Oxidative stability of chilled pork chops following long term freeze storage

Assessing Individual Muscle Characteristics to Enhance Frozen-Thawed Meat Quality

This study assessed previous research aimed at mitigating the adverse effects of freeze-thawing on meat quality. Specifically, it focuses on assessing the physicochemical alterations in meat resulting from freezing, freeze-thawing, or technologies to minimize these alterations. Recent studies have focused on conventional freeze-thaw technology applicable across various livestock species and muscle types. However, recent research has indicated the necessity for developing freeze-thaw technology considering the unique characteristics of individual muscles. In this review, we summarize previous studies that have compared alterations in the physicochemical properties of primary muscles owing to freezing or freeze-thawing. Despite the introduction of various technologies to significantly reduce the adverse effects on meat quality resulting from freeze-thawing, it is essential to consider the unique characteristics (proximate composition, pH, and muscle fiber characteristics) of individual muscles or cuts to develop enhanced the freeze-thaw processing technology.

Challenges and processing strategies to produce high quality frozen meat

Freezing is an effective means to extend the shelf-life of meat products. However, freezing and thawing processes lead to physical (e.g., ice crystals formation and freezer burn) and biochemical changes (e.g., protein denaturation and lipid oxidation) in meat resulting in loss of quality. Over the last two decades, several attempts have been made to produce thawed meat with qualities similar to that of fresh meat to no avail. This is due to the fact that no single technique exists to date that can mitigate all the quality challenges caused by freezing and thawing. This is further confounded by the consumer perception of frozen meat as lower quality compared to equivalent fresh-never-frozen meat cuts. Therefore, it remains challenging for the meat industry to produce high quality frozen meat and increase consumer acceptability of frozen products. This review aimed to provide an overview of the applications of novel freezing and thawing technologies that could improve the quality of thawed meat including deep freezing, high pressure, radiofrequency, electro-magnetic resonance, electrostatic field, immersion solution, microwave, ohmic heating, and ultrasound. This review will also discuss the development in processing strategies such as optimising the ageing of meat pre- or post-freezing, and the integration of freezing and thawing in one process/regime to collapse the difference in quality between thawed meat and fresh-never-frozen equivalents.

A South African beef quality survey

In this study a survey of various meat quality characteristics of beef loin cuts was conducted in the City of Tshwane Metropolitan Municipality (Gauteng Province of South Africa) to determine the variation and consistency of beef quality of products purchased over time. Four hundred and twenty beef loin samples were collected on 20 occasions over 308 days from 13 outlets of 2 supplier types (butcher and supermarket). Packaging type, label information and price were considered for the evaluation of meat tenderness, colour, cooking loss, tissue composition and steak thickness. The results demonstrate that large variation in characteristics relevant to consumers' choice and satisfaction among and within different products sold as porterhouse steak in South Africa. In particular, muscle tenderness varied (P < 0.0001) across the 20 products and also showed significant inconsistency over the 20 purchasing events for certain products.

Research Progress on Nutritional Value, Preservation and Processing of Fish-A Review

The global population has rapidly expanded in the last few decades and is continuing to increase at a rapid pace. To meet this growing food demand fish is considered a balanced food source due to their high nutritious value and low cost. Fish are rich in well-balanced nutrients, a good source of polyunsaturated fatty acids and impose various health benefits. Furthermore, the most commonly used preservation technologies including cooling, freezing, super-chilling and chemical preservatives are discussed, which could prolong the shelf life. Non-thermal technologies such as pulsed electric field (PEF), fluorescence spectroscopy, hyperspectral imaging technique (HSI) and high-pressure processing (HPP) are used over thermal techniques in marine food industries for processing of most economical fish products in such a way as to meet consumer demands with minimal quality damage. Many by-products are produced as a result of processing techniques, which have caused serious environmental pollution. Therefore, highly advanced technologies to utilize these by-products for high-value-added product preparation for various applications are required. This review provides updated information on the nutritional value of fish, focusing on their preservation technologies to inhibit spoilage, improve shelf life, retard microbial and oxidative degradation while extending the new applications of non-thermal technologies, as well as reconsidering the values of by-products to obtain bioactive compounds that can be used as functional ingredients in pharmaceutical, cosmetics and food processing industries.

