Meat Cooking Loss Research Articles

Nutritional evaluation of graded levels of fermented maize milling waste (maize gluten) in rabbit diet

A 70-day feeding trial was conducted with thirty-six 7 weeks old weaned rabbits (mixed breed and sexes), with initial average live weight of 0.81kg to evaluate the nutritional effects of replacing maize at 0,25, and 50%with maize or corn gluten in rabbit diets. Maize gluten is fermented maize milling waste sun dried for three days. The diets were offered to the rabbits which were randomly divided into three (3) groups of 12 rabbits each and each group sub-divided into four (4) replicates of 3 rabbits each in a completely randomized experiment. There was a significant effect (P<0.05) of the treatments on the average daily feed intake of the rabbits as the levels of maize gluten increased. The average weight gain and feed conversion ratio were not significantly (P>0.05) affected by the dietary treatments, nevertheless, the FCR increased across the treatments. Graded levels of maize gluten had no significant (P>0.05) effect on carcass dressing percentage. The percent pelt decreased significantly (P<0.05) as level of maize gluten increased. Furthermore, liver and meat cooking loss percentage values showed significant differences (P<0.05) due to the graded levels of corn gluten fed. The sensory evaluation studies were not statistically affected (P>0.05).

Influence of level of inclusion of Azolla leaf meal on growth performance, meat quality and skeletal muscle p70S6 kinase α abundance in broiler chickens

The interest in biodiesel production from oil-bearing seeds rather than soybean necessitates the scientific validation of other good quality protein sources that could substitute soybean meal in animal diets, particularly, broiler chickens where soybean meal constitutes a large portion of their diet. Therefore, the present study was conducted to investigate the effect of sun-dried Azolla leaf meal (ALM) as an unconventional dietary protein source in broiler chicken diet on growth performance, meat quality, skeletal muscle cell growth and protein synthesis through regulation of ribosomal protein S6 kinase (p70S6 kinase α). A total of 120 male Ross 308 broiler chicks were randomly allocated to three dietary treatments. Each treatment had four cages (i.e. replicates) with 10 birds/cage. The control group was fed with a corn–soy-based diet, the AZ5 group was supplemented with 5% ALM and the AZ10 group was supplemented with 10% ALM for 37 days. A 5-day trial was also conducted to measure the apparent nutrient digestibility. Growth performance parameters were measured weekly. At the end of the experiment, 12 birds from each group (3/cage) were euthanized and used for samplings. Inclusion of ALM tended to improve BW gain (P = 0.06) and increased feed intake (P < 0.01). Additionally, ALM decreased the percentage of breast meat cooking loss linearly (P < 0.01). In addition, ALM at a dose of 5% increased the production of propionate in the cecum (P = 0.01). Activation of breast muscle p70S6 kinase was higher when ALM was included in a dose-dependent manner (P < 0.01). The inclusion of ALM increased breast meat redness (P < 0.01); however, the lightness was within the normal range in all groups. Findings from our study suggest that ALM could be included in a broiler chicken diet up to 5% without any major negative effect on meat quality or performance, and it regulates muscle protein synthesis through activation of mammalian target of rapamycin/6S kinase signaling.

Physical quality of broiler chickens fed diets containing fish oil and different levels of purslane meal

The aim of the study was to investigate the effect of dietary supplementation of purslane meal (Portulaca oleraceae) and sardines fish oil as a source of omega-3 fats on physical quality of broiler chickens. A total of 180 one-day old unsexed Cobb broiler chickens were used in this study. Chickens were randomly placed into 30 pens with each pen consisted of 6 birds. The pens were randomly assigned to five dietary treatments with 6 replicates (36 birds per treatment). The diets were prepared from a basal diet (P0). The experimental diets were formulated by adding the basal diet containing 1.5% sardines fish oil and levels of purslane meal 0 (P1), 6 (P2), 12 (P3), and 18% (P4). Water and diets were provided ad libitum for a period of 35 days. Six chickens for each treatment were processed as carcass and breast meat (Pectoralis Major) samples were collected for physical quality analysis. The data were analysed using analysis of variance (ANOVA). Differences between treatment means were further analysed using Duncan’s New Multiple Range Test. Results showed that the results showed that adding Portulaca oleracea (purslane) meal into the diets at a level of 12 and 18% did not influenced pH value. Feeding diets enriched with purslane meal up to a level of 18% for 35 days did not alter meat WHC with the average of approximately 51%. Diets containing purslane meal decreased meat cooking loss. Meat tenderness of chickens fed diets supplemented with 12% purslane meal (1.12) was higher than those fed 18% purslane meal (1.93). It was concluded that dietary levels of purslane meal up to a level of 12% did not affect the physical quality of broiler chickens.

