Effects of Chilling Rate on the Freshness and Microbial Community Composition of Lamb Carcasses

The freshness and microbial community composition of lamb carcasses were evaluated under three chilling rates treatments: conventional chilling (chilling rate was 1.76 degrees C/h), very fast chilling-I (VFC-I, chilling rate was 12.52 degrees C/h), and very fast chilling-II (VFC-II, chilling rate was 14.52 degrees C/h). The results showed that the freshness indicator including total viable counts (TVC), total volatile basic nitrogen (TVB-N), and thiobarbituric acid reactive substance (TBARS) values of VFC-II treatment were lower than conventional chilling and VFC-I treatments, and the bacterial species richness of the three treatments increased with the extension of storage time. The VFC-II treatment could inhibit the growth of Psychrotrophs and Corynebacterium. At the genus level, the Psychrotrophs became the main dominant spoilage bacterium, and the Turicibacter, Macrococcus, and Brevibacterium were positively correlated with TVB-N significantly. The chilling methods affected the initial diversity of microbiota, and the higher diversity of the microbial community was, the lower abundance of carbon metabolism and purine metabolism was. In conclusion, the VFC-II treatment is conducive to the preservation of lamb carcass.