Analysis of the trend of volatile compounds by HS-SPME-GC-MS and the main factors affecting the formation of rancid odor during the oxidation process of infant nutrition package.

In this study, headspace solid-phase micro-extraction (HS-SPME) coupled with GC-MS was used to analyze the trend of volatile compounds in fresh and oxidative infant nutrition package. Among the volatile compounds, aldehydes and ketones, alcohols, lipids, cycloalkenes, alkanes, alkenes, aromatic hydrocarbons, oxygenated compound were identified. A total of 65 volatile compounds were detected in the fresh nutrition package, whereas 9 new volatile compounds were detected during the accelerated oxidation process, which was oxidized at 45 °C for 4 weeks. The main components of the rancid flavor formed and the relative content of volatile substances gradually changed during the accelerated oxidation process. The volatile substances hexanal, nonanal, and 2-pentylfuran substantially increased. Linalool, α-terpineol, d-limonene, and 1-methoxy-nonane presented an evidently downward trend. The relative content of the newly formed compound 3-hydroxy-2-methylpyran-4-one during the oxidation process was always large, its relative content initially increased, then decreased, and finally increased again. The formation of rancid flavor of the nutrient package was speculated to have been formed by the interaction of hexanal, nonanal, 2-pentylfuran, and 3-hydroxy-2-methylpyran-4-one.

Determination of plant growth regulators in pears by microwave-assisted extraction and liquid chromatography with electrospray ionization mass spectrometry.

A new method for the determination of six plant growth regulators, 3-indolylacetic acid, 3-indolepropionic acid, 2-naphthoxyacetic acid, 2,4-dicholrophenoxyacetic acid, 1-naphthlcetic acid, and methyl naphthalene-1-acetate, in pears was established by liquid chromatography with electrospray ionization mass spectrometry. In this study, a microwave-assisted extraction technique was first applied for the determination of plant growth regulators in fruit and three cleanup techniques were, respectively, investigated for the purification of pear samples. The chromatographic separation was performed on a Diamonsil C18 column by using 0.01 mol/L formic acid/ammonium formate buffer solution (pH 3.5)/methanol (35:65, v/v) as the mobile phase with a flow rate of 0.7 mL/min in 1:1 split mode. The LODs ranged from 0.3 to 1.9 µg/kg. Under optimized conditions, the average recoveries (five replicates) for six plant growth regulators (spiked at 0.01, 0.05, and 0.5 mg/kg) ranged from 78.9 to 118.0%, and the RSDs were 1.4-10.3%.

Study on discrimination of white tea and albino tea based on near-infrared spectroscopy and chemometrics.

BACKGROUND: White tea and albino tea have their own nutritional characteristics, but from the appearance they are quite similar to each other. It is not easy to distinguish them with existing analytical tools or by visual inspection. The current study proposed a rapid method to discriminate them based on near-infrared (NIR) spectroscopy associated with supervised pattern recognition methods. RESULTS: For this purpose, discriminant partial least-squares (DPLS) and discriminant analysis (DA) were employed to build classification models on the basis of a reduced subset of wavenumbers and different pretreatment methods. A completely independent validation set was also used to test the model performance. The results of the DA model showed that with the SNV Karl Norris derivative spectral pre-treatment samples from the two different origins could be 100% correctly discriminated. Similarly, for the DPLS model, the best classification results were obtained with the multiplicative scattering correction (MSC) + first derivative spectral pre-treatments; the accuracy of identification was 98.48% for the calibration set and 100% for the validation set. CONCLUSION: The overall results demonstrated that NIR spectroscopy with pattern recognition could be successfully applied to discriminate white tea and albino tea quickly and non-destructively without the need for various analytical determinations.

Metabolomics applications for plant-based foods origin tracing, cultivars identification and processing: Feasibility and future aspects.

Metabolomics, the systematic study of metabolites, is dedicated to a comprehensive analysis of all aspects of plant-based food research and plays a pivotal role in the nutritional composition and quality control of plant-based foods. The diverse chemical compositions of plant-based foods lead to variations in sensory characteristics and nutritional value. This review explores the application of the metabolomics method to plant-based food origin tracing, cultivar identification, and processing methods. It also addresses the challenges encountered and outlines future directions. Typically, when combined with other omics or techniques, synergistic and complementary information is uncovered, enhancing the classification and prediction capabilities of models. Future research should aim to evaluate all factors affecting food quality comprehensively, and this necessitates advanced research into influence mechanisms, metabolic pathways, and gene expression.