Effect of dietary digestible lysine level on growth performance, blood metabolites and meat quality of broilers 23-38days of age.

This study was done to evaluate the effects of different dietary digestible lysine (dig Lys) levels on growth performance, blood metabolites, carcass and breast yield, and breast meat quality of broilers 23-38days of age. Three hundred 23-day-old Cobb-500 male broiler chickens were allocated to a completely randomized design with five treatments (finisher diet containing 0.88%, 0.94%, 1.00%, 1.06% and 1.12% dig Lys) and six replicates of 10 birds each. Feed intake (FI) was not affected by different dietary dig Lys levels. Weight gain (WG) linearly increased and feed conversion ratio (FCR) linearly decreased with an increasing dietary dig Lys levels. With increasing dietary dig Lys levels, carcass and breast yield and breast meat hue angle (h* ) linearly increased, but abdominal fat decreased quadratically, whereas breast meat lightness (L* ) and ether extract composition linearly decreased. Dietary dig Lys levels did not show any significant effect on serum metabolites, breast meat cooking loss and water holding capacity. Based on the linear broken-line regression models, the weight gain, feed conversion ratio and breast yield were optimized when dietary dig Lys levels were 0.95%, 1.01% and 1.02% respectively. It is concluded that Lys requirements vary according to what productive parameter is taken for optimization. A minimum of 1.02% dig Lys concentration in the finisher diet is suggested to optimize breast yield, feed efficiency and performance in broiler chickens.

Comparison of grain-based diet supplemented with synthetic vitamin E and lucerne hay-based diet on blood oxidative stress biomarkers and lamb meat quality

Individually-housed lambs were used to compare the effect of a grain-based diet supplemented with moderate (MOD) or supranutritional (SUP) levels of vitamin E and selenium, and a lucerne hay-based diet (LUC) on plasma-oxidative stress biomarkers, muscle pH decline and meat quality. Lambs fed LUC had different reactive oxygen metabolite concentrations and biological antioxidant potentials to the MOD and SUP treatment groups. All plasma oxidative stress markers decreased in concentration across the four sampling time points measured over the eight week feeding study, except biological antioxidant potential (BAP). Diet did not impact on lamb muscle pH decline traits. Of the meat quality traits measured, the effect of diet was only significant for shear force which was highest for the LUC lambs. Particle size and carbonyl content in meat were influenced by ageing period. Meat cooking loss, peroxidase activity and oxidation-reduction potentials were not influenced by any experimental factors. These findings show that LUC offers a strategic feeding system that is comparable to MOD and SUP diets.

Cooking of meat: effect on texture, cooking loss and microbiological quality – a review

Cooking can positively affect meat tenderness, on the other hand, the heat treatment also causes weight loss. The resulting tenderness of cooked meat is influenced by the background toughness of fresh meat, by the post mortem ageing process and by the method of cooking. In the case of heat treatment, the temperature and duration of action play a key role. In this respect, the meat tenderness depends on the type of appliance used for cooking. The cooking loss of meat during heat treatment is caused by contraction of muscle fibres and intramuscular connective tissue, the intensity of which also depends on the temperature and device used. The extent of this contraction increases with increasing temperature. Cooking of meat is considered the most effective way of eliminating microorganisms causing food-borne diseases. The recommended combination of temperature and time of 70 °C for 2 min reduces the number of Listeria monocytogenes bacteria by more than 6 log. This temperature is not, however, always attained with the use of many meat cooking methods, such as grilling or frying. This presents the risk of survival of food-borne agents. The latest knowledge indicates that, in the case of cross contamination, the population of food-borne agents is of the order of 1–2 log CFU/cm2 or g. If they do not multiply as a result of a higher environmental temperature, the population of pathogenic bacteria present is then reliably eliminated during adequate cooking, either entirely or to an amount that does not suffice to induce illness.

