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To evaluate the effects of early postmortem vacuum packaging (VP) on meat quality during postmortem chilled storage, hot-boned lamb was vacuum-packaged at 1, 6, 12, 24, and 48 h postmortem and stored around 2°C until 168 h postmortem, with lamb packaged in plastic wrap as the control (aerobic packaging). Intramuscular pH decline was delayed when lamb was vacuum packaged at 1, 6, and 12 h postmortem (p0.05). The lamb vacuum-packaged at 1 h postmortem (VP-1h group) had significantly lower shear force values and purge losses accompanied by lower free thiol group values than other treatments during postmortem storage and was also higher in extractable calpain-1 activity by 6 h postmortem (p0.05). Free thiol group concentrations were significantly higher after VP at 6 and 12 h postmortem (p0.05). Packaging lamb under vacuum very early postmortem produced the lowest shear force and purge loss, likely by slowing heat loss and muscle temperature decline, implying that lamb quality is improved by VP when applied very early postmortem. This was at the expense of protein oxidation, which was unrelated to other meat quality measurements, most likely because potential contracture during hot boning confounded its impact. Further research is required to understand the implications of the interaction between protein oxidation, VP, and hot boning on the acceptability of lamb.

BACKGROUND The abnormal ultimate pH (pHu ) in postmortem muscles affect the meat quality and results in substantial economic losses. Dark, firm, and dry (DFD) meat linked with the higher postmortem pHu values and exhibited many quality issues such as dark color, tough texture and shorter shelf life. This research aimed to investigate the effect of protein phosphorylation on variations in beef pHu in order to explore the possible mechanisms underlying DFD meat formation. RESULTS Glycogen and lactate contents were higher, while L* and a* were lower in high pHu beef. Shear force was higher in intermediate pHu group. Global phosphorylation of sarcoplasmic proteins was higher in low pHu samples on day 1 and of myofibrillar proteins was higher in intermediate pHu meat on days 1 and 2 postmortem. Sarcoplasmic protein bands with different phosphorylation levels were identified as containing some glycometabolism and stress response proteins and phosphorylated myofibrillar protein bands were identified sarcomeric and metabolic proteins. CONCLUSIONS Phosphorylation of multiple proteins of glycolytic pathway and contractile machinery may play critical roles in development of DFD beef. © 2021 Society of Chemical Industry.

Phosphorylation post-translational modification plays an important role in postmortem muscle quality traits. Adenosine triphosphate (ATP) is an energy source and a key substrate of phosphorylation which provides the phosphatase groups to proteins in the presence of protein kinases. However, in postmortem muscle, the effects of ATP content on phosphorylation are poorly studied. The study investigated the effect of ATP on protein phosphorylation and degradation in postmortem ovine muscle. The ground muscle with/without additional ATP were treated/control groups and stored at 25 and 4°C, respectively. The ATP content led to different changes of pH value between the ATP-treated and control groups. The phosphorylation level of myofibrillar proteins was higher (P

Two-step dry fractionation was employed to prepare the liquefied sheep tail oil at the pilot scale. Sheep tail oil was separated into fat residuals, crude oil, stearin A, stearin B, olein A, and olein B. The extracted rates for crude oil, olein A, and olein B were 66.7, 45.9, and 35.0%, respectively. The ratios of saturated/unsaturated fats in the crude oil, olein A fractions, and olein B fractions were 0.62, 0.63, and 0.60, respectively. The olein B was liquid at ambient temperature and its melting point was 5.32 °C. The iodine values of stearin samples were significantly decreased compared to the crude oil samples (P β’ form, and the solid fat content was significantly higher than the olein fractions (P

