EFFECT OF THE PREFORMED COOKED CURED-MEAT PIGMENT (CCMP) ON COLOR PARAMETERS OF MUSCLE FOODS

The color characteristics of comminuted muscle samples from different species treated with varying levels of the preformed cooked cured-meat pigment (CCMP) were compared to those of their nitrite-cured counterparts. Muscle samples tested were beef, chicken, lamb, pork and seal as well as surimi from cod and seal. Hunter L, a, b values of treated meats depended on the original myoglobin content of muscles as well as the addition level of CCMP. Presence of some myoglobin was found necessary in order to impart a cured color to meats and therefore cod surimi treated with CCMP showed a dull uncured rather than a typical cured color observed with other meat tissues.     

Color and Oxidative Stability of Nitrite-Free Cured Meat after Gamma Irradiation

The effects of 5 and 10 kGy irradiation on the color and oxidative stability of meats treated with nitrite or a nitrite-free curing system were investigated. The nitrite-free curing system consisted of the preformed cooked cured-meat pigment, sodium ascorbate and sodium tripolyphosphate with or without sodium acid pyrophosphate. Irradiation had no detrimental effects on the color or flavor of either cured samples. Polyphosphates had a beneficial effect on oxidative stability but had a slight detrimental effect on color stability of irradiated samples.     

Genotoxicity testing of cooked cured meat pigment (CCMP) and meat emulsion coagulates prepared with CCMP

The preformed cooked cured meat pigment (CCMP) synthesized directly from bovine red blood cells or through a hemin intermediate was found to be a viable colorant for application to comminuted pork as a nitrite substitute. However the genotoxicity of CCMP and meat emulsion coagulates prepared with CCMP has not been evaluated. Therefore the objectives of this work were to investigate genotoxicity of CCMP and the influence of CCMP addition on genotoxicity and the content of residual nitrite in model meat emulsion coagulates. Meat emulsions were prepared from white (musculus longissimus dorsi) and red (musculus quadriceps femoris) pork muscles with two different amounts of synthesized pigment CCMP. Comparatively, emulsions with fixed addition of nitrite salt and emulsions without any addition for color development were made. Genotoxicity of CCMP and meat emulsion coagulates was tested with the SOS/umu test and the Ames test. Neither CCMP nor meat emulsion coagulates prepared with CCMP or nitrite salt were genotoxic in the SOS/umu test. In the Ames test using Salmonella Typhimurium strains TA98 and TA100 samples of coagulates prepared with CCMP and with nitrite showed weak mutagenic activity in Salmonella Typhimurium strain TA100 but only in the absence of the metabolic activation, while CCMP was not mutagenic. Coagulates prepared with CCMP contained significantly less residual nitrite than coagulates prepared with nitrite salt. These results indicate that from the human health standpoint the substitution of nitrite salt with CCMP would be highly recommendable.     

Control of lipid oxidation in cooked meats by combinations of antioxidants and chelators

The degree of oxidation in cooked meats treated with phosphates or polyphosphates and sodium ascorbate (SA) or one of its related compounds was determined using the 2-thiobarbituric acid (TBA) test. Combinations of ascorbates with a polyphosphate effectively retarded lipid oxidation in cooked pork during a 5-week storage period at refrigerator temperature. Addition of a phenolic antioxidant—butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), propyl gallate (PG), tert-butylhydroquinone (TBHQ) or trihydroxybutyrophenone (THBP)—to the above mixtures did not affect the TBA numbers substantially (≤0·1 TBA unit). Ethylenediaminetetraacetic acid disodium salt (Na₂EDTA) with sodium ascorbate, with or without a phenolic antioxidant, was effective in protecting cooked pork from oxidation (TBA numbers of ≤1). Commercial antioxidant systems, Tenox A and Tenox II, were also effective in retarding meat rancidity, but Ronoxan A and Ronoxan D20 were only slightly effective.     

Studies on the structure and oxidation properties of extracted cooked cured meat pigment by four spectra

The structure and oxidation properties of cooked cured meat pigment (CCMP) were investigated by comparing the change in spectra of CCMP before and after oxidisation. CCMP was extracted using petroleum ether/acetone/ethyl acetate step by step from precooked cured beef. The extracted sample was oxidised by being exposed to air with normal lighting or adding 1.5 ppm H₂O₂, respectively. The structure of CCMP was identified as a pentacoordinate mononitrosylheme complex by electron paramagnetic resonance (EPR), HPLC/ESI-HR-MS, Raman and FT–IR spectra. The changed EPR spectra of CCMP in acetone oxidised under different conditions suggested a new proposal that the NO⁻ group might not detach itself from iron porphyrin during oxidation in air with normal lighting, but changed in conjugated structure, and the structure tended to axial symmetry by analysis of the changes in g factor. This hypothesis was further supported by the results of the HPLC/ESI-HR-MS and Raman spectrum.     