Comparison of the immersion chilling and freezing and traditional air freezing on the quality of beef during storage

Compared to traditional air freezing, immersion chilling and freezing shows an improvement in the freezing effect on meat quality, but it is not known whether this advantage persists over longer storage periods. Therefore, the objective of the current study was to compare the effects of immersion chilling and freezing (ICF) and traditional air freezing (TAF) on the physical and chemical indexes in beef longissimus muscle during a storage period of 150 days. In the current study, the longissimus muscle from Luxi cattle (aged 20-24 months) was analyzed, with samples independently frozen by ICF and TAF. After the core temperature was frozen to below -18 degrees by the two chilling methods, samples were transferred to a -18 degrees cold room for further storage. During the storage period, physical and chemical indexes, mainly including color and texture qualities, total volatile base nitrogen (TVB-N) and peroxide value (POV) were measured and comparatively analyzed at several fixed time points. A higher freezing rate was observed in ICF (5.124 cm/h) than in TAF (0.194 cm/h), and better microstructure was observed in ICF treatment. Besides, peak force values and total energy values were significantly lower in the TAF group than in the ICF group during the first 45 days of freezing storage time (p < .05). ICF also showed better color quality due to higher L* values than TAF samples during the first 75 days of frozen storage (p < .05). In addition, the thawing loss (after 75 days of storage), total volatile base nitrogen, and peroxide value (in the 30 to 75 days of storage period) were lower in the ICF than in the TAF group. In conclusion, the immersion chilling and freezing is more conducive to the quality of beef during storage at -18 degrees compared to traditional air freezing.

Detection of previously frozen poultry through plastic lidding film using portable visible spectral imaging (443-726 NM)

The objective of this study is to use a portable visible spectral imaging system (443–726 nm) to detect poultry thawed from frozen at the pixel level using multivariate analysis methods commonly used in machine learning (decision tree, logistic regression, linear discriminant analysis [LDA], k-nearest neighbors [KNN], support vector machines [SVM]). The selection of the most suitable method is based on the amount of data required to build an accurate model, computational speed, and the robustness of the model. The training set consists of pixel spectra from packages of chicken thighs without plastic lidding to evaluate the robustness of the models when implemented on the test set with and without plastic lidding. Data subsets were created by randomly selecting 1, 5, 10, 20, and 50% of the pixel spectra of each sample for both the training and test data sets. The subsets of pixel spectra and the full training set were used to train the machine learning algorithms to evaluate how the amount of data influences computational time. Logistic regression was found to be the best algorithm for detecting poultry thawed from frozen with and without plastic lidding film. Although logistic regression and SVM both performed with the same high accuracy and sensitivity for all training subset sizes, the computational time needed to implement SVM makes it the less suitable algorithm for detecting poultry thawed from frozen with and without plastic lidding film.

Effects of freezing temperatures and storage times on the quality and safety of raw turkey meat and sausage products

In this study, the effect of frozen storage of turkey meat on the processing properties into raw sausages was investigated. For this purpose, meat from the Musculus pectoralis of male turkeys was frozen in 3 independent runs for 12 and 24 wk at −18°C and −80°C. After thawing, the meat was examined physicochemically and microbiologically and processed into raw sausages. The sausages were examined on d 0, 7, 14, 21, and 28 of storage. The parameters L*, a*, b*, pH-value and a_w-value did not show any relevant significances between the experimental groups. The analysis of TBARS of the sausages made from frozen meat showed significantly higher values on d 14 and 28 compared to the unfrozen control group. Frozen storage also reduced the growth of Pseudomonas spp. and Enterobacteriaceae.

