Analysis of lard in meatball broth using Fourier transform infrared spectroscopy and chemometrics

Meatball is one of the favorite foods in Indonesia. For the economic reason (due to the price difference), the substitution of beef meat with pork can occur. In this study, FTIR spectroscopy in combination with chemometrics of partial least square (PLS) and principal component analysis (PCA) was used for analysis of pork fat (lard) in meatball broth. Lard in meatball broth was quantitatively determined at wavenumber region of 1018–1284 cm^− 1. The coefficient of determination (R²) and root mean square error of calibration (RMSEC) values obtained were 0.9975 and 1.34% (v/v), respectively. Furthermore, the classification of lard and beef fat in meatball broth as well as in commercial samples was performed at wavenumber region of 1200–1000 cm^− 1. The results showed that FTIR spectroscopy coupled with chemometrics can be used for quantitative analysis and classification of lard in meatball broth for Halal verification studies. The developed method is simple in operation, rapid and not involving extensive sample preparation.     

Bran-induced changes in water structure and gluten conformation in model gluten dough studied by Fourier transform infrared spectroscopy

The impact of bran addition on the state of water and gluten secondary structure in gluten dough was studied using Fourier transform infrared spectroscopy to understand the underlying physical mechanism by which bran impacts dough properties. Comparison of the OH stretch band of water in gluten dough with that of H₂O–D₂O mixture having the same water content revealed formation of two distinct water populations in gluten dough corresponding to IR absorption frequencies at 3580 cm⁻¹ and 3180 cm⁻¹. The band intensity at 3180 cm⁻¹, which is related to water bound to gluten matrix, decreased with increase of moisture content of the dough. Addition of bran to gluten dough caused redistribution of the bound water in the gluten-bran dough system. This water redistribution affected the secondary structure of gluten in the dough as evidenced from changes in the second-derivative spectrum in the amide I region. In the hydrated state, β-turn (in the form of β-spiral) was the major secondary structure (∼60%) in gluten. Addition of bran to gluten dough caused conversion of β-spirals into β-sheet and random structures. However, the extent of this conversion in the presence of bran was inversely related to the moisture content of the dough. This study revealed that when bran is added to gluten dough, water redistribution promotes partial dehydration of gluten and collapse of β-spirals into intermolecular β-sheet structures; this trans-conformation might be physical reasons for the poor quality of bread containing added bran.     

Determination of anthocyanins in red wine using a newly developed method based on Fourier transform infrared spectroscopy

The feasibility of Fourier transform infrared (FTIR) spectroscopy for determination of anthocyanins in red wines was studied. The FTIR spectra were gathered using a WineScan FT 120 instrument. A process based on HPLC was used as reference method to determine the 3-monoglucosides of cyanidin, peonidin, delphinidin, petunidin and malvidin, as well as its acetic acid esters and p-coumaric acid esters. The calibration set was constituted by 350 samples of young red wines from different Spanish Denominations of Origin and the validation set by 40 representative samples. Partial least squares regression (PLS) was the multivariate method that carried out calibrations. Prediction error SEC was between 0.15 and 23.79 mg/L. Validation equations developed to correlate reference and FTIR methods disclosed a systematic error in the determination of certain anythocyanins, however, this error could be overcome by application of a correction factor. The results suggest that the WineScan FT 120 analyzer is suitable for routine laboratory measurement of anthocyanins and provides additional information regarding red wine colour.     

Discrimination between immature and mature green coffees by attenuated total reflectance and diffuse reflectance Fourier transform infrared spectroscopy

