Dietary Iron in Swine Rations Affects Nonheme Iron and TBARS in Pork Skeletal Muscles

Fifteen crossbred pigs (mean wt = 25 kg) were allocated to three groups and fed to market weight (mean wt = 103 kg) on corn-soy based diets containing either 62,131, or 209 ppm iron. After slaughter, the longissimus dorsi (LD) and rectus femoris (RF) muscles were dissected, cooked, and stored in oxygen-permeable bags for 12 days at 4°C. Cooking increased thiobarbituric acid reactive substances (TBARS) but did not affect nonheme iron (NHI) or α-tocopherol. NHI and TBARS increased continuously during storage while α-tocopherol decreased. NHI and TBARS were higher in cooked pork from pigs fed high-iron diets. Liver iron correlated with muscle iron (p<0.05).     

Vacuum Packaging, Ascorbic Acid and Frozen Storage Effects on Heme and Nonheme Iron Content of Mackerel

Vacuum packaging and ascorbic acid were tested for their ability to prevent heme iron loss in mackerel (Scomber scombrus). Vacuum packed samples had less heme breakdown than air packed samples at frozen storage temperatures above ?20°C. Ascorbic acid protected the heme at all temperatures when compared to air or vacuum packed samples.     

去骨方法对牛肉和火鸡肉化学成分及一些特性的影响

本文针对机械去骨和人工去骨的牛肉以及火鸡肉的一些化学、物理特性进行了对比研究。相近成分胆固醇、硫代巴比土酸(TBA)、钙铁含量、颜色参数、脂肪酸成分等指标在样本中得以分析。去骨方法对牛肉和火鸡肉的化学成分有所影响。机械去骨导致较高的胆固醇以及钙铁含量。在手工去骨火鸡肉中,含量最多的脂肪酸是C16:0、C18:1以及C18:2。机械去骨加工使火鸡肉中C18:1、C18:2、C18:3的含量增加。而C16:0、C18:0、C18:1则是机械去骨和手工去骨牛肉中主要的脂肪酸。     

Thermally Induced Changes in Protein Extractability of Postrigor Turkey Breast Meat Measured by Two Methods

Extractability of sarcoplasmic and myofibrillar proteins was reduced in postrigor turkey breast meat held at 40 °C for as short as 30 min. These reductions in protein extractability were successfully detected, using either a filtration-based methodology or one based on centrifugation. However, the coefficient of variation for the filtration method was as much as 4 times greater than for centrifugation. Additionally, the filtration method overestimated sarcoplasmic protein extractability due to the inability to exclude myofibrillar proteins. Centrifugation results indicated the extractability of proteins in 0.55 M KCl was reduced to 52% of controls for samples held at 40 °C for 120 min. Additionally, holding postrigor turkey breast muscle at 40 °C resulted in increased myosin degradation.     

Sodium Tripolyphosphate Stability and Effect in Ground Turkey Meat

Ground turkey meat, cooked and uncooked, was prepared with and without 0.5% sodium tripolyphosphate (SIP) and stored at 5°C for different periods of time. STP stability was evaluated by determining soluble orthophosphate. Water-holding capacity (WHC), pH, and mi-crobial count were also measured. STP hydrolyzed rapidly in uncooked samples. Refrigerated storage time (up to 6 days) did not affect STP hydrolysis in cooked turkey meat. Heating accelerated the rate of STP hydrolysis. End point temperatures (65, 75, and 85 °C) did not affect the extent of STP hydrolysis. STP increased WHC in both cooked and uncooked samples. STP did not inhibit total microbial growth in cooked or uncooked ground turkey meat.     

Lactate Dehydrogenase Monoclonal Antibody Immunoassay for Detection of Turkey Meat in Beef and Pork

Relative epitope binding positions on turkey muscle LDH of four monoclonal antibodies (MAbs) was determined by comparing the absorbance by sandwich ELISA from different combinations of capture and biotinlabeled detector MAbs. Epitopes for MAbs E6B and B3C were close to each other. Binding of MAb B3C and G4D did not inhibit binding of D5E to LDH, thus a sandwich ELISA using D5E as capture MAb, and biotin-labeled B3C as detector MAb was developed. The LDH MAb sandwich ELISA detected 1% adulteration of turkey breast or thigh muscle in raw beef and pork.     

Comparative Study on Three Methods for Determining Air Content in Meat Batters

Measurement of air content in meat batters is useful, as larger amounts of air negatively affect some properties of comminuted products. Three methods were compared. One method (Vemag) involved liberation of entrapped air from the batter by the combined effects of vacuum and mechanical forces. The other two methods involved application of under- (Smrat) or over- (Handtmann) pressure and calculation of the air content using Boyle's ideal gas law. The Smrat showed the lowest reproducibility. However, being the most rapid and easy to use, it was the method of choice for routine quality and process control. The Vemag and more favorably the Handtmann were recommended for accurate and reproducible determinations.     