Review of the flavour-contributing volatiles and water-soluble non-volatiles in pork meat and derived products

In relation to the problem of meat flavour, volatile and minor non-volatile components of raw, cooked and pre-cured cooked pork meat (carbonyls, sulphur compounds, volatile fatty acids, alcohols and other volatiles, nucleotides and their decomposition products, free fatty acids) are considered. Quantitative changes in some of the components, as effected by technological treatments such as heating, curing and curing and heating, are compared. The possibility of evaluating the quality of heated cured pork products by the hydrogen sulphide/mercaptan ratio is indicated.     

Stabilization of meat lipids with nitrite-free curing mixtures

Several nitrite-free meat-curing mixtures have been formulated. The mixtures included salt, sugar, ascorbates, an antioxidant and/or a chelator, an antimicrobial agent and dinitrosyl ferrochemochrome (DNFH). They imparted to meat a similar oxidative stability as that of sodium nitrite. Butylated hydroxyanisole and t-butylhydroquinone were the best anti-oxidants and polyphosphates, ethylenediaminetetraacetic acid and diethylenetriaminepentaacetic acid were the superior chelators. The antimicrobial agents used were potassium sorbate, propryl paraben, fumarate esters and sodium hypophosphite. In the above mixtures, the added effect of (DNFH) on oxidative stability of the cooked meats was similar to the added effect of 150 ppm sodium nitrite.     

The antioxidant activities of nitrite and nitrosylmyoglobin in cooked meats

Low concentrations of nitrite (20 mg/kg) caused significant (p < 0·001) inhibition of lipid oxidation, measured by the TBA test, in a cooked muscle system and 50 mg/kg nitrite resulted in a highly significant (p < 0·001) reduction in TBA values. Similar antioxidant effects of nitrite were observed in heated water-extracted pork muscle systems catalysed by 5 mg/g metmyoglobin (Mb) or 5 mg/kg Fe(2+), Cu(2+) or Co(2+). The cured meat pigment, nitrosylmyoglobin per se exhibited significant (p < 0·05) antioxidant effects in pork muscle systems catalysed by Mb or metal ions. Progressive depletion of nitrite occurred during refrigerated storage of heated and unheated nitrite-treated pork muscle, muscle aqueous extract and in systems containing Mb, Cu(2+) ot Co(2+). Nitrite depletion occurred much more rapidly in Fe(2+)-containing systems and nitrite concentration had decreased to 5% of the original concentration immediately after heating. In addition, nitrite caused a significant (p < 0·05) reduction in the concentration of non-haem iron in heated aqueous-extracts of beef muscle, whereas, in nitrite-free extracts, a highly significant (p < 0·001) increase in the concentration of non-haem iron, probably due to heat denaturation of the haem structure with release of iron, was observed. Based on the results of this study, three co-operative mechanisms for the antioxidative activities in meat are proposed: (a) by the formation of MbNO which has antioxidant properties per se, (b) on heating, MbNO forms a stable complex, nitrosylhaemochrome, which blocks the catalytic activity of haem iron and also prevents release of haem iron as non-haem iron, which is a highly effective catalyst and (c) nitrite appears to 'chelate' non-haem iron-and possibly copper and cobalt-forming a stable complex, thus inhibiting catalytic activity.     

The effect of low- or non-sweet additives on the stability of protein functional properties of frozen cod surimi

The cryoprotective effect of low- or non-sweet additives, Palatinit^R, Polydextrose^R, casein hydrolysate and fish protein hydrolysate (at 8% w/w) as well as lactitol (at 4% and 8% w/w) were compared to an industrial control containing sucrose/sorbitol (8% w/w) and a control without additive in cod surimi stored at –20°C for 4 months. Freeze-induced protein denaturation was evaluated monthly by salt extractable protein and differential scanning calorimetry analyses of surimi followed by texture and expressible moisture analyses of surimi cooked gels. Results revealed that protein functionality was similarly maintained during frozen storage by lactitol, Palatinit^R and Polydextrose^R when incorporated in cod surimi at the 8% level. Surimi gels could be produced with textural attributes comparable to 8% w/w sucrose/sorbitol surimi gels, and the level of lactitol in cod surimi could be reduced to 4% w/w without significant alteration of cryoprotection. Some benefits in gel-forming properties were obtained by adding 8% casein hydrolysate to cod surimi.     

