Gut microbiota are closely linked to host health and adaptability to different geographical environments. However, information on the influence of different geographical conditions on the intestinal microbiota of yaks is limited. In this study, 18 yak fecal samples were collected from three regions of China, namely Shangri-la, Lhasa, and Yushu, and were analyzed via high-throughput sequencing. The alpha diversity, as measured by the Shannon, ACE, and Chao indices, was the highest in the Shangri-la samples. Principal coordinate analysis detected significant differences in the composition of the intestinal microbiota of yaks from different regions. A total of six phyla, 21 families, and 29 genera were identified in the fecal samples. The dominant phyla in the samples were Firmicutes and Bacteroidetes, and the most abundant family was Ruminococcaceae. In addition, Ruminococcaceae_UCG-005 was the predominant genus and was more abundant in Yushu samples than in other samples. However, the predicted functional gene composition of the gut microbiota of yaks from different regions was similar. Our results revealed that geographical conditions influence the diversity and composition of the intestinal microbiota of yaks.

This study was performed to compare the differences in pH, myofibril fragmentation index (MFI), total protein solubility (TPS), sarcoplasmic protein solubility (SPS), myofibrillar protein solubility (MPS), and the microstructure of seven beef muscles during aging. From the six beef carcasses of Xinjiang brown cattle, a total of 252 samples from semitendinosus (ST), longissimus thoracis (LT), rhomboideus (RH), gastrocnemius (GN), infraspinatus (IN), psoas major (PM), and biceps femoris (BF) muscles were collected, portioned, and assigned to six aging periods (1, 3, 7, 9, 11, and 14 day/s) and 42 samples were used per storage period. IN muscle showed the highest pH (p < 0.05) from 1 to 14 days and the lowest TPS (p < 0.01) from 9 to 14 days with respect to the other muscles. Moreover, the changes in IN were further supported by transmission electron microscopy due to the destruction of the myofibril structure. The highest value of MFI was tested in ST muscle from 7 to 14 days. The total protein solubility in PM, RH, and GN muscles were not affected (p > 0.05) as the aging period increased. The lowest TPS was found in the RH muscle on day 1, 3, and 7 and in the IN muscle on day 9, 11, and 14. The pH showed negative correlations with the MFI, TPS, and MPS (p < 0.01). The results suggest that changes in protein solubility and muscle fiber structure are related to muscle location in the carcass during aging. These results provide new insights to optimize the processing and storage of different beef muscles and enhance our understanding of the biological characteristics of Xinjiang brown cattle muscles.

This study focused on characterizing the volatile profiles and contributing compounds in pan-fried steaks from different Chinese yellow cattle breeds. The volatile organic compounds (VOCs) of six Chinese yellow cattle breeds (bohai, jiaxian, yiling, wenshan, xinjiang, and pingliang) were analyzed by GC-Q-Orbitrap spectrometry and electronic nose (E-nose). Multivariate statistical analysis was performed to identify the differences in VOCs profiles among breeds. The relationship between odor-active volatiles and sensory evaluation was analyzed by partial least square regression (PLSR) to identify contributing volatiles in pan-fried steaks of Chinese yellow cattle. The results showed that samples were divided into two groups, and 18 VOCs were selected as potential markers for the differentiation of the two groups by GC-Q-Orbitrap combined multivariate statistical analysis. YL and WS were in one group comprising mainly aliphatic compounds, while the rest were in the other group with more cyclic compounds. Steaks from different breeds were better differentiated by GC-Q-Orbitrap in combination with chemometrics than by E-nose. Six highly predictive compounds were selected, including 3-methyl-butanal, benzeneacetaldehyde, 2-ethyl-6-methyl-pyrazine, 2-acetylpyrrole, 2-acetylthiazole, and 2-acetyl-2-thiazoline. Sensory recombination difference and preference testing revealed that the addition of highly predictive compounds induced a perceptible difference to panelists. This study provides valuable data to characterize and discriminate the flavor profiles in pan-fried steaks of Chinese yellow cattle.

