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%).     

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).     

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.     

CHEMICAL PROPERTIES OF GROUND BEEF PATTIES EXHIBITING NORMAL AND PREMATURE BROWN INTERNAL COOKED COLOR

Premature browning is a condition in which ground beef looks well-done at lower than expected temperatures. To study this color pattern, chemical properties were measured on raw and cooked patties (55, 65 and 75C) that developed normal (NRM) and premature brown (PMB) color when cooked to 55C. NRM patties were visually and instrumentally redder at all temperatures (P<0.05) than PMB patties. Visual color of PMB patties at 55C and NRM patties at 75C were similar (P>0.05). Heme and nonheme iron, total pigment and pH did not differ (P>0.05) between groups. Nonheme iron increased (P<0.05) as endpoint temperature increased. Patties with NRM color had lower (P<0.05) TBA values and oxidative-reduction potentials and higher (P<0.05) total reducing activity than patties with PMB. No difference (P>0.05) occurred in precipitation of juice extracts from NRM and PMB patties during heating (40 to 75C). Premature browning was related to patty oxidation.     

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.     

Heat-Induced Gelation Properties of Surimi From Mechanically Separated Chicken

Chicken surimi was prepared from fresh mechanically separated chicken meat using a sodium bicarbonate washing process. The heat-induced gelation properties were assessed under different conditions of pH, temperature, heating rate, protein and sodium tripolyphosphate (TPP) concentrations. Surimi gel strength increased (p < 0.05) after: reducing pH from 6.4 to 6.0, increasing temperature from 40°C to 80°C, reducing heating rate from 5°C/min to 1°C/min, increasing protein concentration from 4% (w/w) to 8% (w/w) or addition of 0.3% (w/w) TPP. Freeze thaw stability studies revealed that the gel strength of surimi decreased (p < 0.05) when subjected to frozen storage at – 18°C.     

Heating Cruciferous Vegetables Increases in Vitro Dialyzability of Intrinsic and Extrinsic Iron

Iron dialyzability (ID) from three Cruciferae (broccoli, kale and cabbage) was determined by an in vitro digestion method. The effect of added Crucifers on the ID of extrinsic nonheme iron as well as effects of heating were studied. Uncooked Crucifers contained iron of moderate ID (7–9%); cooking resulted in substantial ID increase (200%). Cooked Crucifers increased extrinsic ID three- to fourfold. Time and temperature relationships for the increase suggested that organic acids released after partial cell wall degradation combined with protein denaturation and iron solubilization from fiber were major reasons for differences between raw and cooked vegetables. Cruciferous vegetables can contribute to improved iron nutrition.     

Lipid Oxidation and Warmed-Over Aroma in Cooked Ground Pork from Swine Fed Increasing Levels of Iron

Fifteen crossbred feeder pigs were fed to market weight on corn-soy rations containing either 62, 131, or 209 ppm iron. After slaughter, pork was ground, cooked, and stored at 4°C for 12 days. Heavily fortifying swine rations with iron (≥200 ppm) increased nonheme iron (NHI) and thiobarbituric acid reactive substances (TBARS) in cooked, stored ground pork (GP) but did not increase warmed-over aroma (WOA) (p>0.05). NHI, TBARS, and WOA increased during storage. TBARS strongly correlated with WOA during storage (r=0.903) and with NHI (r=0.901).     

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).     

Oxidative Stability and Textural Quality of Restructured Beef Roasts as Affected by End-point Cooking Temperatures, Storage and the Incorporation of Surimi

Restructured beef roasts containing either 0 or 3.5% surimi were cooked to end-point internal temperatures of 50, 60, and 70°C to assess treatment effects on textural and oxidative quality after 2 and 5 days of refrigerated (4°C) storage. Surimi did not improve binding, cook yield or sensory tenderness and juiciness. The sensory panel was able to distinguish a slightly more pronounced fishy flavor when surimi was added. End-point internal temperature had no effect on tensile strength, however, tenderness increased and juiciness decreased with increased endpoint temperatures. Higher end-point internal temperature enhanced lipid oxidation, which proceeded more rapidly during refrigerated (4°C) storage. Nonheme iron increased with increasing end-point temperature. During storage, phospholipid content decreased while total lipid remained constant.     

Measurement and Content of Nonheme and Total Iron in Muscle

A method for determining the nonheme iron content of meats was evaluated and used to determine the nonheme and heme iron content of selected muscles from beef, pork, and lamb. The method allows a quantitative determination of nonheme iron in meat and is influenced to only a minor degree by the presence of heme iron. Heating meat in a boiling water bath increased the nonheme iron content of the meat. Possibly, heating accelerates oxidative cleavage of the prophyrin ring thereby allowing release of the iron from the heme complex. Total iron content differed between muscles in pork and beef but not in lamb. Heme iron, expressed as percent of the total iron, in raw pork, lamb, and beef average 49, 57, and 62%, respectively.     

