Determination of Volatile Flavour Profiles of Citrus spp. Fruits by SDE-GC-MS and Enantiomeric Composition of Chiral Compounds by MDGC-MS.

INTRODUCTION: Citrus fruits are known to have characteristic enantiomeric key compounds biosynthesised by highly stereoselective enzymatic mechanisms. In the past, evaluation of the enantiomeric ratios of chiral compounds in fruits has been applied as an effective indicator of adulteration by the addition of synthetic compounds or natural components of different botanical origin. OBJECTIVE: To analyse the volatile flavour compounds of Citrus junos Sieb. ex Tanaka (yuzu), Citrus limon BURM. f. (lemon) and Citrus aurantifolia Christm. Swingle (lime), and determine the enantiomeric ratios of their chiral compounds for discrimination and authentication of extracted oils. METHODOLOGY: Volatile flavour compounds of the fruits of the three Citrus species were extracted by simultaneous distillation extraction and analysed by gas chromatography-mass spectrometry. The enantiomeric composition (ee%) of chiral camphene, sabinene, limonene and ß-phellandrene was analysed by heart-cutting multidimensional gas chromatography-mass spectrometry. RESULTS: Sixty-seven (C. junos), 77 (C. limon) and 110 (C. aurantifolia) volatile compounds were identified with limonene, γ-terpinene and linalool as the major compounds. Stereochemical analysis (ee%) revealed 1S,4R-(-) camphene (94.74, 98.67, 98.82), R-(+)-limonene (90.53, 92.97, 99.85) and S-(+)-ß-phellandrene (98.69, 97.15, 92.13) in oil samples from all three species; R-(+)-sabinene (88.08) in C. junos; and S-(-)-sabinene (81.99, 79.74) in C. limon and C. aurantifolia, respectively. CONCLUSION: The enantiomeric composition and excess ratios of the chiral compounds could be used as reliable indicators of genuineness and quality assurance of the oils derived from the Citrus fruit species. Copyright © 2017 John Wiley & Sons, Ltd.

Genomic Analysis and Tracking of SARS-CoV-2 Variants in Gwangju, South Korea, From 2020 to 2022.

BACKGROUND: Since severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was first reported in Wuhan, China, in December 2019, it has spread rapidly, and many coronavirus disease (COVID-19) cases have occurred in Gwangju, South Korea. Viral mutations following the COVID-19 epidemic have increased interest in the characteristics of epidemics in this region, and pathogen genetic analysis is required for infection control and prevention. METHODS: In this study, SARS-CoV-2 whole-genome analysis was performed on samples from patients with COVID-19 in Gwangju from 2020 to 2022 to identify the trends in COVID-19 prevalence and to analyze the phylogenetic relationships of dominant variants. B.41 and B.1.497 prevailed in 2020, the early stage of the COVID-19 outbreak; then, B.1.619.1 mainly occurred until June 2021. B.1.617.2, classified as sublineages AY.69 and AY.122, occurred continuously from July to December 2021. Since strict measures to strengthen national quarantine management had been implemented in South Korea until this time, the analysis of mutations was also able to infer the epidemiological relationship between infection transmission routes. Since the first identification of the Omicron variant in late December 2021, the spread of infection has been very rapid, and weekly whole-genome analysis of specimens has enabled us to monitor new Omicron sublineages occurring in Gwangju. CONCLUSIONS: Our study suggests that conducting regional surveillance in addition to nation-level genomic surveillance will enable more rapid and detailed variant surveillance, which will be helpful in the overall prevention and management of infectious diseases.

Impact of COVID-19 Pandemic Restrictions on Respiratory Virus Patterns: Insights from RSV Surveillance in Gwangju, South Korea.

The social restriction measures implemented due to the COVID-19 pandemic have impacted the pattern of occurrences of respiratory viruses. According to surveillance results in the Gwangju region of South Korea, respiratory syncytial virus (RSV) did not occur during the 2020/2021 season. However, there was a delayed resurgence in the 2021/2022 season, peaking until January 2022. To analyze this, a total of 474 RSV positive samples were investigated before and after the COVID-19 pandemic. Among them, 73 samples were selected for whole-genome sequencing. The incidence rate of RSV in the 2021/2022 season after COVID-19 was found to be approximately three-fold higher compared to before the pandemic, with a significant increase observed in the age group from under 2 years old to under 5 years old. Phylogenetic analysis revealed that, for RSV-A, whereas four lineages were observed before COVID-19, only the A.D.3.1 lineage was observed during the 2021/2022 season post-pandemic. Additionally, during the 2022/2023 season, the A.D.1, A.D.3, and A.D.3.1 lineages co-circulated. For RSV-B, while the B.D.4.1.1 lineage existed before COVID-19, both the B.D.4.1.1 and B.D.E.1 lineages circulated after the pandemic. Although atypical RSV occurrences were not due to new lineages, there was an increase in the frequency of mutations in the F protein of RSV after COVID-19. These findings highlight the need to continue monitoring changes in RSV occurrence patterns in the aftermath of the COVID-19 pandemic to develop and manage strategies in response.

