Functional properties and flavor formation of two Staphylococcus simulans strains isolated from Chinese dry fermented sausages

The objective of this study was to evaluate the functional properties and volatile compounds formation of Staphylococcus simulans HZ01 and HZ02 isolated from Chinese dry fermented sausages. The phylogenetic tree analysis showed that these strains formed an independent evolutionary branch. HZ01 and HZ02 could grow at pH 5.0, 15 degrees C, 150 mg/L NaNO2, and 120 g/L NaCl. The two strains possess high protease and moderate lipase activity. They could hydrolyze sarcoplasmic proteins, and the diameters of halos of HZ01 and HZ02 were 13.1 +/- 0.94 mm and 11.0 +/- 0.35 mm, respectively. Electrophoretic profiles of sarcoplasmic proteins showed that HZ01 could hydrolyze 100% of sarcoplasmic proteins, while HZ02 could hydrolyze 60%. HZ01 and HZ02 could reduce 500 mg/L nitrate to 47.9 +/- 0.52 mg/L and 44.2 +/- 0.14 mg/L nitrite, respectively. Scavenging activities of hydroxyl radicals of HZ01 and HZ02 were 76.1 +/- 3.42% - 92.8 +/- 2.94% and 75.0 +/- 0.05% - 94.4 +/- 2.84%, respectively. HZ01 could significantly (P < 0.05) increase the total sweet amino acids concentration by 14.9% and HZ02 could significantly reduce the total bitter amino acids concentration by 17.9%. The two strains could significantly increase the total esters and aldehydes of volatile compounds of fermented sausages by 37.5% and 35.3%, respectively.