Rapid Method for Quantification of Cholesterol in Turkey Meat and Products

A direct saponification method was developed to determine cholesterol quantitatively in turkey meat and its processed products at a detection limit of 10 ppm. Five solvents and two derivatizing agents were evaluated. The method involved direct saponification with ethanolic KOH, homogeneous-phase toluene extraction of unsaponifiables, derivatization of cholesterol to a trimethylsilyl ether and quantitation by gas chromatography with flame ionization detection using 5α-cholestane as internal standard. Compounds were confirmed by gas chromatography-mass spectrometry.     

Microbial Characteristics of Flaked and Color-Modified Turkey Thigh Meat

Effects of flaking and color modifying (treatment with pH 5.8, 7.4 and 8.0 phosphate buffers) boneless, skinless turkey thighs on microbial numbers were determined. Aerobic, psychotrophic, and coliform analyses were conducted on intact thigh (IT) before processing and on flaked turkey (FT) and color-modified turkey (CMT) held up to 5 days at 3°C and for 30 days at -20°C. Aerobic and psychrotrophic counts were not different (p > 0.05) between IT and 1-day FT or between FT and CMT at any sampling interval. Mean coliform levels in FT did not differ (p < 0.05) from those in CMT after 1 day at 3°C. Properly performed flaking and color modification do not compromise the microbial quality of turkey.     

Carnosine Increases Irradiation Resistance of Aeromonas hydrophila in Minced Turkey Meat

The effect of carnosine on irradiation inactivation kinetics of Aeromonas hydrophilawas studied. In phosphate buffer, carnosine had no effect on survival of the pathogen, whereas in turkey meat supplemented with carnosine the adverse effect of irradiation on A. hydrophila was reduced. Peroxy radicals were toxic to A. hydrophila , and this effect was counteracted by carnosine. Accordingly, in a kinetic test carnosine was capable of scavenging peroxy radicals. These results indicate that a free radical scavenger antioxidant such as carnosine can increase the radiation resistance of A. hydrophila in meat due to the inhibition of lipid peroxidation caused by radiolysis.     

Mechanisms of Pink Color Formation in Irradiated Precooked Turkey Breast Meat

ABSTRACT: Precooked turkey breast meat was aerobically packaged or vacuum-packaged and irradiated at 0, 2.5, or 5.0 kGy. CIE color, reflectance, oxidation-reduction potential (ORP), gas production, and lipid oxidation were determined at 0, 7, and 14 d. Irradiation increased redness of vacuum-packaged meat, and the redness was distinct and stable under vacuum. Irradiation decreased ORP and produced carbon monoxide (CO). This indicated that the pink color was caused by the heme pigment-CO complex formation. The reflectance of meat and the absorption spectra of myoglobin solution supported the assumption that denatured CO-myoglobin is the pigment in irradiated precooked turkey breast.     

Packaging Cooked Turkey Meat Patties while Hot Reduces Lipid Oxidation

Elimination of oxygen by “hot packaging” reduced the 2-thiobarbituric acid reactive substances (TBARS) value of meat patties by about 50% in control and myoglobin added, and between 30-40% in ferrous iron added turkey patties, as compared with “cold packaging.” The TBARS values of hot and cold vacuum packaged patties were significantly lower than those of loosely packaged patties after 1 wk refrigerated storage. Most lipid oxidation in meat patties occurred at day 0, and only small changes in TBARS values were observed after 1 wk storage. Although the prooxidants in meat were major factors in promotion of lipid oxidation of cooked meat, hot packaging minimized their effects.     

Characterization and Modeling of Dielectric Properties of Turkey Meat

ABSTRACT: The dielectric properties of turkey meat at water activities of 0.84 to 0.98 were measured at 2450 and 915MHz. Equations were developed as a function of temperature, moisture, water activity, and ash, and compared to literature equations. Unexpected results were: as the water activity decreased or ash increased, the dielectric constant increased with temperature, and dielectric loss factor of reduced moisture samples was determined by moisture not ash. It is theorized that the effect of temperature on dielectric constant is a function of the ratio of bound to free water. Glycerol did not affect the dielectric properties, while lactic acid decreases them by promoting water loss during protein denaturation.     

Effect of Antioxidants on Consumer Acceptance of Irradiated Turkey Meat

Antioxidants had no effect on the production of sulfur compounds, color change, and off‐odor intensity of irradiated turkey breast meat, but addition of sesamol + tocopherol or gallate + tocopherol was effective in reducing thiobarbituric acid‐reactive substance values and aldehydes, especially under aerobic conditions. Consumers preferred the color of irradiated raw and cooked meat to nonirradiated meat because the pink color of irradiated meat looked fresher. The packaging method was more important than the antioxidant treatment in reducing irradiation off‐odor because S‐compounds produced by irradiation easily volatilized under aerobic packaging conditions. Therefore, the combined use of aerobic packaging and antioxidants is recommended to improve consumer acceptance of irradiated poultry meat.     

