Rapid identification of closely related muscle foods by vibrational spectroscopy and machine learning

Muscle foods are an integral part of the human diet and during the last few decades consumption of poultry products in particular has increased significantly. It is important for consumers, retailers and food regulatory bodies that these products are of a consistently high quality, authentic, and have not been subjected to adulteration by any lower-grade material either by accident or for economic gain. A variety of methods have been developed for the identification and authentication of muscle foods. However, none of these are rapid or non-invasive, all are time-consuming and difficulties have been encountered in discriminating between the commercially important avian species. Whilst previous attempts have been made to discriminate between muscle foods using infrared spectroscopy, these have had limited success, in particular regarding the closely related poultry species, chicken and turkey. Moreover, this study includes novel data since no attempts have been made to discriminate between both the species and the distinct muscle groups within these species, and this is the first application of Raman spectroscopy to the study of muscle foods. Samples of pre-packed meat and poultry were acquired and FT-IR and Raman measurements taken directly from the meat surface. Qualitative interpretation of FT-IR and Raman spectra at the species and muscle group levels were possible using discriminant function analysis. Genetic algorithms were used to elucidate meaningful interpretation of FT-IR results in (bio)chemical terms and we show that specific wavenumbers, and therefore chemical species, were discriminatory for each type (species and muscle) of poultry sample. We believe that this approach would aid food regulatory bodies in the rapid identification of meat and poultry products and shows particular potential for rapid assessment of food adulteration.     

Temperature-jump FT-IR time-resolved spectrometry

A system for performing gas-phase rapid scanning Fourier transform infrared time-resolved Spectrometry (FT-IR/TRS) has been evaluated. This technique can be applied to the study of the lifetimes and reactivity of transient species and can provide detailed information regarding reaction rate constants. Temperature-jump experiments have been initiated and preliminary results are presented.     

Comparison of diffuse-reflectance absorbance and attenuated total reflectance FT-IR for the discrimination of bacteria

A collection of bacteria belonging to the genus Bacillus were analysed by diffuse reflectance absorbance and attenuated total reflectance Fourier transform infrared (FT-IR) spectroscopy in the mid-infrared. The diffuse reflectance absorbance method is a rapid whole organism fingerprinting method, which generates a biochemical profile of the bacteria, where samples are presented to the FT-IR spectrometer dried on a metal carrier. The attenuated total reflectance FT-IR used in conjunction with a diamond attenuated total reflectance (ATR) accessory produces a biochemical profile of the surface chemistry of bacteria directly without the need for drying, and has not previously been used in the discrimination of bacteria. Principal component, discriminant function and hierarchical cluster analysis were performed on the data to discriminate the bacteria. The differentiation of the bacteria to species level was observed in both analyses however, it was concluded that the ATR FT-IR illustrated better sub-species differentiation of the microorganisms. This may imply that the total biochemical profiling infers discrimination to species level whereas strain specific markers are present on the cell surface chemistry.     

Non-thermal synthesis of mesoporous zirconium silicate and its characterization

A simple and rapid method for synthesis of mesoporous zirconium silicate with high thermal stability has been developed using sodium silicate in place of costly silicon alkoxides as a silica source. The product was characterized by means of X-ray diffraction, Nitrogen sorption isotherms, FT-IR spectroscopy, transmission electron microscopy (TEM) and thermogravimetry analysis (TGA).     

Determination of structural modification in acid activated montmorillonite clay by FT-IR spectroscopy

The structural modifications and the Bronsted acid sites generated during the acid treatment of montmorillonite clay with varied concentration of sulphuric acid was determined using FT-IR spectroscopy. Octahedral sheet is affected at low acid concentration resulting into the dissolution of cations; among them Mg2+ cations are prone to dissolve than Fe2+/3+ and Al3+. Tetrahedral sheet is affected at higher acid concentration. The partial substitution of octahedral Al3+ by Mg2+ or Fe2+/3+ cations and the presence of other non-smectite minerals such as kaolinites was also been clearly identified, thus making FT-IR spectroscopy as a rapid technique for monitoring the structural features of montmorillonite clay.     

Study on Angelica and its different extracts by Fourier transform infrared spectroscopy and two-dimensional correlation IR spectroscopy

In order to develop a rapid and effective analysis method for studying integrally the main constituents in the medicinal materials and their extracts, discriminating the extracts from different extraction process, comparing the categories of chemical constituents in the different extracts and monitoring the qualities of medicinal materials, we applied Fourier transform infrared spectroscopy (FT-IR) associated with second derivative infrared spectroscopy and two-dimensional correlation infrared spectroscopy (2D-IR) to study the main constituents in traditional Chinese medicine Angelica and its different extracts (extracted by petroleum ether, ethanol and water in turn). The findings indicated that FT-IR spectrum can provide many holistic variation rules of chemical constituents. Use of the macroscopical fingerprint characters of FT-IR and 2D-IR spectrum can not only identify the main chemical constituents in medicinal materials and their different extracts, but also compare the components differences among the similar samples. This analytical method is highly rapid, effective, visual and accurate for pharmaceutical research.     

