Effects of thawing temperature on the physicochemical properties of pre-rigor frozen chicken breast and leg muscles

Dynamic changes of rumen microbiota and serum metabolome revealed increases in meat quality and growth performances of sheep fed bio-fermented rice straw

BACKGROUND

Providing high-quality roughage is crucial for improvement of ruminant production because it is an essential component of their feed. Our previous study showed that feeding bio-fermented rice straw (BF) improved the feed intake and weight gain of sheep. However, it remains unclear why feeding BF to sheep increased their feed intake and weight gain. Therefore, the purposes of this research were to investigate how the rumen microbiota and serum metabolome are dynamically changing after feeding BF, as well as how their changes influence the feed intake, digestibility, nutrient transport, meat quality and growth performances of sheep. Twelve growing Hu sheep were allocated into 3 groups: alfalfa hay fed group (AH: positive control), rice straw fed group (RS: negative control) and BF fed group (BF: treatment). Samples of rumen content, blood, rumen epithelium, muscle, feed offered and refusals were collected for the subsequent analysis.

RESULTS

Feeding BF changed the microbial community and rumen fermentation, particularly increasing (P < 0.05) relative abundance of Prevotella and propionate production, and decreasing (P < 0.05) enteric methane yield. The histomorphology (height, width, area and thickness) of rumen papillae and gene expression for carbohydrate transport (MCT1), tight junction (claudin-1, claudin-4), and cell proliferation (CDK4, Cyclin A2, Cyclin E1) were improved (P < 0.05) in sheep fed BF. Additionally, serum metabolome was also dynamically changed, which led to up-regulating (P < 0.05) the primary bile acid biosynthesis and biosynthesis of unsaturated fatty acid in sheep fed BF. As a result, the higher (P < 0.05) feed intake, digestibility, growth rate, feed efficiency, meat quality and mono-unsaturated fatty acid concentration in muscle, and the lower (P < 0.05) feed cost per kg of live weight were achieved by feeding BF.

CONCLUSIONS

Feeding BF improved the growth performances and meat quality of sheep and reduced their feed cost. Therefore, bio-fermentation of rice straw could be an innovative way for improving ruminant production with minimizing production costs.

Development of functional, sustainable pullulan-sodium alginate-based films by incorporating essential oil microemulsion for chilled pork preservation

Developing safe, eco-friendly, and functionally edible packaging materials has attracted global attention. Essential oils, can be incorporated into packaging materials as antioxidant and antibacterial agents. However, their high volatility and discontinuous film matrix issues may cause a rough film surface, limiting the application in food packaging. In this study, thyme essential oil microemulsion (TEO-M) was prepared and incorporated into a pullulan-sodium alginate (PS) film. The TEO-M incorporation endowed the PS film with antioxidant and UV protection properties. The antioxidant activities of the TEO-M-incorporated PS film were significantly better than those of the TEO-C (thyme essential oil coarse emulsion)-incorporated PS film. In comparison to TEO-C, the distribution of TEO-M in the film is more uniform. Lipid oxidation and the growth of microorganisms in chilled pork were inhibited by incorporating TEO-M at a concentration of 50 mg/mL in the PS film (PS-50M). After 10 days of storage at 4 °C, the total viable count (TVC) of chilled pork preserved in the PS-50M material was significantly reduced compared to the control group (P < 0.05). This study shows that incorporating TEO-M in the PS film provides a method for applying essential oils in food packaging, which may have great potential in the food industry.

Effect of Liquid Nitrogen Freezing Temperature on the Muscle Quality of Litopenaeus vannamei

The implications of different liquid nitrogen freezing (LNF) temperatures (-35 °C, -65 °C, -95 °C, and -125 °C) on the ice crystal and muscle quality of white shrimp (Litopenaeus vannamei) were investigated in this essay. The results showed that better muscle quality was maintained after LNF treatment compared to that after air blast freezing (AF) treatment. As the freezing temperature of liquid nitrogen decrease, the freezing speed accelerated, with the freezing speed of LNF at -125 °C being the fastest. However, an excessively fast freezing speed was not conducive to maintaining the quality of shrimp. Among all the freezing treatments, LNF at -95 °C led to the lowest thawing losses and cooking losses, and the highest L* values, indicating that LNF at -95 °C could keep the water holding capacity of frozen shrimp better than that with other freezing methods. At the same time, LNF at -95 °C resulted in higher water holding capacity, and hardness values for shrimps than those with other frozen treatments (p < 0.05). In addition, the results of the water distribution of shrimps showed that treatment with a -95 °C LNF reduced the migration rate of bound and free water. Meanwhile, the microstructural pores of shrimps in the -95 °C LNF group were smaller, indicating that the ice crystals generated during -95 °C LNF were relatively smaller than those generated via other frozen treatments. In conclusion, an appropriate LNF temperature (-95 °C) was beneficial for improving the quality of frozen shrimp, and avoiding freezing breakage.