Comparison of meat quality parameters in three chicken strains fed Moringa oleifera leaf meal-based diets

SUMMARY The effect of dietary Moringa oleifera leaf meal (MOLM) on the quality and fatty acid profile of meat from 3 chicken strains, normally used in low-input, extensive production systems, was evaluated. The MOLM was included in a commercial broiler finisher diet at 0 (MOLM0), 25 (MOLM25), 50 (MOLM50), and 100 (MOLM100) g/kg. All diets were formulated to be isonitrogenous and isoenergetic. Two hundred and sixteen (216) Potchefstroom Koekoek (PK), Ovambo (OV) and Black Australorp (BA) chickens were offered the diets for a period of 13 wk in a 2 × 3 × 4 factorial treatment arrangement in a complete randomized design (CRD). The 3-way interaction (diet × strain × gender) term did not (P > 0.05) affect redness (a*), yellowness (b*), pH or meat cooking loss, but significantly influenced (P

Optimization of goose breast meat tenderness by rapid ultrasound treatment using response surface methodology and artificial neural network.

The aim of this study was to develop a prediction model on tenderization of goose breast meat by response surface methodology (RSM) and artificial neural network (ANN). The experiments were operated on the basis of a three-level, three-variable (ultrasound power, ultrasound time, and storage time) Box-Behnken experimental design. Under RSM and ANN optimum conditions, experimental Meullenet-Owens razor shear (MORS) of meat (1862.6g and 1869.9g) was in reasonable agreement with predicted one. Nevertheless, better prediction capability of ANN was proved by higher R2 (0.996) and lower absolute average deviation=4.257) compared to those for RSM (0.852 and 16.534), respectively. These results revealed that ANN was more accurate and much better than RSM model for the optimization of tenderness of meat. The optimum conditions of ultrasound power, ultrasound time, and storage time given by ANN were 812W, 24.5min and 25.7hr, respectively. Under the optimized condition, the cooking loss of meat significantly decreased by ultrasound treatment compared with untreated meat. Lower cooking loss and MORS at the optimal condition were beneficial to meet the satisfaction of consumer and producers for meat factory.

Effects of chlorogenic acids-enriched extract from Eucommia ulmoides leaves on growth performance, stress response, antioxidant status and meat quality of lambs subjected or not to transport stress

