Forms of Iron in Meats Cured with Nitrite and Erythorbate

Solubility, valence, and complexation of iron were measured in four different processed meats cured with or without 156 ppm sodium nitrite and with or without 550 ppm sodium erythorbate (d-isoascorbate). Nitrite caused less ionic iron and erythorbate caused more ferrous and soluble iron after a conventional curing process. Heme iron levels were unchanged. No changes were detected in vacuum packed meats after 160 days at -40 or after 14 days at 5°C. Exposure to air at 5°C depleted ferrous iron and oxidized erythorbate. Boiling for 15 min doubled complexed iron in all four meat formulations. The forms of iron in processed meat depended on the curing ingredients as well as air and heat exposure.     

Evaluation of Iron Binding Compounds as Inhibitors of Gas and Toxin Production by Clostridium botulinum in Ground Pork

Iron binding systems (heme iron binding gases alone or with iron binding salts) were evaluated for antibotulinal activity in ground pork. Compared with meat systems containing nitrite or nitrite plus supplemental iron compounds, carbon monoxide (CO) was not antibotulinal. Nitric oxide (NO) treated meats did swell slower, but nitrite was also found in these systems. Thus, neither CO nor NO would be suitable substitutes for sodium nitrite in meat curing. Addition of ferric chloride or myoglobin decreased the antibotulinal effectiveness of nitrite, but samples containing nitrite plus ethylene-diaminetetraacetate (EDTA) or denatured nitrosylated myoglobin (NOMb) swelled slower. Supplemental iron compounds probably decreased residual nitrite levels in the product, thus permitting botulinal growth, rather than directly stimulating growth by providing iron as an external nutrient.     

Effect of adding smoke-flavouring to frankfurters on nitrite and nitrate levels

Different concentrations of sodium nitrite, potassium nitrate or both together were used to prepare four standard solutions and four frankfurter formulations. These were elaborated with and without the addition of 2 g/kg of a commercial solid smoke-flavouring preparation. Monitoring of nitrite and nitrate residual levels in standard solutions stored at 3 °C showed that smoke-flavouring addition results in a depletion of nitrite levels and/or reduction of nitrate to nitrite. In a much more complex system such as meat products, nitrite and nitrate, incorporated in the formulation separately or combined, were also rapidly depleted when smoke-flavouring was added.     

Blood Fraction Effects on the Antibotulinal Efficacy of Nitrite in Model Beef Sausages

Toxin production by Clostridium botulinum was studied in a model cured beef sausage containing 0–5% added dried bovine blood fractions. Controls which contained nitrite but without blood fractions, were toxic by bioassay in 3 wk at 27°C. Controls without nitrite or blood fractions were toxic at 1 wk, while model sausages supplemented with hemoglobin, red cells, or whole blood were toxic in 1–3 wk. Plasma yielded no detectable toxin for 4 to > 10 wk depending upon addition level. Sausages showing delayed toxigenesis had pH values lower than those which developed toxin earlier. These results demonstrated that use of blood fractions that increased iron levels in beef above 30 μ.g/g interfered with the antibotulinal efficacy of sodium nitrite.     

Iron Distribution in Heated Beef and Chicken Muscles

Distribution of iron in six fractions (water-soluble, water-insoluble, diffusate, hematin, total heme, and ferritin) of beef and chicken muscles hcatcd to 55, 70, 85, and 100°C was determined. Iron content decreased in water-soluble fractions and increased in water-insoluble fractions as temperature increased from 27°C to 100°C. Heme iron decreased more from 55°C to 85°C than from 27°C to 55°C or 85°C to 100°C. The increase in diffusate iron appeared to be less than the decrease in heme iron at each heating temperature. As temperature increased from 27°C to 100°C, hematin iron content increased and extractable ferritin iron content decreased. These findings may help explain rapid development of oxidative rancidity in cooked meat.     