Discovery and identification of natural alkaloids with potential to impact insulin resistance syndrome in Cyclocarya paliurus. (Batal) leaves by UPLC-QTOF-MS combined with HepG2 cells.

Cyclocarya paliurus (Batal.) leaves, which contain a range of bioactive compounds, have been used as a traditional Chinese medicine homologous food since ancient times. However, there is a paucity of literature on comprehensive studies of alkaloids in the leaves of Cyclocarya paliurus (Batal.). For the first time, this study aimed to discover and identify alkaloids extracted from Cyclocarya paliurus (Batal.) leaves by ultra-high performance liquid chromatography-quadrupole-time-of-flight tandem mass spectrometry (UPLC-QTOF-MS). A total of ten alkaloids have been identified from Cyclocarya paliurus (Batal.) leaves based on accurate mass spectra (mass accuracy, isotopic spacing and distribution) and comparison to fragmentation spectra reported in the literature. In vitro, alkaloids alleviated insulin resistance by increasing glucose consumption and glycogen content in insulin resistance HepG2 cells. The RNA-seq and western blotting results showed that alkaloids could upregulate the expression of phosphatidylinositol 3-kinase (PI3K), and increase the phosphorylation of insulin receptor protein kinase B (AKT). This study not only clarified the chemical constituents and revealed that diverse alkaloids also presented from Cyclocarya paliurus (Batal.) leaves, also, it will provide chemical information on potential compounds for developing new drugs.

Regulating the defects of MIL-101(Cr) for the efficient and simultaneous determination of eleven plant growth regulators in fresh fruit juice.

This work presents an efficient sorbent for plant growth regulators (PGRs) by regulating the defects of a metal-organic framework MIL-101(Cr). Using the regulated MIL-101(Cr), we developed a simple and effective method for the simultaneous determination of eleven PGRs in fresh fruit juice. The extraction conditions were optimized by an orthogonal array design. Under optimal conditions, the method showed a satisfactory limit of detection (0.1-1.2 ng/g), recovery rates (83.4-110.2 %), and precision (2.9-18.0 % for intra-day and 2.7-10.8 % for inter-day), as well as a greatly suppressed matrix effect. Notably, regulating the defects significantly enhanced the desorption of PGRs on MIL-101(Cr). The sorbent didn't need to be destroyed to release the adsorbed PGRs and could be reused at least 6 times. Furthermore, the defects of MIL-101(Cr) and interactions between the sorbent and PGRs were studied by TGA, ATR-IR, XPS, NH3-TPD and UV-Vis DRS.

A convenient and effective method for determining organophosphorus pesticides in citrus fruits based on a novel dispersive solid phase extraction using UiO-66/Alg bead as the sorbent.

This work presents a novel, convenient and effective method for assaying organophosphorus pesticides (OPPs) in the pulp and peel of citrus fruits. In this method, shaped UiO-66/alginate (UiO-66/Alg) beads were employed to replace the powder sorbents used in traditional dispersive solid phase extraction (d-SPE) methods. The UiO-66/Alg beads can be easily separated by only using a tweezer within 1 min, which effectively simplifies the sample pretreatment and overcomes the shortages brought by the incomplete separation of powder sorbents. Moreover, the matrix compounds can be effectively excluded by UiO-66/Alg beads, and the UiO-66/Alg beads can be reused at least 8 times. The d-SPE conditions were optimized by a single factor test. The method shows satisfactory sensitivity, accuracy and precision. Furthermore, ATR-FTIR and UV-Vis-DRS were employed to investigate the adsorption mechanism. Finally, the developed method was applied to monitor the OPPs in ten different citrus fruits.

Untargeted metabolomics analysis of Gannan navel orange at different storage periods under room temperature using HS-SPME-GC-MS and UPLC-Q-TOF/MS.

Navel orange remains metabolized continuously during postharvest storage, but few studies have monitored the changes of these metabolites. Therefore, HS-SPME-GC-MS and UPLC-Q-TOF/MS were used to comprehensively investigate the dynamic changes of the components of Gannan navel orange during storage at room temperature. A total of 62 volatile components and 68 non-volatile components were identified. Principal Component Analysis and Partial Least Squares Discriminant Analysis showed that navel orange under different storage periods were clearly distinguished. Combined with VIP > 1 and p < 0.05, 19 volatile and 27 non-volatile differential metabolites were obtained. KEGG enrichment analysis revealed that flavonoid biosynthesis (map00941) was the primary metabolic pathway. The middle storage period had a higher antioxidant enzyme activity, but the malondialdehyde content was the opposite. These results reveal the changes of postharvest components of Gannan navel orange, providing a theoretical basis for the storage and product development of navel orange.

