A Novel qNMR Application for the Quantification of Vegetable Oils Used as Adulterants in Essential Oils

Advanced analytical techniques for authenticity identification and quality evaluation in Essential oils: A review

Essential oils (EO), secondary metabolites of plants are fragrant oily liquids with antibacterial, antiviral, anti-inflammatory, anti-allergic, and antioxidant effects. They are widely applied in food, medicine, cosmetics, and other fields. However, the quality of EOs remain uncertain owing to their high volatility and susceptibility to oxidation, influenced by factors such as the harvesting season, extraction, and separation techniques. Additionally, the huge economic value of EOs has led to a market marked by widespread and varied adulteration, making the assessment of their quality challenging. Therefore, developing simple, quick, and effective identification techniques for EOs is essential. This review comprehensively summarizes the techniques for assessing EO quality and identifying adulteration. It covers sensory evaluation, physical and chemical property evaluation, and chemical composition analysis, which are widely used and of great significance for the quality evaluation and adulteration detection of EOs.

Quality Standards and Pharmacological Interventions of Natural Oils: Current Scenario and Future Perspectives

Medicinal plants are rich sources of natural oils such as essential and fixed oils used traditionally for nutritive as well as medicinal purposes. Most of the traditional formulations or phytopharmaceutical formulations contain oil as the main ingredient due to their own therapeutic applications and thus mitigating several pathogeneses such as fungal/bacterial/viral infection, gout, psoriasis, analgesic, antioxidant, skin infection, etc. Due to the lack of quality standards and progressive adulteration in the natural oils, their therapeutic efficacy is continuously deteriorated. To develop quality standards and validate scientific aspects on essential oils, several chromatographic and spectroscopic techniques such as HPTLC, HPLC, NMR, LC-MS, and GC-MS have been termed as the choices of techniques for better exploration of metabolites, hence sustaining the authenticity of the essential oils. In this review, chemical profiling and quality control aspects of essential or fixed oils have been explored from previously reported literature in reputed journals. Methods of chemical profiling, possible identified metabolites in essential oils, and their therapeutic applications have been described. The outcome of the review reveals that GC-MS/MS, LC-MS/MS, and NMR-based chromatographic and spectroscopic techniques are the most liable, economic, precise, and accurate techniques for determining the spuriousness or adulteration of oils based on their qualitative and quantitative chemical profiling studies. This review occupies the extensive information about the quality standards of several oils obtained from natural sources for their regulatory aspects via providing the detailed methods used in chemoprofiling techniques. Hence, this review helps researchers in further therapeutic exploration as well as quality-based standardization for their regulatory purpose.

An Optimized Two-Dimensional Quantitative Nuclear Magnetic Resonance Strategy for the Rapid Quantitation of Diester-Type C19-Diterpenoid Alkaloids from Aconitum carmichaelii

With the development of nuclear magnetic resonance (NMR) spectrometers and probes, two-dimensional quantitative nuclear magnetic resonance (2D qNMR) technology with a high signal resolution and great application potential has become increasingly accessible for the quantitation of complex mixtures. However, the requirement that the relaxation recovery time be equal to at least five times T₁ (longitudinal relaxation time) makes it difficult for 2D qNMR to simultaneously achieve high quantitative accuracy and high data acquisition efficiency. By comprehensively using relaxation optimization and nonuniform sampling, we successfully established an optimized 2D qNMR strategy for HSQC experiments at the half-hour level and then accurately quantified the diester-type C₁₉-diterpenoid alkaloids in Aconitum carmichaelii. The optimized strategy had the advantages of high efficiency, high accuracy, good reproducibility, and low cost and thus could serve as a reference to optimize 2D qNMR experiments for quantitative analysis of natural products, metabolites, and other complex mixtures.