Effect of the Parabens With and Without Nitrite on Clostridium botulinum and Toxin Production in Canned Pork Slurry

Antimiciobials were evaluated in thioglycollate broth at pH 6.5 for the ability to inhibit growth and toxin production by C. botulinum 12885A and ATCC 7949 (Type B). Methyl, ethyl, propyl, and butyl parabens (0.1%) and sorbic acid (0.2%) were effective in inhibiting growth of C. botulinum 12885A and ATCC 7949 in broth. Ethyl, propyl, and butyl parabens (0.1%) and sorbic acid (0.2%) inhibited toxin production by both strains in culture medium. Ethyl, propyl, butyl parabens (0.1%) and sorbic acid (0.2%) were individually added to a comminuted pork slurry having salt and sugar, with or without 40 ppm sodium nitrite. Cans were inoculated with a mixture of C. botulinum 12885A and ATCC 7949 spores. The canned product was abused by holding at 27°C and was observed over a 3-month period for swollen cans. Swollen cans were examined for botulinal toxin by the mouse bioassay. Propyl and butyl paraben did not inhibit or delay toxin production. Ethyl paraben with or without nitrite delayed toxin production for 4 wk. Sorbic acid inhibited toxin for 3 wk; when 40 ppm nitrite was added to the sorbic acid treatment, toxin production was delayed for 4 wk.     

Effect of Irradiation on Antibotulinal Efficacy of Nitrite

Ground pork meat was cured with the addition of 0, 50, 100, 156, and 200 mg/kg NaNO₂, pasteurized and irradiated with 0, 3, 6, 9, 10, 20, 30, 40, and 50 kGy. After irradiation the samples were inoculated with a mixture of Clostridium botulinum type A, B and E spores, incubated at 30°C for 28 days and tested for the presence of botulinal toxin. Doses up to 9 kGy caused a decrease of NaNO₂ content with a corresponding decrease in antibotulinal activity. High irradiation doses resulted in a dose-dependent decrease in nitrite content with complete loss of antibotulinal activity.     

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.     

Speciation of bioaccessible (heme,ferrous and ferric) iron from school menus

A spectrophotometric method using batho-phenantroline as reagent has been optimized for iron speciation [ionic Fe(II) and Fe(III)] in the mineral soluble (bioaccessible) fraction obtained from the in vitro digestion of food dishes. The effect of the precipitant and reducing reagents, and the amount of sodium nitrite added was studied. Heme-Fe was estimated by subtraction of ionic Fe from the total bioaccessible Fe (determined by atomic absorption spectrometry). The method was applied to 13 dishes included in school menus. Soluble Fe was mainly in ionic form (49–100%). With the exception of spinach and potato omelets, a significant linear correlation (r=0.92) was obtained between Fe(II) and bioaccessible Fe. The Fe(II)/Fe(III) ratio increased with increasing meat protein content in the dish. In the analyzed dishes, heme-Fe content depended on meat content and also on the processing procedure applied.     

Carrageenan Effects on Thermal Stability of Meat Proteins

Meat myofibrillar protein (MP) gels and ground pork were used as model systems for studying thermal transition temperatures. Addition of up 2% of κ, ι, or λ carrageenan (CGN) to MP caused a very slight change in the thermal denaturation of the meat proteins. Three transition temperatures were found in ground pork samples, which were characteristic of myosin (59.4°C), sarcoplasmic proteins (67.8°C), and actin (82.4°C). Mixtures of high ionic strength had lower thermal transition peaks. CGN did not cause major shifts in transition temperatures, suggesting that molecular interactions between CGN and meat proteins did not occur.     

Heating and the Distribution of Total and Heme Iron Between Meat and Broth

The effect of heat on movement of total and heme iron from meat to broth was investigated. Total iron by a wet ash method was nearly identical to the sum of heme iron plus nonheme iron. The total amount of nonheme iron increased with cooking temperature (r = 0.98), as did the amount of nonheme iron in the broth (r = 0.93). Leaching of heme pigments into the broth was greatest at 60°C. Boiling (97°C) rapidly coagulated the meat pigments and minimized the leaching of heme pigments into the broth. More total iron (85.3%) was retained in boiled (97°C) meat than in meat heated 1 hr at 60°C (81.6%), 77°C (78.2%) or autoclaved (77.5%).     