A dispersive solid-phase extraction method for the determination of Aristolochic acids in Houttuynia cordata based on MIL-101(Fe): An analytes-oriented adsorbent selection design.

In view of the molecular structure of Aristolochic acid I (AA-I) and Aristolochic acid II (AA-II), MIL-101(Fe) was selected as the sorbent to develop a dispersive solid-phase extraction (d-SPE) method for capturing the two analytes from Houttuynia cordata. The interactions between the sorbent and analytes were investigated by FT-IR, XPS and UV-Vis DRS spectra. The optimized method demonstrated good linearity with R2 > 0.9999. The limit of detections (LODs) were 0.007 mg/L and 0.014 mg/L for AA-I and AA-II, respectively, lower than the limit stipulated by Chinese Pharmacopoeia (0.001 %, w/w). The recoveries for AA-I and AA-II were within the range of 73.3-106.4 %. The precisions of intra-day and inter-day were 0.9-5.8 % and 2.1-5.8 %, respectively. Thus, the established method demonstrated to be efficient and reliable to determine AA-I and AA-II in Houttuynia cordata.

A simplified dispersive solid-phase extraction using a shaped zirconium-based metal-organic framework: Constructing a novel, facile and efficient method for detecting plant growth regulators in citrus fruits.

A facile, efficient and reliable method was designed and established to analyze the plant growth regulators (PGRs) in citrus fruit, based on a simplified dispersive solid-phase extraction (d-SPE) using a shaped zirconium-based metal-organic framework (UiO-66-PDMS bead) as the sorbent. In this method, UiO-66-PDMS beads directly extracted the targets from the homogenized and could be easily separated with a tweezer. It avoided the centrifugation or filtration operation required in normal d-SPE, greatly simplifying the d-SPE process. Moreover, the matrix substances were efficiently removed by this d-SPE process. The method showed good linearities (R2 ≥ 0.9995) and limits of detection (0.09-0.17 ng/g). The recoveries were in the range of 80.7-97.5 %. The intra-day and inter-day precisions were 1.5-6.3 % and 4.6-11.7 %, respectively. Additionally, the adsorption interactions between UiO-66-PDMS bead and PGRs were studied by ATR-FTIR and UV-vis DRS. Furthermore, the method was employed to screen the PGRs in ten different citrus fruits.

Unique roles in health promotion of dietary flavonoids through gut microbiota regulation: Current understanding and future perspectives.

Advances in understanding the biological effects of dietary flavonoids and flavonoid-rich foods have been reported. Improving knowledge about their beneficial effects, and mechanisms of action, is crucial for better utilization. However, mechanisms responsible for their health benefits are still unclear. Previous research considered has suggested that gut microbiota might be linked to the metabolism of dietary flavonoids. To understand the bioactivities of dietary flavonoids/flavonoid-rich foods better, and the role of microbiota, we explored systematically 1) types of dietary flavonoids and associated health benefits, 2) low bioaccessibilities and metabolic characteristics, 3) gut microbiota role in regulation, and 4) crosstalk between regulation mechanisms. Current challenges and future perspectives were also considered, offering new research directions and identifying trends in the development of flavonoid-rich food products.

Thermosensitive and magnetic molecularly imprinted polymers for selective recognition and extraction of aristolochic acid I.

Recently, the natural compound of aristolochic acid I (AAI) has attracted wide attentions due to its strong nephrotoxicity and carcinogenicity. However, the extraction of AAI based on conventional molecularly imprinted polymers (MIPs) are tedious with extensive eluent, causing secondary pollution and poor regeneration. Herein, thermosensitive and magnetic MIPs (TMMIPs) were synthesized by a surface imprinting method, which achieved thermosensitive capture/release of AAI, along with rapid magnetic separation, significantly shortening the elution time and reducing organic-solvent consumption. TMMIPs with dual-stimuli responses exhibited superior affinity, selectivity, kinetics, and regeneration ability towards AAI. TMMIPs were applied to analyze AAI in Houttuynia cordata via dispersive solid-phase extraction (d-SPE) coupled with high performance liquid chromatography (HPLC), yielding satisfactory recoveries (79.03-99.67%) and relative standard deviations (≤5.78%). The limit of detection of AAI was as low as 26.67 µg/L. TMMIPs demonstrate great applicability for fast, selective and eco-friendly extraction of AAI in complicated matrices.