Background Meat quality is a prerequisite to the consumer's acceptability and industrial profitability. Post-translational modifications, changes in myofibrillar protein degradation and myoglobin oxidation have a great impact on meat quality during post-mortem aging of muscle. Applying proteomics to search for protein biomarkers to accurately assess meat quality is a new strategy to ensure high-quality meat. Scope and approach The current progress of using proteomics to identify potential protein biomarkers of meat quality traits during post-mortem aging of muscles has been reviewed in this paper. The advantages and disadvantages of different methods of protein separation, identification and quantitative analysis are summarized. Some potential protein biomarkers of meat quality traits belonging to different biological pathways involved in muscle contraction, metabolism, heat stress, oxidation, proteolysis and apoptosis are debated. Recently, biomarkers have been used to characterize meat tenderness, color and water-holding capacity to better understand the biological processes and pathways occurring in post-mortem muscles, and their detailed molecular mechanisms are discussed in this review. Key finding and conclusion Post-mortem aging of muscle is a complex process that involves physical and biochemical changes at the cellular level. Clarifying the changes and mechanisms of muscle-to-meat conversion is of great significance in identifying protein markers for assessing meat quality. Previous studies of the biomarkers linked to meat tenderness, color and water-holding capacity are summarized. We found that some great challenges still exist in characterizing and predicting the accuracy, stability and industrial application of meat quality biomarkers. Based on these studies, future research about biomarkers of meat quality traits are proposed to tackle these challenges and to assess the meat quality more accurately. Therefore, applying proteomics as an emerging technology can be helpful to ensure high-quality meat and provide economic benefits for the meat industry.

This study explored the changes in postmortem metabolites of atypical and typical DFD beef using UHPLC-Q-TOF/MS. The longissimus thoracis muscles were categorized into normal, atypical DFD and typical DFD groups. The L

Microorganisms proliferate, consume nutrients, and produce many undesired metabolites, which are the main reason for the spoilage of fresh meat. Screening spoilage markers is of great significance for characterizing the freshness of fresh meat. At present, there are few studies on the volatile spoilage markers (VSMs) of lamb and their relationship with bacteria. In this study, the spoilage evolution of lamb was evaluated by multiple indicators. The changes of bacteria and volatile organic compounds (VOCs) in aerobic-packaged (AP) and vacuum-packaged (VP) lamb were measured by 16S next-generation sequencing (NGS) and headspace solid-phase microextraction (HS-SPME)-gas chromatography-mass spectrometry (GC-MS) respectively. The potential VSMs were also screened. Results showed that the shelf life of AP lamb at 4 °C was less than 10 d and VP lamb was less than 28 d. Pseudomonas was the dominant bacteria in AP lamb, while Latilactobacillus and Lactococcus were the dominant bacteria in VP lamb. Several VOCs could be recommended as potential spoilage markers, including 1-octen-3-ol, 1-hexanol, nonanal, methoxy-phenyloxime, 2,3-octanedione, acetoin and 1-pentanol for AP lamb; acetoin, 1-hexanol, 2,3-octanedione, hexanoic acid, 1-octen-3-ol, nonanal, hexanal and 2,3-octanediol for VP lamb. This study can provide information for characterizing and predicting the freshness of fresh lamb.

To increase the color stability of hemoglobin (Hb) powder, the technological conditions for arginine–hemoglobin (Arg‐Hb) powder preparation were optimized by response surface methodology and the influence of arginine (Arg) on the color stability of Hb powder was evaluated. Results showed that: (a) Arg‐Hb powder had better colors (less MetHb% and higher a* value) than Hb powder (p < 0.05); (b) using MetHb% as an indicator, the optimal conditions to prepare Arg stabilized Hb were Arg concentration of 10.5 mg/ml Hb extract, reaction pH of 10.75, and reaction temperature of 18°C; (c) pH and NaCl had a significant influence on the color stability of Hb (p < 0.05). At various NaCl concentrations and pH conditions, Arg‐Hb solution showed better color than Hb (p < 0.05); (d) Arg‐Hb powder had higher a* values and higher percentages of deoxyhemoglobin and oxyhemoglobin but lower MetHb% than Hb powder during storage (p < 0.05).