Effects of curing sodium nitrite additive and natural meat fat on growth control of Listeria monocytogenes by the bacteriocin-producing Lactobacillus curvatus strain CWBI-B28

In realistic model meat systems, the separate and combined effects of fat content and sodium nitrite on the antilisterial activity of the bacteriocin of Lactobacillus curvatus CWBI-B28 were studied. In laboratory fermentations where Listeria monocytogenes was co-cultured at 4 °C with bacteriocin-producing CWBI-B28 in lean pork meat (fat content: 13%) without added nitrite, a strong antilisterial effect was observed after one week. The effect was maintained for an additional week, after which a slight and very gradual rebound was observed. Both added nitrite (20 ppm) and a high-fat content (43%) were found to antagonise this antilisterial effect, the Listeria cfu count reached after six weeks being 200 times as high in high-fat meat with added nitrite than in lean meat without nitrite. This antagonism could not be attributed to slower growth of the bacteriocin-producing strain, since CWBI-B28 grew optimally in fat-rich meat with 20 ppm sodium nitrite. Bacteriocin activity was also measured in the samples. The observed activity levels are discussed in relation to the degree of antilisterial protection conferred.     

Antioxidative activity of summer savory (Satureja hortensis L.) and rosemary (Rosmarinus officinalis L.) in minced,cooked pork meat

The sensory intensity measured as theabsolute threshold value of spice andrecognition of spice was evaluated for summer savory and rosemary in meat balls. The values forabsolute threshold value of spice were found to be significantly lower for rosemary than for summer savory. The antioxidative activity of the spices was analysed in two accelerated model systems and in a storage experiment. In one of the model systems, oxidation was accelerated by heat and by an elevated pressure of oxygen. Both spices significantly improved the oxidative stability of the meat balls in this model system. In the second model system metal catalyst oxidation in a meat slurry was used and a reduction in the oxidative processes in samples containing the spices was again shown. In both model systems a slightly higher antioxidative activity was seen for rosemary compared to summer savory. In the storage experiment, the spices were added at a sensorially acceptable level and the heat-treated meat balls were stored at 5°C. A significant reduction in the development of warmed-over flavour (WOF) caused by the addition of spices was measured by a reduction in 2-thiobarbituricacid-reactivesubstances (TBARS) and in hexanal. A reduction in TBARS of approximately 30% in meat balls containing added spices was seen independently of packaging in 1% oxygen or in atmospheric air and the reduction (30%) was constant throughout the storage period.     

Gamma-Irradiation of CIostridium botulinum Inoculated Turkey Frankfurters Formulated with Different Chloride Salts and Polyphosphates

The effects of gamma-irradiation doses (0, 0.5, and 1.0 Mrad) on C. botulinum toxin production in turkey frankfurters formulated with three different chloride salts (NaCl, KCl, and MgCl₂) at isoionic strength (equal to 2.5% NaCl) and three types of phosphates added to 2.0% NaCl frankfurters were studied. The use of 2.5% NaCl together with 0.5 or 1.0 Mrad was substantially more effective at inhibitinlg botulinal toxin production when frankfurters were incubated at 27°C than the combination of irradiation with KCl or MgC1₂ (40, 9, and 4 days, respectively, when treated with 1 Mrad). Phosphate addition revealed that 0.4% sodium acid pyrophosphate addition was the most inhibitory for botulinal toxin production followed by hexametaphosphate and tripolyphosphate addition.     

Effect of Sodium Erythorbate on Residual Nitrite, pH and Bacterial Growth in Liver Sausage Formulated with Different Levels of Mechanically Separated Pork

Some microbiological, chemical, and physical characteristics of liver sausage formulated with 0, 25, 50, and 75% mechanically separated pork (MSP), 156 ppm sodium nitrite and 0 or 550 ppm sodium erythorbate were studied during refrigerated storage (5°C, 6 days) and subsequent elevated-temperature holding (20–24°C, 48 hr). Growth of inoculated Clostridium sporogenes was inhibited by 156 ppm nitrite in all sausages even after 48 hr at 20–24°C, regardless of MSP level. Growth of aerobic mesophiles and facultative anaerobes at 20–24°C was also inhibited in sausage formulated with 156 ppm nitrite and 550 ppm erythorbate. Erythorbate addition and increased MSP levels resulted in higher Hunter a color values. Residual nitrite, pH values, and total iron content of liver sausage increased with increasing MSP content.     