Physicochemical Properties of Chicken Breast and Thigh as Affected by Sous-Vide Cooking Conditions

Sous-vide is a cooking method used to improve the tenderness and juiciness of chicken breast. However, the comparative changes in meat quality attributes of sous-vide cooked chicken breast and thigh muscles are not fully understood. The objective of this study was to investigate the effects of sous-vide cooking conditions, based on collagen denaturation temperature of intramuscular connective tissue, on the physicochemical properties of chicken breasts and thighs. Chicken breast and thigh were cooked at four sous-vide cooking conditions (55 °C for 3/6 h and 65 °C for 3/6 h) and conventional cooking at 75 °C (core temperature of 71 °C) as control. No significant differences in pH and lightness were found between the sous-vide cooking conditions. Moisture content, cooking loss, protein solubility, shear force, myofibrillar fragmentation index, and lipid oxidation were affected by sous-vide cooking conditions (p < 0.05). The decreased shear force and total collagen content of 65 °C sous-vide cooking treatment might be associated with collagen denaturation (p < 0.05). Sous-vide cooking at 55 °C could decrease cooking loss, with higher moisture than sous-vide cooking at 65 °C (p < 0.05). These tendencies on water-holding capacity and shear force at the two different temperatures were similarly observed for both chicken breast and thigh. Therefore, this study indicates that chicken breast and thigh are similarly affected by the sous-vide cooking conditions and suggests that a novel strategy to apply together two temperature ranges based on the thermal denaturation of intramuscular connective tissue would be required.

Effect of aerobic and modified atmosphere packaging on quality characteristics of chicken leg meat at refrigerated storage

The demand for chicken meat is continuously increasing in the consumer market. Increasing the shelf-life of chicken meat with modern packaging technology in the supply chain is necessary. Hence research was undertaken to study the effect of aerobic packaging (AP) and modified atmosphere packaging (MAP) on the quality and shelf-life of chicken meat. The chicken leg meat (CLM) was stored under refrigerated storage (4 ± 1°C) in aerobic and modified atmosphere packaging (MAP20 = 20%O₂ + 30%CO₂ + 50%N₂, MAP10 = 10%O₂ + 40%CO₂ + 50%N₂, MAP0 = 0%O₂ + 20%CO₂ + 80%N₂) conditions and evaluated for quality attributes. The results have indicated that MAP of chicken leg meat significantly increased the headspace carbon dioxide, Warner-Bratzler shear force value, standard plate count, color, and odor but decreased the TBARS value, headspace oxygen, and nitrogen when compared with AP. The pH, myoglobin forms, meat pigment, heme iron, CIELAB color space (L*, a*, b*), yeast and mold count, appearance, and sliminess were not affected significantly by AP and MAP. It is concluded that under refrigerated storage conditions, MAP extends the shelf-life of chicken leg meat up to 15 d compared to only 6 d for aerobic packaging.

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Modified atmosphere packaging (MAP) significantly (P < 0.05) increases headspace carbon dioxide, Warner-Bratzler shear force, standard plate count, appearance, color, and odor of chicken leg meat.

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Aerobic packaging (AP) significantly (P < 0.05) decreases the pH, total meat pigment, and heme iron in chicken leg meat.

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Low oxygen, high carbon dioxide MAP (0–20%O₂ + 20–40%CO₂ + 50–80%N2) can increase the shelf-life by 100 to 150% in chicken leg meat under refrigeration storage.

Effects of Chitosan and Duck Fat-Based Emulsion Coatings on the Quality Characteristics of Chicken Meat during Storage

Chicken meat is a popular food commodity that is widely consumed worldwide. However, the shelf-life or quality maintenance of chicken meat is a major concern for industries because of spoilage by microbial growth. The aim of this study was to evaluate the effects of chitosan and duck fat-based emulsion coatings on the quality characteristics and microbial stability of chicken meat during refrigerated storage. The coated chicken meat samples were as follows: control (non-coated), DFC0 (coated with duck fat), DFC0.5 (coated with duck fat and 0.5% chitosan), DFC1 (coated with duck fat and 1% chitosan), DFC2 (coated with duck fat and 2% chitosan), and SOC2 (coated with soybean oil and 2% chitosan). The results showed that the apparent viscosity and coating rate were higher in DFC2 than in other groups. Physicochemical parameters (pH, color, and Warner-Bratzler shear force) were better in DFC2 than those in other groups during 15 days of storage. Moreover, DFC2 delayed lipid oxidation, protein deterioration, and growth of microorganisms during storage. These data suggest that chitosan-supplemented duck fat-based emulsion coating could be used to maintain the quality of raw chicken meat during refrigerated storage.

Effect of freeze-thaw cycles on the physicochemical properties, water-holding status, and nutritional values of broiler chicken drumstick

This study aimed to determine the effects of multiple freeze-thaw (FT) cycles (0, 1, 2, and 4) on the physicochemical properties, water-holding status, and nutritional values of broiler drumsticks. The results showed that L* (lightness) and b* (yellowness) values, thiobarbituric acid-reactive substances, total volatile basic nitrogen, and total viable counts significantly increased but pH values, protein solubility, and sensorial acceptance decreased after four FT cycles (P ˂ 0.05). The decreases in moisture content thawing loss, centrifugation loss, drip loss, and cooking loss indicated that the water-holding capacities of samples subjected to multiple FT cycles were diminished. Results of cell microstructure analysis and sodium dodecyl sulfate polyacrylamide gel electrophoresis revealed the occurrence of ruptured muscle cells with decreased fiber diameters and changes in myosin heavy chain band intensity after multiple FT cycles (P ˂ 0.05). As the number of FT cycles increased, the content of total free amino acids and polyunsaturated fatty acids including linoleic (C18:2), linolenic (C18:3), eicosatetraenoic (EPA, C20:5), and docosahexaenoic (DHA, C22:6) acids decreased (P ˂ 0.05). In conclusion, four repeated FT cycles accelerated the deterioration of physiochemical properties, reduced the water-holding status, and considerably impaired sensory characteristics and nutritional values of chicken meat.