Assessment of quality characteristics and bacterial community of modified atmosphere packaged chilled pork loins using 16S rRNA amplicon sequencing analysis

Modified atmosphere packaging (MAP) is widely applied in packaging meat and meat products. While most studies had employed culture-dependent microbiological analyses or polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE), the recent application of high-throughput sequencing (HTS) has been effective and reliable in detecting the microbial consortium associated with food spoilage. Since MAP application is limited in China, applying HTS in assessing the microbial consortium of meat and meat products in the country becomes imperative. In this study, quality indexes and bacterial enumeration often used as spoilage indicators were employed to assess MAP fresh pork under chilled (4 °C) storage for 21 d. The results indicated that 70%O₂/30%CO₂ (Group A) retained more redness (a*) content, while 70%N₂/30%CO₂ (Group B) markedly reduced spoilage indicators compared to the control group. Notably, high-throughput sequencing indicated that Group B and 20%O₂/60%N₂/20%CO₂ (Group C) inhibited the growth of abundant spoilers, Pseudomonas spp. and Brochothrix spp. Thus, MAP (Group B and C) has promising potential in inhibiting predominant meat spoilers during chilled storage. This study provides valuable information to food industries on the potential application of MAP to control meat spoilage in Chinese markets.

Effects of Different Storage Temperatures on the Physicochemical Properties and Bacterial Community Structure of Fresh Lamb Meat

This study was aimed to compare the physicochemical properties and bacterial community structure of tray-packaged fresh lamb meat under different storage temperatures, such as 4°C (chilling), −1.5°C (supercooling), −4°C (superchilling) and −9°C (sub-freezing). The total viable counts (TVC), total volatile base nitrogen (TVB-N), bacterial diversity and metabolic pathways were investigated. The results indicated that the shelf life of superchilling and sub-freezing storage was over 70 d, which was significantly longer than that of chilling and supercooling storage. TVC and TVB-N values showed an increasing trend and were correlated well (R²>0.92). And the TVB-N values of lamb meat were exceeded the tolerable limit (15 mg/100 g) only found under chilling and supercooling storage during storage period. At the genus level, Pseudomonas was the core spoilage bacteria then followed Brochothrix for chilling and supercooling storage. Pseudomonas, Ralstonia, Psychrobacter and Acinetobacter were the dominant spoilage bacteria for superchilling and sub-freezing storage. Furthermore, the bacterial community diversity of lamb meat stored at chilling and supercooling storage decreased with the storage time prolonged, which was opposite to the outcome of meat stored under superchilling and sub-freezing storage. For chilling and supercooling storage, the abundance of main metabolisms (carbohydrate metabolism and amino acid metabolism, etc.) of bacteria increased with the storage time prolonged, which was opposite to superchilling storage. This may be related to the bacteria community diversity and the formation of dominant spoilage bacteria. In conclusion, this work provides data for the preservation of fresh lamb meat which will benefit the meat industry.

Effect of the type of packaging on the shelf life of ground rabbit meat

Rabbit meat consumption has increased worldwide due to its health benefits in humans but few studies addressed the stability of this food matrix. The effect of two types of packaging (vacuum, VP; and polystyrene tray overwrap with PVC/polyvinyl plastic film, PT) was evaluated on the microbial stability (psychrotrophic; PSY, lactic acid bacteria; LAB, initial coliforms counts) and physicochemical (pH, thiobarbituric acid reactive substances (TBARS), total volatile basic Nitrogen (TBV-N), color and drip loss) changes of ground rabbit meat during its storage at 4 ± 1 °C. VP packaging delayed PSY growth, lipid oxidation, protein degradation and undesirable color changes compared to PT samples. Shelf life of ground rabbit meat in vacuum condition could be around 10 days of storage, while PT samples presented a shorter shelf life of around 5 days. However, sensory studies must be performed in order to assure the exact shelf life of the final product.

