This work studied the changes in microbiological and physiochemical properties during the fermentation of Suan yu by liquid smoking and traditional smoking (batches B, C, and A). Lactobacillus plantarum, Pediococcus pentosaceus, Saccharomyces cerevisiae, and Hansenula polymorpha were the dominant microorganisms in the three samples. Only the acid-resistant Staphylococcus xylosus and Staphylococcus carnosus survived in the acid environment of the final fermented products. The amounts of Enterobacteriaceae, Enterococci, and Pseudomonades in the final fermented products were under the detection limit. Batch B and C samples had higher rate of reduction in pH (4.24 +/- 0.17-4.39 +/- 0.18 from 6.21 +/- 0.24, respectively) and lower acetic acid generation rate (0.06%+/- 0. 00% and 0.05%+/- 0. 00%, respectively) than batch A samples. Large amounts of free amino acids were generated during the fermentation of the samples. Batches B and C had thiobarbituric acid reactive substances (TBARS) value between 0.88 +/- 0.03 and 0.89 +/- 0.03, total volatile basic nitrogen (TVB-N) value between 18.9 +/- 0.34 and 18.8 +/- 0.33 mg/kg, and benzo(a)pyrene (BaP) content of 0.1 +/- 0.00 mu g/kg, which was lower than those of fermented Suan yu prepared by traditional smoking. Sensory analysis indicates that these sample groups have unique smoking and fermentation flavor. Consequently, the fermented Suan yu produced through liquid smoking is a kind of fermented aquatic product with full-bodied smoking flavor, palatable acid flavor, abundant nutrition, and high safety.

This study aimed to determine the predominant processing adaptability of 27 selected isolates of Staphylococcus xylosus in ‘Suan yu’, a traditional Chinese low-salt fermented whole-fish product. The isolates were screened for proteolytic, lipolytic, and enzymatic profiles; amino-acid decarboxylase content; antimicrobial activities; and tolerance to low temperatures, pH 5.0, and salt. Two S. xylosus strains grew at 10 °C in the presence of 10% NaCl and at pH 5.0. Agar-plate assays and sodium dodecyl sulphate–polyacrylamide gel electrophoresis revealed that 21 and 8 of the strains exhibited appropriate proteolytic activities against myofibrillar and sarcoplasmic proteins, respectively. All S. xylosus strains also displayed different enzymatic profiles, and most strains showed negative decarboxylase activities. The results of this step were used as input data for a Principal Component Analysis; therefore, the most technologically relevant strain 3 and 8 were combined with L. plantarum 120 as MS1 and MS2, respectively, were further selected for the fermented fish surimi, and the fish surimi inoculated with mixed starter cultures (MS1, MS2) scored high for overall acceptability. Free amino acid contents of 1757 and 1765 mg/100 g sample were found in fish surimi inoculated with MS1 and MS2, respectively, after 72 h of fermentation. Therefore, Sx-3 and Sx-8, which presented the best predominant processing adaptability, is an eligible starter culture for fermented fish production.