Application of principal component analysis with instrumental analysis and sensory evaluation for assessment of chicken breast meat juiciness

1. The objectives of this study were to use principal component analysis (PCA) to analyse the variability of the three instrumental and 14 descriptive sensory properties of chicken breast meat. The meat was cooked until the internal temperature reached 85°C and further cooked for 0, 20, and 40 min. The second objective was to identify the most critical variables for assessing meat juiciness.2. Cooking loss and moisture content exhibited high correlation with sensorial moisture release and mouth feel.3. The distribution of objects on the axes of the first two principal components (PCs) enabled the identification of three groups undergoing different cooking durations. The four major PCs explained 80.0% of the total variability.4. Cooking loss, moisture content, water-holding capacity, sensorial moisture release and mouth feel were demonstrated as the most effective variables for the first two PCs. PCA with instrumental and sensory analyses proved an effective procedure for systematically and comprehensively judging chicken meat juiciness.

Characteristics of carcass and physicochemical traits of meat from male and female ducks fed a diet based on extruded soybean

Duck' meat is characterized by good nutritional properties and gaining popularity in the consumer market. Extruded soybean is potentially more digestible than commonly use soybean meal (SBM), and is expected to influence carcass traits and the quality of breast and leg muscles. The study' aim was to compare meat quality from both sexes' ducks fed a diet with extruded soybean (ESB) as a substitute for SBM. Cherry Valley ducks were divided into two groups. The control group (1) was fed an SBM-based diet, and the treatment group (2) with ESB. Each group was divided into sex subgroups with 50 birds in each (5 replicates, 10 ducks each). Dissection and analysis of meats' pH, colour, water-holding capacity (WHC), drip loss and chemical composition of breast and leg muscles were done. Interaction of Diet and Sex was calculated. In group 2 higher carcass weight, dressing percentage, weight of wings, leg muscles, total muscles, and better WHC were found. Dressing percentage, the proportion of neck with skin, breasts' and stomach' weight, and the weight and proportion of fat, and pH45min were higher in females (P < 0.05). The interaction was found for the pre-slaughter body weight, the weight of carcass remains, WHC in breasts (P < 0.05). The ESB feed had no negative effect on the analyzed traits and can be used in the ducks' diet. Improved the WHC indicates the high suitability of meat for processing. A positive effect of diet on the muscles' proportion and dressing percentage was noticed, which is important for consumers' market. The sex-related differences and interactions between variables suggest separate rearing due to sex.

Assessment of Physicochemical Characteristics and Microbiological Quality in Broiler Chicken Breast Muscle (Pectoralis major) Subjected to Different Temperatures and Lengths of Cold Transportation

Cold truck transportation is considered one of the most integral parts in a food processing chain. However, countless cases of product spoilage and food poisoning incidents have proven that temperature control during transport has been neglected. Literature on the impact of temperature during distribution is scarce. The objective of this study was to investigate the impact of various transportation temperatures and travel duration on the meat quality and microbial population of broiler chicken breast muscle. Sixty broiler chickens (42 days old) were slaughtered and eviscerated; they then had their breast muscles removed (each bird provided two breast muscle samples: left breast and right breast), which were wrapped in plastic film. All 120 packed boneless breasts (PBBs) were then placed at −18 °C for 24 h. After 24 h, the 60 PBB samples were subjected to transportation for 1 h at 4 °C (20 PBBs), 10 °C (20 PBBs), and 15 °C (20 PBBs) while the remaining 60 samples were transported for 5 h at 4 °C (20 PBBs), 10 °C (20 PBBs), and 15 °C (20 PBBs) before analyses. The samples transported at higher temperatures exhibited higher populations of coliform and Salmonella than those transported at lower temperatures. A significant impact of the transportation duration on the Salmonella population was only observed in samples transported at 4 °C for 5 h. However, a significant impact of transportation temperature on color was only recorded for the redness (a*) values, where the samples transported at higher temperatures exhibited higher redness (a*) values. Significant increases in lightness (L*) and yellowness (b*) values as well as decreases in redness (a*) and pH values were recorded in samples subjected to longer durations of transportation across all the temperatures observed in this study.