This research aimed to investigate the influence of myosin regulatory light chain (MRLC) phosphorylation on actomyosin dissociation and myosin degradation in post‐mortem ovine longissimus thoracis (LT) muscle with a purpose for strategies to improve meat quality in practice. Data obtained show that the highest actomyosin dissociation occurred at 48 h post‐mortem. Based on the cluster analysis of the actomyosin dissociation degree at 48 h post‐mortem, samples were divided into high, middle and low‐actomyosin dissociation groups. During 0.5–72 h post‐mortem, the phosphorylation level of MRLC significantly decreased (P

This work investigated the effects of chilling rate on the progression of rigor mortis and explored possible mechanisms. Silverside from 18 lamb carcasses was assigned to control group (1.94 °C/h), very fast chilling-I group (VFC-I, 12.19 °C/h) and VFC-II group (15.10 °C/h). The shear force, myofibril fragmentation index (MFI), actomyosin ATPase activity, protein degradation and actomyosin dissociation were determined. There was no increase in the shear force in VFC-II group. The activation of actomyosin ATPase at 2–4 h postmortem in VFC-II group resulted in super-contracted sarcomeres and an increase in MFI. The degradation of μ-calpain, troponin T and desmin in VFC-II group was higher than that in control group from 6 to 24 h postmortem. These results suggested that rigor mortis was influenced which resulted in decreased shear force at a chilling rate of 15.10 °C/h by activating actomyosin ATPase and μ-calpain at early postmortem and promoted actomyosin dissociation.

Phosphorylation of myosin regulatory light chain (MRLC) can regulate muscle contraction and thus affect actomyosin dissociation and meat quality. The objective of this study was to explore the mechanism by how MRLC phosphorylation regulates actomyosin dissociation and thus develop strategies for improving meat quality. Here, the phosphorylation status of MRLC was modulated by myosin light chain kinase and myosin light chain kinase inhibitor. MRLC phosphorylation at Ser17 decreased the kinetic energy and total energy of actomyosin, thus stabilized the structure, facilitating the interaction between myosin and actin; this was one possible way that MRLC phosphorylation at Ser17 negatively affects actomyosin dissociation. Moreover, MRLC phosphorylation at Ser17 was beneficial to the formation of ionic bonds, hydrogen bonds, and hydrophobic interaction between myosin and actin, and was the second possible way that MRLC phosphorylation at Ser17 negatively affects actomyosin dissociation.

Meat quality plays an important role in the purchase decision of consumers, affecting producers and retailers. The formation mechanisms determining meat quality are intricate, as several endogenous and exogenous factors contribute during antemortem and postmortem periods. Abundant research has been performed on meat quality; however, unexpected variation in meat quality remains an issue in the meat industry. Protein posttranslational modifications (PTMs) regulate structures and functions of proteins in living tissues, and recent reports confirmed their importance in meat quality. The objective of this review was to provide a summary of the research on the effects of PTMs on meat quality. The effects of four common PTMs, namely, protein phosphorylation, acetylation, S-nitrosylation, and ubiquitination, on meat quality were discussed, with emphasis on the effects of protein phosphorylation on meat tenderness, color, and water holding capacity. The mechanisms and factors that may affect the function of protein phosphorylation are also discussed. The current research confirms that meat quality traits are regulated by multiple PTMs. Cross talk between different PTMs and interactions of PTMs with postmortem biochemical processes need to be explored to improve our understanding on factors affecting meat quality.

