The effective of bacterial community dynamics driven by different starter cultures on the flavor development of Chinese fermented sausages.

This study aimed to understand the community successions driven by different starters and their effects on the flavor development of Chinese fermented sausages. The results showed that the bacterial genus (67.6%) and pH (32.4%) were the key factors influencing the volatile profile. Inoculated the starters composed of Pediococcus and staphylococci maintained the stable community succession patterns dominated by staphylococci (samples T and S). Although the highly acidic environment (pH < 5.2) caused the community to exhibit a fluctuation in succession pattern, the inoculation of Latilactobacillus paracasei (sample Y) maintained microbial diversity and was conducive to the accumulation of aldehydes and esters. In sample P, inoculated the starter with Latilactobacillus and Staphylococcus also maintained microbial diversity, the moderately acidic environment (pH > 5.4) resulted in a stable succession pattern of the microbial community, and it was not conducive to the accumulation of aldehydes, alcohols and esters.

Improving the aroma profile of inoculated fermented sausages by constructing a synthetic core microbial community.

Commercial starter cultures play a critical role in the industrial production of fermented sausages. However, commercial starter cultures could not reproduce the metabolic actions of diverse microorganisms and the aroma profile of the traditional spontaneously fermented sausages. Identifying the core microbial community in spontaneously fermented sausages will facilitate the construction of a synthetic microbial community for reproducing metabolic actions and flavor compounds in spontaneously fermented sausages. This study aimed to reveal the core microbial community of spontaneously fermented sausages based on their relative abundance, flavor-producing ability, and co-occurrence performance. We identified five promising genera to construct the synthetic core microbial community, these were Lactobacillus, Staphylococcus, Macrococcus, Streptococcus, and Pediococcus. Sausages inoculated with a synthetic core microbial community presented higher quality of aroma profile than the fermented sausages inoculated with a commercial starter culture. Some important volatile flavor compounds of spontaneously fermented sausage, such as (-)-ß-pinene, ß-caryophyllene, 3-methyl-1-butanol, α-terpineol, ethyl 2-methylpropanoate, and ethyl 3-methylbutanoate which are associated with floral, fruity, sweet, and fresh aromas, were also detected in fermented sausage inoculated with synthetic microbial community. This indicated that the synthetic core microbial community efficiently reproduced flavor metabolism. Overall, this study provides a practical strategy to design a synthetic microbial community applicable to different scientific fields.

Optimization of Jinhua Ham Classification Method Based on Volatile Flavor Substances and Determination of Key Odor Biomarkers.

Jinhua ham is a traditional cured meat food in China. For a long time, its grade has mainly been evaluated by the human nose through the three-sticks method, which is highly subjective and is not conducive to establishing evaluation standards through odor markers. In this paper, we analyzed the well-graded Grade I-III hams provided by Jinzi Ham Co., Ltd. (Jinhua, China). Firstly, we used different extraction fibers, extraction temperatures, and extraction time to determine the optimal conditions for headspace solid-phase microextraction (HS-SPME). Then, the aroma components of Jinhua ham were analyzed by headspace solid-phase microextraction combined with gas chromatography-mass spectrometry (GC-MS), and OAV was calculated to screen the key aroma volatiles of three kinds of Jinhua ham. It was found that a total of 56 components were detected in the three types of ham. Among them, there are 21 kinds of key aroma volatiles. Aldehydes, alcohols, and acids are the three main components of Jinhua ham, and the content of aldehydes gradually decreases from Grade I to Grade III ham. The content of acids gradually increased, and we speculated that the increase in acid content was caused by the proliferation of microorganisms in Grade III ham. The key flavor volatiles in Grade I hams was hexanal and 2-methylbutanal. Grade I hams had a strong meat aroma, pleasant fatty, and roasted aroma without any off-flavors. In Grade II ham, the characteristic volatiles (E,E)-2,4-decadienal and ethyl isovalerate were detected. These two volatiles contribute greatly to the flavor of Grade II ham, which makes the flavor of Grade II ham have a special fruity aroma. They also may be prone to sourness and affect the flavor of the ham. Volatiles with low threshold values, such as pyrazines, furans, and sulfur-containing compounds, were relatively high in Grade III hams. This may also contribute to the poorer flavor quality of Grade III hams. This experiment provided a reliable test method and evaluation basis for the rating of Jinhua ham. These results have positive implications for the establishment of odor markers-based grading criteria.

Mechanism of action of resolvin D1 in inhibiting the progression of aortic dissection in mice.

BACKGROUND: To investigate the protective effect of resolvin D1 (RvD1) on aortic dissection (AD) in mice and explore the related mechanisms. METHODS: Mice were randomly divided into a blank group, model group, and RvD1 group. The RvD1 and model groups were administered 0.4% ß-aminopropionitrile (BAPN) solution, while the blank group was administered distilled water. When the experiment began, whether mice had AD was determined by echocardiogram. The RvD1 group was also administered RvD1 (30 µg/kg), while the model and blank groups were administered saline intraperitoneally. After 21 d, body weight trend and survival rate in the three groups were compared. The diameter of the ascending aorta of mice was detected by echocardiography. Then, the mice were sacrificed, and histopathological staining procedures were performed. Enzyme-linked immunosorbent assay (ELISA) was used to detect cytokines and chemokines in blood and tissue, respectively. RESULTS: At 21 d, there was no statistically significant difference in body weight between three groups (P>0.05). The survival rate showed a significant difference between the RvD1 and model group (P<0.05). Echocardiography revealed that compared with the RvD1 and blank groups, aortic dilatation was significant in the model group. Pathological staining showed that the destruction of the aortic wall structure and inflammatory cell infiltration were more noticeable in the model group than in the RvD1 group. A slight disintegration of elastic fibers and collagen in the aorta was observed in the RvD1 group, and the aortic structure was clear. The results of ELISA showed that the inflammatory factors levels in the RvD1 group, although higher than those in blank group, were significantly decreased compared with the model group. The ELISA results of AD tissue showed that at 21 d, interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) levels in the aorta were significantly decreased in the RvD1 group compared with the model group (P<0.05). CONCLUSIONS: Administration of RvD1 significantly delayed aortic dilation and disintegration and inhibited local macrophage and neutrophil infiltration in the early stages of aortic injury. Moreover, RvD1 significantly downregulated the expression of cytokines and chemokines in aortic tissues and serum and improved aortic remodeling.

Synthesis, optical properties and cytotoxicity of meso-heteroatom substituted IR-786 analogs.

Eight near-infrared heptamethine cyanines have been successfully synthesized based on IR 786 with oxygen, sulfur and amine moieties at the central position. These dyes show diverse optical properties resulting from different substitutions. Particularly, the heptamethine dyes with amine moieties have larger Stokes shifts and higher quantum yields of fluorescence. We also investigated these dyes for tumor cell cytotoxicity using cell viability and in vitro proliferation assays. Two of the compounds showed high cytotoxicity against PC-3 cancer cells.