This study was conducted to evaluate the effects of chlorogenic acids-enriched extract (CGAE) from Eucommia ulmoides leaves on growth performance, stress response, antioxidant status and meat quality of lambs subjected or not to transport stress. Forty eight weaned male Huzhou lambs (a local breed, average body weight 17.3 ± 1.58 kg) were equally divided into three treatments for a 56 d feeding period and fed the basal diet supplemented with 0 (CGAE0), 1 (CGAE1) or 5 (CGAE5) g of CGAE/kg of the basal diet (dry matter basis). After the feeding trial, eight lambs per treatment were randomly selected, blood sampled and slaughtered without road transport. The remaining 24 lambs were transported for 8 h to simulate stress. After transport, all lambs were blood sampled and slaughtered. Dietary CGAE supplementation did not affect average daily gain, dry matter intake and feed efficiency of lambs. Significant interaction between road transport and dietary CGAE supplementation was found for the glucose concentration (P < 0.01) in blood and the pH24 value (P < 0.05) and malondialdehyde (MDA, P < 0.01) content in meat. Lambs fed the CGAE1 and CGAE5 diets had lower (P < 0.01) glucose and triiodothyronine (T3) concentrations, creatine kinase (CK) activity, white blood cell (WBC) count and neutrophil (NEU): lymphocyte (LYM) ratio and higher (P < 0.01) LYM count than lambs fed the CGAE0 diet. Lambs fed the CGAE5 diet had higher superoxide dismutase (SOD, P < 0.01) activity and total antioxidant capacity (T-AOC, P < 0.01) of serum and T-AOC (P < 0.05) of liver and lower serum cortisol concentration (P < 0.01) and MDA (P < 0.05) contents in serum and liver compared with lambs fed the CGAE0 diet. Road transport increased (P < 0.01) cortisol, glucose, T3 and thyroxine (T4) concentrations, CK activity and WBC count in blood and MDA contents in serum and liver and decreased (P < 0.05) SOD activity and T-AOC of serum. Dietary CGAE supplementation decreased pH24 value (P < 0.05) and MDA content (P < 0.01), but increased (P < 0.05) cooking loss of meat. In contrast, the opposite was true for the effects of road transport on pH24 value (P < 0.05), MDA content (P < 0.01) and cooking loss (P < 0.01) of meat. In conclusion, dietary CGAE supplementation did not affect the growth performance and improved certain stress indicators, meat quality and antioxidant status of lambs, especially for transport-stressed lambs.

Dietary glutamine improves meat quality, skeletal muscle antioxidant capacity and glutamine metabolism in broilers under acute heat stress

ABSTRACTThis study investigated the effects of glutamine (Gln) on meat quality, skeletal muscle antioxidant capacity and Gln metabolism in heat-stressed broilers. Three hundred 42-day-old broilers were randomly divided into five groups: a control group (23 ± 1°C), which was fed basal diet, and four experimental groups (34 ± 1°C), supplemented with 0, 5, 10, and 20 g Gln/kg of basal diet. The experiment lasted for 24 h. Compared with the control group, acute heat stress caused a significant reduction (p < .05) in meat pH, water-holding capacity (WHC), gumminess and hardness, and a significant increase (p < .05) in cooking loss (CL) and lightness (L*) values. However, dietary Gln (20 g/kg) increased (p < .05) meat pH, WHC, gumminess and hardness, but decreased (p < .05) meat CL and L* values in the acute heat-stressed group. In breast and thigh muscles, the acute heat stress group exhibited significantly (p < .05) higher concentrations of malondialdehyde (MDA), but significantly (p < .05) lower levels of Gln, glutamate and glutaminase than the control group; dietary 20 g/kg Gln significantly decreased (p < .05) MDA concentrations, while it increased (p < .05) glutathione, glutathione peroxidas, T-AOC, Gln, glutamate, and glutaminase levels in acute heat-stressed groups. Gln could increase meat quality by improving antioxidative capacity and Gln metabolism in heat-stressed broilers.

Effect of dietary supplementation of hemp seed (Cannabis sativa L.) on meat quality and egg fatty acid composition of Japanese quail (Coturnix coturnix japonica).

This study was conducted in two separate experiments. Experiment I was conducted to investigate the effects of hemp seed (HS) on meat quality traits, and experiment II was designed to determine egg fatty acid (FA) composition in Japanese quail (Coturnix coturnix japonica). In experiment I and experiment II treatments, groups were as follows: (i) control (not included HS0), (ii) 5% HS inclusion to diets, (iii) 10% HS inclusion to diets and (iv) 20% HS inclusion to diets. In experiment I, a total of 192 7-day-old-quail were fed with HS diets for 5weeks, and end of the experiment I, a total of 64 quail (16 each) slaughtered and meat samples were analysed for meat colour, pH, cooking and thawing loss and FA composition. In experiment II, a total of 120 8-week-old laying quail were fed with experimental diets for 6weeks and egg FA composition were determined. Breast meat cooking loss was significantly lower in 20% supplemented group (p<0.01). Hemp seed inclusion to diets caused a linear and cubic increase in redness (a*) of hip meat (p<0.01). Palmitoleic and oleic FAs were decreased with HS addition in breast meat (p<0.05); however, linoleic and linolenic acid contents of meat were linearly increased (p<0.01). In experiment II, the linoleic and linolenic FA contents of egg samples were linearly increased with increasing the dietary HS ratio (p<0.01). Hemp seed addition was provided lower palmitoleic and oleic FAs in quail eggs (p<0.05). In conclusion, HS supplementation to quail diets may increase quail meat redness and meat and egg yolk omega-3 FA content and decrease cooking loss of quail meats.

