Contributions of Fourier-transform mid infrared (FT-MIR) spectroscopy to the study of fruit and vegetables: A review

Near-infrared (12,500-4,000 cm-1; 800-2,500 nm) spectroscopy is the hallmark for one of the most rapidly advancing analytical techniques over the last few decades. Although it is mainly recognized as an analytical tool, near-infrared spectroscopy has also contributed significantly to physical chemistry, e.g., by delivering invaluable data on the anharmonic nature of molecular vibrations or peculiarities of intermolecular interactions. In all these contexts, a major barrier in the form of an intrinsic complexity of near-infrared spectra has been encountered. A large number of overlapping vibrational contributions influenced by anharmonic effects create complex patterns of spectral dependencies, in many cases hindering our comprehension of near-infrared spectra. Quantum mechanical calculations commonly serve as a major support to infrared and Raman studies; conversely, near-infrared spectroscopy has long been hindered in this regard due to practical limitations. Advances in anharmonic theories in hyphenation with ever-growing computer technology have enabled feasible theoretical near-infrared spectroscopy in recent times. Accordingly, a growing number of quantum mechanical investigations aimed at near-infrared region has been witnessed. The present review article summarizes these most recent accomplishments in the emerging field. Applications of generalized approaches, such as vibrational self-consistent field and vibrational second order perturbation theories as well as their derivatives, and dense grid-based studies of vibrational potential, are overviewed. Basic and applied studies are discussed, with special attention paid to the ones which aim at improving analytical spectroscopy. A remarkable potential arises from the growing applicability of anharmonic computations to solving the problems which arise in both basic and analytical near-infrared spectroscopy. This review highlights an increased value of quantum mechanical calculations to near-infrared spectroscopy in relation to other kinds of vibrational spectroscopy.

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Breakthrough Potential in Near-Infrared Spectroscopy: Spectra Simulation. A Review of Recent Developments

The proper functioning of living systems and physiological phenotypes depends on molecular composition. Yet simultaneous quantitative detection of a wide variety of molecules remains a challenge1–8. Here we show how broadband optical coherence opens up opportunities for fingerprinting complex molecular ensembles in their natural environment. Vibrationally excited molecules emit a coherent electric field following few-cycle infrared laser excitation9–12, and this field is specific to the sample’s molecular composition. Employing electro-optic sampling10,12–15, we directly measure this global molecular fingerprint down to field strengths 107 times weaker than that of the excitation. This enables transillumination of intact living systems with thicknesses of the order of 0.1 millimetres, permitting broadband infrared spectroscopic probing of human cells and plant leaves. In a proof-of-concept analysis of human blood serum, temporal isolation of the infrared electric-field fingerprint from its excitation along with its sampling with attosecond timing precision results in detection sensitivity of submicrograms per millilitre of blood serum and a detectable dynamic range of molecular concentration exceeding 105. This technique promises improved molecular sensitivity and molecular coverage for probing complex, real-world biological and medical settings. A vibrational spectroscopy technique that measures the electric field emitted from organic molecules following infrared illumination allows their molecular fingerprints to be separated from the excitation background, even in complex biological samples.

Field-resolved infrared spectroscopy of biological systems

Near-infrared (NIR) spectroscopy occupies a specific spot across the field of bioscience and related disciplines Its characteristics and application potential differs from infrared (IR) or Raman spectroscopy This vibrational spectroscopy technique elucidates molecular information from the examined sample by measuring absorption bands resulting from overtones and combination excitations Recent decades brought significant progress in the instrumentation (eg, miniaturized spectrometers) and spectral analysis methods (eg, spectral image processing and analysis, quantum chemical calculation of NIR spectra), which made notable impact on its applicability This review aims to present NIR spectroscopy as a matured technique, yet with great potential for further advances in several directions throughout broadly understood bio-applications Its practical value is critically assessed and compared with competing techniques Attention is given to link the bio-application potential of NIR spectroscopy with its fundamental characteristics and principal features of NIR spectra

Near-Infrared Spectroscopy in Bio-Applications

Fast and robust small infrared target detection using absolute directional mean difference algorithm

Plant cells, tissues and organs are composed of various biomolecules arranged as structurally diverse units, which represent heterogeneity at microscopic levels. Molecular knowledge about those constituents with their localization in such complexity is very crucial for both basic and applied plant sciences. In this context, infrared imaging techniques have advantages over conventional methods to investigate heterogeneous plant structures in providing quantitative and qualitative analyses with spatial distribution of the components. Thus, particularly, with the use of proper analytical approaches and sampling methods, these technologies offer significant information for the studies on plant classification, physiology, ecology, genetics, pathology and other related disciplines. This review aims to present a general perspective about near-infrared and mid-infrared imaging/microspectroscopy in plant research. It is addressed to compare potentialities of these methodologies with their advantages and limitations. With regard to the organization of the document, the first section will introduce the respective underlying principles followed by instrumentation, sampling techniques, sample preparations, measurement, and an overview of spectral pre-processing and multivariate analysis. The last section will review selected applications in the literature.