As the most important pigment for meat color, myoglobin mainly exists in sarcoplasm, and meat color is determined by its absolute content as well as the relative content of three types of myoglobin (oxymyoglobin, deoxymyoglobin, and metmyoglobin). Previous studies have shown that protein phosphorylation may negatively regulate the stability of meat color through the regulation of glycolysis pathway and myoglobin. The purpose of this research was to study the influence of phosphorylation on myoglobin stability, in order to provide a theoretical basis for improving the stability of meat color through regulating phosphorylation level. Sodium hydrosulfite was used to reduce myoglobin from skeletal muscle, and later was removed by ultrafiltration. Then alkaline phosphatase (AP) was added to in vitro incubation system to catalyze the dephosphorylation of myoglobin. The changes in myoglobin phosphorylation level were measured by SDS-polyacrylamide gel electrophoresis (SDS-PAGE) and Pro-Q Diamond and Ruby phosphoprotein gel staining. We also kept a record of the changes in pH and used ultraviolet spectrophotometer to measure the relative content of three myoglobin redox forms. The ultraviolet spectrophotometer of myoglobin was determined by circular dichroism (CD) spectroscopy. Myoglobin phosphorylation may lead to changes in its secondary structure, therefore reducing myoglobin stability and increasing its autoxidation rate, which further accelerated the accumulation of metmyoglobin. As a result, meat color was found to have a low stability, and this might be one of the explanations that protein phosphorylation negatively regulated meat color stability.

Tenderness is one of the most important quality attributes especially for beef and lamb. As protein phosphorylation and dephosphorylation regulate glycolysis, muscle contraction, and turnover of proteins within living cells, it may contribute to the conversion of muscle to meat. The protein phosphorylation level (P/T ratio) of the tender group increased from 0.5 to 12 h postmortem and then decreased. The P/T ratio of tough group increased during 24 h postmortem, with higher increase rate from 0.5 to 4 h postmortem than from 4 to 24 h postmortem. The global phosphorylation level of tough meat was higher than tender meat at 4, 12, and 24 h postmortem. Protein identification revealed that most of the phosphoproteins were proteins with sarcomeric function; the others were involved in glycometabolism, stress response, etc. The phosphorylation levels of myofibrillar proteins, e.g. myosin light chain 2 and actin, were significantly different among groups of different tenderness and at different postmortem time points. Protein phosphorylation may influence meat rigor mortis through contractile machinery and glycolysis, which in turn affected meat tenderness.

Salting is one of the most ancient preservation methods for food, which is widely used to preserve meat and improve the quality of meat products, such as water holding capacity (WHC), texture, tenderness, flavor, taste, and so on. Protein phosphorylation is one of the most ubiquitous post-translational modifications (PTMs). Reversible protein phosphorylation plays an important role in protein structure, function, signaling, and regulation. As one of the most essential processes for meat products, the effects of salting on muscle protein phosphorylation are unclear. Thus, we investigated the phosphorylation of myofibrillar and sarcoplasmic proteins in response to salt content and salting time. We discovered that salting showed significant effect on myofibrillar protein phosphorylation. Four categories of phosphorylated protein were identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS), involved in stress response (heat shock protein), glycometabolism (glycogen phosphorylase, glyceraldehyde-3-phosphate dehydrogenase), oxidation or reduction (superoxide dismutase), and others (myoglobin). The phosphorylation level of the proteins mentioned above was affected by salting. Thus, salting might influence meat quality through protein phosphorylation, which regulated protein degradation and glycolysis. Furthermore, ten different phosphoproteins (>1.5 fold) induced by salting were identified by LC-MS/MS and the UniProt database, most of which were involved in glycometabolism, protein function, and protein degradation. It was concluded that salting might influence meat quality through protein phosphorylation, which regulated glycolysis metabolism, protein function, and degradation.

μ-Calpain is the key enzyme in postmortem meat tenderization. Studies have shown that μ-calpain can be phosphorylated and phosphorylation influences the activity of μ-calpain. However, whether μ-calpain can be phosphorylated in postmortem muscles and the possible relative influencing mechanism remains unknown. The longissimus lumborum (LL) muscles were used in this research. The relationship between phosphorylation level of sarcoplasmic proteins, μ-calpain activity, and calpastatin degradation in mutton with different tenderness was analyzed. Alkaline phosphatase and phosphatase inhibitor were used to modulate the phosphorylation level of sarcoplasmic proteins, and the effect of phosphorylation of sarcoplasmic proteins on μ-calpain activity was studied. The phosphorylation level of μ-calpain was regulated in vitro, and the influence of dephosphorylation and phosphorylation of μ-calpain on μ-calpain activity was investigated. The changes in the secondary structure of μ-calpain were studied and the phosphorylation sites of μ-calpain were identified to illustrate the directly regulatory mechanism of μ-calpain activity by phosphorylation. The effects of calpastatin on phosphorylated μ-calpain and the effects of phosphorylated calpastatin on μ-calpain were also analyzed. The study of the effects of phosphorylation on the interaction between calpastatin and μ-calpain clarified the indirectly regulatory mechanism of phosphorylation on μ-calpain activity.

