Immunochemical Quantification of Heat Denaturation of Bovine Meat Soluble Proteins

Immunoquantification of myoglobin, L-lactic dehydrogenases (LDH) M4 and H4, albumin, transferrin and immunoglobulin G (IgG) was performed after heat treatment of crude soluble sarcoplasmic protein extract over a range of 54–70°C for 30–780 min. Heat denaturation occurred in the following order: transfenin > IgG > LDH M4 > LDH H4 = myoglobin > albumin and could be described by first order reaction kinetics. The very low coefficient of variation (2–4%) of the single radial immunodiffusion technique resulted in a very weak calculated error (± 0.l–0.2°C) on temperature determination. Monitoring the concentration of LDH M4 appears appropriate for determining the minimum heating achieved in long-time, low-temperature cooking and albumin or myoglobin could be monitored for meat cooked at 69°C without holding time.     

Effects of Postmortem pH and Temperature Muscle Structure and Meat Tenderness

Bovine longissimus muscles with postmortem pH in the range 5.5 - 7.0 were subjected to different postmortem temperatures of 1°, 4°, 25° and 37°C. Intact beef sides with different postmortem pH were also subjected to two different environmental temperatures of 1° and 25°C. High pH muscles exhibited an extensive degradation of Z-lines, whereas low pH muscles showed a preferential degradation of M-lines and myosin heavy chains. Intermediate pH muscles did not show much degradation of muscle proteins, resulting in tougher meat than either low or high pH muscles. High postmortem temperatures enhanced the degradation of muscle proteins in excised and incubated muscle strips, but the delayed chilling of intact beef sides at 25°C for 8-hr did not affect either the structural changes or meat tenderness.     

Size Exclusion/HPLC of Heated Water Soluble Bovine and Porcine Muscle Proteins

Proteins (280 nm absorbance) in water extracts from bovine semi-membranosus and porcine longissimiu were separated by size exclusion (SEC) high performance liquid chromatography(HPLC). SEC/HPLC profiles showed six heat sensitive fractions ≥ 10,000 daltons. These fractions ranged from peak 1 at 375,800 daltons in bovine and 170,000 daltons in porcine down to myoglobin, peak 6, at 15,200 and 19,500 daltons for bovine and porcine, respectively. SEC/HPLC showed the loss of certain peaks at specific time/temperature treatments. Heat labile porcine proteins ≥ 10,000 daltons represented about 41.5 area percent of the total extractable components after heating to 60°C. In bovine, this represented about 37.5 area percent. In both species, heating at 70°C for 30 min or at 75°C for 0 min resulted in protein solubility loss to about 1 area percent or less.     

Enzymic Lipid Peroxidation in Microsomal Fractions from Beef Skeletal Muscle

Enzymic lipid peroxidation in microsomes isolated from beef muscle (longissimus dorsi: LD) has been demonstrated. The reaction requirad NADPH or NADH, ADP, and Fe²⁺ or Fe³⁺. The optimum pH of the reaction was approximately 6.5. The rate of oxidation was higher with NADPH than with NADH and also higher with Fe²⁺ than with Fe³⁺. For microsomes isolated from the LD muscles stored for 3–11 days postmortem at 4°C, the rate of oxidation at pH 6.8 and with 0.1 mM NADPH, 0.1 mM ADP and 0.015 mM Fe³⁺ ranged from 4.89–16.52 nmoles malonaldehyde per mg protein for 30 min incubation at 36°C. Prolonged storage of the intact muscles at 4°C considerably reduced the oxidative enzymic activity of the isolated microsomes.     

Determination of Metmyoglobin Reductase Activity in Bovine Skeletal Muscles

A novel technique was used to obtain an isolate of skeletal muscle containing MetMb reductase. The isolate was then used as the enzyme source in an assay procedure to measure specific MetMb reductase activity. Enzyme activity was highest at pH 6.4 as compared to 5.8 or 7.0 and at 30°C compared to 4°C. Significant differences in enzyme activity were found among beef muscles from the same animal. The order of muscles, when enzyme activity was expressed on the basis of muscle myoglobin content, was: tensor faciae latae > longissimus dorsi > gluteus medius > diaphragma medialis > semimembranosus = psoas major (p = 0.01).     