Lnsolubilization of Orthophosphates in Fresh or Cooked Ground Pork

The insolubilization of added orthophosphate (1000–10000 ppm, equivalent to 0.1–1 .0% w/w) and of orthophosphate generated through enzymatic hydrolysis of added sodium acid pyrophosphate (SAPP) was studied in fresh and in cooked (65.5°C) ground pork held at 5°C for 6 days. Fresh and cooked pork linearly absorbed or otherwise insolubilized orthophosphate added directly to the meat or generated through enzymatic hydrolysis of added SAPP. Orthophosphate insolubilization was constant throughout the range of addition studied and equivalent to 70–80%. Soluble orthophosphate measurements, therefore, could not be used to estimate the proportion of added pyrophosphate that was hydrolyzed in the meat or, by difference, the proportion of residual, unhydrolyzed SAPP.     

Impact of Sodium Ascorbate and Sodium Erythorbate Used in Meat Processing on the Vitamin B12 Contents of Cured Ham

Effects of sodium ascorbate (Na ascorbate) and sodium erythorbate (Na erythorbate) on vitamin B_]2 content of cured, cooked ham were investigated. Paired hams were injected with cure solution containing no curing accelerators or with cure solution containing Na ascorbate or Na erythorbate (3.28, 6.56, 9.84 g/L). There were no differences between vitamin B₁₂ contents of hams containing added curing accelerators and paired controls, indicating that B₁₂ was not destroyed by either Na ascorbate or Na erythorbate. Analysis of ascorbate, dehy-droascorbate, isoascorbate and dehydroisoascorbate showed ascorbate to be the only substance present in Na ascorbate-treated hams and isoascorbic acid to be the only substance present in Na erythorbate-treated hams.     

Use of natural antimicrobials to improve the control of Listeria monocytogenes in a cured cooked meat model system

Concern about nitrite in processed meats has increased consumer demand for natural products manufactured without nitrite or nitrate. Studies on commercial meat products labeled as "Uncured" and "No-Nitrite-or-Nitrate-Added" have shown less control of nitrite in these products and greater potential growth of bacterial pathogens. To improve the safety of the "naturally cured" meats, several natural ingredients were studied in a cured cooked meat model system (80:20 pork, 10% water, 2% salt, and 150 or 50 ppm ingoing sodium nitrite) that closely resembled commercial frankfurters to determine their inhibitory effect on Listeria monocytogenes. Results showed that cranberry powder at 1%, 2% and 3% resulted in 2-4 log cfu/g less growth of L. monocytogenes compared to the control with nitrite alone (P<0.05). Other natural compounds, such as cherry powder, lime powder and grape seed extract, also provided measureable inhibition to L. monocytogenes when combined with cranberry powder (P<0.05).     

Microbial transglutaminase and caseinate as cold set binders: Influence of meat species and chilling storage

The effect of microbial transglutaminase/sodium caseinate (MTG/C) systems on meat batter characteristics (water binding and textural properties of raw and cooked products) was studied in the presence of NaCl (1.5 g/100 g) and sodium tripolyphosphate (0.5 g/100 g), and storage time (96 h at 3 °C) for three meat species (pork, chicken, lamb). Samples prepared from pork and lamb with only MTG/C (no salts) had the highest cooking loss (CL) values, about 23 and 29 g/100 g, respectively; for chicken, the CL was less than 13 g/100 g. Hardness (Hd) and chewiness (Cw) generally tended to be higher in cooked samples containing MTG/C than in samples containing only salts. Products combining salts and MTG/C had higher (P<0.05) Hd and Cw. The efficiency of the MTG/C system as a texture conditioner of cooked products varied with the meat source.     

EFFECTS OF ANTIOXIDANTS ON COPPER INDUCED LIPID OXIDATION DURING SALTING OF COD (GADUS MORHUA L.)

A model system for studying lipid oxidation of salted cod muscle was used for investigating the interaction effects of antioxidants and copper in the brine. The results showed that ascorbate might have pro-oxidative or antioxidative effects depending on the ascorbate and metal concentrations. Without added copper in the brine, concentrations of <500 ppm ascorbate had a pro-oxidative effect. With 5 ppm copper added in the brine, low concentrations of ascorbate (<50 ppm) inhibited the formation of TBARS (thiobarbituric acid - reactive substances) in the cured product. At slightly higher concentrations (100–200 ppm), the antioxidative properties were lost. Above 200 ppm the added ascorbate reduced the oxidation level in the salt-ripened product. The application of ascorbate as an antioxidant in salt curing of cod requires the use of high concentrations (> 1, 000 ppm) in the brine. When similar concentrations (0.5 mM) of EDTA (ethylenediaminetetraacetic acid), citrate or ascorbate were included with 3 ppm copper in the brine, EDTA was the only compound that efficiently inhibited copper-induced lipid oxidation.     

