A combined approach for characterisation of fresh and brined vine leaves by X-ray powder diffraction, NMR spectroscopy and direct infusion high resolution mass spectrometry

Non-Targeted Spectranomics for the Early Detection of Xylella fastidiosa Infection in Asymptomatic Olive Trees, cv. Cellina di Nardò

Olive quick decline syndrome (OQDS) is a disease that has been seriously affecting olive trees in southern Italy since around 2009. During the disease, caused by Xylella fastidiosa subsp. pauca sequence type ST53 (Xf), the flow of water and nutrients within the trees is significantly compromised. Initially, infected trees may not show any symptoms, making early detection challenging. In this study, young artificially infected plants of the susceptible cultivar Cellina di Nardò were grown in a controlled environment and co-inoculated with additional xylem-inhabiting fungi. Asymptomatic leaves of olive plants at an early stage of infection were collected and analyzed using nuclear magnetic resonance (NMR), hyperspectral reflectance (HSR), and chemometrics. The application of a spectranomic approach contributed to shedding light on the relationship between the presence of specific hydrosoluble metabolites and the optical properties of both asymptomatic Xf-infected and non-infected olive leaves. Significant correlations between wavebands located in the range of 530-560 nm and 1380-1470 nm, and the following metabolites were found to be indicative of Xf infection: malic acid, fructose, sucrose, oleuropein derivatives, and formic acid. This information is the key to the development of HSR-based sensors capable of early detection of Xf infections in olive trees.

Dissipation kinetics of some pesticides applied singly or in mixtures in/on grape leaf

BACKGROUND

Grape and leaf quality are often severely reduced by fungi such as grey rot Botrytis cinerea Pers., powdery mildew Erysiphe necator Schwein, and downy mildew Plasmopara viticola (Berk. & M.A.Curtis) Berl. & De Toni and by insects such as Otiorhynchus spp., European grapevine moth Lobesia botrana Den.-Schiff., vine mealybug Planococcus citri Risso, and grape erineum mite Colomerus vitis Pgst. Various pesticides are often applied to mitigate these pest problems. These chemicals used singly as well as in the form of a mixture can leave residues on or in the crop. It is therefore of great importance to study the dissipation of the pesticides applied alone and in mixtures to this crop to protect consumers.

RESULTS

The dissipation kinetics of cypermethrin, boscalid, deltamethrin, kresoxim-methyl, lambda-cyhalothrin, metalaxyl-M, metrafenone, and triadimenol residues were studied in vine leaves grown under sunny conditions in Turkey. The dissipation rate for singly applied pesticides followed first-order kinetics, with half-lifes in grape leaves in the range of 1.85-7.22 days. Changes in the degradation process of pesticide residues were determined after application, as both single applications and mixtures. The degradation of boscalid, cymoxanil, deltamethrin and metalaxyl-M accelerated while the degradation of cypermethrin, kresoxim-methyl, and lambda-cyhalothrin slowed down in mixtures of pesticides.

CONCLUSION

The use of pesticides in mixtures leads to slower degradation and higher residues for some active ingredients and faster degradation and fewer residues for other active ingredients. Therefore, pesticide mixtures should not be applied in the field without having detailed information about their ingredients. © 2022 Society of Chemical Industry.

More than Just Wine: The Nutritional Benefits of Grapevine Leaves

The domesticated species Vitis vinifera L. harbours many cultivars throughout the world that present distinctive phenology and grape quality. Not only have the grapes been used for human consumption, but the leaves are also used as a source of bioactive compounds and are present in the diets of several Mediterranean countries. We have selected seven different cultivars and performed elemental, fatty acid (FA) and pigment profiling. Total reflection X-ray fluorescence (TXRF) enabled the identification of 21 elements. Among them, Na, Ca and K were highly represented in all the cultivars and Zn was prevalent in V. vinifera cv. ‘Pinot noir’ and ‘Cabernet sauvignon’. Through gas chromatography, six FAs were identified, including omega-3 and omega-6 FA, the most abundant mainly in V. vinifera cv. ‘Tinta barroca’, ‘Pinot noir’ and ‘Cabernet sauvignon’. FA composition was used to determine nutritional quality parameters, namely atherogenic, thrombogenic, hypocholesterolemic/hypercholesterolemic and peroxidisability indexes as well as oxidability and oxidative susceptibility. Grapevine leaves were highlighted as a suitable source of health-promoting lipids. Given the popularity of “green” diets, we have also performed a leaf pigment analysis. Seventeen pigments including chlorophylls, trans-lutein, b-carotene and zeaxanthins were detected. ‘C19’ presented the highest content of most of the detected pigments.

