Microwave-Assisted Extraction/UHPLC-Q-Orbitrap-MS-Based Lipidomic Workflow for Comprehensive Study of Lipids in Soft Cheese.

In this work, Microwave-Assisted Extraction (MAE) was proposed as an alternative and environmentally friendly technique in lipidomics to study the lipid fingerprint of soft cheeses, such as mozzarella. For method development, a first step concerning an evaluation of extraction solvents was carried out via testing three different mixtures, including methanol/ethyl acetate, isopropanol/ethyl acetate, and ethanol/ethyl acetate, at a 1:2 v/v ratio. The latter was chosen as a solvent mixture for subsequent method optimization. MAE conditions, in terms of solvent volume, time, and temperature, were explored to define their effects on extraction capability through a full factorial experimental design. The best compromise to extract more lipids at the same time was obtained with 24 mL g-1 for solvent-to-solid ratio, 65 °C for temperature, and 18 min for time. Lipid analyses were conducted by UHPLC-Q-Orbitrap-MS associated with multivariate statistics. The developed lipidomic workflow allowed for the extraction of over 400 lipids grouped into 18 different subclasses. The results confirmed that MAE is a suitable technique for lipid extraction in the omics approach with high efficiency, even using low-cost and less toxic solvents. Moreover, a comprehensive structure characterization of extracted lipids, in terms of fatty acid composition and regiochemistry, was carried out.

Psychrobacter raelei sp. nov., isolated from a dog with peritonitis.

A strain belonging to the genus Psychrobacter, named PraFG1T, was isolated from the peritoneal effusion of a stray dog during necropsy procedures. The strain was characterized by the phylogenetic analyses based on the nucleotide sequences of 16S and 23S rRNA genes and of gyrB, which placed the strain in the genus Psychrobacter. The nucleotide sequence of the chromosome confirmed the placement, showing an average nucleotide identity of 72.1, 77.7, and 77.5 % with the closest related species, namely Psychrobacter sanguinis, Psychrobacter piechaudii, and Psychrobacter phenylpyruvicus, respectively, thus indicating a novel species. The polyphasic characterization by biochemical and fatty acid profiling as well as MALDI-TOF supported those findings. The strain was halotolerant, capable of growing within a temperature range between 4 and 37 °C, it was positive for catalase and oxidase, indole producing, nitrate reducing, and not able to use 5-keto-d-gluconic acid as a carbon source. Taken together, the data suggest that strain PraFG1T could be considered as representing a novel species, with the name Psychrobacter raelei sp. nov. (type strain PraFG1T=CIP 111873T=LMG 32233T).

Headspace Solid-Phase Microextraction/Gas Chromatography-Mass Spectrometry and Chemometric Approach for the Study of Volatile Profile in X-ray Irradiated Surface-Ripened Cheeses.

X-ray irradiation is an emerging non-thermal technology that is used as a preservation and sanitization technique to inactivate pathogens and spoilage organisms, increasing the shelf life of products. In this work, two different types of surface-ripened cheeses, Brie and Camembert, produced with cow milk, were treated with X-rays at three dose levels, 2.0, 4.0 and 6.0 kGy, to evaluate the irradiation effects on the volatile profile using a volatolomic approach. The headspace solid-phase microextraction (HS-SPME) technique combined with gas chromatography-mass spectrometry (GC-MS) was used to extract and analyze the volatile fraction from these dairy matrices. The HS-SPME method was optimized by a central composite design in combination with a desirability optimization methodology. The Carboxen/PDMS fiber, 50 °C for extraction temperature and 60 min for time extraction were found to be the best parameter settings and were applied for this investigation. The obtained fingerprints demonstrated that the irradiation-induced changes are dose dependent. The X-ray irradiation produced many new volatiles not found in the non-irradiated samples, but it also varied the amount of some volatiles already present in the control. Specifically, aldehydes and hydrocarbons increased with the irradiation dose, whereas alcohols, carboxylic acids, esters, methyl esters, ketones, lactones and sulfur-containing compounds showed a non-linear dependence on the dose levels; indeed, they increased up to 4.0 kGy, and then decreased slightly at 6.0 kGy. This trend, more evident in the Camembert profile, is probably due to the fact that these compounds are involved in different oxidation mechanisms of lipids and proteins, which were induced by the radiation treatment. In these oxidative chemical changes, the production and degradation processes of the volatiles are competitive, but at higher doses, the decomposition reactions exceed those of formation. A principal component analysis and partial least square discriminant analysis were used to discriminate between the treated and untreated samples. Moreover, this study allowed for the identification of potential markers of X-ray treatment for the two cheeses, confirming this approach as a useful tool for the control of irradiated surface-ripened cheeses.

Untargeted Lipidomics and Chemometric Tools for the Characterization and Discrimination of Irradiated Camembert Cheese Analyzed by UHPLC-Q-Orbitrap-MS.

In this work, an investigation using UHPLC-Q-Orbitrap-MS and multivariate statistics was conducted to obtain the lipid fingerprint of Camembert cheese and to explore its correlated variation with respect to X-ray irradiation treatment. A total of 479 lipids, categorized into 16 different lipid subclasses, were measured. Furthermore, the identification of oxidized lipids was carried out to better understand the possible phenomena of lipid oxidation related to this technological process. The results confirm that the lipidomic approach adopted is effective in implementing the knowledge of the effects of X-ray irradiation on food and evaluating its safety aspects. Furthermore, Partial Least Squares-Discriminant Analysis (PLS-DA) and Linear Discriminant Analysis (LDA) were applied showing high discriminating ability with excellent values of accuracy, specificity and sensitivity. Through the PLS-DA and LDA models, it was possible to select 40 and 24 lipids, respectively, including 3 ceramides (Cer), 1 hexosyl ceramide (HexCer), 1 lysophosphatidylcholine (LPC), 1 lysophosphatidylethanolamine (LPE), 3 phosphatidic acids (PA), 4 phosphatidylcholines (PC), 10 phosphatidylethanolamines (PE), 5 phosphatidylinositols (PI), 2 phosphatidylserines (PS), 3 diacylglycerols (DG) and 9 oxidized triacylglycerols (OxTG) as potential markers of treatment useful in food safety control plans.