Rapid and quantitative detection of the microbial spoilage of beef by Fourier transform infrared spectroscopy and machine learning

Beef is a commercially important and widely consumed muscle food and central to the protein intake of many societies. In the food industry no technology exists for the rapid and accurate detection of microbiologically spoiled or contaminated beef. Fourier transform infrared (FT-IR) spectroscopy is a rapid, reagentless and non-destructive analytical technique whose continued development is resulting in manifold applications across a wide range of biosciences. FT-IR was exploited to measure biochemical changes within the fresh beef substrate, enhancing and accelerating the detection of microbial spoilage. Separately packaged fresh beef rump steaks were purchased from a national retailer, comminuted for 15 s and left to spoil at ambient room temperature for 24 h. Every hour, FT-IR measurements were collected directly from the sample surface using attenuated total reflectance, in parallel the total viable counts of bacteria were obtained by classical microbiological plating methods. Quantitative interpretation of FT-IR spectra was undertaken using partial least squares regression and allowed for accurate estimates of bacterial loads to be calculated directly from the meat surface in 60 s. Machine learning methods in the form of genetic algorithms and genetic programming were used to elucidate the wavenumbers of interest related to the spoilage process. The results obtained demonstrated that using FT-IR and machine learning it was possible to detect bacterial spoilage rapidly in beef and that the most significant functional groups selected could be directly correlated to the spoilage process which arose from proteolysis, resulting in changes in the levels of amides and amines.     

The rapid differentiation of Streptomyces isolates using Fourier transform infrared spectroscopy

Fifteen putative Streptomyces spp. isolated from soil were selected to be analysed using Fourier transform infrared (FT-IR) spectroscopy and 16S rRNA gene sequencing. Four colour groupings (groups 1–4) were obtained and described according to the colour of their substrate mycelia, aerial mycelia, spore mass and pigmentation. The dendrogram constructed using unsupervised cluster analysis of the FT-IR data was in good congruence with the four colour groups and the neighbour-joining phylogenetic tree for 16S rDNA sequencing. In particular, those isolates having 100% 16S rDNA similarities which are supposed to be from the same species can be separated from each other using FT-IR analysis. This high throughput method only takes 1–10 s to collect a FT-IR spectrum from each sample, and both 96- and 384-well microplates are available for automated analysis. FT-IR therefore presents itself as a rapid, whole-organism fingerprinting approach which can be used for preliminary differentiation of Streptomyces spp. at sub-species or strain level.     

Time-resolved flow-flash FT-IR difference spectroscopy: the kinetics of CO photodissociation from myoglobin revisited

Fourier-transform infrared (FT-IR) difference spectroscopy has been proven to be a significant tool in biospectroscopy. In particular, the step-scan technique monitors structural and electronic changes at time resolutions down to a few nanoseconds retaining the multiplex advantage of FT-IR. For the elucidation of the functional mechanisms of proteins, this technique is currently limited to repetitive systems undergoing a rapid photocycle. To overcome this obstacle, we developed a flow-flash experiment in a miniaturised flow channel which was integrated into a step-scan FT-IR spectroscopic setup. As a proof of principle, we studied the rebinding reaction of CO to myoglobin after photodissociation. The use of microfluidics reduced the sample consumption drastically such that a typical step-scan experiment takes only a few 10 ml of a millimolar sample solution, making this method particularly interesting for the investigation of biological samples that are only available in small quantities. Moreover, the flow cell provides the unique opportunity to assess the reaction mechanism of proteins that cycle slowly or react irreversibly. We infer that this novel approach will help in the elucidation of molecular reactions as complex as those of vectorial ion transfer in membrane proteins. The potential application to the oxygen splitting reaction of cytochrome c oxidase is discussed. An erratum to this article can be found at     

Rapid and quantitative detection of the microbial spoilage in milk using Fourier transform infrared spectroscopy and chemometrics