The objective of this work was to evaluate the potential of Fourier transform infrared spectroscopy (FTIR) in the characterization and discrimination between immature and mature or ripe coffee beans. Arabica coffee beans were submitted to FTIR analysis by reflectance readings employing attenuated total reflectance (ATR) and diffuse reflectance (DR) accessories. The obtained spectra were similar, but in general higher absorbance values were observed for nondefective beans in comparison to immature ones. Multivariate statistical analysis (principal component analysis, PCA, and agglomerative hierarchical clustering, AHC) was performed in order to verify the possibility of discrimination between immature and mature coffee samples. A clear separation between immature and mature coffees was observed based on AHC and PCA analyses of the normalized spectra obtained by employing both ATR and DR accessories. Linear discriminant analysis was employed for developing classification models, with recognition and prediction abilities of 100%. Such results showed that FTIR analysis presents potential for the development of a simple routine methodology for separation of immature and mature coffee beans. Practical Application: The ultimate goal of this research is to be able to propose improvements in the way immature coffee beans are separated from graded mature beans in coffee facilities (cooperatives and other coffee producer's associations). The results obtained herein point toward FTIR as a potential tool for the aimed improvements.     

Rapid classification of virgin and recycled EPS containers by Fourier transform infrared spectroscopy and chemometrics

ABSTRACT

A rapid and sensitive method for classification of virgin and recycled expanded polystyrene (EPS) food containers was developed using Fourier transform infrared spectroscopy (FTIR) and chemometrics. This method includes preparing a transparent film by dissolution, examining by FTIR and developing classification models. The degradation of EPS containers occurring during the recycling process was reflected by the carbonyl region of the infrared spectrum which was used as variables for multivariate data analysis. PCA was used to reduce the data dimension and view the sample similarities. Soft independent modelling of class analogy (SIMCA), partial least squares-discrimination analysis (PLS-DA) and linear discrimination analysis (LDA) were applied to construct three classification models. The best discrimination results were obtained by an LDA model, with all samples correctly classified. PLS-DA and SIMCA could not classify the recycled EPS samples with low levels of adulteration. When applying this method to commercially available EPS containers, about 45% of samples were shown to contain recycled polystyrene resins. It is concluded that the carbonyl region of the infrared spectra coupled with chemometrics could be a powerful tool for the classification of virgin and recycled EPS food containers.     

Rapid discrimination of pork in Halal and non-Halal Chinese ham sausages by Fourier transform infrared (FTIR) spectroscopy and chemometrics

Rapid discrimination of pork in Halal and non-Halal Chinese ham sausages was developed by Fourier transform infrared (FTIR) spectrometry combined with chemometrics. Transmittance spectra ranging from 400 to 4000cm(-1) of 73 Halal and 78 non-Halal Chinese ham sausages were measured. Sample preparation involved finely grinding of samples and formation of KBr disks (under 10MPa for 5min). The influence of data preprocessing methods including smoothing, taking derivatives and standard normal variate (SNV) on partial least squares discriminant analysis (PLSDA) and least squares support vector machine (LS-SVM) was investigated. The results indicate removal of spectral background and baseline plays an important role in discrimination. Taking derivatives, SNV can improve classification accuracy and reduce the complexity of PLSDA. Possibly due to the loss of detailed high-frequency spectral information, smoothing degrades the model performance. For the best models, the sensitivity and specificity was 0.913 and 0.929 for PLSDA with SNV spectra, 0.957 and 0.929 for LS-SVM with second derivative spectra, respectively.     

基于傅里叶变换红外光谱的不同茶山古树普洱茶鉴别研究

目的 基于混合物红外光谱原理及方法,对不同茶山普洱茶组成差异进行整体分析与评价,探讨普洱茶一山一味说法的科学性.方法 选取易武、景迈等云南12座茶山的古树晒青茶,采用透射法傅里叶变换红外光谱(Fourier transform infrared spectroscopy,FT-IR)采集其超微茶粉、水提取物及茶渣的...     

Differentiation of brewing yeast strains by pyrolysis mass spectrometry and Fourier transform infrared spectroscopy

Two rapid spectroscopic approaches for whole-organism fingerprinting—pyrolysis mass spectrometry (PyMS) and Fourier transform infrared spectroscopy (FT-IR)—were used to analyse 22 production brewery Saccharomyces cerevisiae strains. Multivariate discriminant analysis of the spectral data was then performed to observe relationships between the 22 isolates. Upon visual inspection of the cluster analyses, similar differentiation of the strains was observed for both approaches. Moreover, these phenetic classifications were found to be very similar to those previously obtained using genotypic studies of the same brewing yeasts. Both spectroscopic techniques are rapid (typically 2 min for PyMS and 10 s for FT-IR) and were shown to be capable of the successful discrimination of both ale and lager yeasts. We believe that these whole-organism fingerprinting methods could find application in brewery quality control laboratories. © 1998 John Wiley & Sons, Ltd.     