Myofibrillar proteins degradation contributes to meat tenderization during postmortem. Protein phosphorylation has been revealed to be associated with meat tenderness in recent years. This chapter aimed to investigate the effect of myofibrillar protein phosphorylation on the degradation susceptibility by μ-calpain. Protein kinase A (PKA) and alkaline phosphatase (AP) were added to myofibrillar proteins, extracted from ovine longissimus lumborum (LL) muscles, to modify the phosphorylation level for 30 min at 30 °C. The samples were then incubated with μ-calpain at 4 °C at different Ca2+ concentrations. The results showed that more degradation products of myosin heavy chain, actin, titin, desmin, and troponin T were detected with the increase of Ca2+ concentration. The protein degradation was higher in AP treated group compared to the control group. This research indicated that phosphorylation prevented proteolytic susceptibility of myofibrillar proteins to degradation by μ-calpain. Protein phosphorylation made a major contribution in meat tenderization during postmortem.

Developing new techniques to improve meat quality is a popular topic. In this chapter, three novel methods for improving the meat quality are provided, including controlled freezing point storage (CFPS), low-variable temperature and high humidity thawing (LVTHHT), and pulsed vacuum pickling (PVP) technologies. Meat stored in CFPS treatment for 10 days proved to have better color stability in comparison with those in 4 °C storage. The LVTHHT could significantly prevent the deterioration of lamb quality, and it was low cost and easy to operate. PVP could improve salting efficiency and meat quality.

With the advancement of technical approaches, signaling pathways have been continuously discovered in numerous biological processes. Majority of these signaling pathways include the protein phosphorylation, which is a main post-translational modification affecting the structure and function of proteins within the cell. Consequently, determining the locations and extent of the protein phosphorylation of any specific protein or set of proteins, either qualitatively or quantitatively, has become a routine and extremely vital step in many fields of life sciences, and recently in meat science as well. However, when choosing the method to detect protein phosphorylation, it can be different depending on several aspects, particularly under consideration of the availability of the related reagents and equipment. Although different methods have their own advantages, but this is also a matter of fact that every method is associated with several drawbacks such as poor specificity, low sensitivity, safety issues, or intensive labor. In this chapter, we outlined the routine methods used to detect the protein phosphorylation and discussed their advantages and disadvantages, especially focusing on the usage of gel and liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) techniques to identify phosphorylated proteins in meat science field.

Water holding capacity and its corollary, drip loss, are important meat quality indicators. The high drip loss muscle had lower pH, higher brightness, higher shear force value, and shorter sarcomere length than the low drip loss muscle. The protein phosphorylation level of different drip loss muscles was detected via the sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) in this study. The results showed that the phosphorylation level of sarcoplasmic and myofibrillar in the high drip loss group was higher than that in the low drip loss group. Combined with the gray value analysis, the bands with higher phosphorylation levels of sarcoplasmic proteins were mainly enzymes involved in glycolysis which could affect the pH; while the bands with higher phosphorylation levels of myofibrillar proteins were mainly cytoskeletal proteins and contractile proteins. It can be concluded that the low pH and increased muscle contraction had a major influence on muscle drip loss.