Microbiological safety plays a very significant part in the quality control of milk and dairy products worldwide. Current methods used in the detection and enumeration of spoilage bacteria in pasteurized milk in the dairy industry, although accurate and sensitive, are time-consuming. FT-IR spectroscopy is a metabolic fingerprinting technique that can potentially be used to deliver results with the same accuracy and sensitivity, within minutes after minimal sample preparation. We tested this hypothesis using attenuated total reflectance (ATR), and high throughput (HT) FT-IR techniques. Three main types of pasteurized milk - whole, semi-skimmed and skimmed - were used and milk was allowed to spoil naturally by incubation at 15 degrees C. Samples for FT-IR were obtained at frequent, fixed time intervals and pH and total viable counts were also recorded. Multivariate statistical methods, including principal components-discriminant function analysis and partial least squares regression (PLSR), were then used to investigate the relationship between metabolic fingerprints and the total viable counts. FT-IR ATR data for all milks showed reasonable results for bacterial loads above 10(5) cfu ml(-1). By contrast, FT-IR HT provided more accurate results for lower viable bacterial counts down to 10(3) cfu ml(-1) for whole milk and, 4 x 10(2) cfu ml(-1) for semi-skimmed and skimmed milk. Using FT-IR with PLSR we were able to acquire a metabolic fingerprint rapidly and quantify the microbial load of milk samples accurately, with very little sample preparation. We believe that metabolic fingerprinting using FT-IR has very good potential for future use in the dairy industry as a rapid method of detection and enumeration.     

Identification of species’ blood by attenuated total reflection (ATR) Fourier transform infrared (FT-IR) spectroscopy

Blood is one of the most common and informative forms of biological evidence found at a crime scene. A very crucial step in forensic investigations is identifying a blood stain’s origin. The standard methods currently employed for analyzing blood are destructive to the sample and time-consuming. In this study, attenuated total reflection (ATR) Fourier transform infrared (FT-IR) spectroscopy is used as a confirmatory, nondestructive, and rapid method for distinction between human and animal (nonhuman) blood. Partial least squares-discriminant analysis (PLS-DA) models were built and demonstrated complete separation between human and animal donors, as well as distinction between three separate species: human, cat, and dog. Classification predictions of unknown blood donors were performed by the model, resulting in 100 % accuracy. This study demonstrates ATR FT-IR spectroscopy’s great potential for blood stain analysis and species discrimination, both in the lab and at a crime scene since portable ATR FT-IR instrumentation is commercially available.     

Determination of the Effect of Temperature on the Concentration of keto form of D-Fructose by FT-IR Spectroscopy

Abstract

FT-IR spectroscopy has been employed in the detection of the carbonyl absorption band centered at 1728 cm^?1 and assigned to the open form of D-fructose in deuterium oxide or water. Changes in the intensity of the band at 1728 cm^?1 allowed the monitoring of the concentration of the open form of the keto sugar D-fructose at different temperatures and pHs. The concentration of the open form was observed to increase with increasing temperature and was an order of magnitude higher at 80 °C compared to 30 °C. The buildup of the open form was found to be extremely rapid. The new equilibrium can be reversed with decreasing temperature with a slight hysteresis. This work demonstrates the potential of applying FT-IR spectroscopy in studying the effect of environmental factors on the level of the open chain form of sugars.     

Photo- and thermoinitiated oxidation of high-impact polystyrene. I. Characterization by FT-IR spectroscopy

The photo- and thermooxidative degradation of different grades of high-impact polystyrene (HIPS) has been studied by FT-IR spectroscopy. The oxidized films were treated with NH₃ and SF₄ for the rapid identification and resolution of the various carbonyl species, alcohols, and hydroperoxides. All the sample gave similar oxidation products, but in varying quantities. The heterogenity in the film was also determined by micro-FT-IR spectroscopy. The thermal degradation processes at different temperature were compared. © 1994 John Wiley & Sons, Inc.     

Investigating natural rubber composition with Fourier Transform Infrared (FT-IR) spectroscopy: A rapid and non-destructive method to determine both protein and lipid contents simultaneously

A large panel of Natural Rubber (NR) samples was characterized using Fourier Transform Infrared (FT-IR) spectroscopy in Attenuated Total Reflection (ATR) configuration. Specific vibrational bands were attributed to some non-isoprene compounds naturally present in NR composition. A rapid and non-destructive method was developed to investigate some specific functional groups contained in lipids (ester and carboxyl groups) and proteins (amides). Ester and carboxyl groups were quantified using calibration curves developed from synthetic cis-1,4-polyisoprene mixtures with either methyl stearate or stearic acid. Amide groups of proteins and peptides were found to be directly quantifiable from NR FT-IR spectra. The clonal origin and processing were found to influence the non-isoprene composition of NR. Significant correlations were found between FT-IR results and conventional chemical analyses: nitrogen content for proteins and total lipid extract.     

