Purge Loss Research Articles

Effects of alternating electric field during freezing and thawing on beef quality.

Alternating electric field (AEF) technology was used during freezing-thawing-aging (FA) of beef aged for 0, 1, 3, 5 and 7days. Color, lipid oxidation, purge loss, cooking loss, tenderness, and T2 relaxation time were determined for frozen-thawed-aged beef with AEF (AEF+FA) or without AEF (FA) and compared to aged only (OA) controls. FA increased purge loss, cooking loss, shear force values and lipid oxidation (P<0.05) but decreased a* values compared with AEF+FA treatment. It also exacerbated the spaces between muscle fibers and contributed to the transformation of immobile water to free water. AEF served to maintain meat quality by reducing purge loss, cooking loss and increasing meat tenderness and maintaining color and lipid oxidation only in steak that was frozen before aging. This most likely occurred due to AEF increasing the speed of freezing and thawing and by reducing the space between muscle fibers compared to FA alone.

Impact of a constant current electrical stimulation (CCES) system and hormonal growth-promoting (HGP) implants on meat quality and palatability of finished steers

This study evaluated the effects of a constant current electrical stimulation (CCES) system and hormonal growth-promoting (HGP) implants on the quality and palatability of the longissimus thoracis et lumborum (LTL) from yearling-finished steers. The experiment used a total of 46 Angus cross steers, which were either non-implanted (n = 20) or implanted with trenbolone acetate and estradiol benzoate (n = 26). The CCES was applied to one side of each carcass during the slaughter process, whereas the other side remained unstimulated. Regardless of the application of HGP implants, the CCES reduced pH at 3 and 72 h post-mortem and shear force at all ageing times (P < 0.05), improved colour at 72 h post-mortem and during the retail display (P < 0.05), increased initial and overall tenderness (P < 0.01), and decreased the amount of perceived connective tissue and the proportion of trained panelists detecting spongy texture (P < 0.05) compared to meat from unstimulated carcass sides. Although CCES increased meat purge losses and reduced moisture content (P < 0.05), this did not affect meat juiciness (P > 0.10). CCES interacted with HGP to prevent increase in drip loss (P > 0.10), increase frequency of panelists detecting bloody/serumy flavour and typical texture, and reduce the proportion of panelists detecting rubbery texture in meat (P < 0.05). Regardless of stimulation treatment, meat from implanted animals had a more pronounced pH decline at 72 h post-mortem (P < 0.05) and a higher proportion of panelists finding no off-flavours (P < 0.05) or bloody/serumy flavour (P < 0.01) than non-implanted cattle. The CCES system tested in this study improved LTL quality and palatability of heavier beef carcasses.

Extended Storage of Beef Steaks Using Thermoforming Vacuum Packaging.

Extended storage duration often results in negative quality attributes of fresh or frozen beef steaks. This study focused on evaluating the fresh and cooked meat quality of beef steaks stored using vacuum packaging for 63 days. Steaks 2.54 cm thick were packaged into one of three thermoforming films VPA (250 µ nylon/EVOH/enhanced polyethylene coextrusion), VPB (250 µ nylon/EVOH/enhanced polyethylene coextrusion), or VPC (125 µ nylon/EVOH/enhanced/polyethylene coextrusion). Steaks placed in VPA were lighter (L*) and redder (a*) in surface color (p < 0.05) as the display period increased, whereas steaks packaged in VPB and VPC became darker. Yellowness, hue angle (Hue°), and chroma (C*) values were greater (p < 0.05) in steaks using VPC film as the storage period increased. Calculated spectral values of red to brown were greater (p < 0.05) for steaks in VPA and VPB than in VPC. However, steaks placed in VPC films contained greater (p < 0.05) forms of metmyoglobin and oxymyoglobin and lower calculated relative values of deoxymyoglobin. In addition, packaging treatment altered (p > 0.05) lipid oxidation, but storage time had a greater (p < 0.05) influence on purge loss, cook loss, and Warner-Bratzler shear force (WBSF). Current results suggest that the use of vacuum packaging for extended storage of beef steaks (>60) days is plausible.

Developments of Plant-Based Emulsion-Type Sausage by Using Grey Oyster Mushrooms and Chickpeas.