The effect of different slaughter weights on some meat quality traits of musculus longissimus dorsi thoracis of male Anatolian buffaloes

This research was performed to examine the effects of different slaughter weights (SWs) on some meat quality traits of Anatolian Buffaloes (n = 20). Weaned 5-month-old Anatolian Buffalo calves with an average live weight of 100 kg were used as the animal material of the study. Experimental calves were randomly divided into four different slaughter weight groups 200 kg (SW-1: n = 5), 250 kg (SW-2: n = 5), 300 kg (SW-3: n = 5), and 350 kg (SW-4: n = 5). Anatolian buffalo calves were fed with 30:70 roughage/concentrate feed ration. Meat quality attributes of musculus longissimus dorsi thoracis (LT) muscle of calves slaughtered at target slaughter weight were investigated. The quality traits included 45th minute pH (pH_45min), 24th hour pH (pH_24h), 1st and 24th hour color parameters (L* (lightness), a* (redness) and b* (yellowness), water holding capacity (WHC), drip loss (3rd day (DL-3) and 7th day (DL-7)), freeze-thaw loss (FTL), cooking loss (CL), chemical composition), fatty acid, and cholesterol profiles. The differences in LT muscle pH_24h, 24th hour a* and b* color parameters and WHC values of SW groups were not found to be significant (P > 0.05). The lowest DL-3 was observed in SW-1 (6.89%) and the greatest in SW-2 (8.96%) groups. Ether extract (EE) ratios increased (P < 0.01) and polyunsaturated fatty acid (PUFA)/saturated fatty acid (SFA) proportions decreased (P > 0.05) with increasing SWs. The differences in total cholesterol contents of SW groups were not detected to be significant (P > 0.05). Among the SW groups of Anatolian Buffaloes, SW-1 was found to be prominent with high WHC, CP, and PUFA/SFA ratio and the least DL-3 ratio.

Meat Value Chain Losses in Iran

To stop hunger, reducing food losses is a potential movement towards saving food. A large portion of these losses could be avoided and reduced through the improved food chain in many countries. Raising awareness on how and where food losses occur will help recovering foods such as meat by identifying solutions and convincing people to implement those solutions. This, in turn, will lead to private and public efforts to recover meat that might be otherwise wasted. After highlighting the importance of food saving benefits and relevant statistics, this paper explains the possible ways to reduce meat loss and waste in abattoirs and presents a framework for prevention according to the estimates of meat losses in Iran meat supply. The current article answers the questions of where do we have the meat loss in Iran and what approaches are most successful in reducing losses in the meat industry. The national average loss and waste in meat production are about 300,000 metric tonnes (about 15%). Many segments and players are involved with this huge amount of losses in the meat value chain, a large portion of these losses could be avoided and reduced by about 25% through using by-products with the mechanization of design and manufacturing. The production amount of mechanically deboned meat (MDM) is 105,091,000 kg, concluding the major waste (88.33%) of total poultry losses. Ensuring appropriate actions by exploiting the full potential of engaged Iranian associations and institutes is considered to reduce the losses.

Radio frequency processing and recent advances on thawing and tempering of frozen food products

During radio frequency (RF) thawing-tempering (defrosting) of frozen food products, some regions, mostly along the corners and edges, heat-thaw first due to the strong interaction of electric field and evolved heating leading to temperature increase. Resulting higher power absorption along these regions, compared to the rest of the volume, is the major cause of this problem. Besides, increase in temperature with phase change results in a significant increase of dielectric properties. This situation leads to runaway heating, which triggers the non-uniform temperature distribution in an accelerated manner. All these power absorption and temperature non-uniformity-based changes lead to significant quality changes, drip losses, and microbial growth. Based on this background, the objective of this review was to provide a comprehensive background regarding the most relevant and novel defrosting application studies using RF process, dielectric property data for frozen foods in the RF band, and novel mathematical modeling based computer simulation approaches to achieve a uniform process. Experimental and modeling studies were related with electrode position, sample geometry and size, electrode gap of the applied RF process, and the potential of charged electrode. Applying translational and rotational movement of the food product and the charged electrode vertical movement during the process to adjust the electric field and use of two-cavity systems and curved electrodes were also explained in detail. The data presented in this review is expected to give an insight information for further development of innovative RF thawing/tempering systems.

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.

Meat quality traits of European quails reared under different conditions of temperature and air velocity

This study’s objective was to evaluate the influence of thermal environment and air velocity during the rearing phase on European quail meat quality traits. A total of 1,152 one-day-old European quail chicks were placed inside floor pens within environmental chambers. Each experimental period was approximately 5 wks, with birds slaughtered at 37 d of age. The experimental design consisted of a 2 × 4 factorial arrangement of treatments in completely randomized design with 2 air velocities (0 and 2 m/s) × 4 air temperatures (severe cold [SC], moderate cold, thermal comfort, and moderate heat [MH]). ANOVA, with air velocity and thermal environment as fixed effects, was performed to evaluate the effect of main factors and their interaction on meat quality traits, using the GLM procedure (SAS 9.4). Least square means of treatments effects were compared using Tukey’s test (α = 0.05). Lightness (L∗), redness (a∗), and yellowness (b∗), of quail meat were affected by thermal environment and air velocity (P < 0.05). Initial and final L∗ values were greater for MH (P < 0.05). Meat from birds subjected to 2 m/s air velocity had lower final L∗, but no velocity effect was noted for initial L∗. Quail meat from SC presented higher initial and final a∗ values compared with the other thermal environment groups (P ≤ 0.001). Final a∗ was affected by air velocity (P < 0.05). Initial and final b∗ values for meat from MH were greater, 13.8 and 15.2, respectively, differing from the other treatment environments (P < 0.05). However, air velocity did not influence b∗ values (P > 0.05). Interactions were not significant for pHu (P = 0.993). Thawing loss and shear force were affected by treatments (P < 0.05) but not ultimate pH, drip loss, or sarcomere length. This study demonstrates that thermal environments and air velocity affect quail meat quality traits. Further investigation is recommended to explore effects of air velocity and thermal environment on muscle proteolysis of quail meat quality.

