Aromatic profiles and enantiomeric distributions of volatile compounds during the ripening of Dendropanax dentiger honey.

Dendropanax dentiger honey (DDH) is a specialty herbal honey from China. Previous research on DDH has mostly focused on its composition and potential chemical markers, no studies have been conducted on the changes in aroma characteristics and chiral odorants during its maturation. Therefore, the present study aims to address the missing parts. The proportions and total concentrations of 185 volatile compounds identified in different classes varied with DDHs ripening. Fourteen common odor-active compounds were identified by odor activity values (OAVs) and GC-olfactometry (GC-O) analysis. The aroma profiles of DDHs were observed to vary at different ripening stages, although the dominant aroma characteristic was "fruity" aroma, which became more pronounced with increasing maturity. The enantiomeric contents and distributions of 7 volatile enantiomers were related to specific physicochemical indicators and the maturity of DDHs, among which the enantiomers of linalool oxide A may be a potential indicator to identify its maturity. Furthermore, precise quantification and OAVs calculation showed that the enantiomer (2S, 5S)-linalool oxide A presented the highest concentration (8.83-27.39 ng/mL) and only the enantiomer R-linalool (OAVs: 5.56-6.14) was an important contributor to the aroma profiles of DDHs at different stages of maturity. These results provided a new research idea for quality control and identification of DDHs at different maturity stages.

Dynamic variation in the aroma characteristics of Rhus chinensis honey at different stages after capping.

The ripening characteristics after capping of honey are favourable for improving its quality. However, research on the variation and formation of aroma characteristics of honey in this process is lacking. Therefore, the present study was carried out with different stages of Rhus chinensis honeys (RCHs) after capping and identified 192 volatiles with varying levels of concentration. "Fruity" was the main aroma characteristic of RCHs at different stages after capping, mainly contributed by (E)-ß-damascenone. Methyl salicylate might be a potential indicator for differentiating RCHs at different stages after capping. The metabolic pathway analyses revealed that the aroma compounds in RCHs undergo transformation at different stages after capping, which subsequently affects its aroma characteristics formation. This work is the first to study the dynamic changes in honey aroma characteristics after capping from multiple perspectives, and the results are of great significance for understanding the aroma characteristics after capping and quality control of honey.

Beneficial Effect of Proline Supplementation on Goat Spermatozoa Quality during Cryopreservation.

Sperm cryopreservation contributes to the extensive utilization of artificial insemination (AI) in the daily livestock industry. However, due to the presence of few sperm with good biological function in post-thaw goat sperm, its use has been limited for AI purposes. Hence, its improvement has been the focus of many research studies. This study aimed to investigate the effects of proline supplementation of the freezing medium on goat sperm. The goat semen was cryopreserved with freezing medium supplementation of different concentrations of proline (0, 0.5, 1, 2 and 4 mM). The post-thaw sperm motility patterns, membrane integrity, acrosome integrity, lipid peroxidation (LPO) levels, malondialdehyde (MDA) levels, total antioxidant capacity (T-AOC), proline dehydrogenase (PRODH) activity, superoxide dis-mutase (SOD) activity, glutathione (GSH) levels and GSH/GSSG were evaluated. Likewise, the expression and immunofluorescent localization of PRODH in post-thaw goat sperm was also detected. It was observed that addition of 2 mM proline to the freezing medium significantly enhanced post-thaw goat sperm total motility, progressive motility, straight-linear velocity (VSL), curvilinear velocity (VCL), average path velocity (VAP), straightness (STR), linearity (LIN), membrane integrity and acrosome integrity. Interestingly, PRODH was expressed in post-thaw goat sperm, especially in the post-acrosome and sperm tail. Addition of 2 mM proline also significantly increased the post-thaw sperm PRODH activity compared to the control. Moreover, post-thaw goat sperm LPO levels and MDA levels were reduced by supplementation of 2 mM proline. Furthermore, compared to the control, the values of post-thaw goat sperm T-AOC, SOD activity, GSH level and GSH/GSSG were also significantly increased in 2 mM proline treatment. Reduction of post-thaw goat sperm apoptosis in 2 mM proline treatment was also observed as the levels of Caspase3 and Caspase9 were decreased by the supplementation with 2 mM proline. These observations suggest that the addition of 2 mM proline to the freezing medium increased post-thaw goat sperm quality by reducing oxidative stress during cryopreservation. These findings also provide novel insights into the use of proline as an efficient additive to enhance post-thaw goat sperm quality during cryopreservation.