Effect of Carcass Management on Horse Meat Quality

ObjectivesCanada is one of the largest exporters of horse meat. To remain competitive, it is necessary to ensure the highest quality of horse meat. Hence, the objective of the current study was to characterize the meat quality of horse meat aged under vacuum for up to 90 d to ensure the highest quality of horse meat.Materials and MethodsTwelve Semimembranosus (SM) muscles were collected over 4 consecutive visits from an Alberta abattoir, with 3 muscles collected at each visit. Visits were performed over a 3 wk interval. At each visit, at 17 h post mortem the SM muscles were separated from the right side of 3 randomly selected carcasses. The collected SM muscles were cut into 5 equal portions, with each portion consisting of 2 steaks. Portions were randomly distributed to either 3, 30, 60, and 90 d ageing (at 0 ± 0.5°C) with the exception of the third and middle portion, which was frozen and stored at –18°C on d 3 for intramuscular connective tissue analysis. The steaks within the remaining portions were packaged individually under vacuum for ageing. After each ageing period, 1 steak within each portion was assessed for purge loss, cooking loss, Warner Bratzler Shear force (WBSF) while the other steak was cubed and freeze dried for proximate (protein, fat, moisture) analysis. Prior to these analyses, the color (L*, a*, b*; Commission Internationale ĹEclairage) and pH were measured in both steaks at 3 different places in each steak. Data were analyzed by R (version 3.3.1) using the package nlme as a mixed model, where ageing was a fixed effect, visit a random effect, and carcass weight a covariate. Differences between least square means (p < 0.05) were determined by Tukey’s multiple comparison and Pearson correlations were used to identify significant linear relationships.ResultsThere was no effect of ageing on horse meat cooking loss and intramuscular fat (IMF) content. However, the meat color as indicated by L* and b* changed (p < 0.05) throughout the ageing period. The L* gradually decreased as ageing time increased, with mean L* value highest and lowest on d 3 and d 60 post mortem, respectively. The highest value of b*, however, was observed on d 30 and the lowest value at d 3 post mortem. Muscle pH increased with length of ageing, with the mean pH value for d 3 being less than that at d 30 and 60. Similarly, mean purge loss gradually increased with length of ageing, with the highest purge losses observed at d 60 and the lowest at d 3. WBSF decreased with length of ageing period, with the highest and lowest mean WBSF values observed at d 3 and 60, respectively. Besides ageing period, WBSF at d 3 appeared influenced by muscle pH and IMF content, as there was a positive correlation between muscle pH and WBSF (r = 0.69, p = 0.013) and a negative correlation between WBSF and IMF content (r = –0.64, p = 0.025).ConclusionThese preliminary results suggested that meat color and WBSF did not differ between d 30 and d 60; therefore, horse meat quality appeared to be optimal at d 30 post mortem as it exhibited minimum purge loss while still having the best technological quality.

