Exploring the roles of microorganisms and metabolites in the 30-year aging process of the dried pericarps of Citrus reticulata 'Chachi' based on high-throughput sequencing and comparative metabolomics

Metabolic profile and bioactivity of the peel of Zhoupigan (Citrus reticulata cv. Manau Gan), a special citrus variety in China, based on GC-MS, UPLC-ESI-MS/MS analysis, and in vitro assay

Zhoupigan (Citrus reticulata cv. Manau Gan) is a local citrus variety in China. Its peel, known as Zangju peel (ZJP). The metabolic profile and bioactivity of ZJP have not been adequately studied, resulting in underutilization of ZJP and a serious waste of resources. In this study, GC-MS identified 46 components in ZJP, which defined ZJP's distinct aroma. Furthermore, UPLC-ESI-MS/MS detected 1506 metabolites in ZJP, and the differential metabolites were primarily involved in the biosynthesis of flavonoids and phenylacetone. Additionally, 56 key differential metabolites with metabolic pathways were identified. ZJP had significant antioxidant activity and the enzyme inhibitory activity ranking as pancreatic lipase (IC50 = 3.71 mg/mL) > α-glucosidase (IC50 = 6.28 mg/mL) > α-amylase (IC50 = 8.02 mg/mL). This study aimed to evaluate the potential of ZJP as natural antioxidant and functional food source and to serve as foundation for the further development of ZJP products with specific functional attributes.

Flavonoid Profiles in the Pulp of Different Lemon Cultivars and Their Antioxidant Activity Based on UPLC-Q-TOF-MS

Previous studies have indicated that there may be differences among the varieties of lemon flavonoids, but the details have not yet been made clear, which limits the comprehensive use of different cultivated lemon varieties. In this study, ultra-performance liquid chromatography-quadrupole-time-of-flight-mass spectrometry (UPLC-Q-TOF-MS) and ultraviolet-visible spectroscopy (UV-Vis) were used to investigate the types and contents of flavonoids in the flesh of the main cultivated variety (Eureka) and five common lemon varieties, as well as their in vitro antioxidant activity. A total of 21 compounds were identified, five of which were common compounds. Among them, Verna, Lisbon, and Bearss each have characteristic components that can serve as potential criteria for variety identification. Each of the six varieties of lemon has strong antioxidant activity. The antioxidant activity of different lemon varieties is related to flavonoids. Therefore, Eureka and the other five varieties of lemon are good natural antioxidants, and the cultivation and industrial production of lemons should consider the needs and selection of suitable varieties.

Influence of microorganisms on flavor substances and functional components of sojae semen praeparatum during fermentation: A study integrating comparative metabolomics and high-throughput sequencing

Sojae semen praeparatum (SSP), a fermented product known for its distinctive flavor and medicinal properties, undergoes a complex fermentation process due to the action of various microorganisms. Despite its widespread use, the effect of these microorganisms on the flavor compounds and functional components of SSP remains poorly understood. This study aimed to shed light on this aspect by identifying 20 metabolites as potential key flavor substances in SSP. Moreover, glycine and lysine were identified as crucial flavor substances. Additionally, 24 metabolites were identified as key functional components. The dominant microorganisms involved in the fermentation process were examined, revealing six genera of fungi and 12 genera of bacteria. At the species level, 16 microorganisms were identified as dominant through metagenome sequencing. Spearman correlation analysis demonstrated a strong association between dominant microorganisms and both flavor substances and functional components. Furthermore, the study validated the significance of four core functional microorganisms in improving the flavor and quality of SSP. This comprehensive exploration of functional microorganisms of SSP on key flavor substances/functional components during SSP fermentation. The study findings serve as a valuable reference for enhancing the overall flavor and quality of SSP.

Insights into metabolic characteristics and biological activity changes in Zangju (Citrus reticulata cv. Manau Gan) peel at different maturity stages through UPLC-MS/MS-based metabolomics

In this study, comprehensive and systematic nontargeted metabolomics analysis was performed with the metabolites of Zangju peel (Citrus reticulata cv. Manau Gan, CRZP, which has been cultivated for over 400 years in Derong County, China.) at four different mature stages. A total of 1878 metabolites were identified, among which flavonoids were the most abundant (62.04 %), and identified 62 key differential metabolites significantly affected by maturity. Based on biological activity measurements, CRZP showed better antioxidant activity, lipase inhibition ability, inhibition of adipogenic differentiation in 3TT-L1 cells and promotion of lipid metabolism, with the biological activity of CRZP at different maturity stages being associated with key differential metabolite. Thus, CRZP is natural antioxidants and possess anti-obesity potential, and industrial production needs to consider the Maturity stage of its collection.