In order to study the effects of lactic acid bacterial (LAB) starter cultures on microbial quantity, microbial diversity and sensory quality during the ripening of air-dried sausage, three commercial mixed-strain starter cultures, namely SHI-59 (Staphylococcus xylose + Pediococcus pentosus + Lactobacillus plantarum), WBL-45 (Staphylococcus xylose + Staphylococcus carnosus + Lactobacillus sake), and PRO-MIX5 (Staphylococcus xylose + Lactobacillus sake + Lactobacillus paraplantarum) were separately inoculated into ground meat and fermented for 12 days to produce air-dried sausage, and non-inoculated sausage was served as the control group. Samples were taken on days 0, 3, 6, 9 and 12 of ripening to determine the changes in LAB count, total viable count (TVC), Enterobacteriaceae, Pseudomonas and Staphylococcus counts. The samples on days 6 and 12 were analyzed by 16S rDNA high-throughput sequencing, and sensory evaluation was carried out on sausage on day 12. The results showed that LAB count, TVC, the numbers of Enterobacteriaceae, Pseudomonas and Staphylococcus increased first and then decreased with ripening time. SHI and WBL grew and multiplied rapidly in ground meat, and TVC, and the numbers of Enterobacteriaceae and Pseudomonas significantly decreased in the WBL group (P < 0.05), which was found to be beneficial to improve the safety and quality of air-dried sausage. The number of Staphylococcus in the SHI, WBL and PRO groups was significantly higher than that in the control group (P < 0.05), and the increase in Staphylococcus was found to have a positive effect on the formation of the color and flavor of sausages. The analysis of microbial diversity showed that air-dried sausages contained mainly Firmicutes, Proteobacteria and Actinomycetes at the phylum level, among which Firmicutes was the dominant phylum for the four groups, and that the relative abundance of Firmicutes was the highest in the WBL group. The relative abundance of Lactobacillus and Vogococcus in the three inoculated groups was higher than that in the control group. The results of texture analysis and sensory evaluation showed that the combination of LAB starter cultures and a blend of fermented bovine bone flavoring and antioxidants (FBFA) could synergistically improve the sensory quality of air-dried sausage. WBL fermented sausage had a unique flavor and good sensory quality.

In order to study the effect of microbial fermentation on the formation and change of flavor substances in air-dried sausages, commercial mixed-strain starters SHI-59 (Staphylococcus xylose, Pediococcus pentosaceus, and Lactobacillus plantarum), WBL-45 (S. xylose, S. botulinus, and L. sake) and PRO-MIX5 (S. xylose, L. sake, and L. plantarum) were inoculated separately into minced meat and after 12 days of air drying, fermented air-dried sausages were produced and denoted as SHI, WBL and PRO, respectively, and a non-inoculated sample was used as a control. Samples subjected to air drying for 6 and 12 days were analyzed for the content of free amino acids. The flavor changes of air dried sausages during the air drying process were determined by a Heraclesii ultra-fast gas chromatography electronic nose, an electronic tongue and gas chromatography-mass spectrometry (GC-MS). The results showed that as the air drying time increased from six to 12 days, the total amount of free amino acids significantly increased, and the total amounts of free amino acids in SHI, WBL and PRO were 2409.78, 2317.74 and 2655.18 mg/100 g, respectively, significantly higher than that in the control group (2137.82 mg/100 g)(P < 0.05). The four groups of samples could be clearly distinguished in terms of their smell and taste. The flavor richness of PRO was the strongest, followed by SHI and WBL, which had similar smell and taste, and the control group had the smallest flavor richness. Totally 80, 79, 76 and 83 volatile flavor substances were detected in the control, SHI, WBL and PRO groups, respectively. Esters, aldehydes, alcohols, acids and heterocyclic compounds were the major flavor substances of air-driedsausages. The percentages of esters in SHI (20.6%), WBL (24.13%) and PRO (21.71%) were higher than that in the control (19.13%) group, and the ester content of SHI was the highest (2271.62 μg/kg). (E,E)-2,4-Nonadienal and 3-methylbutyric acid made the greatest contribution to the flavor of the control and SHI groups. SHI and WBL contained heptanaldehyde with an odor activity value (OAV) greater than 1, responsible for the fruit flavor, while ethyl butyrate (OAV > 1), responsible for the pineapple-like aroma, was unique to PRO. The results showed that the application of PRO-MIX5 was more conducive to improve the flavor and taste of air-dried sausage compared with the other commercial starters.