Effect of Heat Processing of Dried Egg White on In Vitro Iron Bioavailability

Egg white (EW) was desugared, adjusted to either pH 7 or pH 9, and freeze-dried. Portions were held at 25°, 50°, 60°, 70° or 80°C for 1 wk. In vitro iron bioavailability (IVIB) was estimated by the method of Kane and Miller (1984) and no differences in IVIB were observed due to EW pH. IVIB of EW held at 50°, 60°, or 70°C was not different (P>0.05) than that of EW held at 25°C [9.87% dialyzable iron (DI)]; only the 80°C treatment led to IVIB lower (6.76% DI, P<0.05) than the 25°C control. Differential scanning calorimetry and nondissociating electrophoresis showed that native protein structure, including that of the iron-binding protein ovotransferrin, was maintained after the 70°C treatment but not after the 80°C treatment.     

The effects of heating and chemical treatment on the haem and non-haem iron content of heat-induced porcine blood curd

The effect of heating temperature (40–80°C), time (0–50 min), additions of ascorbic acid (0–5 g litre^?1) and sodium nitrite (0–200 mg litre^?1) on total, non-haem and haem iron of heat-induced porcine blood curd (a famous edible blood food in Taiwan) was investigated. The results show that non-haem iron content increased significantly (P < 0.05) when heated at above 55°C and was enhanced linearly (r = 0.96) with heating time at 80°C, while haem iron decreased relatively. In addition, a non-haem iron increase was observed in ascorbic acid, the maximum found with treatment at 4 g litre^?1. On the contrary, haem iron content increased with the presence of sodium nitrite and there was a significant change with addition above 50 mg litre^?1.     

Microencapsulated Iron for Food Fortification

Lipid microcapsules of FeSO₄, alone or with ascorbic acid, and FeCl₃, were developed to fortify cheese and other high moisture foods with iron. Varying lipid coat composition and amount of core iron solution optimized their stability. A high melting fraction of milk fat (m.p. 43.5°C) was oxidized by iron and was thus unsuitable as coat material. Microcapsules made with cottonseed stearine (m.p. 62.8°C) had good oxidative stability and retained more iron under rapid stirring at 39°C than those made with hydrogenated milk fat (m.p. 49.0°C). Microcapsules having good oxidative stability and low leakage of iron were coated with stearine and had a ratio of 0.10g Fe solution/g lipid coat. Microencapsulation may allow fortification of cheese and other iron sensitive foods.     

Extraction of boldo (Peumus boldus M.) leaves with supercritical CO2 and hot pressurized water

High-activity fractions in boldo leaves were extracted with supercritical CO₂ (SC-CO₂) and hot pressurized water (HPW). Total yield after 3 h of extraction (0.6–3.5%) in low-pressure SC-CO₂ experiments increased with process pressure (60–150 bar) and decreased with temperature (30–60 °C), as expected. The extract obtained with SC-CO₂ at 50 °C and 90 bar contained approximately 50% of essential oil components. In higher pressure experiments with solvent mixtures, the yield increased with pressure (300–450 bar) and modifier concentration (2–10% ethanol), ranging 0.14–1.95 ppm for the alkaloid boldine and 1.8–4.8% for total solids following 1.5 h treatment at 50 °C. Boldine recovery was solubility-controlled, reaching 7.4 ppm after 7-h extraction at 450 bar and 50 °C using an ethanol–SC-CO₂ mixture (5% co-solvent). Boldine solubility and yield decreased when using pure CO₂ at higher pressure (600 bar, 50 °C). The extract yield after 3 h batch-wise HPW extraction increased from 36.9% at 100 °C to 53.2% at 125 °C, and then decreased as temperature was increased to 175 °C. Boldine yield decreased from 26.8 ppm at 100 °C to 0.7 ppm at 125 °C, and was negligible at ⩾150 °C. The essential oil yield increased to a maximum at 110 °C and was negligible at ⩾150 °C also. The ranking of antioxidant potency of various extracts was as follows: HPW at 110 °C > methanol (soxhlet extraction) ≫ high-pressure SC-CO₂ with or without polar co-solvent > low-pressure SC-CO₂.     

Influence of post-harvest application rates of cyprodinil,treatment time and temperature on residue levels and efficacy in controlling green mould on ‘Valencia’ oranges