Effect of Dietary Supplementation with α-Tocopheryl Acetate on the Stability of Reformed and Restructured Low Nitrite Cured Turkey Products

The objective of this study was to investigate the effects of sodium (Na) nitrite reduction on the oxidative and colour stability of reformed and restructured cured cooked turkey products manufactured from meat containing high and low levels of dietary α-tocopheryl acetate. Turkeys were randomly assigned to either a control group, fed a basal α-tocopheryl acetate diet (20mg/kg feed), or a treatment group fed a supplemented α-tocopheryl acetate diet (600mg/kg feed). Diets were fed ad libitum from day 1 until slaughter on day 147. Breast meat from control and treatment groups was used to manufacture cured reformed cooked turkey ham and cured restructured cooked turkey patties. Residual levels of 60 and 120mg Na nitrite/kg of meat were used. Turkey products were packaged in either overwrap or vacuum packaging and stored under refrigerated (4°C) illuminated display for 10 days. Results showed that dietary supplementation with α-tocopheryl significantly (p<0·05) improved the oxidative and colour stability of all low nitrite products produced when compared to non-supplemented controls.     

An Improved Method for Preparation of Nitric Oxide Myoglobin

We developed an improved method for preparation of bovine nitric oxide myoglobin using the following starting materials: 0.1 mM purified metmyoglobin; 0.1 mM (7 ppm) sodium nitrite; and 1.76 mM (350 ppm) sodium ascorbate. The method requires complete deoxygenation of the reacting system. NOMb prepared in this manner is a source of cured meat pigment which contains a minimum of impurities, since the nitrite reacts quantitatively with the myoglobin in this method.     

In Vitro Zinc Protoporphyrin IX Formation in Different Meat Sources Related to Potentially Important Intrinsic Parameters

For several years, researchers have studied the formation of zinc protoporphyrin IX in meat, as it is considered to be an important natural colouring agent in dry cured or fermented meat products in the absence of nitrite and/ or nitrate. Until now, however, mainly pork meat is used for these investigations. The goal of this research was to relate in vitro zinc protoporphyrin IX and protoporphyrin IX formation in eight meat sources (chicken, turkey, pork, lamb, beef, veal, horse and porcine liver) to eight intrinsic parameters using partial least squares regression (PLS) analysis. Significant differences in pH, initial metmyoglobin formation, metmyoglobin reduction ability, total heme, zinc chelatase activity, and total iron and zinc concentration between meat sources were found. Water activity, however, was not significantly different between meat sources. Liver tissue and horse meat showed the best ability to form zinc protoporphyrin IX. Formation of protoporphyrin IX was limited in all meat sources. PLS analysis revealed that mainly zinc chelatase activity, followed by total heme, total iron and zinc content, were predominant intrinsic parameters to explain variations in zinc protoporphyrin IX formation. These findings could be important for meat industry in order to establish the production of red coloured nitrite-free meat products.     

A Rapid and Small-Scale Method for Estimating Antioxidative Potency of Peanut Sprouts

A method for estimating antioxidative potency (AOP) was achieved by incubating emulsified linoleic acid in a 1 mL iron/ascorbate system at 37 °C for 30 min followed by absorbance measurement at 234 nm to determine the conjugated diene hydroperoxide (CDHP) content. By that method, 100% AOP was obtained when 10 ppm butylated hydroxytoluene or 50 ppm α‐tocopherol was introduced. When freeze‐dried peanut sprouts were cooked with ground pork‐fat patties and the separated oils were stored at 60 °C for CDHP determination, the highest AOP was observed in the 144 h germinated sprout roots. After extracting the sprout roots with methanol and AOP evaluation by the iron/ascorbate and pork‐oil storage methods, both showed similar AOP trends as affected by extract concentration.     

Microbiological, Chemical, and Physical Changes in Fresh, Vacuum-Packaged Pork Treated with Organic Acids and Salts

The effects of selected organic acids and salts on microbial numbers, pH, exudate, and color were studied for vacuum-packaged, fresh pork chops. Pork chops were dipped for 2 min in (v/v) 1% acetic acid, 1% acetic/1% lactic acid, 1.5% acetic/1.5% sodium acetate, 3% acetic/3% sodium ascorbate, 3% acetic/2% NaCl or sterile, distilled water before being vacuum-packaged and stored at 2°– 4°C for 6 weeks. Treatments containing 3% acetic acid resulted in lower aerobic microbial numbers (P < 0.05) and effectively inhibited Enterobacteriaceae. Treatments containing 1% acetic acid, with or without 1% lactic acid, were ineffective. All acid treatments increased exudate and were detrimental to meat color (P < 0.05) although sodium ascorbate reduced color damage. Chops treated with 3% acetic acid/3% sodium ascorbate had the highest Hunter a and L color scores.