Physicochemical Properties and Protein Denaturation of Pork Longissimus Dorsi Muscle Subjected to Six Microwave-Based Thawing Methods

Physicochemical changes and protein denaturation were evaluated for pork longissimus dorsi muscle subjected to different thawing methods. Fresh pork longissimus dorsi muscle served as a control. Microwave (MT), microwave combined with ultrasonic (MUT), microwave combined with 35 °C water immersion (MIT), microwave combined with 4 °C refrigeration (MRT), microwave combined with air convection (MAT), and microwave combined with running water (MWT) were applied. All microwave-based methods excepted for MT avoided localized overheating. The changes in the water holding capacity (WHC), color, TBARS, and protein solubility were lowest with MAT. Differential scanning calorimetry (DSC) and dynamic rheological property measurements indicated, that the MAT samples changed only slightly and presented with complete peaks and high G' values compared with the other treatments. Thus, MAT may reduce protein denaturation associated with meat thawing. The results of this study indicated that MAT effectively shortens thawing time, preserves meat quality and uniformity, and could benefit the meat industry and those who consume its products.

Changes in physicochemical characteristics and oxidative stability of pre- and post-rigor frozen chicken muscles during cold storage

The objective of this study was to investigate the effects of rigor state on physicochemical characteristics and the oxidative stability of chicken leg and breast muscles as a function of freezing time. Breast and leg muscles were excised from 24 broiler chickens at 30 min or 1.5 h postmortem (PM), frozen overnight at - 75 °C immediately, and then stored at - 20 °C for 90 days to measure the meat quality traits. Results showed that longer freezing led to deterioration of meat quality with higher deterioration for post-rigor frozen muscles. Pre-rigor frozen muscles had higher pH, water holding capacity (around 90%), and sarcomere length with a lower thaw and cook loss than post-rigor frozen muscles. The Warner-Bartzler shear force (WBSF) values for chicken leg and breast muscles were insignificant (except pre-rigor leg muscles which had significantly higher WBSF value only at 90th day of storage). The lightness (L*) value increased significantly with increasing storage for all samples. Post-rigor muscles had significantly higher TBARS values (0.62 mg MDA/kg) than the pre-rigor muscles. The leg muscles had better physicochemical characteristics compared to breast muscles, except for the cook loss. Therefore, immediate freezing (prior to onset of rigor) could be an effective way to minimize the quality deterioration of frozen chicken muscles.

Carcass yields, muscle amino acid and fatty acid profiles, and antioxidant indices of broilers supplemented with synbiotic and/or organic acids

The objective of the current research was to explore the possible impacts of dietary supplementation with synbiotic and/or organic acids (OA) on the performance traits, carcass yields and muscle amino acid and fatty acid (FA) profiles of broilers. Randomly, a total of 160 day-old chicks (Ross 308) were assigned into four equal groups (40 birds each), with each group subdivided into eight replicates (five birds/pen). The control group (CON) fed the basal diet with no supplements, while diets of the treated groups were supplemented with OA (Sodium butyrate 40%; 1 g/kg), synbiotic (comprised Bacillus subtilis, Saccharomyces cerivisiae, Streptococcus faecium, Mannan-Oligosaccharides and β-Glucan; 1 g/kg) and equal mix of OA and synbiotic (2 g/kg). Broilers fed the diets supplemented with synbiotic or synbiotic plus OA produced a significantly higher feed utilization efficiency (p = 0.021) and carcass yields (p = 0.038) than the CON and OA-supplemented groups. The group fed the diet supplemented with the synbiotic showed lowered serum cholesterol (p = 0.049), triglycerides (p = 0.001) and very low density lipoprotein (p = 0.032) when compared with the CON group. Regarding the polyunsaturated FA (PUFA) of breast muscles, synbiotic-supplemented birds had significantly lower n-6:n-3 ratio (p = 0.047), however, a greater hypocholesterolaemic to hypercholesterolaemic FA (H/H) ratio was reported when compared with the CON group (p = 0.002). Among the essential amino acids, the contents of leucine and methionine in the breast (p = 0.032 and 0.007 respectively) and thigh (p = 0.023 and 0.003 respectively) muscles were greater in the synbiotic-supplemented birds compared with the CON group. In conclusion, the synbiotic-supplemented diet improved the PUFA:SFA, n-6:n-3 and H/H ratios by altering the FA composition of broiler muscles, which are important with regards to human health.