The effectiveness of heat treatments with water and cyprodinil in controlling post-harvest green mould caused by Penicillium digitatum was investigated on artificially inoculated ‘Valencia’ oranges. Residue levels of cyprodinil were determined in the oranges as a function of active ingredient concentration, temperature and treatment time. Cyprodinil residues were significantly dependent on treatment time when applied at 600 mg l^?1 and 20°C, but not when fruit were treated at 150–300 mg l^?1. The application of cyprodinil at 50 or 100 mg l^?1 at 55°C for 30 s produced similar residue levels, while residues increased when the application rate was 150 mg l^?1. Cyprodinil at 100 mg l^?1 and 60°C produced a significant increase in residues compared to treatment at 50 mg l^?1; no significant increase in residues was found when the application rate was raised from 100 to 150 mg l^?1. In comparison to treatments performed at 20°C, the application of a heated cyprodinil mixture resulted in significantly higher residues in fruit. All treatments with cyprodinil at 20°C similarly reduced green mould after 7 days of storage at 20°C. After 18 days, treatment with cyprodinil at 600 mg l^?1 for 30 s was more effective than at 150–300 mg l^?1. When dip time was extended to 90 or 180 s, treatment efficacy was positively related to fungicide concentration. Treatments with water at 55°C for 30 s were as effective as cyprodinil at 50–100 mg l^?1, but less effective than cyprodinil at 150 mg l^?1. After 7 days, treatment with water or cyprodinil at 50–150 mg l^?1 and 60°C were equally effective in controlling green mould; while, after 18 days, treatment with cyprodinil at 150 mg l^?1 was consistently more effective than at 50–100 mg l^?1 or hot water alone.     

Three Methods for Determining Nonheme Iron in Turkey Meat

The ferrozine, the Schricker and modified Schricker methods were used to measure the non-heme iron in raw and cooked turkey meat. The ferrozine method gave the lowest non-heme iron values, while results from the Schricker and modified Schricker were not different (p<0.05). When hemoglobin (Hb) was added to breast meat, how-ever, differences (p<0.05) between the Schricker and modified Schricker, and Schricker and ferrozine methods were observed in cooked meat with NaCl. Cooking and addition of NaCl caused increase in measured nonheme iron content and had a synergistic effect on the release of nonheme iron in meat.     

Protein Oxidation in Frankfurters with Increasing Levels of Added Rosemary Essential Oil: Effect on Color and Texture Deterioration

The development of protein oxidation as assessed by the total carbonyl content and its influence on color and texture deterioration during the refrigerated storage (+4 °C/60 d) of frankfurters, were studied. The effect of the addition of a rosemary essential oil at different levels (150, 300, and 600 ppm) on the protein oxidative stability of the frankfurters was also evaluated. Frankfurters with no added essential oil were used as controls. The amount of carbonyls from protein oxidation significantly increased during refrigerated storage, and this increase was significantly higher in control frankfurters than in those treated with 300 and 600 ppm. Rosemary essential oil at levels of 300 and 600 ppm successfully protected the heme molecule from degradation and significantly inhibited the increase of nonheme iron (NHI) in refrigerated stored frankfurters. Color changes were directly related to oxidation processes because frankfurters with added antioxidants (300 and 600 ppm) suffered less color modifications than the controls. The addition of rosemary essential oil enhanced texture characteristics of frankfurters by reducing hardness, adhesiveness, gumminess, chewiness, and controlling the lost of elasticity during refrigeration. Statistically significant correlations were calculated between protein oxidation and instrumentally measured parameters, suggesting that the alteration of protein functionality caused by oxidation likely affected color and texture characteristics of frankfurters.     

Lipid Stability of Beef Model Systems with Heating and Iron Fractions

Catalytic effects of different temperatures (55, 70, 85, and 100°C) on lipid oxidation were studied in aqueous- and chloroform/methanol-extracted beef model lipid systems containing iron forms inherent in beef (water-extractable, diffusate, nondiffusate, ferritin, myoglobin, hemoglobin), hematin, FeCl₂, or FeCl₃. Heating increased thiobarbituric acid and peroxide values in both systems. All forms of iron catalyzed lipid oxidation in aqueous systems, with greatest oxidation by heme and low molecular weight iron fractions. Oxidation in lipid extracts was not increased by ferritin, FeCl₂, or FeCl₃, but heme iron was the major oxidation catalyst. Lipid stability decreased with addition of any iron forms inherent in beef or with increased heating, which helps understanding of rapid oxidation of meat during refrigerated storage or after cooking.     

Effect of initial aflatoxin concentration,heating time and roasting temperature on aflatoxin reduction in contaminated peanuts and process optimisation using response surface modelling

Response surface methodology was applied to optimise the aflatoxin reduction in both naturally and artificially contaminated samples using dry oven. The effect of initial aflatoxin concentration (0–400 ng g^?1), heating time (30–120 min) and temperature (90–150 °C) was evaluated. The maximum reduction of AFB1 (78.4%) and AFB2 (57.3%) of artificially contaminated samples with initial aflatoxin concentration of 237 and 68 ng g^?1, and those of AFG1 (73.9%) and AFG2 (75.2%) with initial aflatoxin concentration of 215 and 75 ng g^?1 was obtained at 150 °C. The maximum reduction of AFB1 (80.2%) and AFB2 (69.7%) of naturally contaminated samples with initial aflatoxin concentration of 174 and 25 ng g^?1 was obtained at 150 °C and 130 °C, respectively.