Secondary structural studies of bovine caseins: temperature dependence of β-casein structure as analyzed by circular dichroism and FTIR spectroscopy and correlation with micellization

To obtain a molecular basis for the similarities and dissimilarities in the functional, chemical, and biochemical properties between β-casein and the other caseins, three-dimensional models have been presented. Secondary structural prediction algorithms and molecular modeling techniques were used to predict β-casein structure. The secondary structure of bovine β-casein was re-examined using Fourier transform infrared and circular dichroism spectroscopies to test these predictions. Both methods predict a range of secondary structures for β-casein (28–32% turns, 32–34% extended) at 25°C. These elements were highly stable from 5 to 70°C as viewed by circular dichroism. More flexible conformational elements, tentatively identified as loops, helix and short segments of polyproline II, were influenced by temperature, increasing with elevated temperatures. Another view is that as temperature decreases, these elements are lost (cold denaturation). Several distinct transitions were observed by circular dichroism at 10, 33 and 41°C, and another transition, extrapolated to occur at 78°C. Calculations from analytical ultracentrifugation indicate that the 10, 33 and 41°C transitions occur primarily in the monomeric form of the protein. As β-casein polymers are formed, and increase in size, the transitions at higher temperature may reflect changes in the more flexible conformational elements as they adjust to changes in surface charge during polymer formation. The transition at 10°C may represent an actual general conformational change or cold denaturation. Over the range of temperatures studied, the sheet and turn areas remain relatively constant, perhaps forming a supporting hydrophobic core for the monomers within the micelle-like polymer. This interpretation is in accord with the known properties of β-casein, and those predicted from molecular modeling.     

大豆分离蛋白与低浓度尿素相互作用红外光谱分析

对大豆分离蛋白(SPI)与低浓度尿素溶液相互作用红外光谱进行酰胺Ⅲ带研究。研究结果表明,溶解在不同浓度尿素溶液中大豆分离蛋白二级结构与大豆分离蛋白水溶液相比发生很大变化,在0.1mol·L~(-1)尿素溶液中大豆分离蛋白β-折叠含量最小,随着尿素浓度增加,β-折叠含量增加,无规卷曲含量在0.1mol·L~(-1)尿素溶液中达到最大,之后随尿素浓度增加而降低;α-螺旋和β-转角随着尿素浓度增加,其含量都呈现先增加后下降趋势,在1mol·L~(-1)尿素溶液中两者含量与大豆分离蛋白水溶液中含量相比变化不大。     

二阶导数傅里叶变换红外光谱鉴别植物油和地沟油

利用傅里叶变换红外光谱法测定了食用植物油、地沟油和模拟的复热油的光谱并进行二阶导数处理分析。结果表明:地沟油和模拟的复热油的饱和脂肪酸、反式脂肪酸的含量均明显高于正常食用油的;二阶导数光谱中3 009、1 737、966、723 cm~(-1)4处特征吸收峰的变化可作为判定是否为地沟油的参考。用此方法鉴别油品用量少且无需样品预处理,分析速度快,可为地沟油检测方法的建立提供依据。     

Electrostatic effects on β-lactoglobulin transitions during heat denaturation as studied by differential scanning calorimetry

