The objective of this study was to evaluate the effects of chilling rate on porcine meat quality from the perspective of proteome using data independent acquisition (DIA)-based quantitative proteomic strategy. M. longissimus thoracis et lumborum (n = 9) was assigned randomly to the control group (3.72 ℃/h), very fast chilling-Ⅰ group (VFC-Ⅰ, 9.31 ℃/h) and VFC-Ⅱ group (14.43 ℃/h). The DIA was used to analyze the difference in proteins under different chilling rates. Results showed that tenderness was improved significantly in meat at the chilling rate of 14.43 ℃/h. Seventy-nine differential abundant proteins (fold change >1.5, P <0.05), including 46 up-regulated and 33 down-regulated proteins, were identified and mainly involved in carbon metabolism, pyruvate metabolism and proteasome pathways. These pathways indicated that VFC delayed cell metabolism and glycolysis by down-regulating the expression of metabolic enzymes. The tenderness was improved by up-regulating the expression of proteasome and m-calpain.

Microbial growth causes lamb spoilage. This study explored the spoilage ability of Latilactobacillus sakei (L. sakei), Serratia proteamaculans (S. proteamaculans) and Hafnia proteus (H. proteus) in vacuum-packed raw lamb, including growth ability, degradation of protein and lipid, and change of volatile organic compounds (VOCs) profile, meanwhile screened the key VOCs produced by the targeted strains with meat background excluding, finally confirmed the volatile spoilage marker of vacuum-packaged lamb by comparing with our previous work. The results showed that L. sakei, S. proteamaculans and H. proteus had excellent growth ability. L. sakei inoculated group significantly reduced the pH value, showed higher TCA-soluble peptides content, and excellently degraded sarcoplasmic and myofibrillar proteins. About free amino acids, L. sakei significantly degraded serine, arginine and aspartic acid, while S. proteamaculans and H. proteus significantly degraded serine and lysine. In addition, L. sakei had a strongest effect on promoting free fatty acids production, followed by S. proteamaculans and finally H. proteus. Evaluating from various indicators, the co-culture of the three strains did not have any effect. The key volatiles produced by L. sakei were 1-hexanol, acetic acid and hexanoic aicd, S. proteamaculans were 1-hexanol and acetoin, and H. proteus was 1-hexanol, acetic acid and acetoin. In the end, 1-hexanol, hexanoic acid and acetoin were proven to be spoilage markers for vacuum-packaged and chilled lamb. This study can provide fundamental information for inhibiting and rapid identification of spoilage in vacuum-packaged lamb.