Effects of Cooking and Chemical Treatment on Heme and Nonheme Iron in Meat

Treatment of ground beef samples with heat (conventional and microwave), ascorbic acid, or H₂O₂ increased nonheme iron concentrations. The increases ranged from less than 10% to more than 100% depending on the type, length, and severity of the treatment. Cooking of fresh beef round using common household methods (braising, roasting, microwave cooking) resulted in nonheme iron increases that were generally less than 10%. Treatment of hemin and meat extract solutions with heat and H₂O₂ resulted in destruction of the iron-porphyrin complex. Oxidative cleavage of the porphyrin ring followed by release of the iron is probably the mechanism for the observed increases in nonheme iron.     

Effect of Antioxidants on the Production of Off-Odor Volatiles and Lipid Oxidation in Irradiated Turkey Breast Meat and Meat Homogenates

The addition of gallate, sesamol, trolox, and tocopherol was effective, but sesamol, sesamol + tocopherol, and gallate + tocopherol were among the most effective antioxidants in reducing thiobarbituric acid reactive substances, volatile production, and off‐odor intensity in turkey breast homogenates. Also, these 3 antioxidant treatments were effective in controlling lipid oxidation and off‐odor intensity in both vacuum and aerobically packaged patties. However, aerobic packaging was better than antioxidant treatments in reducing off‐odor intensity of irradiated turkey patties. Antioxidants had no effect on redness, but increased lightness and yellowness of irradiated turkey breast. It was concluded that a combination of antioxidant and aerobic packaging was more useful than antioxidant and vacuum packaging in controlling off‐odor problems in irradiated raw turkey meat.     

Proteins Associated with Thermally Induced Gelation of Turkey Breast Meat

ABSTRACT:  Principal component analysis was performed on turkey breast muscle that originated from a pool of genetically distinct turkeys by separating the salt-soluble from the salt-insoluble proteins. The salt-soluble proteins (SSP) formed thermally induced meat gels and the viscoelastic properties of the gels were analyzed. The storage modulus (G') at 80 °C of thermally induced gels derived from the SSPs ranged from 3 to 400 Pa. Each protein fraction was analyzed using 5% to 20% sodium dodecyl sulfate polyacrylamide gel electrophoresis. Reverse stepwise regression analysis of the electrophoretic fingerprints of the protein fractions showed that G' at 80 °C was associated with the 2 protein bands from the salt-soluble fraction ( R ²= 0.87, P < 0.01) and 1 protein from the salt-insoluble fraction ( R ²= 0.27, P < 0.05). Primary sequence analysis identified one of the SSPs positively associated with G' at 80 °C as α-tropomyosin and the other SSP negatively associated with G' at 80 °C as pyruvate kinase. The salt-insoluble protein identified as triose phosphate isomerase was negatively associated with G' at 80 °C. These findings are unique in that they show that proteins other than myosin and actin participate in the mechanisms of forming thermally induced meat gels.     

Some Factors Influencing the Nonheme Iron Content of Meat and Its Implications in Oxidation

Three different methods for determining nonheme iron content of meat extracts which differed in final pH and either in heating or not heating of the samples, were compared. The final pH of meat extracts had little effect on the level of nonheme iron but heating gave higher values. Both final temperature and rate of heating influenced release of nonheme iron from meat pigment extracts, with the optimum temperature being 63-70°C. Slow heating resulted in release of more noneheme iron than fast heating. Nitrite was shown to prevent release of heme iron, apparently through stabilizing the porphyrin ring. Sources of nonheme iron and their relationship to oxidation in cooked meat are discussed.     

Processing and Frozen Storage Effects on the Iron Content of Cod and Mackerel

Processing and subsequent frozen storage affected the iron content of cod (Gadus morhua) and mackerel (Scomber scombrus) muscle tissue. Frame mince was obtained from the bone rack, without the head or viscera remaining, after filleting. Frame mince had significantly higher iron levels than intact fillets with or without skin or fillets that were subsequently minced. Skin-on fillets had more iron than skin-off fillets. Cod frame mince had about 50% heme iron, while mackerel frame mince ranged from 20-64%. Nonheme iron increased during frozen storage due to heme breakdown. Storage above ?14°C was more deleterious to the heme molecule than lower temperatures (?20°C or ?40°C).     

Prevention of Lipid Oxidation in Precooked Turkey Meat Patties with Hot Packaging and Antioxidant Combinations

The effects of antioxidants or hot packaging and their combination on lipid oxidation were quite variable depending on the additives in turkey meat. The TBARS values of cooked patties were greatly affected by the degree of oxidation in the raw meat, and the effectiveness of antioxidants varied with added prooxidants. Ascorbate and free radical terminators had stronger antioxidant effects than iron chelators, and chelating iron alone could not eliminate lipid oxidation in either raw or cooked meat with added NaCl. The combination of hot packaging and antioxidants provided cooked patties with better protection from lipid oxidation than either treatment alone.