as acid and saponification value and determine the stability of the product, was situated in the second common dimension. FTIR analysis, by exerting a minor influence on the common dimensions, was considered dispensable in evaluating the quality of vegetable oils by common components and specific weights analysis. Therefore, multiblock analysis could efficiently discriminate vegetable oils.  相似文献   

20.
研究利用傅里叶红外光谱结合化学计量学方法来实现对苏丹阿拉伯胶的产地和蛋白质含量的快速无损检测的可行性。采集自6?个不同的产地,每个产地12?个,总计72?个阿拉伯胶样本,作为研究对象,运用线性判别分析(linear discriminant analysis,LDA)和反向区间偏最小二乘(backward interval partial least squares,Bi-PLS)法分别实现对苏丹阿拉伯胶的产地区分和蛋白质含量检测。结果表明,当主成分数为6时,LDA对样本的训练集(48?个样本)和预测集(24?个样本)的识别率都为100%。Bi-PLS法回归联合20?个光谱子区间中的4?个子区间得到最佳的蛋白质预测模型,其预测集相关系数为0.937?3,均方根误差为0.173%。因此,利用傅里叶红外光谱结合化学计量学方法可实现对苏丹阿拉伯胶的产地以及蛋白质的含量的快速无损检测。  相似文献   

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