Comparative Meat Qualities of Boston Butt Muscles (M. subscapularis) from Different Pig Breeds Available in Korean Market

This study aimed to determine the effects of breed on meat quality characteristics of porcine Boston butt muscles (M. subscapularis) from three different pig breeds: Landrace×Yorkshire×Duroc (LYD), Berkshire, and Ibérico available in Korean market. Ibérico showed significantly higher fat content, yellowness (CIE b*), cooking loss, and lower shear force values than LYD and Berkshire. Moreover, the contents of oleic acid (18:1) and palmitic acid (16:0) were significantly higher in Ibérico breed, but stearic acid (18:0) was higher in LYD. As linoleic acid (18:2) and arachidonic acid (20:4) were higher in Berkshire sows as compared to the other breeds, atherogenicity and thrombogenicity indexes were significantly lower in Berkshire sow. Ibérico had lower the ω-6/ω-3 fatty acids ratio, and higher taurine and free amino acids compared with the others. Ibérico also showed significantly greater lipid oxidation, lower antioxidant capacity, and higher hypoxanthine contents, whereas the Berkshire had higher inosine-5’-monophosphate and lower K-index value as compared to the Ibérico. The breed did not impart any significant effect on the size and density of muscle fibers. Thus, quality characteristics of Boston butt varied from breed to breed, and certain consumer preferences for Ibérico can be explained, in part, by the unique quality characteristics imparted by higher contents of intramuscular fat, oleic acid, and free amino acids.

Effects of duration and temperature of frozen storage on the quality and food safety characteristics of pork after thawing and after storage under modified atmosphere

The aim of this study was to investigate the influence of the duration of frozen storage (12 and 24 weeks) and the storage temperature (-18 °C or - 80 °C) on the shelf life of pork in MAP for up to 14 days after thawing. Frozen meat was compared to unfrozen meat in different physicochemical and microbiological parameters. The parameters a*, b*, pH value, cooking loss, shear force and antioxidant activity showed no significant changes depending on the freezing process. The total moisture loss was significantly higher for frozen/thawed pork compared to unfrozen pork. The storage loss of all frozen samples showed higher values than the unfrozen samples on all examination days. The level of TBARS reached comparable values for all experimental groups. On examination days 7 and 14, significantly lower values of total plate count (TPC) and Pseudomonas spp. were measured for frozen pork compared to unfrozen pork. The temperature of frozen storage had no significant influence on the quality of pork.

Pork Loin Chop Quality and Muscle Fiber Characteristics as Affected by the Direction of Cut

In this study, the relationship between muscle fiber characteristics and meat quality of pork loin chops prepared using different directions of cut (vertical to the muscle length, M-Vertical; vertical or parallel to the muscle fiber orientation, F-Vertical or F-Parallel) was evaluated under different storage conditions (fresh, cold storage/aged, and freeze–thawed). Among the three groups, F-parallel displayed considerably larger size of muscle fibers, regardless of their type. This group also displayed an increase in discoloration in aged chops and a decrease in purge loss and tenderness than in other cut groups (p < 0.05). Freeze–thawing accelerated deterioration of meat quality, especially water-holding capacity and tenderness in all groups (p < 0.05), but was most prominent in F-Parallel. Therefore, to avoid excessive deterioration of fresh, aged, or frozen/thawed pork loin chops, it is important to consider the direction in which the chop is cut with respect to the muscle fiber orientation.

Effect of Different Combinations of Freezing and Thawing Rates on the Shelf-Life and Oxidative Stability of Ostrich Moon Steaks (M. Femorotibialis medius) under Retail Display Conditions

The aim of this study was to investigate the interaction between different rates of freezing and thawing on whole ostrich moon steaks to establish a combination or singular main effect that minimises thaw loss and maximises the retail display shelf-life regarding moisture loss, colour, lipid oxidation and tenderness. Five characteristic freezing rates (FR: 1, 2, 4, 8, 24 h) were compared with five characteristic thawing rates (TR: 1.5, 3, 6.5, 14, 21 h) in a completely randomised block design. Moon steaks (M. femorotibialis medius) from 125 birds were randomly assigned to a specific treatment combination before being subjected (after thawing) to a 10-day chilled storage at 4 °C shelf-life trial. Thawing rate had no effect (p > 0.05) on any of the quality (colour, drip and cooking losses, shear force, 2-thiobarbituric acid (TBARS)) parameters whilst freezing rate and display time both had significant (p < 0.05) influences. Thaw loss was lowest (p < 0.05) for the FR_1h and FR_2h, followed by FR_4h, FR_8h and FR_24. The FR_1h had the highest (p < 0.05) drip and shear force values during display while the FR_2h and FR_8h had the highest rate of oxidation (TBARS and metmyoglobin formation). FR_24h had the second best (p < 0.05) colour retention after FR_4h and minimal package drip. Overall, FR_4h resulted in the best quality meat over the entire shelf-life with high bloom retention, low TBARS and shear force, and average thaw, drip and cooking loss.