Glycolysis, the core metabolic pathway in muscle, is very significant to the ultimate meat quality. The objective of this chapter was to confirm the involvement of protein phosphorylation on postmortem glycolysis and the possible regulatory mechanism from the perspective of enzyme activity. The global phosphorylation level of sarcoplasmic protein increased early postmortem and then decreased afterwards in muscle. Protein bands with significantly different phosphorylation level were identified as glycometabolism related enzymes. By applying quantitative proteomic tools (isobaric Tags for Relative and Absolute Quantitation, iTRAQ) and bioinformatics analysis, 24 phosphoproteins clustered in glycolysis and muscle contraction were identified to be glycolytic rate related proteins, and phosphorylation of pyruvate kinase at Thr 157 was negatively correlated with glycolytic rate. Furthermore, the animal muscle was treated with a kinase inhibitor, dimethyl sulfoxide, or a phosphatase inhibitor. Protein phosphorylation was positively correlated with the activity of glycogen phosphorylase, pyruvate kinase, and phosphofructokinase. In conclusion, protein phosphorylation played a role in postmortem glycolysis through the regulation of enzyme activity in muscle. Protein phosphorylation was related to postmortem glycolysis and glycolytic enzymes, and the phosphorylation level of glycolytic enzymes may influence its activities, further regulating postmortem glycolysis.

Extensive studies have revealed that protein phosphorylation plays an important role in postmortem meat quality, such as tenderness, color, and water holding capacity. During storage of meat, the storage temperature is one of the most important factors that determine meat quality. High temperature promotes meat spoilage by accelerating biochemical reactions and microbial growth. However, whether storage temperature affects the development of meat quality through phosphorylation is not well understood. In order to investigate it clearly, the postmortem ovine muscle samples were stored at 25 °C, 15 °C, 4 °C, and −1.5 °C from 0.75 h to 21 days. The correlation between temperature, pH, adenosine triphosphate (ATP) content, and phosphorylation levels was analyzed, and then differential phosphorylated proteins were identified by using liquid chromatography-tandem mass spectrometry (LC-MS/MS) and gene ontology analysis. Myosin binding protein C, troponin T3, actinin, myosin light chain, heat shock protein 90, glucose-6-phosphate, pyruvate kinase, enolase, fructose-bisphosphate aldolase, L-lactate dehydrogenase, etc. were phosphorylated in postmortem ovine muscles. Moreover, ATP content was a vital factor which had the strongest correlation with the phosphorylation level of individual protein band. In order to prove whether ATP content mainly affected phosphorylation level, ATP was added to ground ovine muscle in vitro, which showed that ATP improved the phosphorylation level of myofibrillar proteins. The phosphorylation reaction was reversible. However, ATP was unnecessary for dephosphorylation. Whether the particular temperature and pH (5.2, 5.8, 6.4) had effect on the dephosphorylation of myofibrillar protein through alkaline phosphatase are need to be studied. The result showed that −1.5 °C and pH 5.2 restrained the activity of alkaline phosphatase and decreased phosphorylation level. Phosphorylation was an essential post-translational modification and more insights were needed for the complicated formation in postmortem muscle.

The relationship between meat color stability and protein phosphorylation was studied. By adding phosphatase and protein kinase inhibitors into sarcoplasmic proteins from minced ovine longissimus thoracis et lumborum (LTL) muscle, we found out that protein phosphorylation had a significant relationship with lactate accumulation, as well as pH decline rate and extent. Also, meat color stability had a negative correlation with sarcoplasmic protein phosphorylation level. Therefore, how protein phosphorylation regulated glycolysis and myoglobin redox forms, and furthermore meat color stability was investigated in the second step. Results showed that phosphorylation differences existed in some individual protein bands, but not in whole sarcoplasmic proteins, from muscle groups with different meat color stability. Glycolytic enzymes turned out to be the most color stability related proteins, and myoglobin phosphorylation level was negatively related to meat color stability, which meant protein phosphorylation might regulate meat color stability via glycolysis and myoglobin redox stability. At the third step, the protein phosphorylation level of muscles with different color stability was examined with quantitative analysis. We successfully identified 3412 phosphopeptides from 1070 phosphoproteins, and among which 243 had a significant correlation between phosphorylation level and meat color stability. With further study into these phosphopeptides through informatics analysis, 27 of them were highly related to meat color stability, and glycolytic enzymes were the biggest group. Moreover, there was a negative correlation between the Ser133 phosphorylation level in myoglobin and meat color stability. In conclusion, our results revealed that protein phosphorylation may regulate meat color stability through glycolytic enzymes and myoglobin redox forms, and Ser133 played a key role in the process.