Effect of Using Tapioca By-Product and Tofu Waste Fermented With A Mix Culture of Aspergillus Niger and Rhizopus Oligosporus as A Substitute for Corn on Physical Qualities by Broiler

The experiment was conducted to evaluate physical quality of meat in broiler fed diets with addition of tapioca by-product and tofu waste fermented with a combination Aspergillus niger and Rhizopus oligosporus as a substitution for corn. Two hundred DOC’s unsex Lohmann Platinum strain were randomly divided into 25 groups containing eight birds each. Experiment was designed by using “Completely Randomized Design” with five treatments, replicated five times. The treatments of feed used were P0 = basal diet + corn P1 = basal diet + Corn subtituted 5% OAF, P2 = basal diet + Corn subtituted 10% OAF, P3 = basal diet + Corn subtituted 15% OAF, P4 = basal diet + Corn subtituted 20% OAF. Chickens were raised for 35 days. Drinking water and feed were given ad libitum. Meat samples (Pectoralis superficialis) were taken to determine the physical qualities of meat. The results showed that addition of OAF did not exertisignificant effect on carcass presentage, pH, water-holding capacity, and cooking loss of meat of broiler. The conclusion was that the additional of OAF cannot improve the quality of physical broiler meat. The best result showed at third treatment with 15% OAF substitution of feed.

DAYA MENGIKAT AIR DAN SUSUT MASAK DAGING SAPI BLANSIR YANG DIKERINGKAN DALAM OVEN DAN DIKEMAS VAKUM

WATER HOLDING CAPACITY AND COOKING LOSS OF DRIED AND VACUUM PACKAGE BEEF MEAT. Fresh meat is categorized into perishable physical and chemical material product due to high nutrient composition as the main media of growing microorganism. This meat damage could be handled by drying and vacuum package method. The objective of this study was to evaluate effect of drying time period and storage time period on water holding capacity and cooking loss of vacuum package beef meat. Treatment was conducted using completely randomized design divided into two factors with three replications in each combination of the factors. Factor A, as main plot of drying time period was divided into 12 hours (A1), 16 hours (A2) and 20 hours (A3). Factor B as sub plot of storage time period in room temperature of 270 C was divided into 00 C (B0), 120 C (B1), 240 C (B2), and 360 C (B3). Results showed that treatments affected significantly quality of beef meat. There was no interaction effect on water holding capacity and cooking loss of vacuum package beef meat. Beef meat being dried during 16 hours with temperature of 60 0C using vacuum package and stored at room temperature of 270 C during 36 days produced normal standard of water holding capacity and cooking loss of meat. Key words: water-holding capacity, cooking loss, vacuum package.

Antioxidant Enzyme Activity and Meat Quality of Meat Type Ducks Fed with Dried Oregano (Origanum vulgare L.) Powder.

One-day-old Cherry valley meat-strain ducks were used to investigate the effect of supplemental dried oregano powder (DOP) in feed on the productivity, antioxidant enzyme activity, and breast meat quality. One hundred sixty five ducks were assigned to 5 dietary treatments for 42 days. The dietary treatment groups were control group (CON; no antibiotic, no DOP), antibiotic group (ANT; CON+0.1% Patrol), 0.1% DOP (CON+0.1% DOP), 0.5% DOP (CON+0.5% DOP), and 1.0% DOP (CON+1.0% DOP). Upon feeding, 1,1-diphenyl-2-picryl-hydrazyl (DPPH) radical scavenging activity of oregano extracts was higher than that of tocopherol, although it was less than that of ascorbic acid. As a result of in vivo study, DOP in the diet showed no effects on final body weight, feed intake, or feed conversion ratio. However, dietary 0.5% and 1% DOP supplementation caused a significant increase in the serum enzyme activity of superoxide dismutase (SOD) compared with CON and ANT, while glutathione peroxidase (GPx) in tissue was increased as compared to ANT (p<0.05). Cooking loss from ducks fed with DOP decreased compared with the control ducks. Thiobarbituric acid reactive substance (TBARS) values of duck breast meat at 5 d post slaughter was found to be significantly reduced in ducks whose diets were supplemented with 0.5% and 1% DOP (p<0.05). These results suggest that diets containing 0.5% and 1% DOP may beneficially affect antioxidant enzyme activity of GPx and SOD, improve meat cooking loss, and reduce TBARS values in breast meat at 5 d of storage in ducks.