Plant-based (PB) meat alternatives are developing due to the consumer's demand, especially those who are mainly health-concerned. Soy proteins (SP) are commonly used as the main ingredients for PB meat analogues; however, SP may have adverse effects on the cognitive function and mood of humans. This study aimed to use grey oyster mushroom (GOM) and chickpea flour (CF) as an alternative source of SP to prepare emulsion-type sausages (ES). The effect of different hydrocolloids and oil on the quality of sausage was also investigated. The sausage was prepared using different concentrations of GOM and CF (20:20, 25:15, and 30:10 w/w). The GOM to CF ratio 25:15 was selected for the ES based on protein content, textural properties, and sensory attributes. The result indicated that sausage containing konjac powder (KP) and rice bran oil (RBO) provided a better texture and consumer acceptability. The final product showed higher protein (36%, dry basis), less cooking loss (4.08%), purge loss (3.45%), higher emulsion stability, and better consumer acceptability than the commercial sausage. The best recipe for mushroom-based ES is 25% GOM, 15% CF, 5% KP, and 5% RBO. In addition, GOM and CF could be an alternative option to replace SP in PB meat products.

Changes of Raw Texture, Intramuscular Connective Tissue Properties and Collagen Profiles in Broiler Wooden Breast during Early Storage.

A recently identified broiler myopathy known as wooden breast (WB) is predominantly found in the pectoralis major muscle of fast-growing broiler hybrids and is causing significant losses to the poultry industry. The aim of this study was to investigate the effects of WB syndrome on raw meat texture, purge loss and thermal properties of intramuscular connective tissue of pectoralis major muscle in the early postmortem period (1-3 days). Results showed that the presence of the WB muscles condition at 1 day postmortem was associated with significantly increased stiffness (27.0 N vs. 23.1 N) and significantly increased purge loss (1.8% vs. 1.0%) compared to normal breast (NB). However, on 3 days postmortem, these parameters did not differ between WB and NB groups. Insoluble and total collagen content was significantly higher in WB muscles compared to NB muscles, and the extractability of intramuscular connective tissue (IMCT) of WB was also higher (0.42% vs. 0.37%) compared to NB and remained stable in the early postmortem period. There was significantly lower protein content in the sarcoplasmic protein fraction and myofibrillar protein fraction of WB muscles compared to NB muscles (p < 0.05). The IMCT of these two groups showed different thermal properties, as the enthalpy of denaturation (ΔH) was significantly lower in WB muscles compared to NB muscles. The WB syndrome had a great effect on the texture and connective tissue properties of the meat compared to normal muscle, with a tendency for having a lower purge loss and higher raw meat hardness.

초고압 처리된 돈육으로 제조된 인산염 무첨가 돈육 겔의 품질 특성

This study investigated the quality properties of pork gels manufactured by the pork treated with high hydrostatic pressure (HHP) that was adopted to replace the function of phosphate in pork sausages. The biceps femoris muscles were collected from the pork carcasses. Half of the muscles were subjected to HHP at 200 MPa for 3 min (200 MPa pork), and the rest were used as control (0.1 MPa pork). The pork meat batters were prepared with 200 MPa pork without phosphate (HHP pork gel), or 0.1 MPa pork and phosphate (control), and cooked until it reached 75°C of internal temperature. The actomyosin content was significantly lower in 200 MPa pork than in 0.1 MPa pork (p&lt;0.05). The solubility of myofibrillar proteins tended to be higher than 200 MPa to 0.1 MPa pork (p=0.99). The myosin extracted from 200 MPa pork had a higher α-helix and a lower β-sheet and random coil than that of 0.1 MPa pork (p&lt;0.05). The purge loss of HPP pork gel was not different from that of control after 10 and 20 days of storage at 4°C. However, HPP pork gel showed a lower gel strength than the control (p&lt;0.05). Therefore, we conclude that the water holding ability of pork sausages manufactured without phosphate can be improved using pork treated with HHP. However, the ways for the strength of pork sausages including no phosphate to be similar to that manufactured with phosphate should be further studied.

