The aim of this study was to investigate the effects of arabinoxylan and its blend with β-glucan on fecal metabolites in mice with high-fat diet-induced obesity. Sixteen male ICR/KM mice were randomly divided into four groups: normal diet (CON), high-fat diet (HFD), high-fat diet supplemented with arabinoxylan (HFAX) and high-fat diet supplemented with arabinoxylan + β-glucan (HFAβ). The composition and content of fecal metabolites in each group of mice were investigated by ¹H-NMR-based metabolomics. The results showed that a total of 67 small molecule metabolites, including amino acids, peptides, organic acids, carbohydrates, nucleosides, nucleotides and their derivatives, were identified. Compared with the normal diet group, the HFD group had significantly higher levels of fecal cholate, xanthine and pyroglutamate (P < 0.05) and significantly lower levels of valine, acetoacetate, 4-hydroxyphenylacetate, 3,4-dihydroxybenzeneacetate, phenylacetate, glutamine, isoleucine and asparagine (P < 0.05). Compared with the HFD group, the concentrations of glutamine, acetate, 4-hydroxyphenylacetate, glucose, asparagine, isobutyrate and threonine increased significantly in the arabinoxylan supplement group (P < 0.05), while the concentrations of nicotinate, pyroglutamate and cholate decreased significantly (P < 0.05). In particular, compared with the HFAX group, the amount of pyroglutamate increased significantly (P < 0.05), while the levels of acetate, butyrate, glucose, glutamine, isobutyrate and propionate decreased significantly in the HFAβ group (P < 0.05). The metabolic pathway and enrichment analysis revealed that the major pathways included the synthesis and degradation of ketone bodies, phenylalanine, tyrosine and tryptophan biosynthesis, tyrosine metabolism, butanoate metabolism, and alanine, aspartate and glutamate metabolism. In conclusion, arabinoxylan and its mixture with β-glucan supplementation could improve fecal metabolomic profiles in mice with high-fat diet-induced obesity.

In order to study the correlation between characteristic flavor compounds and microbial community composition during the fermentation of sour beef, an electronic nose, an electronic tongue, gas chromatography-ion mobility spectrometry (GC-IMS) and high-throughput sequencing technology were used to determine flavor compounds and microbial community composition. Principal component analysis (PCA) was used to identify characteristic flavor compounds, and the correlation between microbial communities and characteristic flavor substances was explored by Spearmen correlation analysis. The results showed that a total of 40 volatile compounds were detected. Among them, 17 compounds including n-hexanol were considered as key flavor compounds. The relative abundance of Lactobacillus and Weissellla increased during the fermentation process, while the relative abundance of Staphylococcus, Alcaligenes, Pseudomonas and Macrococcus decreased. The results of Spearman correlation analysis indicated that Lactobacillus, Staphylococcus and Leuconostoc were significantly positively correlated with the production of various flavor compounds such as n-hexanol M and isoamyl alcohol M. In summary, Lactobacillus is the dominant genus in the fermentation process of sour meat, which plays an important role in promoting the formation of esters and alcohols. In addition, Staphylococcus and Leuconostoc also promote the formation of esters and alcohols in sour beef.

In order to deeply understand the impact of clinical mastitis on the physicochemical properties, flavor and taste of cow milk, a milk composition analyzer combined with an electronic nose and an electronic tongue was used to distinguish milk from cows with and without clinical mastitis. Moreover, nuclear magnetic resonance (NMR) spectroscopy was used to identify and quantify small molecules in milk samples. The fat content of mastitic milk was significantly lower than that of milk form healthy cows, while the density, protein and freezing point were significantly higher than those of milk from healthy cows. The electronic nose and the electronic tongue were able to distinguish the differences in the flavor and taste of milk from normal and mastitic milk. A total of 54 small molecules were identified in the two milk samples, including amino acids (17), organic acids (15), carbohydrates (7), nucleosides, nucleotides and their derivatives (5). The concentrations of 23 compounds significantly differed between both milks. A total of 16 predominant compounds were found in normal milk, and seven in mastitic milk. The contents of amino acids and organic acids in mastitic milk significantly increased, resulting in unpleasant sour odor of milk. This study provides a scientific rationale for the discrimination between normal and clinical mastitic milk and for the quality control of raw milk

In order to investigate the effect of fermentation using whole kiwifruit on the flavor profile of kiwifruit wine, the flavor profiles of kiwifruit wine fermented from whole and peeled kiwifruit were analyzed by gas chromatography-ion mobility spectrometry (GC-IMS), headspace-solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) and sensory evaluation. The results showed that a total of 124 volatile compounds were detected in the two wine samples by the combined use of GC-IMS and HS-SPME-GC-MS, which were much more than those detected by single techniques. This suggests that the combination of multiple techniques provides more comprehensive and systematic flavor characterization of kiwifruit wine than their separate use. Compared with the wine made from peeled kiwifruit, the one made from whole kiwifruit contained 13 more eater and aldehyde compounds and four less acids and ketones. Moreover, the relative contents of ethyl decanoate, n-octanal, isoamyl hexanoate, 2-methylethyl acetate, ethyl valerate, butyl valerate, and cis-rose oxide were significantly higher in whole kiwifruit wine (P < 0.05) while the relative contents of 3-octanol and 2,6-dimethylpyridine were significantly lower (P < 0.05), compared with that made from peeled kiwifruit. Sensory evaluation results showed that whole kiwifruit wine had higher overall scores with a prominent characteristic aroma, which was superior to peeled kiwifruit wine in terms of overall balance. In summary, this study showed that fermentation using whole kiwifruit improved the flavor quality of kiwifruit wine. This finding provides a theoretical basis and data support for the optimization of the kiwifruit wine brewing process and quality improvement.

Staphylococcus aureus is one of the important pathogens that cause food contamination worldwide, and poses a great danger to people. The common treatment is antibiotic therapy; however, the misuse of antibiotics has led to the continuous emergence of drug-resistant strains. Therefore, new antibacterial methods need to be explored. In this study, a lytic S. aureus phage (named SP-CmSa-11) was isolated from dairy farms which belongs to the Myoviridae phage family. The optimal multiple of infection of SP-CmSa-11 is 0.1, and the host range included 7 strains of mastitis cow-derived S. aureus, 12 strains of animal-origin methicillin-resistant S. aureus, 1 strain of S. xylosus, 1 strain of S. epidermidis and 1 strain of Enterococcus faecalis. SP-CmSa-11’s burst period was 40 min, and the burst size was about 130 PFU/cell. SP-CmSa-11 was inactivated after 10 min in a water bath at 70 °C, and the pH tolerance of SP-CmSa-11 ranges from 4 to 10 in 2 h. It’s insensitive to chloroform and ultraviolet radiation. The total genome length of SP-CmSa-11 is 45 816 bp. The G + C content is 27.23%, and has 59 putative open reading frames. SP-CmSa-11 showed good antibacterial effects in vitro and milk. These results suggest that SP-CmSa-11 may be a promising alternative therapy for food contamination caused by S. aureus.