Nontargeted metabolomics coupled with multivariate modelling techniques for discrimination of Cyclocarya paliurus (Batal.) Ijinskaja leaves from different geographic altitudes.

Altitude-associated nutrition-compositional evaluation is critical for quality control and value determination of plants. Herein, an exploratory study was applied to investigate the differences in the metabolites of Cyclocarya paliurus (CP) leaves from different altitudes (200-1000 m) using a UPLC-QTOF-MS-based metabolomics method, employed to create models for discrimination of CP leaves. On the one hand, 70 metabolites exhibiting significant distinctions within various components in different altitude environments were detected and identified, of which majority showed a close connection. High altitude environments with a decrease in temperature accompanied by enhanced UV-B radiation significantly influenced the profile of flavonoids and organic acids. On the other hand, the PLS-DA model (R2 = 0.994 and Q2 = 0.990) with the VIP variable selection method and P-value were selected to characterize fifteen potential differential metabolites. Moreover, the DD-SIMCA model involving the above-mentioned differential compounds showed both good specificity and accuracy of 100%. These results provide guidance for the discrimination of CP leaves from different geographic altitudes, which may be extended to improve the growing conditions of CP leaves.

A simple, environmental-friendly and reliable d-SPE method using amino-containing metal-organic framework MIL-125-NH2 to determine pesticide residues in pomelo samples from different localities.

A simple, environmentally-friendly and reliable method was developed to simultaneously monitor the residue of methyl 1-naphthalene acetate, parathion-methyl, fenitrothion, bromophos and phenthoate in pomelo by using dispersive solid-phase extraction technique (d-SPE). In this method, these target analytes were captured by MIL-125-NH2 and detected by GC-MS/MS. The key parameters of d-SPE were optimized by the single factor experiment. Under the optimized conditions, a good determination coefficient (R2 > 0.9922) and extraction recoveries (64.7-116.8%) are obtained. The limit of detections (0.03-1.07 ng/g) is lower than the MRLs in citrus fruits established by EU (10-15000 ng/g) and China (10-10000 ng/g). The precisions of intra-day and inter-day are 1.3-8.9% and 3.8-14.9%, respectively. In addition, the sorbent MIL-125-NH2 is stable and can be reused at least eight times. These results prove the established method is efficient and reliable to detect the pesticide residues in pomelo.

Study on the preparation of molecular imprinted polymer for analysis of N-phenylglycine in human urine.

N-phenylglycine (NPG) in human urine could be an important biomarker for predicting cancers, but its detection has difficulty due to its low abundance in urine. Herein, we report a molecular imprinted polymer (MIP) method to efficiently recognize NPG in urine. The MIP was prepared by precipitation polymerization, adopting NPG as the template, acrylamide (AM) as functional monomer, trimethylpropane triacrylate (TRIM) as crosslinking agent, and acetonitrile as porogen. The specificity and selectivity of MIP towards NPG in human urine were determined by comparing MIP's adsorption to the NPG and N-crotonylglycine (NTG) under the same conditions. The result ß = QMIP-NPG/QMIP-NTG = 4.7 indicated the satisfactory specificity and selectivity. Parameters affecting the extraction efficiency were further optimized. Under the optimum conditions, the linear range, limit of detection, and limit of quantification of NPG were 0.5-100 mg∙L-1, 1.6 × 10-2 mg∙L-1, and 5.5 × 10-2 mg∙L-1, respectively. Recoveries of NPG in human urine were in the range of 84.7-100.0% with RSDS of 3.8-10.8%. The developed method demonstrated superior selectivity to the target analyte, which can be applied to separate and enrich the NPG from urine samples.

Variations in phenolic acids and antioxidant activity of navel orange at different growth stages.

Ripe navel orange has abundant amounts of phenolic compounds. Few studies monitored changes in these compounds during ripening. In this study, the effects of navel orange maturation on dynamic changes in antioxidant activity, total phenolic content (TPC), total flavonoid content (TFC) and phenolic acids were investigated. Five growth stages of navel orange were studied, and nine phenolic acids were detected via high performance liquid chromatography-triple quadrupole mass spectrometry (HPLC-QQQ-MS). Results showed that antioxidant activity, TFC and TPC decreased gradually with fruit ripening. The concentrations of most phenolic acids also declined during fruit maturation, except for free fractions of sinapic acid and bound fractions of ferulic and caffeic acids. Ferulic acid was the most dominant of all phenolic acids at all growth stages. Partial least-squares showed significant differences among fruits of different maturities. A significant correlation between antioxidant capacity, TPC, TFC and some phenolic acids was found.