Physicochemical and Sensory Properties of Broiler Chicken Breast Meat Stored Frozen and Thawed Using Various Methods

The paper presents an analysis of the impact of freezing storage duration (1, 3, 5, and 7 months) and thawing methods, namely, in atmospheric air, water, and using microwave oven on the quality properties of broiler chicken breast meat. The physicochemical indicators of raw breast meat after thawing and after being subjected to heat treatment were evaluated. The sensory evaluation was also conducted. The findings indicate that the duration of storage has effects on the quality of meat stored frozen at −20°C. Unfavourable changes (p<0.05) were observed between the first and seventh months of freezing storage in respect of such areas as increased drip loss, increased thermal loss, colour changes, and reduced ash content in thawed breast meat as well as in those subjected to heat treatment. Unfavourable changes in the sensory properties, namely, diminished intensity of flavour and aroma, were also observed. The analysis revealed significant (p<0.05) impacts of thawing methods on the meat’s quality properties, depending on the duration of freezing storage. The application of microwave oven method of thawing meat enabled the retention of better physicochemical properties (reduction of drip and thermal losses and increased ash content) as well as sensory properties such as the desirability of the flavor and juiciness of meat stored for one-month period. A longer period of freezing storage (5 and 7 months) revealed higher degrees of colour saturation towards red (a∗) in raw breast meat as well as reduced brittleness of breast meat thawed using microwave oven method prior to and after the heat treatment in comparison to those thawed using atmospheric air and water. Practical Applications. The duration of freezing storage and thawing methods has impacts on the meat’s quality, including its processing value. The current study has its practical implications due to the immense consumption of broiler chicken meat, the high proportion of deep frozen meat products in commerce, and the acceptability and popularity of frozen stored meat in households. The current study enables one to ascertain how the physicochemical and sensory properties of broiler chicken breast meat change over the period of freezing storage (for 1, 3, 5, and 7 months) and which of the applied thawing methods (in atmospheric air, water, or microwave method) is most favourable for retaining meat’s best quality.

Physicochemical determinants of pH in pectoralis major of three strains of laying hens housed in conventional and furnished cages

1. Post-mortem decline in muscle pH has traditionally been attributed to glycogenolysis-induced lactate accumulation. However, muscle pH ([H⁺]) is controlled by complex physicochemical relationships encapsulated in the Stewart model of acid-base chemistry and is determined by three system-independent variables - strong ion difference ([SID]), total concentration of weak acids ([A_tot]) and partial pressure of CO₂ (PCO₂). 2. This study investigated these system-independent variables in post-mortem pectoralis major muscles of Shaver White, Lohmann Lite and Lohmann Brown laying hens housed in conventional cages (CC) or furnished cages (FC) and evaluated the model by comparing calculated [H⁺] with previously measured [H⁺] values. 3. The model accounted for 99.7% of the variation in muscle [H⁺]. Differences in [SID] accounted for most or all of the variations in [H⁺] between strains. Greater PCO₂ in FC was counteracted by greater sequestration of strong base cations. The results demonstrate the accuracy and utility of the Stewart model for investigating determinants of meat [H⁺]. 4. The housing differences identified in this study suggested that hens housed in FC have improved muscle function and overall health due to the increased opportunity for movement. These findings support past studies showing improved animal welfare for hens housed in FC compared to CC. Therefore, the Stewart model has been identified as an accurate method to assess changes in the muscle at a cellular level that affect meat quality that also detect differences in the welfare status of the research subjects.

Active packaging of chicken meats with modified atmosphere including oxygen scavengers

The effects of modified atmosphere packaging (MAP-70% CO2/30%N2) and iron-based oxygen scavengers (OS) with various absorption capacities (Ageless® ss100, ss300, and ss500) as an active packaging system on microbiological and oxidative changes in chicken thigh meats were evaluated during refrigerated storage (4°C) for 19 d at 3-day intervals. Total aerobic mesophilic bacteria counts exceeded the acceptability limit at d 7 in the control group without MAP (AIR), and at d 19 in MAP and OS containing samples. OS utilization resulted in around 1.5 and 1.0 log unit reductions in Pseudomonas spp. counts at d 7 and d 10 of storage, respectively, as compared with AIR and MAP groups (P < 0.05). MAP and OS groups had fewer (P < 0.05) coliform counts than did the AIR group, with an approximately 1.0 log reduction observed at d 10. Although in some cases OS utilization resulted in lower TBARS values and carbonyl and sulphydryl contents, particularly during later stages of refrigerated storage as compared to AIR and MAP groups, in general, these effects were not always apparent. The results of this study suggested that MAP suppressed microbiological growth and retarded lipid and protein oxidation in chicken thigh meats, with a 9-day shelf-life extention with insignificant effects of OS.

Effect of tempering methods on quality changes of pork loin frozen by cryogenic immersion

The quality characteristics of pork loin frozen by cryogenic immersion were examined, such as the drip loss, cooking loss, water holding capacity, moisture content, protein solubility, lipid and protein oxidation, color, and microstructure, and compared after different tempering methods: radio frequency (27.12MHz), water immersion, forced-air convection, and microwave tempering. Forced-air tempering was the most time-consuming process, whereas electromagnetic energy methods (radio frequency and microwave) were the shortest. The tempering rate of radio frequency at 400W was 5 and 94 times greater than that obtained with water immersion and forced-air tempering, respectively. The drip loss, water holding capacity, moisture content, color, and microstructure of pork samples all declined as a result of microwave tempering. By contrast, the least degree of changes in the drip loss, microstructure, and color of the pork loin samples was obtained with radio frequency tempering, suggesting its potential application in providing rapid defrosting without quality deterioration in the frozen meat industry.