Species-Specific Effects of Sarcoplasmic Extracts on Lipid Oxidation in vitro

ABSTRACT:  The degree to which lipid and myoglobin (Mb) oxidation processes interact in meat can be species-specific. We investigated the effects of beef and pork sarcoplasmic extracts containing different Mb concentrations on lipid oxidation in a liposome system. Sarcoplasm was extracted from beef and pork longissimus dorsi and psoas major muscles. Beef sarcoplasm was diluted with 0.1 M phosphate buffer to obtain a Mb concentration equivalent to that in pork sarcoplasm. Conversely, equine heart Mb was added to pork sarcoplasm to match the myoglobin concentration of beef sarcoplasm. This resulted in beef and pork sarcoplasms, each with 2 different Mb concentrations for the longissimus (0.02 mM and 0.07 mM) and psoas (0.05 and 0.12 mM). Sarcoplasm (or phosphate buffer control) was incorporated within a phosphatidylcholine liposome preparation and incubated at 25°C. Thiobarbituric acid reactive substances (TBARS) were measured at 0, 30, 60, 90, and 120 min of incubation. Regardless of species, greater Mb concentration within the sarcoplasm increased lipid oxidation ( P < 0.05). Across muscles, pork sarcoplasm had lower TBARS values than beef sarcoplasm ( P < 0.05). Our results suggest that pork sarcoplasm has a lesser effect on lipid oxidation than beef sarcoplasm for a common Mb concentration. However, increased myoglobin concentration within sarcoplasm promotes lipid oxidation regardless of species.     

Effects of Beef Carcass Electrical Stimulation and Hot Boning on Display Color of Unfrozen Vacuum Packaged Steaks

Ninety-six beef sides from 48 carcasses were used to determine effects of control (C, chilled 48 hr at 5°C), electrical stimulation (ES, 45 min postmortem, 400 volts for 2 min, pulsed), and hot boning (HB, 2 hr postmortem), and combination (ESHB) treatments on muscle color of longissimus (LD) and semimembranosus (SM), vacuum packaged steaks. HB muscles frequently were visually brighter purplish-red than other treatments. Compared to ESHB, ES LD was not different, but ES SM was duller purplish-red in color. Reflectance indicators of reduced myoglobin and metmyoglobin were essentially the same across treatments in both muscles. Vacuum packaged fresh beef steaks from all treatments were acceptable in color at 0, 3, 7, and 14 days of display. Vacuum packaging appears suitable for steaks from any of these carcass treatments but is especially useful for steaks from hot boned cuts.     

Flavor, Color, and Other Characteristics of Beef Longissimus Muscle Heated to Seven Internal Temperatures Between 55° and 85° C

Beef longissimus muscle steaks were broiled or roasted to 7 internal temperatures. Mouth-filling-blend and browned flavor increased, whereas bloody-serumy, metallic, and sour flavors and juiciness decreased with increased internal temperature. Roasted muscles had flavor characteristics more like muscle cooked to lower internal temperatures than broiled. Protein denaturation, as indicated by differential scanning calorimetry, appeared to be mostly complete after muscle samples were heated to 80 ° C. Visual color change occurred between 55° and 65° C, between 65° and 75° C, and between 75° and 80° C. HunterLab a values decreased and reflectance readings at 547 nm increased significantly between 75° and 80° C. Instron shear and compression and pH values did not vary significantly.     

Tenderness of pork m. longissimus thoracis et lumborum after accelerated boning. Part I. Effect of temperature conditioning

This research investigated the effect on tenderness and meat quality of temperature conditioning at 0, 7, 14 or 21?°C of pork longissimus muscle after accelerated boning (removal from the carcass within 30 min post slaughter). The conditioning temperature had no effect (P>0.05) on tenderness at the end of the conditioning period (i.e. at the onset of rigor) but had a significant effect (P<0.05) after the muscles were aged for four days at 2?°C. After aging, the muscles conditioned at 14?°C were more tender than muscles conditioned at the other three temperatures; the muscles conditioned at 0?°C were tougher than the muscles conditioned at the higher three temperatures. Conditioning at 14?°C produced muscles that had lighter surface colour and lower drip loss due to prevention of cold toughening which occurred at lower temperatures or protein denaturation at the higher temperatures.     

Reduced Fat, High Moisture Beef Frankfurters as Affected by Chopping Temperature

Six treatment combinations were studied to determine the effects of initial temperature (0, 15, 30°C) and endpoint chopping temperatures (0, 15, 30, 45°C) on texture and stability of reduced fat, high moisture beef frankfurters. Textural properties (raw batter, frankfurter) and purge loss were determined over 8 wk storage. As endpoint chopping temperature increased, batter stability and shear force decreased. In most samples, initial temperature did not affect texture or stability. Endpoint chopping temperatures of ± 15°C resulted in most stable batters. Chopping > 15°C lowered product quality.     