Unconventional Methods of Preserving Meat Products and Their Impact on Health and the Environment

A dual objective of food storage is to retain nutritional value and safe consumption over time. As supply chains have globalized, food protection and preservation methods have advanced. However, increasing demands to cater for larger volumes and for more effective food storage call for new technologies. This paper examines promising meat preservation methods, including high pressure process, ultrasounds, pulsating electric and magnetic field, pulsed light and cold plasma. These methods not only make it possible to obtain meat and meat products with a longer shelf life, safer for health and without preservatives, but also are more environment-friendly in comparison with traditional methods. With the use of alternative methods, it is possible to obtain meat products that are microbiologically safer, whilst also high quality and free from chemical additives. Moreover, these new technologies are also more ecological, do not require large quantities of energy or water, and generate less waste.

Physicochemical Properties of Pork Neck and Chicken Leg Meat under Various Freezing Temperatures in a Deep Freezer

This study was conducted to investigate the effects of freezing and storage temperature (−18°C, −50°C, and −60°C) on the physicochemical properties of pork neck and chicken leg meat in home-scale deep freezers. Pork neck was cut into a thickness of 3 cm (9×9×3 cm, 150 g), individually packed in air-containing packages, and stored at different temperature (−18°C, −50°C, and −60°C) for 6 months. Chicken leg meats were prepared (10 cm long, weighing 70 g) and packed in the same manner. Frozen samples were thawed at 2°C. Physicochemical properties such as thawing loss, cooking loss, water-holding capacity, color, volatile basic nitrogen (VBN), and thiobarbituric acid reactive substances (TBARS) were evaluated. The samples frozen by deep freezing (−60°C) was favorable with respect to thawing loss, color, and VBN. Samples frozen at −60°C had lower values of thawing loss and VBN than those frozen at −18°C for all storage periods (p<0.05). Color parameters were more similar to those of fresh meat than to those of samples frozen at −18°C for 6 months. The TBARS of all samples were below 0.3 mg malondialdehyde/kg, thereby indicating oxidative stability of lipids. Consequently, deep freezing at −60°C may be acceptable for maintaining the quality of fresh pork neck and chicken leg meat for 6 months without deterioration.

Effects of freezing and thawing on microbiological and physical-chemical properties of dry-aged beef

This study evaluated the effects of freezing, prior to and after dry aging, on the microbiological and physical-chemical quality of beef. Strip loins (n = 24) from 12 carcasses were assigned to four treatments: non-frozen dry aging (Dry); dry aging, steak fabrication, freezing and slow thawing (Dry + ST); freezing, fast thawing (FT; 20 °C/15 h) and dry aging (FT + Dry); freezing, slow thawing (ST; 4 °C/48 h) and dry aging (ST + Dry). Freezing conditions were - 20 °C/28 days and dry aging conditions were 2 °C/70% relative humidity, for 28 days. Freezing prior to dry aging did not affect the microbial counts compared to Dry. However, FT + Dry and ST + Dry increased (16%) total process loss (P < .05) compared to Dry and Dry+ST. Moreover, freezing changed volatile compounds profile. Thus, freezing prior to dry aging was not a feasible process due to increased process loss, while freezing after dry aging was considered a viable alternative to preserve the steaks without compromising beef physical-chemical traits.