Effects of probiotics feeding on meat quality of chicken breast during postmortem storage

This study evaluated the effects of dietary probiotic supplement and postmortem storage on meat quality of chicken breast during retail display. A total of 35 birds were randomly obtained from 3 feeding groups (control without probiotic supplement, 250 ppm Sporulin, and 500 ppm PoultryStar). The probiotic supplement had no influence on feed conversion ratio and body weight gain, as well as body weight at 29 and 44 d (P > 0.05). After slaughter, each side of the breast muscles (M. Pectoralis major) was assigned to either one d or 5 d of postmortem storage. Probiotic supplement had no influence on the rate of pH decline of chicken breast muscles during the initial 6 h postmortem (P > 0.05). No interactions between probiotic supplement and postmortem storage on meat quality were found (P > 0.05). Postmortem storage decreased drip loss from 25.30 to 18.05% (P < 0.05). Probiotics-fed chicken groups, particularly PoultryStar treatment, had a higher myofibrillar fragmentation index than the control group (P < 0.05). However, shear force values were not affected by the probiotic treatments. Decreases in color and lipid stabilities of breast muscles were found during display (P < 0.05), but were not affected by the probiotic supplement (P > 0.05). Our result suggests that probiotic supplement had no adverse impacts on proteolysis and oxidative changes during 5 d postmortem display storage.

Consumer Attitudes Toward Storing and Thawing Chicken and Effects of the Common Thawing Practices on Some Quality Characteristics of Frozen Chicken

In this study, a survey was conducted to both evaluate the consumers’ general attitudes for purchasing and storing the raw chicken and determine the thawing practices used for defrosting frozen chicken at home. About 75% of the consumers indicated purchasing chicken meat at least once a week or more. Furthermore, the majority (82.16%) of those who stored at least a portion of the raw chicken stated freezing the raw chicken meat at home. Freezing the chicken meat was considered to have no effect on the quality by 43.49% of the consumers while 56.51% thought that freezing had either negative or positive effects on the quality. The survey study indicated that top five most commonly used thawing practices included thawing on the kitchen counter, thawing in the refrigerator, thawing in the warm water, thawing in the microwave, and thawing under tap water. In addition, an experimental study was conducted to determine the effects of these most commonly used thawing practices on some quality characteristics of the chicken meat including pH, drip loss, cooking loss, color analysis and textural profile analysis. Although, L* value for thawing on the kitchen counter was the lowest, after cooking, none of the thawing treatments have a significant effect on the color values. Thawing in the microwave produced the highest drip loss of 3.47% while the lowest drip loss of 0.62% was observed with thawing in the refrigerator. On the other hand, thawing in the microwave and refrigerator caused the lowest cooking loss values of 18.29% and 18.53%, respectively. Nevertheless, there were no significant differences among textural parameter values of the defrosted and then cooked samples using the home based thawing practices, indicating similar quality characteristics among the samples.

Physico-chemical characteristics of Longissimus lumborum muscle in goats subjected to halal slaughter and anesthesia (halothane) pre-slaughter

This study assessed the effect of halal slaughter and anesthesia pre-slaughter followed by bleeding on meat quality characteristics of goats. Eleven male Boer cross goats were divided into two groups and subjected to either halal slaughter (HS) or anesthesia with halothane and propofol pre-slaughter (AS). At pre-rigor, HS had significantly lower (P < 0.05) muscle pH and glycogen than AS. However, no significant difference was observed in the pH and glycogen content between the treatments on 1, 3 and 7 days post mortem. The drip loss of HS was significantly lower (P < 0.05) than that of AS at all aging periods. Treatment had no effect on sarcomere length, myofibrillar fragmentation index and shear force values, loss of thiol groups and degradation of major myofibrillar proteins. It can be concluded that HS did not have deleterious effect on meat quality traits of goat when compared to AS.

Evaluation of meat quality after application of different feed additives in diet of broiler chickens

The present study was conducted to investigate the effect of natural feed additives, namely bee pollen extract, propolis extract and probiotic preparation, on technological properties of meat in order to evaluate the meat quality of Ross 308 broiler chickens.  The feeding of chickens (180 pcs) lasted for a period of 42 days. The experiment was carried out without segregation between the genders. The chickens were randomly divided into 4 groups. The control group was fed a basal diet, whereas the other three groups were fed diets supplemented with natural additives, i.e. bee pollen extract at level of 400 mg.kg-1 of feed mixture, propolis extract at level of 400 mg.kg-1 of feed mixture, and probiotic preparation based on Lactobacillus fermentum (1.109 CFU per 1 g of bearing medium) in an amount of 3.3 g added to water (for 30 pcs chickens until 21 days of age, for 20 pcs chickens from 22nd to 42nd day of age) given to group E1, group E2 and group E3, respectively. The feed mixtures were produced without any antibiotic preparations and coccidiostatics. During the whole period of experiment, the broiler chickens had ad libitum access to feed and water. The following technological properties were examined: cooling loss (after 24 h of storage at 4 °C), freezing loss (after 3 months of storage at -18 °C), roasting loss (performed on roasted meat that was stored at -18 °C for 3 months before thawing), colour parameters based on CIELab system (the L*, a*, b* values of raw breast and thigh muscle), and tenderness (as shear force of roasted breast and thigh muscle). We have made a finding, that the examined additives had only little impact on meat quality in most of the investigated parameters, except the significant increase (p ≤0.05) in redness (a*) values and the slight decrease in roasting loss and shear force determination after propolis extract supplementation. Therefore, it may be inferred that propolis extract has been shown as the most appropriate feed additive among the applied supplements.