Nontargeted metabolomics reveals the discrimination of Cyclocarya paliurus leaves brewed by different methods.

An original way of brewing Cyclocarya paliurus leaves, especially in China, is to steep leaves in hot water before people drink it directly. Recently, infusing tea leaves with cold water, a creative way in Taiwan, has become a popular way of making tea. This study was designed to investigate the differences in metabolites among three brewing methods (cold-brewing, steep-brewing, and boil-brewing) based on UPLC-QTOF-MS metabolomics experiments and the feasibility of cold-brewing methods for C. paliurus leaves. Unsupervised analysis (PCA) explained 54.6% (positive ion mode) and 57.4% (negative ion mode) of the total variance, whereas supervised analysis (OPLS-DA) with cross-validated R2Y and Q2 values > 0.5, could reveal potential metabolites with better discrimination among the three brewing methods. Fifteen potential differential metabolites were chosen and identified, and nine of them were further confirmed with reference standards. This study suggested that the cold-brewing method without an increase in temperature protected the phenol aromatic ring, thereby obtaining more phenolic acid compounds from C. paliurus leaves. These results provided a basis for making cold tea and promoting the development of cold tea with C. paliurus leaves as raw materials.

Dispersive solid-phase extraction using microporous metal-organic framework UiO-66: Improving the matrix compounds removal for assaying pesticide residues in organic and conventional vegetables.

An efficient dispersive solid-phase extraction method was developed to trace pesticide residues in commonly consumed vegetables. In this method, UiO-66 with uniform micropores was used as sorbent, and gas chromatography-mass spectrometry was applied to detect the pesticides. Thanks to the size sieving action of uniform micropores, UiO-66 directly extracted the target pesticides from vegetable matrices and excluded the relatively large matrix compounds. This well eliminated the matrix effect. The important experimental conditions were evaluated by orthogonal array experimental design. In optimized conditions, good linearity (R2 ≥ 0.99), detection limits (0.4-2.0 ng/g), recoveries (60.9-117.5%) and precision (relativestandarddeviations < 14.6%) were achieved. Moreover, the sorbent UiO-66 can be reused more than 20 times. These demonstrate a simple, reliable and robust method to screen the pesticide residues in vegetables. Furthermore, the validated method was applied to detect the pesticides in various organic and conventional vegetables.

Simultaneous determination of organophosphorus pesticides in Chinese herbal medicines by microwave-assisted extraction coupled with dispersive-solid phase extraction and gas chromatography.

A reliable, rapid and nontoxic analytical method was proposed for the simultaneous determination of 16 organophosphorus pesticides in Chinese herbal medicines. The pesticides were extracted by ethanol and the experimental variables, such as temperature, extraction time and volume of ethanol, were optimized through orthogonal array experimental design. Cleanup of extracts was performed with dispersive-solid phase extraction using primary secondary amine as the sorbent. The determination of pesticides in the final extracts was carried out by gas chromatography-flame photometric detection. Under optimized conditions the obtained recoveries, except for isocarbophos, were in the range 73.8-123%, with relative standard deviations equal to or lower than 15.2% and limits of detection ranging from 0.001 to 0.009 mg/kg.

A magnetic hydrophilic molecularly imprinted material with multiple stimuli-response properties for efficient recognition of bisphenol A in beverages.

A magnetic hydrophilic molecularly imprinted material (MIM) with multiple stimuli-responses was prepared for efficient recognition of bisphenol A (BPA). MIM consisted of a magnetic core, an inner silica dioxide shell and an outer hydrophilic polymer shell, responsive for rapid magnetic separation, protection of the magnetic core and pH-/thermo-sensitivity to BPA, respectively. Controlled adsorption and release of BPA by pH/temperature regulation were realized through the reversible components of poly[N-isopropylacrylamide-co-2-(dimethylamino)ethyl methacrylate (NIPAM-DMAEMA)] (PND). The resultant MIM possessed superior affinity, selectivity and kinetics to BPA in aqueous solution. MIM was successfully applied to detect BPA in beverages via dispersive solid-phase extraction (d-SPE) coupled with high performance liquid chromatography (HPLC), exhibiting satisfactory recoveries of 80.70-108.18% with relative standard deviations (RSD) below 6.08%. The limit of detection of BPA was obtained as low as 3.75 nmol/L. The versatile MIM could be a promising alternative for extraction/removal of BPA in complicated samples by multiple-stimuli regulations.