A Comprehensive Review on Lipid Oxidation in Meat and Meat Products

Meat and meat products are a fundamental part of the human diet. The protein and vitamin content, as well as essential fatty acids, gives them an appropriate composition to complete the nutritional requirements. However, meat constituents are susceptible to degradation processes. Among them, the most important, after microbial deterioration, are oxidative processes, which affect lipids, pigments, proteins and vitamins. During these reactions a sensory degradation of the product occurs, causing consumer rejection. In addition, there is a nutritional loss that leads to the formation of toxic substances, so the control of oxidative processes is of vital importance for the meat industry. Nonetheless, despite lipid oxidation being widely investigated for decades, the complex reactions involved in the process, as well as the different pathways and factors that influenced them, make that lipid oxidation mechanisms have not yet been completely understood. Thus, this article reviews the fundamental mechanisms of lipid oxidation, the most important oxidative reactions, the main factors that influence lipid oxidation, and the routine methods to measure compounds derived from lipid oxidation in meat.

Physicochemical and sensory properties of beef muscles after Pulsed Electric Field processing

This study investigated the effects of pulsed electric field (PEF) processing on the sensory and physicochemical properties of beef biceps femoris (BF) and semitendinosus (ST) muscles. The fresh and frozen-thawed muscles were treated at an electric field strength of 0.8-1.1 kV/cm, pulse width of 20 μs, frequency of 50 Hz and specific energy of 130 kJ/kg. PEF treated samples improved meat tenderness and colour. However increased fat oxidation and increased saturated fatty acids were evident in PEF processed frozen samples. Temporal dominance of sensations results showed that although oxidation was the most dominant in temporal perception, the samples were only found to be detrimental to the sensory quality of PEF processed beef muscles stored for 7 days.

Assessment of chicken breast meat quality after freeze/thaw abuse using magnetic resonance imaging techniques

BACKGROUND

Freezing/thawing meat can result in quality losses as a result of the formation, melting and reformation of ice. These changes in water state can result in alterations in texture, water holding and other key quality attributes. It was hypothesized that magnetic resonance imaging (MRI) could quantify changes in mobility and localization of water as a function of freezing/thawing, which could be correlated with quality measurements.

RESULTS

Drip loss increased significantly for unbrined samples by over 100% after each freeze/thaw cycle (1.5% to 3.3% to 5.3% drip loss). Brine uptake decreased 50% after 2 cycles (from 53% to 28% mass uptake). Drip loss for brined samples increased after 2 cycles; other attributes were not significantly affected. MRI showed brined samples had less change in both proton density and T₂ distributions. High-field nuclear magnetic resonance (NMR) imaging showed greater change in T₂ distributions.

CONCLUSION

As freeze/thaw damage increased, meat quality was reduced in both brined and unbrined chicken breasts, with more prominent changes in unbrined meat. These decreases in quality correlated with changes, albeit small, in water mobility and localization as measured by MRI. High-field NMR micro-imaging showed more dramatic changes in T₂ distributions in unbrined samples. These MRI techniques are shown to be useful in the assessment of meat quality after freeze/thaw abuse. © 2018 Society of Chemical Industry.

Preparation of Gallic Acid-Grafted Chitosan Using Recombinant Bacterial Laccase and Its Application in Chilled Meat Preservation

To improve the antibacterial and antioxidant properties of chitosan (CS), CS grafted with gallic acid (GA) using recombinant bacterial laccase from Bacillus vallismortis fmb-103 (fmb-rL103) as a catalyst. The structures of grafted chitosans were identified using Fourier transform infrared spectroscopy (FT-IR) and UV visible spectrum (UV–Vis spectroscopy). After gallic acid grafting, the antibacterial properties of chitosans against Pseudomonas, Acinetobacter, Brochothrix thermosphacta, Escherichia coli, Staphylococcus aureus, Salmonella, and Listeria monocytogenes were significantly improved. Meanwhile, 1,1-Diphenyl-2-picrylhydrazyl (DPPH) radical scavenging results showed that the antioxidant properties of grafted CS increased as well. The preservative effects of the grafted chitosan on chilled meat were then investigated. For this purpose, the quality indexes of the chilled meat during the storage were monitored, including total bacterial count, total basic volatile nitrogen (TVB-N) content, pH value, color and thiobarbituric acid reactive substances (TBARS) and so on. The results showed that coating with the grafted chitosan retarded the growth of spoilage bacteria, and decreased TVB-N and TBARS values of meat. The shelf life of chilled meat coated by CS grafted with GA (GA-g-CS) also extended from 6 days to 18 days at 4°C. These results provided a theoretical basis for the future application of the GA-g-CS in the preservation of chilled meat.

