Traditional fermented yak milk has immense cultural and nutritional significance for Tibetan herders. In this study, we investigated the microbial community structure and flavour compounds in traditional fermented yak milk from three distinct regions of Gannan to explore the relationship between microbial composition and flavour compounds. The findings revealed significant variations in flavour compounds and the bacterial microbiota among the samples from the three regions. The dominant species identified in fermented yak milk were Streptococcus salivarius subsp. Thermophilus, Lactobacillus helveticus, and Kluyveromyces marxianus. Bidirectional orthogonal partial least-squares (O2PLS) analysis highlighted five bacterial genera and three fungal genera as contributors to the production of flavour-related compounds. Furthermore, regression analysis revealed that the Lactobacillus and Streptococcus genera were associated with the production of 2,3-pentanedione as well as eight predicted KEGG pathways. These findings provide valuable insights into the intricate relationship between flavour compounds and microbiota in traditional fermented yak milk.

This study aimed to investigate the microbial community structure and flavor compounds, including amino acids, fatty acids, and volatile compounds in traditional fermented yak milk from three distinct regions of Gannan, as well as their relationship. The findings revealed significant variations in flavor compounds, particularly amino acids among the three regions. Similar with the variation in flavor profile, there was also a significant variation in bacterial microbiota among the three regions. The dominant species were identified as Streptococcus salivarius subsp. Thermophiles, Lactobacillus helveticus and Kluyveromyces marxinu, Tausania pullulans in fermented yak milk. Bidirectional orthogonal partial least squares identified five bacterial and three fungi genera as contributors to flavor production, including ethyl acetate and some fatty acids. Furthermore, through regression analysis, we associated the genera of Lactobacillus and Streptococcus with 2,3-pentanedione via 8 KEGG pathways predicted by PICRUST2, such as fatty acid biosynthesis, pentose phosphate, and Alanine, aspartate and glutamate metabolism.

Frozen storage can delay mutton meat spoilage to the maximum extent, prolonging its shelf life. In this experiment, mutton refrigerated for 24 h was used as the control group and that stored at -18 degrees C was used as the experimental group to explore the effects of frozen storage for 90 days on FA, AA, and VOC of the mutton. The results showed that FA, AA, and VOC changed significantly during storage. PUFA and n-3 FA contents were the highest at 3 days of freezing (54.92 and 15.28 mg/100 g, respectively). AA contents were higher in the experimental group than in the control group, and Glu contents were the highest during the whole storage period, ranging from 2.94% to 3.28%, and the maximum value was on the 3rd day. In total, 38 volatile compounds were detected, and the most abundant volatile compounds were detected at 60 days. The variance contribution rates of PCA were 48.7%, 19.4%, and 14.8%, the PCA model can be used as a separation model. Novelty impact statement This study simulated the storage of mutton by household users and shortened the detection time point at the initial freezing stage, indicating that the differences in flavor substance changes in mutton at the initial freezing stage was little. On the other hand, GC-IMS was effectively used to visualize flavor substance changes during storage, providing a new method to distinguish the storage time of meat products. In conclusion, this study can provide basic research data for long-term storage of mutton and provide technical reference for meat storage identification.

The changes in quality indices (pH, acidity, protein, fat, and lactose) of yak, cattle-yak, and cow milk were analyzed during cold storage at 4 degrees C. The effects of cold storage time on volatile compounds of three kinds of raw milk were compared and the potential volatile compounds associated with raw milk deterioration were screened by headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS) and principal component analysis (PCA). During the whole refrigeration process, yak milk showed more obvious changes in pH and acidity than cow milk and cattle-yak milk, the change was more significant in the later stage of refrigeration (p < 0.05). And the contents of fat, protein, and lactose in yak milk changed significantly after 1 d of cold storage (p < 0.05). In total, 35 volatile components (including ketones, esters, aldehydes, alcohols, and others) were identified in the three raw milk samples during cold storage, including 13 common compounds. Their contents were higher in yak milk than in cattle-yak and cow milk. The contents of 2-ethyl-5-methylpyrazine, 2-pentanone, pyridine, 2-butanone, n-butyraldehyde, and 2,3-butanedione showed a gradual increase with the increase in cold storage time in three kinds of raw milk. These results can be used as monitoring markers of raw milk freshness.