A Review of Mid-Infrared and Near-Infrared Imaging: Principles, Concepts and Applications in Plant Tissue Analysis

Glucomannan (GM) is a polysaccharide of the mannan family of compounds found in some plant species. The dried and powdered tubers of some orchid species, collectively known as ?salep powder,? are a commercially important crop for human consumption and are one of the primary sources of GM. GM content is the primary indicator for the yield and quality of salep powder. We hypothesized that it would be more practical and accurate to measure GM content within tuber powder directly, prior to any purification or pre-processing. The GM content of tubers of 14 different orchid species was evaluated and compared using Fourier transform infrared (FTIR) spectroscopy and an enzymatic colorimetric method. RESULTS Among the analyzed modes, the sum of the peak areas at 873 and 812 cm?1, which represent the CH bending attributed to the ?-pyranose form of d-glucose and d-mannose, respectively, gave the only confirmation using colorimetric methods. It was found that the tubers of Himantoglossum caprinum and Serapias vomeracea had the highest GM concentrations among the analyzed species. After conducting different pre-processing steps on Serapias vomeracea tubers, it was found that treating the tubers with milk, or high temperature resulted in an apparent increase in GM concentrations. CONCLUSION Himantoglossum caprinum and Serapias vomeracea give the highest yields of GM and should be used for commercial horticulture. GM estimation should be made prior to any pre-processing. FTIR spectroscopy is effective and reliable for directly comparing GM content of different orchid species, without the need for any purification or pre-processing. ? 2019 Society of Chemical Industry

FTIR‐based comparative analysis of glucomannan contents in some tuberous orchids, and effects of pre‐processing on glucomannan measurement

Tianeptine, olanzapine and fluoxetine show similar restoring effects on stress induced molecular changes in mice brain: An FT-IR study.

Amsonia orientalis Decne. (syn. Rhazya orientalis (Decne.) A. DC.) is only cultivated as an ornamental plant but also has a medicinal merit. The natural populations of the species were taken under conservation as per the Bern Convention by European Council. As one of the most common plant growth regulators and synthetic agricultural fertilizers, the effects of 6-benzylaminopurine (BAP) at different concentrations on primary metabolites of in vitro propagated A. orientalis have been investigated by using Fourier transform infrared (FT-IR) spectroscopy. Among all applied concentrations, 2.0 mg l -1 BAP resulted in increment of hydrogen bonded polysaccharide and proteins concentrations, lipid structure and membrane fluidity. Treatments of 2.0 and 4.0 mg l -1 BAP increased the existence of ferulic acid which also indicates the linkage of xylan and both cellulose and hemicellulose content. There was a significant decrease in the area of the peak which indicated the C=O stretching of proteins and pectins for 0.5 and 1.0 mg l -1 BAP while there was a significant increase for 2.0 and 4.0 mg l -1 of BAP treatments. The evaluation of molecular data from FT-IR spectroscopy as in the current study might help to estimate different physiological changes at the molecular level in plants depending on plant growth regulator and/or fertilizer applications. Thus, this FT-IR based method can be applied to in vitro propagation studies and also to studies focused on effects of pesticide and/or herbicide applications on plants to understand the metabolic changes in target species.

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FT-IR Spectroscopy Based Evaluation of Changes in Primary Metabolites of Amsonia orientalis after In vitro 6-benzylaminopurine Treatment

In the current study, effects of chitosan oligomers (CHI-OM) with different polymerization degrees (DP) between 2 and 15, and polymeric chitosan (CHI-P) with a DP of 70 were compared with kinetin (KIN), 6-benzylaminopurine (BAP), indole-3-butyric acid (IBA), indole-3-acetic acid (IAA), and jasmonic acid (JAS) on the structure and composition of several biomolecules in the root system of Serapias vomeracea. Evaluation of molecular alterations in the root system of S. vomeracea through an infrared spectroscopic approach provided insight into the differentiation between action mechanisms of chitosan and commonly used plant growth regulators. The results revealed that CHI-P and JAS treatments at low concentrations might enhance the lignin content in the cell walls. Also, JAS, CHI-OM, and CHI-P treatments enhanced cell wall lignification. The water-associated cellulose content of the cell walls was affected by the DP of chitosan. Membrane lipid stabilization and protein content were enhanced after CHI-P, JAS, and KIN treatments, while BAP and CHI-OM treatments triggered lipid, protein, and cell wall polysaccharide synthesis. In particular, CHI-OM treatment also enhanced rhamnogalacturonan and β-galactan content as well as xyloglucans and glucomannans, while the auxin treatments had a similar impact only on glucomannan content. These findings suggest that chitosan may show either purine-based cytokinin-like or lipid-based jasmonic acid-like activity in the root system of S. vomeracea. Additionally, depending on its degree of polymerization, the effects of chitosan may vary on root system development in S. vomeracea.

Biomolecular Structure and Composition Changes in the Root System of Long-Lipped Serapias ( Serapias vomeracea ) After In Vitro Chitosan and Plant Growth Regulator Treatments

Sevgi Türker-Kaya

Papers

A Review of Mid-Infrared and Near-Infrared Imaging: Principles, Concepts and Applications in Plant Tissue Analysis

FTIR‐based comparative analysis of glucomannan contents in some tuberous orchids, and effects of pre‐processing on glucomannan measurement

Tianeptine, olanzapine and fluoxetine show similar restoring effects on stress induced molecular changes in mice brain: An FT-IR study.

FT-IR Spectroscopy Based Evaluation of Changes in Primary Metabolites of Amsonia orientalis after In vitro 6-benzylaminopurine Treatment

Biomolecular Structure and Composition Changes in the Root System of Long-Lipped Serapias ( Serapias vomeracea ) After In Vitro Chitosan and Plant Growth Regulator Treatments