Volatolomic approach by HS-SPME/GC-MS and chemometric evaluations for the discrimination of X-ray irradiated mozzarella cheese.

In this work, an untargeted screening of the volatile profile of X-ray irradiated mozzarella cheese was carried out to study the possible radio-induced modifications. A Central Composite Design (CCD) for Response Surface Methodology (RSM) was employed to optimise the HS-SPME analysis of volatile organic compounds (VOCs). The optimised HS-SPME conditions, in terms of sample amount (5.0 g), extraction temperature (50 °C) and extraction time (75 min), were used to analyse non-irradiated and irradiated samples at three dose levels, 1.0, 2.0, 3.0 kGy. Partial Least Squares-Discriminant Analysis (PLS-DA) and Linear Discriminant Analysis (LDA) were applied to explore the variation of volatile profile with respect to the X-ray irradiation treatment. Both methods highlighted a high discriminant capability with excellent values of accuracy, specificity and sensitivity, demonstrating the effectiveness of the volatolomic approach to evaluate the variations induced by the treatment and allowing to select a total of 35 VOCs as potential irradiation markers.

Optimizing accelerated solvent extraction combined with liquid chromatography-Orbitrap mass spectrometry for efficient lipid profile characterization of mozzarella cheese.

In this study, a novel Accelerated Solvent Extraction (ASE) procedure combined with UHPLC-Q-Orbitrap-MS was developed for detailed untargeted lipid profile of mozzarella cheese. Response Surface Methodology and Pareto front, using a Central Composite Design (CCD), were employed to define the optimised combination of extraction temperature, number of extraction cycles and mix of solvents. LipidSearch™ software was used for a reliable and accurate lipid identification. A total of 13 subclasses, including ceramides, diacylglycerols, triacylglycerols, lysophosphatidylcholines, lysophosphatidylethanolamines, phosphatidylcholines, phosphatidylethanolamines, phosphatidylinositols, sphingomyelins, bismethyl phosphatidic acids, cholesterol ester, zymosterol ester, hexosyl ceramides were measured. The elaboration of the CCD showed that the solvents ratio was the main factor affecting the extraction efficiency. The optimised ASE method, together with the Folch extraction, synergistically contributed to a complete characterization of lipid profile of mozzarella cheese, confirming ASE technique, associated with high resolution mass spectrometry detection, as an efficient tool for Lipidomics in food science.

Lipidomics profile of irradiated ground meat to support food safety.

Meat irradiation is considered as an effective treatment that expose the advantageous effects on meat preservation. This research, based on untargeted LC-HR orbitrap MS-based lipidomics strategy was meant to estimate the alterations in lipid profile of irradiated chicken, turkey and mixed (chicken, turkey and pork) ground meat in order to evaluate if exists any food safety issue concerning the lipidome alteration. Special attention was paid on oxidation triggered by irradiation. All three matrices exhibited a characteristic lipidome profile which was affected differently by five levels of irradiation intensity. Overall, 345 lipids categorized into 14 subclasses were identified. Remarkably, the oxidized glycerophosphoethanolamines and oxidized glycerophosphoserines were identified in irradiated turkey meat, while for all three categories a characteristic diacylglycerols profile was recognised. Our analytical approach highlighted that the estimation of qualitative variations in lipid portion might be valuable in food inspection purposes, especially when the samples from animal origin are suspected on irradiation treatment.

Assessment of fumonisins B1 and B2 levels in commercial maize-based food products by liquid chromatography with fluorimetric detection and postcolumn chemical derivatization.

The occurrence of the fumonisins B(1) and B(2) in maize-based food products marketed in Italy was examined. A simply and reliable chromatographic method with fluorimetric detection and postcolumn o-phtalaldehyde derivatization was used for a monitoring of 100 samples (8 flours, 21 corn-meal, 16 snacks, 7 maize samples, 13 gluten-free products, and 35 corn-flakes) bought in local supermarkets during the years 2008 and 2009. The presence of both fumonisins B(1) and B(2), at a concentration higher than 15 µg/kg, was observed in all samples of corn-meal and maize-flour, in 75% of snacks, in 57% of maize samples, in 54% of gluten-free products, and in 29% of corn-flakes. A total of 7 samples including 4 corn-meals, 2 maize-flours, and 1 maize showed a value exceeding the maximum level fixed in the Regulation 1126/2007/EC; no positive sample was observed in corn-flakes, snacks, and gluten-free foods. Fumonisins contamination, on the whole range of maize-based food products analyzed, emphasizes the need of improve agricultural practices, and increase official control and monitoring studies.

Palladium-catalyzed borylation of phenyl bromides and application in one-pot Suzuki-Miyaura biphenyl synthesis.

The coupling reaction of pinacolborane with various aryl bromides in the presence of a catalytic amount of Pd(OAc)(2) together with DPEphos as ligand and Et(3)N as base provided arylboronates. High yields were obtained in the case of electron-donor substituted aryl bromides. The direct preparation of arylboronates allowed the one-pot, two-step synthesis of unsymmetrical biaryls in high yields. [reaction: see text]