Monitoring the dynamic changes in aroma during the whole processing of Qingzhuan tea at an industrial scale: From fresh leaves to finished tea.

Aroma is one of the most outstanding quality characteristics of Qingzhuan tea (QZT), but its formation is still unclear. Thus, the volatile organic compounds (VOCs) during the whole processing of QZT were investigated by headspace solid-phase microextraction/gas chromatography-mass spectrometry. Based on 144 identified VOCs, the results showed that de-enzyming, sun-drying, and piling fermentation were the key processes of QZT aroma formation. Furtherly, 42 differential VOCs (VIP > 1.0 and p < 0.05) and 16 key VOCs (rOAV > 1.0 and/or ROAV > 1.0) were screened. Especially, sulcatone and ß-ionone (rOAV > 100 and ROAV > 10) were considered the most important contributors to the aroma of QZT. The metabolisms of key VOCs were mainly involved in oxidative degradation of fatty acids, degradation of carotenoids, and methylation of gallic acid. This study could help to more comprehensively understand the aroma formation in QZT processing at an industrial scale.

The Impact of Psychological Contract, Physical and Mental Health on Burnout in Grassroots Civil Servants: Evidence from China.

Introduction: The report of the 20th Party Congress proposes to build a high-quality cadre capable of taking on the important task of national rejuvenation. Grassroots civil servants are facing great pressure and challenges, and alleviating burnout has become an important issue in the construction of grassroots civil servants. Empirically analysing the impact of psychological contract on burnout of grassroots civil servants in the Chinese context will help to build a high-quality grassroots civil service team. Methods: Using a sample of 1824 grassroots civil servants in China, this study empirically examined the effect of the psychological contract on burnout among grassroots civil servants using the OLS methodology, conducted a robustness test by way of substituting variables and research methods, and then discussed the mediating effect of physical and mental health in the psychological contract and burnout among grassroots civil servants. Results: The study showed that grassroots civil servants' psychological contract had a significant negative impact on burnout; transactional psychological contract was positively related to burnout, and relational and developmental psychological contracts were negatively related to burnout in grassroots civil servants. The results of the heterogeneity analysis showed that the effect of psychological contract on burnout differed by age, gender, exercise frequency, and sleep status. The results of the mediation analysis showed that higher psychological contract scores were related to better physical and mental health, thus inhibiting burnout among grassroots civil servants. This indicates a significant mediation effect of physical and mental health in the relationship between psychological contract and burnout of grassroots civil servants. Conclusion: The psychological contract of grassroots civil servants has a significant negative effect on burnout, and physical and mental health mediate between the two. These conclusions are of great theoretical and practical significance for alleviating the stress of grassroots civil servants and improving their work performance.

The Impact of Internet Use on the Happiness of Chinese Civil Servants: A Mediation Analysis Based on Self-Rated Health.

With the rapid socioeconomic development of China, studies related to Internet use and civil servants' happiness have become a research hotspot in Chinese academia. This study empirically analysed the impact of Internet use on the happiness of Chinese civil servants using a sample of 3793 civil servants in Hunan Province, China. It showed that Internet use significantly enhanced the subjective well-being of Chinese civil servants. Furthermore, heterogeneity analysis revealed significant heterogeneity in the effect of the Internet on civil servants' happiness, which varied across civil service groups with different education and gender. Moreover, the effect of Internet use on the happiness of the male and better educated civil servant groups was more pronounced than in the female and less educated civil servant groups. Additionally, mediation analysis revealed that Internet use and the happiness of civil servants were not linear, with health having a significant mediating effect. This indicates that Internet use helps civil servants maintain good health, and thereby enhances the happiness of civil servants. In addition, we also use a propensity score matching model (PSM) to address the endogeneity problem due to sample selectivity bias. The results show that the estimates are more robust after eliminating sample selectivity bias. The effect of Internet use on civil servants' subjective well-being would be underestimated if the sample selectivity bias is not removed.

Microbial community succession in the fermentation of Qingzhuan tea at various temperatures and their correlations with the quality formation.

With the aim to reveal the microbial community succession at various temperatures in the fermentation of Qingzhuan tea (QZT), the Illumina NovaSeq sequencing was carried out to analyze bacterial and fungal community structure in tea samples collected from the fermentation set at various temperatures, i.e., 25 °C, 30 °C, 37 °C, 45 °C, 55 °C, and room temperature. The results showed that fermentation temperature profoundly affected the microbial community succession in the QZT fermentation. Microbial richness and community diversity decreased along with the increase of fermentation temperature. Despite the differences between microorganisms and their metabolic types among various temperatures, most bacteria and fungi showed positive correlations at the genera level. Klebsiella, Paenibacillus, Cohnella, and Pantoea were confirmed as the main bacterial genera, and Aspergillus and Cyberlindnera were the main fungal genera in QZT fermentation. The microbial genera (i.e. Aspergillus, Rhizomucor, Thermomyces, Ralstonia, Castellaniella, and Vibrio) were positively correlated with fermentation temperature (P < 0.05), while Klebsiella, Paenibacillus, and Aspergillus had good adaptability at different temperatures. Conversely, Pantoea and Cyberlindnera were only suitable for low temperature (≤37 °C) growth, and Thermomyces was only suitable for high temperature (>37 °C) growth. Aspergillus had a significant positive correlation with tea aroma quality (r = 0.64, p < 0.05). This study would help to understand the formation mechanism of QZT from microflora perspective.