The freshness and microbial community composition of lamb carcasses were evaluated under three chilling rates treatments: conventional chilling (chilling rate was 1.76 °C/h), very fast chilling-I (VFC-I, chilling rate was 12.52 °C/h), and very fast chilling-II (VFC-II, chilling rate was 14.52 °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.

Summary Heterocyclic aromatic amines (HAAs) are mutagenic and carcinogenic compounds, which are commonly detectable in cooked meat products. The objective of this study was to evaluate the effect of sheep breeds on the formation of HAAs in smoking cooked lamb. The results showed that HAAs in smoked lamb meat products were generally low (2.74–5.42 ng g−1), with most being Harman and Norharman. IQ, MeIQx, 4,8-DiMeIQx, Trp-p-2, PhIP and MeAaC were not detected in smoked lamb meat products in the present study. The total content of HAAs differed between meat products of different sheep breeds, but no difference in the order of magnitude was determined. Smoking altered the content of protein, fat, moisture and free amino acids in lamb meat products, which was probably mostly contributed by the reduction in meat moisture. Free tryptophan decreased in all breeds after smoking, which was probably used to synthesise HAAs. In summary, HAAs were low in smoked lamb meat products of all sheep breeds; thus, consumption of smoked lamb meat products should contribute very limited intake of HAAs.

Two studies were performed to assess the efficacy of Lactobacillus plantarum B1 in prevention of pathogenic Escherichia coli K88 gastrointestinal infection in broilers. In an in vitro study, L. plantarum B1 showed resistance to acid and bile and inhibited the growth of E. coli K88. Additionally, L. plantarum B1 exhibited high ability to adhere to broiler embryo ileal epithelium. In an animal trial, 240 broilers at 1 d of age were randomly assigned to one of 4 treatment arms: negative control (NC) broilers fed a basal diet and not challenged; positive control (PC) broilers fed a basal diet and challenged with E. coli K88; L. plantarum (LP) treatment broilers fed a basal diet containing 2 × 109 cfu/kg L. plantarum B1 and challenged with E. coli K88; and antibiotic treatment (Anti) broilers fed a basal diet supplemented with colistin sulfate (20 mg/kg) and challenged with E. coli K88. Broilers fed L. plantarum B1 had greater (P ≤ 0.05) BW than those in the PC treatment on d 14 and 28. Dietary L. plantarum B1 decreased (P < 0.05) E. coli counts in the cecal contents on d 10 and 14, and increased (P < 0.05) cecal lactic acid bacteria (LAB) on d 8, 10, 14, and 28 compared with the PC treatment. Dietary supplementation of L. plantarum B1 increased (P < 0.05) the ileal mucosal secretory IgA concentration and reduced (P < 0.05) IL-2, IL-4, IFN-γ, and tumor necrosis factor-α levels in the ileum. Overall, these results suggest dietary supplementation of L. plantarum B1 promotes growth performance, lowers cecal E. coli counts, and increases the population of cecal LAB, as well as improves intestinal mucosal immunity in E. coli K88-challenged broilers.

The study explored the preservative effects of adding different levels of cinnamon bark oil on meat quality of ground lamb. The longissimus thoracis et lumborum (LTL) meat samples were treated with 0 (control), 0.01%, 0.025%, 0.05%, and 0.5% of cinnamon bark oil and stored at 4 °C for 16 days. Microbial populations of TVC, lactic acid bacteria, and Enterobacteriaceae were reduced up to 0.6 to 1.9 log CFU/g than control from day 4 to 16 during storage. The samples adding 0.025% and 0.05% cinnamon bark oil showed lower thiobarbituric acid reactive substance (TBARS) and pH values but higher L⁎, a⁎, R630/580 and Chroma values than all the other samples (P