Strategies to Reduce Purge Losses in Meat Products Stuffed in Plastic Casings

Two different meat emulsions were prepared with different physical stability: R1 with 6.28 ± 1.13% total expressible fluid and R2 with 17.7 ± 1.48%. The emulsions were placed in plastic casings at three different surface tensions (ST), expressed as contact angle, and three distinct overstuffing percentages (OS). The stuffed samples were cooked in an industrial oven. After cooling, purge losses (PL) and texture profile analysis (TPA) were measured. The reduced surface tension of the plastic casings significantly decreased the PL of both recipes. In the case of R2, a combination of high OS and low ST was necessary to reduce PL in a 60%. In the case of TPA, OS had a statistical influence on parameters like chewiness, cohesiveness, and hardness. Plastic casings with different surface tension (to increase adherence of meat emulsion to the casing) stuffed at different levels of overstuffing percentages (to reduce free space between meat emulsion and casing) represent a potential tool to reduce PL of products based on low stability meat emulsions.

Investigation of changes in proteomes of beef exudate and meat quality attributes during wet-aging

This study was performed to evaluate the effects of wet-aging (3, 7, 14, 21, and 28 d at 2 °C) on beef (longissimus lumborum muscles) exudate proteome and meat quality changes. The pH, purge loss, and tenderness of beef increased with aging (P < 0.05), while color and lipid oxidative stabilities decreased, especially when long-term (14 and 21 d) aged meat were repackaged and displayed under retail condition (P < 0.05). Nineteen proteins changed significantly with aging (FDR < 0.05), in which most of them progressively accumulated in exudates over aging periods. Combined with partial least squares discriminant analysis, 16 proteins (including 9 structural proteins, 3 metabolic enzymes, 1 heat shock protein, 2 binding proteins, and KBTBD10 protein) were screened as characteristic proteins that could be used for potential meat quality indication. These findings offered novel insight into the utilization of exudates for meat quality assessment.

Bos indicus Carcasses Suspended by the Pelvic Bone Require a Shorter Aging Time to Meet Consumer Expectations Regarding Meat Quality.

This study evaluated the effects of hanging the carcass by the Achilles tendon (AS) versus pelvic suspension (PS) on meat quality traits. Bos indicus carcasses of two distinct biological types/sex categories comprised 10 young Brangus heifers and 10 Nellore bulls which were finished in a feedlot. Half-carcasses of each biological type/sex category were randomly hung using Achilles suspension (n = 20, AS) or pelvic suspension (n = 20, PS) for 48 h. At boning, longissimus samples were collected for evaluation by untrained consumers for tenderness, liking of flavor, juiciness and overall acceptability, after aging for 5 or 15 days. Objective samples were also tested for shear force (SF), Minolta meat colour, ultimate pH, cooking loss (CL) and purge loss (PL). There was a positive effect (p < 0.01) of PS on the sensory tenderness of Nellore bulls and Brangus heifers aged for 5 days compared to the AS method. At 15 days of aging, difference in sensory tenderness was observed (p < 0.05) in either group. Additionally, an interaction occurred between the suspension method and the aging of Nellore beef (p < 0.05) on liking of flavor, juiciness and overall acceptance, while the same effects were not observed for Brangus beef (p > 0.05). Nellore carcasses submitted to PS tended (p = 0.06) to produce more tender meat than those submitted to AS (SF = 44.62 ± 6.96 vs. 50.41 ± 8.04 N), and lower CL (p < 0.05) were found (27.7 vs. 30.9%). Carcass-suspension methods did not influence meat color, pH or PL in either group (p > 0.05). The PS contributes to improve the quality of Bos indicus bulls loins; in addition, this method allows a reduction in the aging time from 15 to 5 days, and it can be used to supply meat consumer markets which accept a certain level of eating quality.

Product Yield and Color of Striploin and Sirloin Cuts Transported at Different Refrigerated Temperatures