This work comprises the study of the thermal treatment of β-lg and its denaturation as a function of pH and ionic strength followed by differential scanning calorimetry. The concentration of protein was 14 (w/v)% in order to study the behaviour of highly concentrated β-lg solutions during heating. The denaturation temperature of β-lg was dependent on both pH and ionic strength, meaning that electrostatic interactions between protein monomers in the native state were important for the denaturation of β-lg. The thermograms from the calorimetric measurements also revealed that the quarternary structure of β-lg at pH-values close to the isoelectric point was influenced by the presence of salt and the nature of the salt (NaCl, KI and LiI). Small exotherms emerged in the thermograms at the low temperature side of the denaturation temperature for β-lg. The presences of these exotherms are probably caused by restructuring of the quarternary structure of native β-lg prior to denaturation, due to dissociation into smaller entities and possible also formation of a liquid crystalline-like structure in the highly concentrated protein solution. The present study provides a contribution to the understanding of the importance of the electrostatic interactions between native β-lg molecules and how different salts and ionic strengths affect the denaturation properties of the protein in concentrated systems.     

Caprine CSN1S1 haplotype effect on gene expression and milk composition measured by Fourier transform infrared spectroscopy

The Norwegian dairy goat population has a high frequency of a CSN1S1 (α_S1-casein) haplotype with negative effects on protein and fat content. It is characterized by a single point deletion in exon 12 of CSN1S1, leading to a truncated protein and hence a low content of α_S1-casein in the milk. This haplotype together with another haplotype with a deletion in exon 9 are called “weak” haplotypes. “Strong” haplotypes, on the other hand, have positive effects on important milk production traits. We show that expression of CSN1S1 in the mammary gland of lactating goats is significantly lower in animals with 2 weak haplotypes. Moreover, the effects of defective alleles were not detected in animals having 1 strong and 1 weak haplotype. Expression levels of other genes in the casein cluster were not affected by the CSN1S1 haplotypes investigated. Milk samples from goats with 2 weak haplotypes could be distinguished from the other milk samples using Fourier transform infrared (FTIR) spectroscopy and partial least squares discriminant analysis (PLS-DA). The PLS-DA components were related to spectra of pure caseins and whey proteins, hence FTIR has a potential for identifying milk samples with low α_S1-casein content and different protein composition. The results indicate that FTIR-based measurements can be incorporated into breeding plans, or for selection of milk samples with high casein content, which in turn may improve cheese-making properties of the milk.     

近红外光谱应用于高粱中总淀粉、直链淀粉与支链淀粉的定量分析

酱香型白酒以高粱为主要原料发酵而成,高粱中的淀粉,尤其是支链淀粉的含量对于酱香型白酒的产品质量起着至关重要的作用,因此针对其总淀粉、直链淀粉与支链淀粉的检测手段研究也应受到人们高度的重视。傅里叶变换近红外光谱法因其准确性高、稳定性好以及快速无损检测等特点,在建立总淀粉、直链淀粉和支链淀粉同时定量分析模型方面得到了较为成功的应用。结果表明,总淀粉、直链淀粉以及支链淀粉的定量分析模型相关系数分别达到0.954 9、0.923 6和0.940 1,交互验证均方根误差分别为1.027 1、0.088 5和1.264 6。可见,基于近红外光谱技术的定量分析方法可适用于高粱中总淀粉、直链淀粉与支链淀粉的同时定量分析。     

Molecular studies of pressure/temperature‐induced structural changes in bovine β‐lactoglobulin

β‐Lactoglobulin in 50 mM Tris/HCl buffer at pH 7 was subjected to combined pressure and temperature treatments using a central composite experimental design. Pressures up to 294 MPa, temperatures up to 62 °C and processing times up to 30 min were studied. The molecular structure at the secondary and tertiary levels was analysed post‐processing using far‐ and near‐UV circular dichroism. It was found that, although the pressures applied were moderate, the far‐UV circular dichroism spectra showed important changes corresponding to an increase in α‐helix content. The tertiary structure was almost completely lost for the highest processing intensities. This suggests a transition to the molten globule state. The percentage change in molar ellipticity at 293 nm (tertiary structure) was found to be linearly connected to the three independent variables, hence possibly allowing process optimisation for that response. Pressure was found to be the most important parameter to bring about the molecular changes at the two molecular levels investigated. Copyright © 2004 Society of Chemical Industry