Quality characteristics and flavor profile of Harbin dry sausages inoculated with lactic acid bacteria and Staphylococcus xylosus

Pediococcus pentosaceus (Pp), Lactobacillus curvatus (Lc), Lactobacillus sakei (Ls) and Staphylococcus xylosus (Sx) were evaluated to determine their roles in the quality characteristics and flavor formation in Harbin dry sausage. The inoculation of dry sausages with bacterial strains, especially mixed strains (Pp + Sx + Lc and Pp + Sx + Ls), significantly decreased the moisture content and water activity. Compared with the sausages inoculated with a single strain and non-inoculated, those inoculated with mixed strains had shorter transverse relaxation time T-21 that represents the immobilized water (P < 0.05) after a nine-day fermentation. The texture profile analysis showed that inoculation with bacterial strains increased the hardness and springiness of sausages. The sausages inoculated with mixed strains showed higher a*-values (P < 0.05). Furthermore, the percentages of some aldehydes, ketones, alcohols, acids and esters in the sausage inoculated with Pp + Sx + Lc were significant higher than that in control sausages (P < 0.05), which may be derived from carbohydrate catabolism (such as 3-hydroxy-2-butanone), amino acid metabolism (such as 3-phenylpropanol, 2,3-butanediol, phenylethyl alcohol, 2-methyl-propanal, 2-methyl-butanal and 3-methyl-butanal), beta-lipid oxidation (such as 2-pentanone, 2-heptanone and 2-nonanone) and esterification (such as ethyl esters).