Cortisol Hormone Concentration and Meat Quality of Beef Cattle Stunned by Captive Bolt Stun Gun before Slaughtering

This study was aimed to describe cortisol hormone concentration and meat quality which were produced in beef cattle stunned with captive bolt stun gun before slaughtering. Blood and meat samples were taken from Brahman cross steers (n= 11) in two abattoirs located in West Java and Banten. Blood samples were collected immediately after slaughtering. Cortisol hormone concentration in the serum was measured by using radioimmunoassay (RIA). The descriptive, correlation, and regression analyses were used to interprete data. Meat quality assessment was based on pH, cooking loss, and complete drainage of blood. The average of cortisol hormone concentration was 26.59 ng/mL. Meat pH at 1 h postmortem and 24 h postmortem were 6.65 and 6.21, respectively. Meat cooking loss was 26.77%. Blood drainage in meat samples of each cattle showed complete drainage. There was a significant correlation (P<0.05) between cortisol concentrations and pH at 1 hour postmortem as well as cortisol concentration and cooking loss. There was no significant correlation between pH at 24 h postmortem and cooking loss. Cattle was stunned with a captive bolt stun gun before slaughtering produced meat with complete blood drainage but had high cortisol hormone concentration and pH ultimate. Key words: cortisol, quality of meat, stunning, captive bolt stun gun

Comparison of broiler meat quality when fed diets supplemented with neutralized sunflower soapstock or soybean oil

The objective of the current study was to evaluate the effect of dietary fat type and level on broiler meat quality. A 2 × 3 factorial arrangement with 2 types of fat including neutralized sunflower soapstock (NSS) and soybean oil (SO) at 3 levels of fat inclusion (2, 4, and 6%) was used with 5 replicates per treatment using 750 one-day-old broiler chicks in a completely randomized design. At the end of the study (d 36), 10 broilers from each replication were processed at a commercial slaughtering facility. Six carcasses from each replicate were used for meat quality evaluation. With the exception of 3 responses [breast meat lightness (L*) at 1 and 2 d, and redness (a*) at 5 d], there were no interactions between fat source and level. Breast meat pH at 15 min was not significantly affected by the dietary treatments. However, breast meat pH at 24 h postmortem was decreased (P < 0.01) in broilers fed the NSS. Breast meat cooking loss, shear force, and color did not differ between fat sources. Breast meat cooking loss decreased (P < 0.05) when the dietary levels of fat increased. Thigh meat TBA reactive substances were not different due to dietary fat source and level. Breast meat and skin L* value significantly decreased when the dietary levels of fat increased. Breast meat a* value was highest for the 6% fat fed birds on d 2 (P < 0.05) and d 5 (P < 0.01). Higher dietary fat levels decreased the b* values of breast meat except d 5. Breast skin yellowness (b*) value was higher (P < 0.01) for the SO-fed birds compared with NSS-fed birds. Thigh meat of the birds fed the NSS was lighter (P < 0.05) than that of the birds fed SO diets except d 5. Overall, data suggest that NSS can be used as an alternative fat source to SO with little effect on meat quality.

Effects of dietary glutamine and gamma-aminobutyric acid on meat colour, pH, composition, and water-holding characteristic in broilers under cyclic heat stress