The objective of this study was to determine the impact of environmental temperature during subprimal transporton moisture loss, color, and tenderness. Cases of striploins (n=24) and sirloins (n=24) were placed on 2 pallets. Each pallet was loaded on a refrigerated truck prechilled to −2.2°C (−2.2FT) or 3.3°C (3.3FT) and transported for 12 h prior to arriving at the South Dakota State University (SDSU) Meat Laboratory. One subprimal was subset from each case for further analysis. Purge loss was measured prior to fabrication into eight 2.54-cm steaks. Steaks were overwrapped and packaged in modified atmosphere packaging prior to a second transport. Four steaks from each subprimal were placed on 1 of 2 pallets. Each pallet was placed on a prechilled refrigerated truck set at −2.2°C or 3.3°C. The steaks were transported for 12 h prior to returning to SDSU, subjected to case life analysis, and stored fresh or frozen. Steaks were evaluated for color, cook loss, purge loss, and Warner-Bratzler shear force. Data were analyzed as a split plot design with main effects of first transport temperature, second transport temperature, and aging day. Data from fresh and frozen product were analyzed separately. Purge loss was increased for 3.3FT sirloins compared with −2.2FT (P=0.0362). L* values for −2.2FT strip steaks were increased (P&amp;lt;0.0001) and purge loss decreased (P=0.0188) compared with 3.3FT steaks. L* values and fresh steak purge loss for 3.3FT sirloins were increased (P=0.0356 and P=0.0460, respectively) compared with −2.2FT steaks. These data indicate varied responses to temperature differences based on subprimal. Thus, a universal recommendation for all meat products could not be made. Further investigation into the impacts of transportation temperatures on various meat products is vital to optimization of the meat supply chain.

Characterizing the sarcoplasmic proteome of aged pork chops classified by purge loss.

Unpredictable variation in quality, including fresh pork water-holding capacity, remains challenging to pork processors and customers. Defining the diverse factors that influence fresh pork water-holding capacity is necessary to make progress in refining pork quality prediction methods. The objective was to utilize liquid chromatography and mass spectrometry coupled with tandem mass tag (TMT) multiplexing to evaluate the sarcoplasmic proteome of aged pork loins classified by purge loss. Fresh commercial pork loins were collected, aged 12 or 14 d postmortem, and pork quality and sensory attributes were evaluated. Chops were classified into Low (N = 27, average purge = 0.33%), Intermediate (N = 27, average purge = 0.72%), or High (N = 27, average purge = 1.19%) chop purge groups. Proteins soluble in a low-ionic strength buffer were extracted, digested with trypsin, labeled with 11-plex isobaric TMT reagents, and detected using a Q-Exactive Mass Spectrometer. Between the Low and High purge groups, 40 proteins were differentially (P < 0.05) abundant. The Low purge group had a greater abundance of proteins classified as structural and contractile, sarcoplasmic reticulum and calcium regulating, chaperone, and citric acid cycle enzymes than the High purge group. The presence of myofibrillar proteins in the aged sarcoplasmic proteome is likely due to postmortem degradation. These observations support our hypothesis that pork chops with low purge have a greater abundance of structural proteins in the soluble protein fraction. Together, these and other proteins in the aged sarcoplasmic proteome may be biomarkers of pork water-holding capacity. Additional research should establish the utility of these proteins as biomarkers early postmortem and over subsequent aging periods.

Relationship between pre-rigor temperature of pork longissimus muscle, myofibril-bound calpain activity and protein degradation

The effect of pre-rigor temperature incubation on the activity and distribution in sarcoplasmic and myofibrillar fractions of calpains, and meat quality attributes was investigated. Porcine longissimus thoracis muscles were incubated pre-rigor at 14, 22, 30 and 38 °C to 6 h postmortem, followed by another 2 h incubation at 14 °C. Thereafter, muscles were stored at 2 °C for 1 or 4 days. With higher pre-rigor temperature, sarcoplasmic Ca2+ concentration, purge loss and myofibril-bound calpain-1 content increased, while shear force declined. Water-holding capacity of isolated myofibrils was lower after pre-rigor incubation at 38 °C. Desmin and troponin T degradation, and myofibril fragmentation was greater upon incubation of isolated myofibrils with added Ca2+ in the order 800 μM Ca2+ > 40 μM Ca2+ > no Ca2+, suggesting that calpain-1 and calpain-2 were associated to myofibrils and proteolytically active with sufficient Ca2+. Activity of myofibril-bound calpain-1 in muscle incubated pre-rigor at 22 and 30 °C were higher than when incubated at 14 and 38 °C. These results indicate that calpains translocate from the sarcoplasm onto myofibrils with higher pre-rigor temperature to 30 °C and the proteolytic potential of myofibril-associated calpains is thereby increased.