Colour Changes in Meat of Foals as Affected by Slaughtering Age and Post-thawing Time

The aim of the present work was to investigate how colour changes of foal meat can vary after thawing out in relation to the slaughtering age of the horses and to the post-thawing time. Eighteen Italian Heavy Draught Horse (IHDH) foals were used for the trial. They were subdivided in three groups according to their slaughtering age (6, 11 and 18 months). Two different surfaces were investigated for each sample: a fresh cut surface (daily renewed cutting surface: DRCS), and not-renewed cutting surface (NRCS). The redness of both investigated surfaces increased with slaughtering age (p<0.01). Moreover, this parameter decreased during post-thawing time (p<0.01) only on the NRCS, probably due to the myoglobin oxidation processes. Colour is an important visual cue denoting perceived quality by consumers. So, by a chromatic perspective the thawed meat of IHDH foals slaughtered at 6 and 11 months proved to be that which best meets the market requirements.

Japanese quail meat quality: characteristics, heritabilities, and genetic correlations with some slaughter traits

The aim of this study was to evaluate the genetic parameters of several breast meat quality traits and their genetic relationships with some slaughter traits [BW, breast yield (BRY), and abdominal fat yield (AFY)]. In total, 1,093 pedigreed quail were slaughtered at 35 d of age to measure BRY, AFY, and breast meat quality traits [ultimate pH (pHU), Commission Internationale d'Eclairage color parameters (L*, lightness; a*, redness; and b*, yellowness), thawing and cooking loss (TL and CL, respectively), and Warner-Bratzler shear value (WB)]. The average pHU, L*, a*, and b* were determined to be 5.94, 43.09, 19.24, and 7.74, respectively. In addition, a very high WB average (7.75 kg) indicated the firmness of breast meat. High heritabilities were estimated for BW, BRY, and AFY (0.51, 0.49, and 0.35). Genetic correlations of BW between BRY and AFY were found to be high (0.32 and 0.58). On the other hand, the moderate negative relationship between BRY and AFY (-0.24) implies that selection for breast yield should not increase abdominal fat. The pHU was found to be the most heritable trait (0.64), whereas the other meat quality traits showed heritabilities in the range of 0.39 to 0.48. Contrary to chickens, the genetic correlation between pHU and L* was low. The pHU exhibited a negative and high correlation with BW and AFY, whereas L* showed a positive but smaller relationship with these traits. Moreover, pHU exhibited high negative correlations (-0.43 and -0.62) with TL and WB, whereas L* showed a moderate relationship (0.24) with CL. This genetic study confirmed that the multi-trait selection could be used to improve meat quality traits. Further, the ultimate pH of breast meat is a relevant selection criterion due to its strong relationships with either water-holding capacity and texture or low abdominal fatness.

Effect of Acacia karroo Supplementation on Growth, Ultimate pH, Colour and Cooking Losses of Meat from Indigenous Xhosa Lop-eared Goats

The objective of the study was to determine the effect of Acacia karroo supplementation on growth, ultimate pH, colour and cooking losses of meat from indigenous Xhosa lop-eared goats. Eighteen castrated 4-month-old kids were used in the study until slaughter. The kids were subdivided in two treatment groups A. karroo supplemented (AK) and non-supplemented (NS). The supplemented goats were given 200 g per head per d of fresh A. karroo leaves. The kids were slaughtered on d 60 and sample cuttings for meat quality assessment were taken from the Longistimus dorsi muscle. The supplemented kids had higher (p<0.05) growth rates than the non-supplemented ones. The meat from the A. karroo supplemented goats had lower (p<0.05) ultimate pH and cooking loss than the meat from the non-supplemented goats. Acacia karroo supplemented goats produced higher (p<0.05) b* (yellowness) value, but supplementation had no significant effect on L* (lightness) and a* (redness) of the meat. Therefore, A. karroo supplementation improved growth performance and the quality of meat from goats.

Effects of rigor state, thawing temperature, and processing on the physicochemical properties of frozen duck breast muscle

The objectives of this study were to evaluate effects of rigor state, thawing temperature, and processing on the physicochemical properties of intact frozen duck breast muscle and homogenates prepared with the frozen-thawed muscles. Prerigor breast muscle was frozen at -25°C and thawed at 4 and 15°C, and the physicochemical properties of duck breast frozen prerigor compared with those in frozen postrigor and 4°C chilled postrigor muscles. The homogenates prepared with duck breast frozen prerigor showed similar physicochemical properties as the frozen-thawed postrigor muscle homogenate. The thawing temperature did not affect the physicochemical properties of homogenates prepared with duck breast muscle frozen prerigor. Also, no significant differences (P > 0.05) in the ultimate pH value and color parameters were observed among the frozen-thawed treatments despite the differences in rigor state and thawing temperature. However, a higher thawing temperature of the intact frozen prerigor muscle resulted in an increase in thawing loss and shear force due to excessive muscle shortening. In this study, the intact duck breast that has undergone thaw-rigor showed main problems associated with thaw-rigor, such as higher thawing loss and shear force, regardless of thawing temperature. However, the processing (grinding and salting) decreased the difference in physicochemical properties due to rigor state before freezing and thawing temperature. Therefore, the frozen-thawed duck breast muscle used to manufacture ground-type meat product may be frozen before rigor onset.