Search Results (5)

To further develop Liupao tea products and enhance their flavor, this study investigated the effects of different fermentation methods on the aroma quality of Liupao tea. The aroma quality of Liupao tea was comprehensively analyzed using HS-SPME in combination with GC-Q-TOF-MS, electronic nose, and sensory evaluations. Electronic nose detection showed that the aroma fingerprints of Liupao tea samples with different fermentation methods were different. Sulfides, alcohols, ketones, and methyls were the main aroma categories affecting the aroma of the four groups of Liupao tea samples. GC-Q-TOF-MS analysis revealed significant differences in the composition of aroma components among the four fermentation methods of Liupao tea (p < 0.05). Furthermore, the total amount of aroma compounds was found to be highest in the group subjected to hot fermentation combined with the inoculation of Monascus purpureus (DMl group). Based on the OPLS-DA model, candidate differential aroma components with VIP > 1 were identified, and characteristic aroma compounds were selected based on OAV > 10. The key characteristic aroma compounds shared by the four groups of samples were 1,2,3-Trimethoxybenzene with a stale aroma and nonanal with floral and fruity aromas. The best sensory evaluation results were obtained for the DMl group, and its key characteristic aroma compounds mainly included 1,2,3-Trimethoxybenzene, nonanal, and cedrol. The results of this study can guide the development of Liupao tea products and process optimization. Full article

Sample preparation remains both a challenging and time-consuming process in the field of bioanalytical chemistry. Many traditional techniques often require multi-step processes, which can introduce additional errors to the analytical method. Given the complexity of many biological matrices, thorough analyte extraction presents a major challenge to researchers. In the present study, a headspace solid-phase microextraction (HS-SPME) coupled with a GC/Q-ToF-MS method, was developed to quantify in vitro metabolism of β-caryophyllene by both human liver microsome (HLM) and S9 liver fractions. Validation of the method was demonstrated both in terms of linearity (R² = 0.9948) and sensitivity with a limit of detection of 3 ng/mL and a limit of quantitation of 10 ng/mL. In addition, the method also demonstrated both inter- and intra-day precision with the relative standard deviation (RSD) being less than 10% with four concentrations ranging from 50–500 ng/mL. Since this method requires no solvents and minimal sample preparation, it provides a rapid and economical alternative to traditional extraction techniques. The method also eliminates the need to remove salts or buffers, which are commonly present in biological matrices. Although this method was developed to quantify in vitro metabolism of one analyte, it could easily be adapted to detect or quantify numerous volatiles and/or semi-volatiles found in biological matrices. Full article

Untargeted metabolomics approaches are emerging as powerful tools for the quality evaluation and authenticity of food and beverages and have been applied to wine science. However, most fail to report the method validation, quality assurance and/or quality control applied, as well as the assessment through the metabolomics-methodology pipeline. Knowledge of Mexican viticulture, enology and wine science remains scarce, thus untargeted metabolomics approaches arise as a suitable tool. The aim of this study is to validate an untargeted HS-SPME-GC-qTOF/MS method, with attention to data processing to characterize Cabernet Sauvignon wines from two vineyards and two vintages. Validation parameters for targeted methods are applied in conjunction with the development of a recursive analysis of data. The combination of some parameters for targeted studies (repeatability and reproducibility < 20% RSD; linearity > 0.99; retention-time reproducibility < 0.5% RSD; match-identification factor < 2.0% RSD) with recursive analysis of data (101 entities detected) warrants that both chromatographic and spectrometry-processing data were under control and provided high-quality results, which in turn differentiate wine samples according to site and vintage. It also shows potential biomarkers that can be identified. This is a step forward in the pursuit of Mexican wine characterization that could be used as an authentication tool. Full article

The bacterial pathogen ‘Candidatus Liberibacter solanacearum’ (Lso) is transmitted by the tomato potato psyllid (TPP), Bactericera cockerelli, to solanaceous crops. In the present study, the changes in metabolic profiles of insect-susceptible (cv CastleMart) and resistant (RIL LA3952) tomato plants in response to TPP vectoring Lso or not, were examined after 48 h post infestation. Non-volatile and volatile metabolites were identified and quantified using headspace solid-phase microextraction equipped with a gas chromatograph-mass spectrometry (HS-SPME/GC-MS) and ultra-high pressure liquid chromatography coupled to electrospray quadrupole time-of-flight mass spectrometry (UPLC/ESI-HR-QTOFMS), respectively. Partial least squares-discriminant analysis (PLS-DA) was used to define the major uncorrelated metabolite components assuming the treatments as the correlated predictors. Metabolic changes in various classes of metabolites, including volatiles, hormones, and phenolics, were observed in resistant and susceptible plants in response to the insects carrying the pathogen or not. The results suggest the involvement of differentially regulated and, in some cases, implicates antagonistic metabolites in plant defensive signaling. Upon validation, the identified metabolites could be used as markers to screen and select breeding lines with enhanced resistance to reduce economic losses due to the TPP-Lso vector-pathogen complex in Solanaceous crops. Full article

The artificial production of Ophiocordyceps sinensis mycelia and fruiting bodies and the Chinese cordyceps has been established. However, the volatile components from these O. sinensis products are not fully identified. An efficient, convenient, and widely used approach based on headspace solid-phase microextraction (HS-SPME) combined with comprehensive two-dimensional gas chromatography and quadrupole time-of-flight mass spectrometry (GC×GC-QTOFMS) was developed for the extraction and the analysis of volatile compounds from three categories of 16 products, including O. sinensis fungus, Thitarodes hosts of O. sinensis, and the Chinese cordyceps. A total of 120 volatile components including 36 alkanes, 25 terpenes, 17 aromatic hydrocarbons, 10 ketones, 5 olefines, 5 alcohols, 3 phenols, and 19 other compounds were identified. The contents of these components varied greatly among the products but alkanes, especially 2,5,6-trimethyldecane, 2,3-dimethylundecane and 2,2,4,4-tetramethyloctane, are the dominant compounds in general. Three categories of volatile compounds were confirmed by partial least squares-discriminant analysis (PLS-DA). This study provided an ideal method for characterizing and distinguishing different O. sinensis and insect hosts-based products. Full article