内容: 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.

内容: Salt plays an important role in giving saltiness and adjusting taste in daily life. However, excessive intake of salt will cause certain harm to the body. Therefore, it has become an urgent need to develop new food processing strategies to reduce salt without reducing saltiness. In present study, Maillard reaction was employed to improve the flavor of Katsuwonus pelamis hydrolysates (KPSPs) with saltness. The change of flavor was measured by electronic tongue and sensory evaluation. After Maillard reaction of KPSPs and xylose, the bitter and other unpleasant flavor of the hydrolysates were reduced, whereas the saltiness and acceptability were enhanced significantly. The content of bitter amino acids of the Maillard reaction products of KPSPs (M-KPSPs) was reduced. Due to the covalent bonding between the peptide chain and the sugar molecules, the intrinsic fluorescence intensity was weakened with a redshift of the maximum emission wavelength, indicating that the tryptophan microenvironment became looser and more hydrophilic. The decrease in the composition of bitter amino acids and a change in the secondary structure of the peptides might lead to the change in the perception of flavor. The findings suggested that Maillard reaction affected the flavor characteristics, which provided a new idea for the improvement on non-Na+ saltiness of healthy food additives via Maillard reaction between protein hydrolysate and reducing sugars.

内容: The objective of this study was to investigate the effects of feed restriction on the slaughter performance of rabbit, and antioxidant activity, chemical composition, physical characteristics, amino acid, fatty acid, and volatile compound contents of rabbit meat. A total of 48 male rabbits with similar body weights were randomly allocated into two equal treatment groups: the control group, which received ad libitum access to the feed (AL), and the treatment group, which received 80% of the feed consumed by the control (FR). The results indicated that there were no significant differences in the slaughter performance parameters between the two groups (P > 0.05). Compared with the AL treatment, the FR treatment significantly increased muscle superoxide dismutase activity, 1,1-diphenyl-2- picrylhydrazyl radical scavenging activity, and crude protein content (P < 0.05), whereas it significantly decreased the content of malondialdehyde, water loss rate, and shear force (P < 0.05). Compared with those in the AL treatment group, the rabbits in the FR treatment group presented significantly greater levels of threonine, glutamate, alanine, tyrosine, histidine, proline, and total amino acids (P < 0.05). Moreover, the AL treatment resulted in significantly greater concentrations of C16:0, C16:1, C18:1 n-9c, and monounsaturated fatty acids (P < 0.05), whereas it resulted in significantly lower levels of C18:2 n-6c, C20:4 n-6, and polyunsaturated fatty acids than the FR treatment did (P < 0.05). Furthermore, the FR treatment resulted in significantly greater levels of benzaldehyde, octanal, decanal, hexadecane, carbamodithioic acid diethyl-methyl ester, 2-heptanone, N-ethyl-ethanamine, dimethyl sulfone, and N,N-diethyl-formamide than did the AL treatment (P < 0.05). Overall, mild feed restriction can increase meat quality by increasing muscle antioxidant activity and improving the physical characteristics, amino acid, fatty acid, and volatile compound contents of rabbits under the conditions of this experiment.

内容: The skin of the Chinese giant salamander (Andrias davidianus) is a rich source of collagen. However, current research indicates limited efficiency and activity in collagen protease hydrolysis from this source. Further enzymatic hydrolysis to produce small molecular weight active peptides and their antitumor potential remain underexplored. This study employed a two-step enzymatic hydrolysis method to prepare small molecular weight collagen peptides (SMWCPs), followed by ultrafiltration separation. The extraction process was optimized using single-factor and response surface methodology. The amino acid composition of SMWCPs was analyzed, and their antitumor activity was assessed in vitro through cell migration, cell cycle, and apoptosis assays. Results revealed a negative correlation between collagen peptide molecular weight and antitumor activity, with optimal antitumor activity observed for peptides with a molecular weight of 300–1 000 Da (neutral protease hydrolyzed Chinese giant salamander skin collagen peptides (NP-GSKCP)). Optimal extraction conditions were: enzyme dosage 8 000 U/g, enzymatic hydrolysis temperature 52.6 °C, enzymatic hydrolysis pH 7.1, and enzymatic hydrolysis time 4.3 h, yielding 87.82% NP-GSKCP-IV. Notably, NP-GSKCP-IV contained 55.31% hydrophobic amino acids. Treatment of A549 cells with 5 mg/mL NP-GSKCP-IV significantly altered cell morphology, inhibited migration, arrested the cell cycle at G0/G1 phase, and induced early apoptosis. This study contributes to the development of efficient extraction techniques for antitumor active ingredients from Chinese giant salamander skin and informs the potential development of medicinal functional foods.