Re-Emergence of HMPV in Gwangju, South Korea, after the COVID-19 Pandemic.

The non-pharmaceutical interventions implemented to prevent the spread of COVID-19 have affected the epidemiology of other respiratory viruses. In South Korea, Human metapneumovirus (HMPV) typically occurs from winter to the following spring; however, it was not detected for two years during the COVID-19 pandemic and re-emerged in the fall of 2022, which is a non-epidemic season. To examine the molecular genetic characteristics of HMPV before and after the COVID-19 pandemic, we analyzed 427 HMPV-positive samples collected in the Gwangju area from 2018 to 2022. Among these, 24 samples were subjected to whole-genome sequencing. Compared to the period before the COVID-19 pandemic, the incidence rate of HMPV in 2022 increased by 2.5-fold. Especially in the age group of 6-10 years, the incidence rate increased by more than 4.5-fold. In the phylogenetic analysis results, before the COVID-19 pandemic, the A2.2.2 lineage was predominant, while in 2022, the A2.2.1 and B2 lineage were observed. The non-pharmaceutical interventions implemented after COVID-19, such as social distancing, have reduced opportunities for exposure to HMPV, subsequently leading to decreased acquisition of immunity. As a result, HMPV occurred during non-epidemic seasons, influencing the age distribution of its occurrences.

Origin discrimination of defatted pork via trace elements profiling, stable isotope ratios analysis, and multivariate statistical techniques.

This study verified the origin of 346 defatted Korean and non-Korean pork samples via trace elements profiling, and C and N stable isotope ratios analysis. The analyzed elements were 6Li, 7Li, 10B, 11B, 51V, 50Cr, 52Cr, 53Cr, 55Mn, 58Ni, 60Ni, 59Co, 63Cu, 65Cu, 64Zn, 66Zn, 69Ga, 71Ga, 75As, 82Se, 84Sr, 86Sr, 87Sr, 88Sr, 85Rb, 94Mo, 95Mo, 97Mo, 107Ag, 109Ag, 110Cd, 111Cd, 113Cd, 112Cd, 114Cd, 116Cd, 133Cs, 206Pb, 207Pb, and 208Pb. Content (mg/kg) of 51V (0.012), 50Cr (0.882), 75As (0.017), 85Rb (57.7), and 87Sr (46.3) were high in Korean pork samples whereas 6Li, 7Li, 59Co, 55Mn, 58Ni, 84Sr, 86Sr, 88Sr, 111Cd, and 133Cs were found higher in non-Korean samples. The results of discriminant analysis showed that the trace elements content and stable isotope ratios were significant for the discrimination of geographical origins with a perfect discrimination rate of 100%.

Determination of volatile organic compounds, catechins, caffeine and theanine in Jukro tea at three growth stages by chromatographic and spectrometric methods.

Tea contains characteristic volatile organic compounds, polyphenols, caffeine and catechins, and is therefore among the most widely consumed beverages all over the world. In this study, fresh Jukro tea leaves collected from Damyang-gun (Jeollanam-do) at 40, 60 and 90day growth stages, were semi-fermented. The volatile organic compounds (VOCs) were extracted by simultaneous distillation-solvent extraction (SDE) and analyzed by gas chromatography/mass spectrometry (GC/MS). Catechins, caffeine and theanine were analyzed by high performance liquid chromatography (HPLC). A total of 159 VOCs were identified in the analyzed Jukro tea leaves. Comparatively, the increase in the concentrations of VOCs was high in 60day leaves. The content of catechins increased along the three growth stages, whereas caffeine, compared to 90day leaves, was higher for 40 and 60day leaves. Based on the results, the 60day leaves were found to be the most suitable and useful for making semi-fermented Jukro tea.