Validation of a Rapid Multiresidue Method for the Determination of Pesticide Residues in Vine Leaves. Comparison of the Results According to the Different Conservation Methods

The QuEChERS method was applied to the determination of pesticide residues in vine (Vitis vinifera) leaves by LC-MSMS. The method was validated in-house for 33 pesticides representing 17 different chemical groups, that are most commonly used in grape production. Recoveries for the pesticides tested ranged from 75 to 104%, and repeatability and reproducibility relative standard deviations (RSD_r% and RSD_Rw%) were less than 20%. The method was applied to the analysis of pesticide residues in 17 market brands of vine leaves processed according to three different preservation methods and sampled from the Lebanese market. Dried vine leaves were more contaminated with pesticide residues than those preserved in brine or stuffed vine leaves. The systemic fungicides were the most frequently detected among all the phytosanitary compounds usually applied to grape production. Brine-preserved and stuffed vine leaves contained lower concentrations of the residues but still contained a cocktail of different pesticides.

Multivariate Analysis Applications in X-ray Diffraction

Multivariate analysis (MA) is becoming a fundamental tool for processing in an efficient way the large amount of data collected in X-ray diffraction experiments. Multi-wedge data collections can increase the data quality in case of tiny protein crystals; in situ or operando setups allow investigating changes on powder samples occurring during repeated fast measurements; pump and probe experiments at X-ray free-electron laser (XFEL) sources supply structural characterization of fast photo-excitation processes. In all these cases, MA can facilitate the extraction of relevant information hidden in data, disclosing the possibility of automatic data processing even in absence of a priori structural knowledge. MA methods recently used in the field of X-ray diffraction are here reviewed and described, giving hints about theoretical background and possible applications. The use of MA in the framework of the modulated enhanced diffraction technique is described in detail.

Comparative quantification of chlorophyll and polyphenol levels in grapevine leaves sampled from different geographical locations

Near infrared spectroscopy (NIRS) and mid-infrared spectroscopy (MIRS) in combination with chemometric analysis were applied to discriminate the geographical origin of grapevine leaves belonging to the variety “Touriga Nacional” during different vegetative stages. Leaves were collected from plants of two different wine regions in Portugal (Dão and Douro) over the grapes maturation period. A sampling plan was designed in order to obtain the most variability within the vineyards taking into account variables such as: solar exposition, land inclination, altitude and soil properties, essentially. Principal component analysis (PCA) was used to extract relevant information from the spectral data and presented visible cluster trends. Results, both with NIRS and MIRS, demonstrate that it is possible to discriminate between the two geographical origins with an outstanding accuracy. Spectral patterns of grapevine leaves show significant differences during grape maturation period, with a special emphasis between the months of June and September. Additionally, the quantification of total chlorophyll and total polyphenol content from leaves spectra was attempted by both techniques. For this purpose, partial least squares (PLS) regression was employed. PLS models based on NIRS and MIRS, both demonstrate a statistically significant correlation for the total chlorophyll (R²_P = 0.92 and R²_P = 0.76, respectively). However, the PLS model for the total polyphenols, may only be considered as a screening method, because significant prediction errors, independently of resourcing on NIRS, MIRS or both techniques simultaneously, were obtained.

Vitis vinifera ‘Pinot noir’ leaves as a source of bioactive nutraceutical compounds

V. vinifera ‘Pinot noir’ leaves have a high content of biologically active phytochemical compounds of interest for pharmaceutical and food industries.

Performance Assessment in Fingerprinting and Multi Component Quantitative NMR Analyses

An interlaboratory comparison (ILC) was organized with the aim to set up quality control indicators suitable for multicomponent quantitative analysis by nuclear magnetic resonance (NMR) spectroscopy. A total of 36 NMR data sets (corresponding to 1260 NMR spectra) were produced by 30 participants using 34 NMR spectrometers. The calibration line method was chosen for the quantification of a five-component model mixture. Results show that quantitative NMR is a robust quantification tool and that 26 out of 36 data sets resulted in statistically equivalent calibration lines for all considered NMR signals. The performance of each laboratory was assessed by means of a new performance index (named Qp-score) which is related to the difference between the experimental and the consensus values of the slope of the calibration lines. Laboratories endowed with a Qp-score falling within the suitable acceptability range are qualified to produce NMR spectra that can be considered statistically equivalent in terms of relative intensities of the signals. In addition, the specific response of nuclei to the experimental excitation/relaxation conditions was addressed by means of the parameter named NR. NR is related to the difference between the theoretical and the consensus slopes of the calibration lines and is specific for each signal produced by a well-defined set of acquisition parameters.

Volatile components of vine leaves from two Portuguese grape varieties (Vitis vinifera L.), Touriga Nacional and Tinta Roriz, analysed by solid-phase microextraction

The purpose of this work was to study the volatile composition of vine leaves and vine leaf infusion prepared from vine leaves collected at 30 and 60 days after grape harvest of two Vitis vinifera L. species. Eighteen volatile compounds were identified by gas chromatography-mass spectrometry in vine leaves and in vine leaf infusions. It was observed that the volatile compounds present in vine leaves are dependent on the time of harvest, with benzaldehyde being the major volatile present in vine leaves collected at 30 days after harvesting. There are significant differences in the volatile composition of the leaves from the two grape cultivars, especially in the sample collected at 60 days after grape harvest. This is not reflected in the volatile composition of the vine leaf infusion made from this two cultivars, the more important being the harvesting date for the volatile profile of vine leaf infusion than the vine leaves grape cultivar.