The aim of this study was to evaluate the effects of the chitosan/collagen peptides/cinnamon bark essential oil composite coating on dry-aged beef. Chitosan (2%, w/v), collagen peptides (1%, w/v), and cinnamon bark essential oil (1%, v/v) were homogenized to obtain the coating. Beef samples were divided into three groups (traditional dry-ageing, in-bag dry-ageing, and coating and then dry-ageing) and dry-aged for 42 days. Physiochemical, microbial, and sensorial parameters of samples were determined during the dry-ageing process. There were no significant differences (p > 0.05) in pH values, shear force values, cooking loss, color, juiciness, tenderness, and flavor across groups. The total volatile base nitrogen value of the coating group was lower than those of the other two groups. Compared to traditional dry-ageing, in-bag and coating dry-ageing reduced (p < 0.05) many volatile compounds such as alcohols, aldehydes, ketones, and acetate. In-bag and coating dry-ageing had no impact on the fungal community, but changed the bacterial community by inhibiting Pseudomonas. This study demonstrates that the chitosan/collagen peptides/cinnamon bark essential oil coating reduces microbial spoilage during dry-ageing, and has a small influence on product quality.

The purpose was to investigate the quality characteristics of dry-cured beef with different storage times under a high-voltage electrostatic field (HVEF) condition. The pH, moisture content, meat color, and volatile compounds of dry-cured beef samples treated with HVEF (3 kV) were compared with those of a common refrigerator (CON) at days 0, 3, 7, 10, and 14. The results showed that, compared with CON group, the decline rates of the pH and moisture content of beef and ∆E values were lower under HVEF storage condition. From the fingerprints, the 42 volatile compounds identified were mainly aldehydes, alcohols, ketones, and esters. The benzaldehyde, trimethyl pyrazine, and maltol contents in the HVEF group exhibited a dramatic increase after 10 days of storage. Principal component analysis revealed clustering of compound classes, distributed in a separate time. Based on the above findings, we concluded that HVEF treatment could promote color stability and enhance characteristic flavor during the storage of dry-cured beef. These results suggested that HVEF might be applicable for dry-cured meat storage techniques.

Dry-aged beef has gained interest worldwide in recent years due to its improved sensory attributes. This enhancement is thought to be partially driven by microbial activities, particularly lipolysis and proteolysis. In this study, dry-aged beef manufactured by seven commercial producers in China was analyzed. The pH value and total volatile base nitrogen value of dry-aged beef were determined. High-throughput amplicon sequencing of full-length 16S rRNA genes and internal transcribed spacer (ITS) regions was used to analyze the microbial community. A total of 207 proteolytic and lipolytic isolates were identified by sequencing 16S rRNA genes for bacteria and sequencing the D1/D2 region of 28S rRNA genes and the ITS region for fungi. The results revealed that the crust harbored greater numbers of bacteria and fungi than the interior. The bacterial community was dominated by Pseudomonas species, which were core members in both the crust and interior, while Brochothrix thermosphacta was identified as a core bacterium exclusively in the crust. The fungal community primarily constituted Candida sake, Kurtzmaniella species, and members of the phylum Chytridiomycota. Proteolytic and lipolytic isolates were mainly identified as Pseudomonas sp., B. thermosphacta, Carnobacterium maltaromaticum, Candida zeylanoides (teleomorph: Kurtzmaniella zeylanoides), C. sake, and Debaryomyces hansenii. Two strains of C. zeylanoides and C. sake exhibiting high proteolytic and lipolytic activities effectively hydrolyzed beef fat, myofibrillar protein, and sarcoplasmic protein. This study characterized the main microorganisms and their enzymatic functions associated with dry-aged beef, highlighting the need to explore their contributions to the sensory attributes of dry-aged beef.