Synthesis, crystal structure, electrochemistry and in situ FTIR spectroelectrochemistry of a bisferrocene pyrazole derivative

One novel bisferrocene pyrazole derivative, bis [2-(5-trifluoromethyl-3-ferrocenyl) pyrazolyl] methane (abbreviated as (3)), was synthesized and fully characterized. A single crystal of (3) was obtained and solved by X-ray diffraction analysis. The bisferrocene derivative exhibits MLCT (metal to ligand charge transfer) and π→π* transitions in the UV-visible range, which have been verified by density functional theory (DFT) calculations. Its electrochemical properties were studied with the aid of cyclic voltammetry (CV), differential pulse voltammetry (DPV) and rapid scan time-resolved Fourier transform infrared spectroscopy (RS-TRS FT-IR) analysis. Furthermore, the electrochemical mechanism was elucidated based on the results from the cyclic voltabsorptometry (CVA) determination technique. (3) apparently shows a single wave in the cyclic voltammetric experiments which indicates there is no intermediate, however, the intermediate of (3) was observed by employing the RS-TRS FT-IR spectroelectrochemistry technique. The detailed investigation brought us safely to the conclusion that the methylene can also act as a linker, leading to electronic communication in either D-π-D and A-π-A systems.     

Quantification of erythromycin in pharmaceutical formulation by transmission Fourier transform infrared spectroscopy

A simple, cost-effective and environmental friendly analytical method was developed for the quantification of erythromycin in tablet formulation using transmission Fourier Transform Infrared (FT-IR) spectroscopy for routine quality control analysis. There is no need of sample preparation except pellet formation for FT-IR analysis. Use of solvent was totally avoided in this method. Calibration was carried out by using simple Beer’s law in the FT-IR region between 1743 and 1697 cm⁻¹. The excellent coefficient of determination (R² = 0.998) was achieved with 0.0247 and 1.14 root mean square error of prediction (RMSEP) and root mean square error of cross validation (RMSECV), respectively. The results of the study revealed that the transmission FT-IR spectroscopy could be effectively used for rapid determination of active ingredients like erythromycin in pharmaceutical formulations to control the quality of finished products.     

Application of FT-IR spectroscopy to the characterisation and classification of wines, brandies and other distilled drinks

FT-IR spectra were employed for the differentiation and classification of wines and brandies during their ageing process, as well as for the characterisation and differentiation of distilled drinks from several producing countries. The FT-IR spectra have enabled the differentiation of the six scales of ageing of sherry wine. A good linear regression fit (regression coefficient=0.995) has been obtained between ageing scale and the data of the FT-IR spectrum. In the case of Brandy of Jerez, it has been possible to differentiate the three degrees of ageing and to devise a system of classification by means of linear discriminant analysis, with a reliability of 83%. The application of the regression by partial least squares has allowed us to obtain a regression between the degree of ageing and the data of the FT-IR spectrum (correlation coefficient=0.986). Lastly, Spanish, French and South African brandies, as well as cognacs and armagnacs have been characterised, and a complete differentiation of the latter two types from the rest of the samples of distilled drinks has been obtained.     

Acid sites characterization of niobium phosphate catalysts and their activity in fructose dehydration to 5-hydroxymethyl-2-furaldehyde

The nature of different acid sites on the surface of various niobium-based catalysts has been spectroscopically investigated by means of FT-IR and UV–VIS techniques. Surface acidity has been further characterized by acetonitrile adsorption and subsequent FT-IR analysis. The catalytic activity of the different examined samples has been preliminarily tested in the fructose dehydration to 5-hydroxymethyl-2-furaldehyde, a reaction of relevant industrial interest.     

Synthesis of a polymer-capped palladium nanoparticles and its application as a reusable catalyst in oxidative coupling reaction of α-hydroxyketones and 1,2-diamines for preparation of pyrazines and quinoxalines

A novel method for the synthesis of pyrazines and quinoxalines has been developed using α-hydroxyketones and 1,2-diamines in the presence of cross-linked poly(4-vinylpyridine)-stabilized Pd(0) nanoparticles, [P4-VP]-PdNPs. The catalyst was easily prepared and characterized using various techniques such as FT-IR and UV–Vis spectroscopy, AAS, TEM, FESEM, EDX analysis and XRD. The results confirm a good dispersion of palladium nanoparticles on the polymer support. The catalyst displayed good catalytic activity when applied to the synthesis of quinoxalines via condensation of α-hydroxyketones with 1,2-diamines. A few pyrazine derivatives and various quinoxalines are prepared via coupling reaction of α-hydroxyketones and 1,2-diamines in high–excellent yields (81–99%) with short reaction times. The quinoxalines products were characterized by FT-IR, ¹H and ¹³C NMR spectroscopy, and the physical properties were compared to the literature values of known compounds. The advantages of the present method over conventional classical methods are rapid and very simple work-up, and the catalyst is reusable many times without a significant loss in its activity.