Interaction of chitosan gel at different pH conditions prepared with acetic acid as food acidulant in fish protein emulsion sausages

Chitosan gel with various concentrations (0.12–0.33 g) at different pH conditions (pH 3.8 to 5.2) was prepared in eleven combinations as per the Central Composite Design (CCD) for incorporation into fish (Pangasianodon hypophthalmus) mince formulated sausage. Emulsion stability, gel strength, and water holding capacity of the treatment combinations were considered for optimization of chitosan concentration and pH through Response Surface Methodology. Furthermore, the process parameters, i.e., pH (batter and sausage), cooking loss, purge loss, as well as textural and sensory properties, were evaluated for further validation of the findings. It was observed that the gel having 0.3 g of chitosan at a pH of 5 had the highest acceptability and was considered the best combination for desired properties. Increasing pH decreased the cooking loss and purge loss parameters of the sausages, signifying the role of pH in these parameters. However, the range of cooking loss and purge loss in all experimental groups was within an acceptable range. The hardness was increased at lower pH while the adhesiveness was influenced by the combined interactive effect of pH and chitosan concentration. On other hand cohesiveness had shown a direct relationship with pH while springiness did not varied much between the combinations. Sensory evaluation indicated equal acceptance among the panelists except for the sausages with lowest pH range. The study concludes an overall quality improvement in sausages in terms of functional, sensorial, and textural attributes, when the range of chitosan and pH is optimized scientifically before incorporation.

Effects of Physicochemical Characteristics and Storage Stability of Porcine Albumin Protein Hydrolysates in Pork Sausage

In this study, the physicochemical characteristics and storage stability of porcine albumin protein hydrolysates (PAPH) in sausage were evaluated. Four concentrations of PAPH were added to pork emulsion sausage (T1, 0.3%; T2, 0.6%; T3, 0.9%; T4, 1.2%) and compared to the control (CON, 0%). On day 0, proximate composition, cooking loss, and sensory evaluation were compared. Purge loss, color, texture profile analysis, shear force, free amino acids, lipid oxidation, microbial counts, and volatile basic nitrogen (VBN) were compared on day 0 and after 4 weeks of refrigeration. The content of essential amino acids and redness(a*) increased as the level of PAPH added increased (p&lt;0.05). Also, the cooking loss was improved (p&lt;0.05). However, lipid oxidation, microbial counts, and VBN were increased significantly during storage for 4 weeks (p&lt;0.05). The findings indicated that the addition of PAPH improved cooking loss and the protein composition of sausages, but negatively affected storage stability.

Characterization of Pork Loin Chop Color Stability Using Loin Quality Traits and Instrumental Discoloration Measures

The objective of this study was to characterize the color stability of pork loin chops using fresh quality traits and instrumental measures of discoloration. Boneless pork loins (N=484) were evaluated for quality traits at 11 or 14 d post-mortem. One chop was cut from each loin near the 10th rib for retail display, overwrapped, and displayed under constant fluorescent lighting for 7 d. Objective color, myoglobin redox forms, and subjective visual discoloration traits were evaluated daily. After retail display, chops were categorized based on final visual discoloration (Day 7) as Very Color Stable (VCS; 0% to 5% discoloration), Color Stable (CS; 5% to 10% discoloration), Neutral (10% to 25% discoloration), Color Labile (CL; 25% to 30% discoloration), or Very Color Labile (VCL; &amp;gt;30% discoloration). Quality and color traits were analyzed using the GLIMMIX (visual discoloration) or MIXED (all other measures) procedure of SAS. Retail display data were analyzed as repeated measures. Chops ultimately classified as CS or VCS were darker, redder, and had lesser surface metmyoglobin (P&amp;lt;0.01) than CL and VCL chops at both Day 1 of retail display and throughout display. Stable chops also had generally increased R630/580 values as well as decreased visual discoloration scores and yellowness during display. A group×day interaction was observed for all traits measured during retail display (P&amp;lt;0.0001). No differences in aged loin ventral surface redness were observed between color stability groups (P≥0.16). Overall, chops ultimately classified as CS came from aged loins that were generally darker, redder, and less yellow, with greater pH values, greater marbling scores,and decreased purge loss.

Vacuum Packaging Maintains Fresh Characteristics of Previously Frozen Beef Steaks during Simulated Retail Display.