Electrical Stimulation of Mutton

Electrically stimulated ovine muscles, restrained from shortening during rapid chilling at 0-1 or 15-16°C, had lower Warner-Bratzler (WB) shear force values after 1 and 2 days aging at 0-1°C than un-stimulated controls, but were not significantly different at ≥4 days aging. Direct measurement of muscle fiber length showed that contraction values obtained for muscles assigned to go into rigor at 0, 15, 30 or 40°C were significantly less for stimulated muscles than for control muscles at 0°C, but of same magnitude or at rigor temperatures ≥15°C. WB shear force values indicated that, at temperatures ≥15°C, increase in tenderness due to stimulation became small after 7 days aging at 0-1°C, whereas at 0°C aging further increased improvement due to stimulation. Results were thus consistent with electrical stimulation reducing myofibrillar shortening at rigor temperature <15°C but at temperature ≥15°C stimulation had the same effect as a few days aging.     

Effects of Beef Carcass Electrical Stimulation and Hot Boning on Muscle Display Color of Polyvinylchloride Packaged Steaks

Ninety-six beef sides from 48 carcasses were used to determine the effects of control (C, chilled 48 hr at 5°C), electrical stimulation (ES, 45 min postmortem, 400 volts for 2 min, pulsed), hot boning (HB, 2 hr postmortem), and combination (ESHB) treatments on muscle color of longissimus (LD) and semimembranosus (SM) steaks packaged in polyvinylchloride film. LD from HB was mostly visually darker, had less oxymyoglobin, and more metmyoglobin than other treatments as was the SM, but SM had fewer differences between HB and ESHB. ES and ESHB muscles were visually similar, suggesting ES minimized the darkening effect of HB. Regardless of treatment, muscle color was acceptable at 0, 1, 3 and 5 days of display.     

Cooking Temperature of Turkey Ham Affects Lactate Dehydrogenase, Serum Albumin and Immunoglobulin G as Determined by ELISA

Protein indicators were identified and enzyme-linked immunosorbent assays (ELISA) were developed for verifying endpoint processing temperatures (EPT) of turkey ham. Lactate dehydrogenase (LDH), immunoglobulin G (IgG), and turkey serum albumin (TSA) were identified by electrophoresis, Western blotting or enzyme assays as potential markers in turkey ham processed between 66.9 and 73.9°C. TSA and IgG were quantified using indirect competitive ELISAs, and LDH was quantified by a sandwich ELISA. The concentration of all indicators decreased as processing temperatures were increased. At 73.8°C, 9.3 μg TSA and, 0.5 μg LDH or TSA were detected/g meat. At the USDA required EPT of 68.3°C, residual concentrations of 1221 ng IgG/g meat, 330 ng LDH/g meat and 51,852 ng TSA/g meat were detected.     

Muscle metabolic traits, post mortem-pH-decline and meat quality in pigs subjected to regular physical training and spontaneous activity

Ninety-six female and male pigs were assigned to one of three treatments, 'confined' (C),'trained'(T) or 'free' (F) allowing for different levels of physical activity during the growth interval from 30 to 100kg. Treatment C consisted of individual housing in pens of 2.5 m(2); treatment T of individual housing and regular treadmill training and treatment F of housing in pens of 36 m(2) (40 pigs/pen). In m. biceps femoris (BF), the activity of lactate dehydrogenase (LDH) was decreased between 9 and 12% by training (treatment T vs C). Likewise, in BF from female pigs, training increased the activity of citrate synthase (CS) and of 3-OH-acyl-CoA-dehydrogenase (HAD) by 18 and 21%, respectively. Spontaneous activity (treatment F) reduced the activity of LDH for five muscles between 10 and 16% when compared with treatment C. Around the time of slaughter, glycogenolysis of BF was less for treatment F (6-17%) than for C and T (33-38%). Moreover, in BF from female pigs in treatment F, the initial but not the ultimate pH was increased when compared with treatment C. In comparison to C and T, treatment F improved juiciness in BF from male pigs and increased the amount of salt soluble protein in m. longissimus dorsi.     

Lipid Oxidation Potential of Beef, Chicken, and Pork

Beef and pork longissimus dorsi and semimembranosus muscles and chicken breast and thigh muscles were excised 24 hr postmortem from carcasses of marketweight grain-finished feedlot beef cattle, marke-tweight hogs on a typical finishing diet, and broilers on a commercial grain diet. Muscle samples were immediately ground and formed into patties and stored raw or after cooking, at 4°C (cooked) or ?20°C (raw and cooked). TBA values (on sample weight basis) of frozen raw samples were higher for beef and pork than for chicken, as was heme iron content. However, TBA values of cooked samples were highest for chicken thigh muscles, which contained the most polyunsaturated fatty acids, at all storage temperatures.     