Multivariate Statistical Models for the Authentication of Traditional Balsamic Vinegar of Modena and Balsamic Vinegar of Modena on 1H-NMR Data: Comparison of Targeted and Untargeted Approaches

This work aimed to compare targeted and untargeted approaches based on NMR data for the construction of classification models for Traditional Balsamic Vinegar of Modena (TBVM) and Balsamic Vinegar of Modena (BVM). Their complexity in terms of composition makes the authentication of these products difficult, which requires the employment of several time-consuming analytical methods. Here, ¹H-NMR spectroscopy was selected as the analytical method for the analysis of TVBM and BVM due to its rapidity and efficacy in food authentication. ¹H-NMR spectra of old (>12 years) and extra-old (>25 years) TVBM and BVM (>60 days) and aged (>3 years) BVM were acquired, and targeted and untargeted approaches were used for building unsupervised and supervised multivariate statistical modes. Targeted and untargeted approaches were based on quantitative results of peculiar compounds present in vinegar obtained through qNMR, and all spectral variables, respectively. Several classification models were employed, and linear discriminant analysis (LDA) demonstrated sensitivity and specificity percentages higher than 85% for both approaches. The most important discriminating variables were glucose, fructose, and 5-hydroxymethylfurfural. The untargeted approach proved to be the most promising strategy for the construction of LDA models of authentication for TVBM and BVM due to its easier applicability, rapidity, and slightly higher predictive performance. The proposed method for authenticating TBVM and BVM could be employed by Italian producers for safeguarding their valuable products.

Quantification of polyols in sugar-free foodstuffs by qNMR

We present a qNMR method for the determination of low calories sweeteners (erythritol, mannitol, maltitol, sorbitol, isomalt and xylitol) in sugar-free foodstuff. The structural similarities of these compounds determine often a severe spectral overlap that hampers their quantification via conventional 1D and 2D NMR spectra. This problem is here overcome by exploiting the resolving capabilities of the CSSF-TOCSY experiment, allowing the quantification of all six polyols, with satisfactory results in terms of LoQ (2.8-7.4 mg/L for xylitol, mannitol, sorbitol, 15 mg/L for erythritol, 38 mg/L for maltitol and 91 mg/L for isomalt), precision (RSD% 0.40-4.03), trueness (bias% 0.15-4.81), and recovery (98-104%). Polyol's quantification in different sugar-free confectionary products was performed after a simple water extraction without any additional sample treatment. While these results demonstrate the robustness of the proposed method for polyols quantification in low calories foods, its applicability can be further extended to other food matrices or biofluids.

Characterization and Valorization of the Agricultural Waste Obtained from Lavandula Steam Distillation for Its Reuse in the Food and Pharmaceutical Fields

The main focus of the current research was the characterization of the by-products from the steam distillation of Lavandula angustifolia Mill. (LA) and Lavandula x intermedia Emeric ex Loisel (LI) aerial parts, as they are important sources of bioactive compounds suitable for several applications in the food, cosmetic, and pharmaceutical industries. The oil-exhausted biomasses were extracted and the total polyphenol and flavonoid contents were, respectively, 19.22 ± 4.16 and 1.56 ± 0.21 mg/g for LA extract and 17.06 ± 3.31 and 1.41 ± 0.10 mg/g for LI extract. The qualitative analysis by liquid chromatography-electrospray tandem mass spectrometry (HPLC-ESI-MS) revealed that both the extracts were rich in phenolic acids and glycosylated flavonoids. The extracts exhibited radical scavenging, chelating, reducing activities, and inhibitory capacities on acetylcholinesterase and tyrosinase. The IC50 values against acetylcholinesterase and tyrosinase were, respectively, 5.35 ± 0.47 and 5.26 ± 0.02 mg/mL for LA, and 6.67 ± 0.12 and 6.56 ± 0.16 mg/mL for LI extracts. In conclusion, the oil-exhausted biomasses demonstrated to represent important sources of bioactive compounds, suitable for several applications in the food, cosmetic, and pharmaceutical industries.