In order to systematically explore the effect of starter on the antioxidant activity of peptides from fermented sausage, the in vitro antioxidant activity of crude peptides extracted from naturally and starter fermented sausage were assessed. The results showed that the peptides from starter fermented sausage had a stronger ability to chelate metal ions and scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH) and hydroxyl radicals, which increased by 13%, 10% and 20%, respectively, compared with the control group, while the 2,2’-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging capacity was weaker than that of the peptides from naturally fermented sausage. Furthermore, the in vivo antioxidant activity of the peptides from starter fermented sausage was evaluated using a mouse model of D-galactose-induced aging. The results of growth performance showed that the crude peptides could promote the growth of mice and increase visceral indices. Moreover, the crude peptides significantly increased the activities of various antioxidant enzymes in the mouse serum and liver tissue including superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) as well as total antioxidant capacity (T-AOC) and reduced malondialdehyde (MDA) content, restoring the antioxidant capacity to normal and even higher than normal levels. This study has shown that the crude peptides from starter fermented sausage have outstanding antioxidant activity, and thus can provide another option for the development of protein-derived antioxidant peptides.

Fermented sausages were manufactured with Staphylococcus simulans NJ201 as a starter, and naturally fermented sausages were used as a control. The pH, color parameters, texture, peroxide value (POV) and thiobarbituric acid reactive substances (TBARS) value, protein carbonyl content, total sulfhydryl content, and volatile flavor composition in fermented sausages were measured to explore the effect of S. simulans NJ201 on the quality and oxidative stability of fermented sausages. The results showed that inoculation with S. simulans NJ201 significantly lowered the pH value of fermented sausage during its fermentation and maturation (P < 0.05), and improved the color and the texture characteristics. The POV, TBARS value and protein carbonyl content of the inoculated group were significantly lower than those of the control group (P < 0.05), whereas the sulfhydryl content was significantly higher than that of the control group (P < 0.05). The number and amount of volatile flavor substances in the inoculated group were higher than those in the control group. In summary, inoculation with S. simulans NJ201 can improve the taste and enhance the flavor of fermented sausages, effectively inhibit fat oxidation and protein oxidation and increase the oxidative stability of fermented sausages.

To explore the effect of functional starter cultures on the quality, flavor and antioxidant activity of fermented fish sausage, we prepared fermented fish sausage by inoculation with a cocktail of the functional starter culture strains Lactobacillus plantarum CD101 and Staphylococcus simulans NJ201 or natural fermentation as a control, and we measured the pH, texture, color difference, antioxidant capacity, volatile flavor substances and free amino acids of the prepared samples. The results showed that inoculation with functional starter culture could rapidly reduce the pH of fish sausage during fermentation and improve the stability and safety of the sausage; improve the hardness and chewiness, and enhance the brightness and color, thereby making the sausage have better quality; significantly increase the scavenging capacity of sausage-derived peptides against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) cation radical cation and hydroxyl radical, contributing to improving the antioxidant activity of sausage-derived peptides; and increase the contents of ketones, esters and other flavor substances, enriching the flavor of the sausage and making it have a stronger sweetness and fruity aroma. Moreover, inoculation with functional starter culture promoted the release of free amino acids from the sausage, which was conducive to enhancing the nutritional properties, antioxidant capacity and flavor of the sausage.

In this study, sauced beef was prepared by three different cooking processes: ultrasonic-assisted stepwise cooking (CF), stepwise cooking (F) and traditional cooking (CT). In order to investigate changes in the flavor substances of sauced beef during different cooking processes, the effect of the three cooking processes on the flavor of sauced beef were analyzed from the perspective of the Maillard reaction. Absorbance at 294 nm (A_{294 nm}) and 420 nm (A_{294 nm}), which can reflect the amount of Maillard reaction products (MRPs) formed in the middle and late stages, respectively, were measured. The results showed significant differences in A_{294 nm} between the CF and CT groups at 0.5 h of cooking (P < 0.05), but no significant differences between the CF and CT groups at 2 and 4 h (P > 0.05). A_{294 nm} and A_{420 nm} were significantly higher in the F group than in the CT and CF groups at 0.5 and 4 h. The CF group had the highest fluorescence intensity. Protein secondary structure analysis indicated an increase in the relative content of β-sheet and a decrease in the relative content of α-helix in the CF and F groups compared with the CT group; α-helix unfolding led to the exposure of intramolecular hydrophobic groups, thereby increasing the surface hydrophobicity and fluorescence intensity. Ultra-high performance liquid chromatography-mass spectrometry (UPLC-MS) identified 103, 167, and 200 differential metabolites in the CT, F, and CF groups, respectively, and a large number of amino acids, dipeptides, nucleosides, and heterocyclic compounds were produced in the CF group; gas chromatography-mass spectrometry (GC-MS) results showed that CF and F promoted the production of volatile flavor substances in sauced beef. The above results indicated that both cooking processes could promote the Maillard reaction and consequently improve the flavor of sauced beef.

In this study, we aimed to investigated the effect of mixed cultures on improving the physiochemical properties, flavor and antioxidant activity of peptides of fermented mutton sausage. The physicochemical indexes such as pH, color and texture, as well as the types and contents of free amino acids and volatile flavor substances in fermented mutton sausage prepared with mixed culture of Lactobacillus plantarum CD101 and Staphylococcus simulans NJ201 and naturally fermented sausage as a control were measured, and the scavenging ability of peptides extracted from the sausages against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals, 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) cationic radicals and hydroxyl radicals were tested. The results showed that the mixed culture was able to rapidly reduce the pH of fermented mutton sausage during fermentation, improve its safety, enhance its brightness, color, hardness and chewiness, thereby improving its quality. Moreover, the mixed culture increased the total amount of free amino acids, the types and contents of volatile flavor substances and consequently enhanced the flavor of fermented mutton sausage, as well as significantly increased the radical scavenging capacity of peptides from fermented mutton sausage. In conclusion, inoculated fermentation could significantly improve physicochemical properties, flavor and antioxidant capacity of peptides from fermented mutton sausage. This study can provide a theoretical basis for the industrial production of fermented meat products.