In this study, by comparing the four groups of sausages, namely, CO (without starter culture), LB (with Lactobacillus sakei), LS (with L. sakei 3X-2B + Staphylococcus xylosus SZ-8), and LSS (with L. sakei 3X-2B + S. xylosus SZ-8 + S. carnosus SZ-2), the effects of mixed starter cultures on physical–chemical quality, proteolysis, and biogenic amines (BAs) during fermentation and ripening were investigated. Inoculation of the mixed starter cultures increased the number of lactic acid bacteria and staphylococci in sausages during fermentation and ripening for 0 to 5 days. The L. sakei 3X-2B + S. xylosus SZ-8 + S. carnosus SZ-2 mixed starter accelerated the rate of acid production and water activity reduction of sausages and improved the redness value. Compared with CO, the mixed starter effectively inhibited Enterobacteriaceae. At the end of ripening, the LSS group was approximately 1.25 CFU/g, which was less than the CO group, thereby reducing the total volatile basic nitrogen (TVB-N) in the LSS group. The free amino acids in the LS and LSS groups (224.97 and 235.53 mg/kg dry sausage, respectively) were significantly (p < 0.001) higher than that in the CO group (170.93 mg/kg dry sausage). The level of histamine, cadaverine, putrescine, and common BAs showed an opposite trend to the increase of the corresponding precursor amino acid content, which were significantly lower (p < 0.001) in the LS and LSS sausages than in CO. This study showed that L. sakei 3X-2B + S. xylosus SZ-8 + S. carnosus SZ-2 is a potential mixed starter for fermented meat products.

To isolate a novel peptide with calcium-binding capacity, sheep bone protein was hydrolyzed sequentially using a dual-enzyme system (alcalase treatment following neutrase treatment) and investigated for its characteristics, separation, purification, and structure. The sheep bone protein hydrolysate (SBPH) was enriched in key amino acids such as Gly, Arg, Pro, Leu, Lys, Glu, Val, and Asp. The fluorescence spectra, circular dichroism spectra, and Fourier-transform infrared spectroscopy results showed that adding calcium ions decreased the α-helix and β-sheet content but significantly increased the random and β-turn content (p < 0.05). Carboxyl oxygen and amino nitrogen atoms of SBPH may participate in peptide–calcium binding. Scanning electron microscopy and energy dispersive spectrometry results showed that SBPH had strong calcium-chelating ability and that the peptide–calcium complex (SBPH–Ca) combined with calcium to form a spherical cluster structure. SBPH was separated and purified gradually by ultrafiltration, gel filtration chromatography, and reversed-phase high-performance liquid chromatography. Liquid chromatography-electrospray ionization/mass spectrometry identified the amino acid sequences as GPSGLPGERG (925.46 Da) and GAPGKDGVRG (912.48 Da), with calcium-binding capacities of 89.76 ± 0.19% and 88.26 ± 0.25%, respectively. The results of this study provide a scientific basis for the preparation of a new type of calcium supplement and high-value utilization of sheep bone.

Beef jerky is a traditional fermented meat product from Inner Mongolia, handcrafted by artisans. We investigated the bacteria of the microbial community, volatile flavor components, and biogenic amines of Inner Mongolia beef jerky via high-throughput sequencing, solid-phase microextraction with gas chromatography–mass spectrometry, and high-performance liquid chromatography, respectively. Thirty-three bacteria were identified, predominantly from the genera Pseudomonas (45.4%), Ralstonia (13.4%), and Acinetobacter (7.3%). Fifty-nine volatile flavor compounds and eight biogenic amines were detected. Based on Spearman’s correlation coefficient, 20 bacterial genera were significantly associated with the dominant volatile compounds in the beef jerky samples (p < 0.05). The results demonstrated that beef jerky may be toxic due to cadaverine, putrescine, and histamine; moreover, the amounts of putrescine and cadaverine were positively correlated with the abundance of unclassified_f_Enterobacteriaceae (p < 0.05). These findings shed light on the formation of the microbial community, flavor components, and biogenic amines of beef jerky, thereby providing a basis for improving its quality.