Thermal processing enhances anti‐radical activity and reduces pro‐oxidant activity in water‐soluble fraction of selected Allium vegetables

Both the pro‐ and antioxidant activities were found in water‐soluble components contained in onion, leek and garlic samples, and effects of thermal treatment on such activities were investigated. Raw vegetable extracts were prepared by squeezing vegetable homogenates followed by centrifugation at 4 °C. The extracts were subjected to thermal treatment at 75 or 100 °C for 30 and 60 min. The water‐soluble extracts were assayed for antiradical activity using both a chemical and a cellular system. Heating onion and leek extracts at 100 °C for 60 min, and garlic extract at 100 °C for 30 min, yielded strong antioxidant components that are able to scavenge free radicals, in either system, significantly. Measuring total phenolic content by the Folin–Ciocalteu method, we observed that thermal treatment significantly decreased the phenolic contents in leek and garlic extract. In addition, we estimated pro‐oxidant activities in the vegetable extracts, using reactive oxygen species (ROS)‐sensitive 2′,7′‐dichlorofluorescin diacetate; we found that extracts of raw alliums have strong ROS activity, and that thermal treatment destroyed most of the ROS activity present in the raw extracts. These findings indicate that thermal processing enhanced the nutritional value of alliums by increasing the total antioxidant activity, and reducing the pro‐oxidant elements. Copyright © 2007 Society of Chemical Industry     

Optimisation of a Mashing Program for 100% Malted Buckwheat

The objective of this study was to develop a temperature programmed mashing profile for 100% buckwheat malt. Both standard brewing methods and a rheological tool (Rapid Visco Analyser) were used to characterise worts and mashes. An optimal grist: liquor ratio of 1:4 was observed. At this ratio, buckwheat malt showed a gelatinisation temperature of 67°C and barley malt 62°C. A one hour stand at 65°C exhibited higher FAN levels, fermentable extracts and lower viscosity values than stands at 67°C or 69°C, and was therefore used in further mashing trials. An extra mashing step of 30 min, at any of the tested temperatures, increased extract values a minimum of 4%, decreased viscosities a minimum of 0.20 mPas, and increased fermentable extracts 12%. Best results were obtained when a mashing‐in temperature was used in the range of 35°C to 45°C. These mashing‐in temperatures were used to design an optimal mashing procedure: 15 min at 35°C; 15 min at 45°C; 40 min at 65°C; 30 min at 72°C; 10 min at 78°C. This program showed higher extract values and fermentable extract values (72.7% and 49.9%) than obtained by congress mashing (65.3% and 40.0%), thus successfully optimising the mashing program.     

Effects of Endpoint Temperature on the Internal Color of Pork Loin Chops of Different Quality

ABSTRACT: The effects of 5 endpoint temperatures for cooked, internal color were determined for boneless pork longissimus muscle from 4 treatment groups: normal, normal-injected, PSE, and DFD. Visual and instrumental color, myoglobin denaturation, and acid phosphatase (ACP) of raw and cooked samples were evaluated. Visual internal color became (P < 0.05) less pink as endpoint temperature increased; however, DFD chops were more pink (P < 0.05) and PSE chops were less pink (P < 0.05) than other treatments at most endpoint temperatures. Cooked color was similar (P > 0.05) for chops from normal and normal-injected groups. Myoglobin denaturation increased as endpoint temperature increased. ACP activity in raw chops was not affected by treatment group and it was a good indicator of doneness at 71.1 °C.     

The Effects of Subcritical Water Treatment on Antioxidant Activity of Golden Oyster Mushroom

Subcritical water (SCW) extraction of golden oyster mushroom (GOM) was carried out at various temperatures (50, 100, 150, 200, 250, and 300 °C) for 10, 30, and 60 min, and the antioxidant and certain physiological activities of the extracts were evaluated. SCW treatment of GOM increased the antioxidant activity of the extracts. The SCW extraction of GOM at 250 °C for 60 min or 300 °C for 30 min showed relatively high levels of total phenolic content, 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity, and reducing power. The β-glucan content was the highest when SCW extraction was carried at 200 °C for 60 min, while the highest 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) radical scavenging activity occurred at 300 °C for 60 min. These results indicate that the temperature and time of SCW extraction significantly affect the antioxidant activity as well as the nutraceutical compound levels of GOM extracts.     

Quantifying changes in tenderness during storage of beef

An exponential decay equation was used to quantify changes in beef toughness during storage at constant temperatures between 0° and 20°C. Temperature had the greatest effect on tenderising rate—thirty-two times that due to animals and ten times that due to muscles which were M. longissimus dorsi, M. psoas major and M. semitendinosus. A common rate constant, derived at each temperature, showed that an increment in rate produced by a 5°C rise in storage temperature was then detectable and that the enthalpy of activation (ΔH¹) was 76 kJ/mole. Toughness constants differed most between muscles.