The impact of frozen storage on beef steaks prior to the retail setting may result in changes to the quality and safety of the packaged meat. Therefore, the objective of the current study was to evaluate fresh characteristics on previously frozen steaks during a simulated retail display. Steaks were allocated to one of three packaging treatments (MB, MDF, MFS) and stored frozen (−13 °C) for 25 days in the absence of light. After thawing, steaks were stored in a lighted retail case at 3 °C and evaluated for instrumental surface color, pH, purge loss, lipid oxidation, and microbial spoilage organisms throughout the 25-day fresh display period. There was an increase (p < 0.05) for aerobic plate counts and lipid oxidation from day 20 through 25 on steaks packaged in MFS and MDF, respectively. Steaks packaged in MB were redder (p < 0.05) and more vivid (C*) as storage time increased. Whereas lipid oxidation was greater (p < 0.05) throughout the entire display for steaks packaged in MFS and MDF. It is evident that barrier properties of MB limiting oxygen exposure of the steak preserved fresh meat characteristics after frozen storage. Results from the current study suggest that vacuum packaging films can aid in retarding detrimental effects caused by frozen storage after placing the steaks in fresh retail conditions.

Proteolysis and changes in meat quality of chicken pectoralis major and iliotibialis muscles in relation to muscle fiber type distribution

The proteolysis trends and meat quality of the chicken pectoralis major (PM) and iliotibialis (IL) muscles stored at 4°C for 7 d were investigated. After 7 d of storage, the purge loss was higher (P < 0.05) in PM than in IL muscle. The difference in the composition of muscle fibers between PM (100% fast type) and IL (88.85% fast and 11.15% slow types) resulted in differences in proteolysis. Fructose-bisphosphate aldolase, troponin I, myosin heavy chain, and malate dehydrogenase exhibited the same tendencies, but pyruvate kinase, creatine kinase, L-lactate dehydrogenase, and triosephosphate isomerase exhibited different tendencies in the 2 muscles. The activity of cathepsin B was higher in PM than in IL during storage (P < 0.05). These results indicate that the proteolysis trend and changes in meat quality during cold storage are dependent on the different muscle fiber characteristics.

Physical properties during a 28-day ageing period of blesbok (Damaliscus pygargus phillipsi) Longissimus thoracis et lumborum and Biceps femoris muscles

The study aimed to determine the effect of sex, muscle-type, and ageing on the physical properties of blesbok (Damaliscus pygargus phillipsi) Longissimus thoracis et lumborum (LTL) and Biceps femoris (BF) muscles. Randomly assigned steak samples from twenty mature blesbok (10 of each sex) antelope were vacuum-packed and stored at 4.4 ± 1 °C for 2, 4, 7, 10, 17 and 28 ageing days. Cumulative purge loss, pH, colour (L*, a*, b), cooking loss, and Warner Braztler shear force were determined. Males had meat with higher (P = 0.032) pH values than females, while all other attributes were similar (P > 0.05). The LTL had greater (P < 0.05) purge losses, L* and a* values than the BF muscle, while other quality attributes were greater (P < 0.05) for the BF muscle. Despite fluctuations, there was an overall decrease in shear force with ageing time. According to all quality parameters measured, the optimum ageing period for blesbok would seem to be 10 days.

Shelf-life extension of chilled and superchilled dark-cutting beef held under combined anoxic master packaging and high-oxygen packaging both enriched with carbon dioxide

The microbiological and quality attributes of dark-cutting (DC) beef were assessed during chilled and superchilled anoxic packaging storage (80% CO2 MP: 80% CO2/20% N2; 40% CO2 MP: 40% CO2/60% N2; VP: vacuum packaging) followed by a chilled high-oxygen packaging display period (HiOx-MAP: 60% O2/40% CO2). During storage, both MP steaks showed lower (P < 0.05) purge loss and pH than VP steaks, and superchilling significantly suppressed lipid oxidation. The following HiOx-MAP produced a bright red color in all steaks during display, and MP storage rendered displayed steaks higher (P < 0.05) redness values than VP storage. Both superchilled MP-HiOx systems exerted the best preservation for DC beef with lower bacterial counts and TVB-N values among the packaging types, in which the display-life was prolonged to 14 days after 21-days storage. Despite the levels of CO2 influenced microbiota dynamics during anoxic storage, Carnobacterium finally became the predominant bacteria under HiOx-MAP.

The Influence of Vacuum Packaging of Hot-Boned Lamb at Early Postmortem Time on Meat Quality during Postmortem Chilled Storage

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 (p<0.05). 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 (p<0.05). Free thiol group concentrations were significantly higher after VP at 6 and 12 h postmortem (p<0.05). 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.