Aroma plays an important role in fruit quality and varies among different fruit cultivars. In this study, a sensitive and accurate method based on headspace solid-phase microextraction (HS-SPME) coupled with comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (GC×GC-TOFMS) was developed to comprehensively compare aroma components of five pear cultivars. In total, 241 volatile compounds were identified and the predominant volatile compounds were esters (101 compounds), followed by alcohols (20 compounds) and aldehydes (28 compounds). The longyuanyangli has the highest relative concentration (838.12 ng/g), while the Packham has the lowest (208.45 ng/g). This study provides a practical method for pear aroma analysis using SPME and GC×GC-TOFMS.

To comprehensively understand the volatile compounds and assess the aroma profiles of different types of Pyrus ussuriensis Maxim. Anli, Dongmili, Huagai, Jianbali, Jingbaili, Jinxiangshui, and Nanguoli were detected via headspace solid phase microextraction (HS-SPME) coupled with two-dimensional gas chromatography/time-of-flight mass spectrometry (GC×GC-TOFMS). The aroma composition, total aroma content, proportion and number of different aroma types, and the relative quantities of each compound were analyzed and evaluated. The results showed that 174 volatile aroma compounds were detected in various cultivars, mainly including esters, alcohols, aldehydes, and alkenes: Jinxiangshui had the highest total aroma content at 2825.59 ng/g; and Nanguoli had the highest number of aroma species detected at 108. The aroma composition and content varied among pear varieties, and the pears could be divided into three groups based on principal component analysis. Twenty-four kinds of aroma scents were detected; among them, fruit and aliphatic were the main fragrance types. The proportions of aroma types also varied among different varieties, visually and quantitatively displaying changes of the whole aroma of the different varieties of pears brought by the changes in aroma composition. This study contributes to further research on volatile compound analysis, and provides useful data for the improvement of fruit sensory quality and breeding work.

To achieve rapid screening and semi-quantitative analysis of pesticide residues in mobile laboratories and on-site tea testing, a novel method based on thermal-assisted plasma ionization–time-of-flight mass spectrometry (TAPI-TOF/MS) has been developed for the detection of 20 pesticide residues, including insecticides and fungicides, in tea. This method eliminates the need for liquid chromatography, or column connections. Instead, it utilizes the high temperature of the sample inlet and stage to fully volatilize and inject the sample. By integrating TAPI-TOF/MS with an automated pesticide residue pretreatment instrument, the entire sample extraction process can be performed automatically. The analysis time for each sample has been reduced to 1.5 min, allowing for the processing of 60 samples per batch. An accurate mass spectrometry database has been established for screening and confirmation purposes. The software automatically matches the mass spectrometry database by analyzing the measured ion mass deviation, ion abundance ratio, and the relative contribution weight of each ion, generating a qualitative score ranging from 0 to 100. The lowest concentration yielding a qualitative score of ≥75 was defined as the screening limit, which ranged from 0.10 to 5.00 mg/kg for the 20 pesticides. Within their respective linear ranges, the method demonstrated good linearity with correlation coefficients (R²) ranging from 0.983 to 0.999. The average recovery rates (n = 5) of the target pesticides ranged from 70.6% to 117.0% at the set standard concentrations, with relative standard deviations (RSD) ranging from 1.7% to 13.1%. Using this method, 15 tea samples purchased from the Rizhao market in China were analyzed. Ten samples were found to contain residues of metalaxyl or pyraclostrobin, yielding a detection rate of 66.7%. This technology provides technical support for the rapid detection and quality control of multiple pesticide residues in tea, meeting the requirements for high-throughput and on-site analysis.

Through field trials, this study comprehensively investigated the dissipation, metabolism, processing factors (PFs), and risk assessment of dinotefuran, imidacloprid, pyraclostrobin, thiamethoxam, and their metabolites in shiitake mushrooms from cultivation to postharvest processing. In the laboratory, common postharvest industrial and household processing methods were simulated, including washing, boiling, pickling, stir-frying, sauce processing, hot-air processing, and crisp processing. Understanding the fate of residues is crucial for ensuring food safety and safeguarding human health. The limit of quantification (LOQ) for 6-chloronicotinic acid, thiamethoxam and clothianidin was 10 μg/kg, while the LOQs for other analytes were 2 μg/kg. Field trials showed that the degradation of the four pesticides followed first-order kinetics, with half-lives ranging from 1.1 to 1.8 days. After washing, boiling, pickling, stir-frying, and sauce processing, the concentrations of all pesticides—except for a metabolite of pyraclostrobin (BF-500-3)—were reduced to varying degrees (PF < 1). Hot air processing led to 4.3- and 4.6-fold increases in the concentrations of dinotefuran and 6-chloronicotinic acid, respectively, while the concentrations of all other pesticides decreased (PF < 1). Crisp processing increased the concentration of all pesticide residues by a factor of 2.0 to 4.0. Additionally, the content of BF-500-3 increased significantly by 2.9–4.9 times after washing, boiling, pickling, and stir-frying. However, it decreased after hot air processing and sauce processing. The risk quotient values of all pesticides were below 1, indicating that both chronic and acute dietary risks were acceptable. This study provides valuable data for the control of pesticide residues in processed products, which has both theoretical and practical significance in ensuring the quality and safety of shiitake mushrooms and protecting human health.