In this study, gas chromatography coupled to an ion mobility spectrometry (GC-IMS) was used for analyzing some volatile components and flavor fingerprint in samples from Jingyuan lambs of different ages (2, 6, and 12 months). The data obtained from ion mobility were processed using laboratory analysis view processing software for fingerprint recognition, and the principal component analysis (PCA) was performed. GC-IMS provided information on the characteristics and strength of 66 volatile flavor compounds (monomers and dimers). The differences in flavoring substances between lambs of different ages were observed. The compounds with higher intensity peaks in the lamb meat samples were alcohols (1-octen-3-ol, ethanol, (E)-2-hexen-1-ol, 1-pentanol, and 2-propanol), ketones (2-pentanone, 2-heptanone, 3-hydroxy-2-butanone, 2-hexanone, 2-butanone, 2-propanone, and 4-methyl-2-pentanone), aldehydes (n-nonanal, octanal, heptanal, 3-methylbutanal, hexanal, pentanal, 2-methylbutanal, (E)-2-octenal, (E)-2-nonenal, methional, and phenylacetaldehyde), esters (methyl benzoate), furan (2-pentylfuran), and thiazole (trimethylthiazole). The results showed that the flavor fingerprint in samples from Jingyuan lambs of different ages (2, 6, and 12 months) can be established by GC-IMS and PCA based on the identified volatile compounds. This method might be used for the rapid and comprehensive analysis of volatile components in lamb meat.

Beef is rich in amino acids and vitamin B6, carnitine, potassium, protein, and other nutrients. It can improve the body’s ability to resist disease and is especially suitable for growth, development, and postoperation and postrehabilitation care. Under such circumstances, the demand for beef consumption in various countries continues to grow steadily. At present, domestic beef prices continue to rise, and beef supply is insufficient. In addition, fresh beef is easy to be infected with microorganisms in the process of cold storage, which makes fresh beef deteriorated. Therefore, it is very important to add preservatives to prolong the shelf life of chilled beef. In this paper, the preservation of chilled beef with nanocapsules made of natural essential oil from plant extracts was studied. In this study, cumin, Zanthoxylum, ginger, cinnamon, clove, and thyme were selected to study the effect of six kinds of essential oils on beef preservation through comparative experiments. On the basis of such research data, the six kinds of essential oils were compounded, respectively, and different nanoessential oil capsules were applied to the fresh-keeping of chilled beef to make different kinds of nanoessential oil capsules. Through the experiment, the compound essential oil with better preservation effect was obtained. And through the comparison, cinnamon essential oil has obvious antibacterial activity, while ginger essential oil has the worst antibacterial effect. The pH value of beef can be changed and the degradation rate of protein in beef will be slowed down by applying appropriate amount of decomposed plant essential oil to beef samples. Through the above experimental results, we applied the compound essential oil to the preservation of cold and fresh beef at nanometer level and found that the effect was significant, which was worthy of application in major beef products processing plants.

A specific, precise and accurate high performance liquid chromatographic (HPLC) analytical method with a fluorescence detector (FLD) was established for the simultaneous determination of nine bisphenols (BPs) in milk samples. Samples were extracted ultrasonically with acetonitrile and cleaned using the QuEChERS technique. Under the optimized conditions, good linearity was obtained for the nine BPs and the correlation coefficients (R-2) ranged from 0.9942 to 0.9997. Recovery values for the nine bisphenols in spiked samples were 75.82-93.86% with intra-day and inter-day relative standard deviations (RSDs) from 2.6 to 11.1%. The limits of detection (LODs) and quantification (LOQs) were 1.0-3.1 mu g/kg and 3.5-9.8 mu g/kg, respectively. The results demonstrated clearly that the approach developed provides reliable, simple, rapid and environmentally-friendly quantification and identification of nine bisphenols in a fatty matrix and could be used for monitoring bisphenols in milk.

The social lifestyle of different countries form different diet culture and table manner, which is an important part of non-language culture.Table manner culture is a part of the diet cultures, reflects the difference between Chinese and western culture.The paper from the perspective of different etiquette about dining in China and West, analyzes the differences and causes of table manners between China and West, aims to promote cross-cultural communication activities between China and West through learning more about the differences between Chinese and western cultures.