Highlights:(1)

The temperature and pH-stable bacterial laccase was used to synthesize gallic acid grafted chitosan.

(2)

Antioxidant and antibacterial properties of chitosan were improved through grafting gallic acid.

(3)

Storage properties of chilled meat were improved by coating with gallic acid grafted chitosan.

Display stability of fresh and thawed lamb supplemented with vitamin E or sprayed with an antioxidant borage seed extract

BACKGROUND

The commercialization of thawed lamb packaged in modified atmosphere and maintained on display could serve as an alternative capable of satisfying the requirements of both customers and distributors. However, previous studies have suggested that lipid oxidation may accelerate post-thawing because peroxidation occurs during frozen storage, thereby leading to rapid and severe secondary lipid oxidation. The addition of an antioxidant compound either in the lamb diet or in the packaged meat could resolve this problem. Therefore, the present study aimed to compare the effect of dietary vitamin E (1000 mg of dl-α-tocopheryl acetate per kg of basal diet) and the spraying of borage seed aqueous extract (10% p/v) on the quality of fresh and thawed lamb leg chops.

RESULTS

Both borage extract and vitamin E improved colour (as measured via instrumental and visual assessment of colour) and lipid stability (thiobarbituric acid reactive substances) of fresh and thawed lamb throughout display, although neither of them had any antimicrobial effect. Freezing/thawing accelerated bone marrow darkening and reduced redness but delayed microbial growth.

CONCLUSION

Both of these antioxidant strategies would be very profitable for the preservation of lamb meat, allowing thawed meat packaged in a modified atmosphere to be commercialized. However, additional studies should be carried out to determine how bone darkening in thawed chops can be avoided. © 2017 Society of Chemical Industry.

Impacts of post-mortem ageing prior to freezing on technological and oxidative properties of coarse ground lamb sausage in a model system

Objective

The objective of this study was to evaluate the effects of ageing time of lamb loins prior to freezing on technological characteristics and oxidation stability of coarse ground lamb loin sausage using in a model system.

Methods

Lamb loins (M. longissimus lumborum, n = 25) were aged at −1.5°C for 0, 1, 2, 3, and 8 wk and then frozen for the remaining days (a total of 30 wk). The aged/frozen/thawed lamb loins were ground, and model sausages were formulated with 75% aged/frozen/thawed lamb loin, 25% water, 1.5% sodium chloride (NaCl) and 0.3% sodium tripolyphosphate. The pH and thaw/purge loss of aged/frozen/thawed lamb loins were evaluated, and protein functionality (protein solubility and emulsifying capacity), water-holding capacity and textural properties of model sausages were determined. Cooked model sausages were vacuum-packaged in a plastic bag and displayed under continuous fluorescent natural white light (3°C±1°C). Colour and lipid oxidation of the cooked model sausages were evaluated on 0 and 21 d of display storage.

Results

Ageing prior to freezing had no impact on pH and purge/thaw loss of lamb loins and the colour of cooked sausages (p>0.05) made from the loins. Lamb loins aged for at least 3 wk prior to freezing numerically improved total and myofibrillar protein solubilities (p>0.05) and emulsion activity index (p = 0.009) of meat batter, but decreased cooking loss (p = 0.003) and lipid oxidation (p<0.05) of model sausages.

Conclusion

This study suggests that post-mortem ageing of raw meat prior to freezing could improve water-holding capacity and lipid oxidative stability of sausage made from the meat.