COMBINED EFFECTS OF ELECTRICAL STIMULATION AND METHODS OF MEAT PRESERVATION UPON THE SURVIVAL OF BACTERIA1

The synergistic effect caused by electrical stimulation and methods of meat processing on microbial numbers in meat was investigated. Electrical stimulation in all experiments reduced initial bacterial numbers and lowered tissue pH. Under the conditions of this research, no synergistic effect could be proven for electrical stimulation and 3% salt or 3% salt and 200 ppm of nitrite or for storage at -21°C. However, a synergistic effect was observed for electrical stimulation and heating at 60°C. This reduction in thermoresistance caused by electrical stimulation did not appear to be caused by the lowering of pH of the heating media.     

L-Ascorbic Acid and Its 2-Phosphorylated Derivatives in Selected Foods: Vitamin C Fortification and Antioxidant Properties

Two carbonated beverages fortified with 30 mg L-ascorbic acid (AsA) equivalents/250 mL in the form of L-ascorbate 2-monophosphate (AsMP) and stored at 25–35°C retained more vitamin C than those with added AsA or L-ascorbate 2-polyphosphate (AsPP). Breads enriched with ferrous iron and fortified with 560 AsA eq./100g flour in the form of AsPP and AsA retained 40% and 5% vitamin C, respectively, after 6 davs at 25°C. Bran (40%) flakes fortified with 0.19% AsA ea. as AsMP and AsPP gave much improved retention of vitamin C during storage for 7 mo at 25–40°C and 7–11% moisture levels. The sodium salts of AsA, AsMP, and AsPP, when injected into whole eye of round beef at 0.18% AsA eq., inhibited hexanal formation after the meat was roasted and stored for 5 days at 5°C. Those sodium salts did not prevent accumulation of peroxides in peanut paste.     

DSC study on the influence of meat source, salt and fat levels, and processing parameters on batters pressurisation

 Hydrostatic high-pressure/temperature treatments were conducted at low (10 °C) and high temperatures (60, 70, and 80°C) on different types of meat batters. Pressure-induced effects on proteins were intensified by sodium chloride molarity at low and high temperatures. Treatments at 10°C under pressurisation yielded net thermal destabilisation effects on meat proteins pertaining either to muscle or batter systems. Heating at usual cooking temperature of 70°C under pressure yielded net stabilising effects on meat batter proteins. Overheating at 80°C was needed for entire protein denaturation. Pork and chicken meats were very similar in behaviour but chicken batters exhibited relatively higher thermal- and pressure-induced protein denaturation. Both kinds of physical destabilisation/stabilisation of proteins by pressure-induced effects increased with pressure level. Received: 30 December 1999 / Revised version: 14 February 2000     

The oxidative stability of lard at −20°C: Evidence for a synergistic prooxidant effect of copper and curing salts

In connection with an interest in the problem of rancidity development in cold-stored cured meat products (particularly bacon), the effect of certain trace components and permitted food additives on the oxidative stability of model systems containing lard was examined. Lard, to which additions of various single additives or combination of additives had been made, was stored for periods of up to 16 weeks at ?20°C. Samples were removed during this time to assess the extent of their oxidation by chemical analysis (peroxide value determination) and sensory evaluation (odour). The additives studied included water, sodium chloride, sodium nitrate, sodium nitrite and copper (as palmitate, acetate and sulphate). It was observed that there was progressive oxidative deterioration of the lard with noticeable rancidity developing after 8 to 16 weeks' storage at ?20°C when water, sodium chloride, sodium nitrate, sodium nitrite and copper were present in combination.     

Binding of Meat Pieces: Influence of Some Processing Factors on Binding Strength and Cooking Losses

Evacuation of the chamber of the press used to form flaked beef into a restructured meat product (patty) did not affect the binding strength of the cooked patty but under some conditions decreased the cooking loss. In studies using patty mixes containing 0–1.0% added sodium chloride, meat binding strength increased with decrease in the temperature of the mix when formed into patties over the temperature range - 1° to -5°C. The largest effect generally occurred between - 1° and -2°C. However, the effect was only noted in patties that were frozen (-30°C) before being cooked for assessment. With decrease below - 1°C of the temperature of patties when pressed, cooking losses increased for the patties without added salt but decreased for those with added salt (0.5% or 1%). Change in the pressure applied to form the patty (in the range 1.4–13.7 MPa) can affect binding strength.