Characterization of key aroma compounds and relationship between aroma compounds and sensory attributes in different aroma types of Fu brick tea.

Aroma is one of the most important sensory properties of tea. Floral-fungal aroma type, ripe-fungal aroma type and fresh-fungal aroma type were the main aroma types of Fu brick tea by QDA. A total of 112 volatile compounds were identified and quantified in tea samples by HS-SPME/GC-MS analysis. Ten voaltiles in floral-fungal aroma type, eleven voaltiles in ripe-fungal aroma type, and eighteen voaltiles in fresh-fungal aroma type were identified as key aroma compounds for the aroma characteristics formation in three aroma types of Fu brick tea. In addition, PLS analysis revealed that 3,4-dehydro-ß-ionone, dihydro-ß-ionone, (+)-carotol and linalool oxide Ⅱ were the key contributors to the 'floral and fruity' attribute, α-terpineol contributed to 'woody' and 'stale' attributes, and thirteen aroma compounds related to 'green' attribute. Taken together, these findings will provide new insights into the formation mechanism of different aroma characteristics in Fu brick tea.

Cross-neutralization of antibodies induced by inactivated SARS-CoV-2 vaccine against Beta and Delta variants / 中华微生物学和免疫学杂志

Objective:To evaluate the in vitro cross-neutralization of serum antibodies in human and mice immunized with inactivated SARS-CoV-2 vaccine against Delta and Beta variants. Methods:Human serum samples after a second and a third dose of inactivated SARS-CoV-2 vaccine and mouse serum samples after a two-dose vaccination were collected. The neutralizing antibodies in the samples against SARS-CoV-2 strains of prototype, Delta and Beta variants were detected using micro-neutralization assay in biosafety level Ⅲ laboratory. The seroconversion rates and geometric mean titers (GMTs) of antibodies were calculated.Results:The seroconversion rates of antibodies in human serum samples against different SARS-CoV-2 strains were all above 95%. After two-dose vaccination, the GMTs of neutralizing antibodies against the prototype, Delta and Beta strains were 109, 41 and 15, respectively. The GMTs decreased by 2.7 folds and 7.3 folds for the Delta and Beta variants as compared with the prototype strain. After the booster vaccination, the GMTs of neutralizing antibodies against the prototype, Delta and Beta strains were 446, 190 and 86, respectively. The GMTs of neutralizing antibodies against Delta and Beta variants decreased by 2.3 folds and 5.2 folds as compared with that against the prototype strain. The seroconversion rates of antibodies against different SARS-CoV-2 strains in mouse serum samples were all 100%. The GMTs of neutralizing antibodies against the prototype, Delta and Beta strains were 2 037, 862 and 408, respectively. The GMTs decreased by 2.4 folds and 5.0 folds for the Delta and Beta variants.Conclusions:Inactivated SARS-CoV-2 vaccine could induce a certain level of neutralizing antibodies against Delta and Beta variants in both human and mouse models. Moreover, a third dose of vaccine induced higher levels of neutralizing antibodies against Delta and Beta variants in human. This study provided valuable data for the clinical application and protective evaluation of the inactivated SARS-CoV-2 vaccine.