1. An experiment was conducted to evaluate the effects of dietary glutamine (Gln, 0 and 5 g/kg) and gamma-aminobutyric acid (GABA, 0 and 100 mg/kg) on raw breast meat colour, pH, composition and water-holding characteristic of broilers under cyclic heat stress (HS). 2. A total of 360 21-d-old Arbor Acres male chicks were randomly assigned to 5 treatment groups (6 replicates of 12 birds per cage). The positive control (PC) broilers were kept in a thermoneutral chamber (22–24°C) and fed on the basal diet. The other 4 groups were kept in a cyclic HS chamber (30–34°C) for 9 h (from 09:00 to 18:00). 3. A significant increase was observed in breast meat lightness at 28, 35 and 42 d; and pH values at 28, 35 and 42 d; while a significant decrease was observed in breast meat cooking loss (CL) and contents of moisture, crude protein (CP), crude fat (CF) and crude ash (CA) due to HS. 4. The supplementation with 0·5 g Gln/kg decreased lightness at 28, 35 and 42 d; while increasing redness at 28 d, yellowness at 35 d, contents of CP, CF and CA, thawing loss (TL) and drip loss (DL). The addition of 100 mg GABA/kg decreased lightness at 28 and 35 d, pH value at 28, 35 and 42 d, and TL; while increasing redness at 28 d, 35 and 42 d, contents of moisture, CP and CF. 5. The lightness, redness, and pH value; contents of moisture, CP, CF and CA; and TL, DL and CL of breast meat of broilers fed with the mixture of Gln and GABA under cyclic HS were similar to those of the broilers in the PC group. 6. Significant interactions were found between Gln and GABA for yellowness at 28 and 35 d; pH at 28, 35 and 42 d; moisture content, CP content, water-holding capacity and TL. 7. These results demonstrated that dietary Gln and GABA offer a potential nutritional strategy to prevent cyclic HS-related depression in broiler meat chemical composition and quality.

Morphological Examinations of Oxidatively Stressed Pork Muscle and Myofibrils upon Salt Marination and Cooking To Elucidate the Water-Binding Potential

Pork longissimus muscle samples were subjected to the following three marination conditions: (A) oxidation (40 min) in hydroxyl radical-generating solutions (HRGS; 10 μM FeCl(3)/100 μM ascorbate with 5 or 20 mM H(2)O(2), pH 6.2) containing 0.1 M NaCl and then marination (40 min) in 0.6 M NaCl with 15 mM pyrophosphate (PP); (B) simultaneous oxidation/marination (40 min) in HRGS containing 0.6 M NaCl and 15 mM PP; or (C) the same as condition B except that PP was omitted. Protein oxidation, measured by the carbonyl and tryptophan fluorescence changes, enhanced hydration but increased cooking loss of meat. Light microscopy revealed a dense muscle structure characterized by swollen fibers and reduced intercellular spacing in intermediately oxidized muscle samples marinated with 0.6 M NaCl and 15 mM PP. However, oxidized fibers were more susceptible to transverse shrinkage upon cooking than nonoxidized fibers, which was supported by the dynamic ultrastructural changes in myofibrils observed using phase contrast microscopy. These findings provide a further understanding of the complex impact of oxidation on meat hydration and water-binding.

The Effects of Different Chilling Methods on Meat Quality and Calpain Activity of Pork Muscle Longissimus Dorsi

The objective of this study was to investigate the effects of conventional chilling (0 to 4 °C), rapid chilling (RC, -20 °C for 30 min, followed by 0 to 4 °C), and short-duration chilling (0 to 4 °C for 30 min, followed by 25 °C) on meat quality and calpain activity of pork muscle longissimus dorsi (LD). The muscle quality characteristics pH, color, cooking loss, pressing loss and tenderness, and calpain activities were measured 0-, 3-, 12-, and 24-h postmortem. Results show that the RC resulted in a faster temperature decline of the muscle, and prevented the meat pH and Commission Internationale de l'Eclairage L* value from declining during postmortem aging. RC also reduced meat cooking loss and pressing loss compared with the other two chilling methods. However, the chilling methods did not significantly affect meat shear force. During the first 24-h postmortem, there was not a noticeable change in the activity of m-calpain. But μ-calpain activity decreased regardless of chilling method. In the rapidly chilled carcasses, μ-calpain activity remained the same 3- and 12-h postmortem. However, in the short-duration chilled and conventionally chilled carcasses, the activity was visibly reduced. At 24-h postmortem, no clear zones on the gel were observed in all three treatments. Conventional and RC methods are commonly used for pork in commercial practice nowadays. Compared with conventional chilling, the effect of RC on quality parameters of pork varies. In recent years, short-duration chilling (SC) is widely used in many Chinese pig slaughtering facilities. However, few researchers have studied the effect of SD on pork quality. Therefore, the present study investigated the effect of different chilling methods on functionalities or quality of chilled pork meat.