In order to study the effects of different types of electric field combined with controlled freezing-point storage on the water retention properties of fresh pork, the changes in the moisture content, storage loss, cooking loss, transverse relaxation time T₂, surface hydrophobicity and structure of myofibrillar protein in pork Longissimus dorsi were comparatively analyzed under different storage conditions, namely alternating electric field-assisted controlled freezing-point storage (−1.0 ± 0.5) ℃, electrostatic field-assisted controlled freezing-point storage and controlled freezing-point storage (control group). The results showed that the moisture content and relaxation peak area percentage (P₂₁) for immobile water in the alternating electric field and electrostatic field treatment groups were significantly higher than those in the control group (P < 0.05), and the storage loss, cooking loss, surface hydrophobicity of myofibrillar protein and relaxation peak area percentage (P₂₂) for free water were significantly lower than those in the control group (P < 0.05), but there was no significant difference between the electrostatic field treatment groups. In conclusion, both electrostatic fields can delay the degradation of myofibrillar protein and the transformation of immobile water into free water, consequently improving the water retention properties and reduce the juice loss of fresh pork during storage.

The slaughter performance and the nutritional quality and processing quality of the meat of Laiwu black goats were analyzed by measuring dressing percentage, meat pH, meat color, cooking loss, crude protein, crude fat contents and the number of fast and slow muscle fibers. Sensory evaluation was also performed on meat samples. The results showed that there were significant differences in all tested parameters among goat carcasses slaughtered at different ages. However, there was no significant difference in dressing percentage between carcasses at 12 (48.21%) and 24 months (48.75%) of age, which was significantly higher than that (43.55%) at 8 months, and the meat to bone ratio at 12 months was 4.04, lower than that at 8 and 24 months. The meat color at 8 months of age was redder and brighter than that at other ages. The crude protein contents of goat meat at 8, 12 and 24 months were 19.29%, 21.34% and 22.00% respectively, and the crude fat contents were 1.83%, 2.08% and 2.10% respectively. The shear force of meat at 8 months was 4985.98 g, which was significantly lower than that at other ages. The best meat tenderness appeared at the slaughter age of 8 months. At this age, the number of fast muscle fibers was the highest and the ratio of fast to slow muscle fibers was 6.36, significantly higher than that at other ages; the sensory evaluation score was the highest. Based on the above experimental results, 8-month-old Laiwu black goats can be produced as high-grade lamb, and the slaughter benefit of 12-month-old lamb carcasses is higher.

This study was conducted in order to explore the effects of packaging methods and packaging at different postmortem times on the quality changes of lamb meat during postmortem storage. Lamb Longissimus thoracis et lumborum muscle, obtained from carcasses hot-boned at 1 h postmortem or chilled carcasses boned at 24 h postmortem, were packaged by four different methods, heat shrink packaging (HSP), vacuum packaging (VP), skin packaging (SP), modified atmosphere packaging (MAP) with 50% O₂ + 50% CO₂, and were stored at (2 ± 2) ℃. The pH, color, purge loss, cooking loss, centrifugal loss, shear force and volatile odor of lamb meat were analyzed during storage. Results showed that compared with that packaged at 24 h postmortem, lamb meat packaged at 1 h postmortem had a higher pH after 14 days of storage, maintained its color better during the storage period, and exhibited a lower purge loss. Overall, lamb meat subjected to the three vacuum treatments (HSP, VP and SP) had a higher tenderness than that in MAP packaged lamb meat; lamb meat vacuum-packaged at 1 h postmortem had the highest tenderness, while that packaged in modified atmosphere at 24 h postmortem had higher tenderness at early period of storage. Irrespective of packaging time, HSP and MAP significantly lowered purge loss compared with the other treatments (P < 0.05). The color and color stability of lamb meat in the HSP and MAP groups remained good during the early period of storage, whereas the color stability declined noticeably during the late period of storage. The color of MAP packaged lamb meat became partly green after 14 days of storage, and the volatile odor greatly changed after 21 days. In conclusion, packaging at 1 h postmortem contributes to maintain the color and water-holding capacity of lamb meat during storage and improve the tenderness of vacuum-packaged meat. Packaging at 24 h postmortem is beneficial to improve the tenderness of MAP packaged lamb meat during the early period of storage. HSP and MAP packaged lamb meat has a higher water-holding capacity, and their color and color stability remain good during the early period of storage. The quality of VP and SP packaged lamb meat remains relatively stable and thus, they can be stored for a long period of time.

Microbial growth causes lamb spoilage. This study explored the spoilage ability of Latilactobacillus sakei, Serratia proteamaculans and Hafnia 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 trichloroacetic acid-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 the strongest effect on promoting free fatty acid 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 acid, S. proteamaculans produced 1-hexanol and acetoin, and H. proteus produced 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.

Chilling is an essential process in chilled meat production, and various chilling methods are available for actual production. Different chilling methods have different effects on meat quality. Very fast chilling has several advantages like shortening the chilling time of livestock and poultry meat, reducing the chilling loss, delaying the postmortem physiological and biochemical processes, and reducing the proliferation of microorganisms on the surface of meat. However, no consensus has been reached on the effect of very fast chilling on the tenderness of meat, which may be associated with its unclear mechanism. This limits the application of very fast chilling technology. Therefore, this article systematically reviews recent progress in understanding the effect of very fast chilling on postmortem muscle tenderness, with a focus on its potential mechanism from five aspects: physical restraint, physical damage, early postmortem release of calcium, the glycolysis process and the apoptosis process, in order to provide a theoretical basis for the development and application of very fast chilling technology.

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.