ABSTRACT

The effect of increasing cooking temperatures of meat on nonheme iron absorption from a composite meal was investigated. Cysteine-containing peptides may take a office in the atomic number 26 absorption enhancing issue of musculus proteins. Rut treatment can modify the content of sulfhydryl groups produced from cysteine and thereby touch on iron absorption. Twenty-ane women (25 ± iii y) were served a basic meal without meat and two other meals consisting of the basic meal plus 75 g of pork meat cooked at seventy, 95 or 120°C. The meals were extrinsically labeled with 55Fe or 59Fe. Atomic number 26 assimilation was determined from measurements of whole-trunk 59Fe retention and the action of 55Fe and 59Atomic number 26 in blood samples. Nonheme iron absorptions were 0.9 (0.5–4.0)% (P = 0.06), 0.seven (0.four–iii.9)% (P = 0.1) and 2.0 (one.three–3.1)% (P < 0.001) greater when meat cooked at 70, 95 or 120°C, respectively, was added to the basic repast. Increasing the cooking temperature of meat did not impair nonheme atomic number 26 assimilation compared with cooking at lxx°C. Considering the cysteine content of meat decreased with increasing cooking temperature, this argues against a specific contribution of sulfhydryl groups from cysteine residues in the promotion of nonheme iron absorption past meat proteins.

Atomic number 26 deficiency is a major health problem in developing countries (ane), but it is too prevalent in adult countries in women of childbearing ages (2) and children (3). An increased intake of creature protein could be an important dietary approach to amend iron condition. In addition to a high content of highly absorbable heme iron (4), muscle protein (beefiness, veal, pork, lamb, chicken and fish) enhances the assimilation of nonheme (5,half-dozen) and heme iron (four), the so-called "meat-outcome."

Withal, it has not been systematically investigated to what extent nutrient preparation, such as cooking, affects the iron absorption promoting effect of meat. Cysteine-containing peptides of meat, e.g., glutathione, have been suggested to be responsible for the "meat-issue" (vii,8). An increase in cooking temperatures at low levels (30–70°C) increases the content of reactive sulfhydryl (SH) groups in undigested meat considering the unfolding of meat proteins exposes SH groups otherwise hidden within the protein structure (9). Notwithstanding, at college cooking temperatures (90 and 120°C), the SH content decreases because they are oxidized to disulfide (SS) groups. Hence, if the "meat upshot" tin can exist ascribed to cysteine-containing peptides, information technology could be expected to decrease at higher cooking temperatures. Alternatively, college cooking temperatures may enhance nonheme iron absorption due to structural changes of the meat proteins, such as thermal denaturation.

In the present study, we investigated the influence of increased cooking temperature of meat on nonheme iron absorption from a composite meal designed to provide an appreciable amount of nonheme atomic number 26, but a low bioavailability of atomic number 26.

SUBJECTS AND METHODS

Subjects.

Twenty-one healthy nonsmoking and nonpregnant/lactating women aged 25 ± 3 y (mean ± sd), weighing 62 ± 6 kg (mean ± sd) and with a body mass alphabetize of 23 ± two kg/m2 (mean ± sd), volunteered for the written report. None of the women took whatever vitamin- or mineral supplements for at least 2 mo before or during the study. None were routinely taking any medication except for contraceptives, and claret donation was not allowed two mo before or during the report. The participants were informed orally and in writing nearly the details of the report before written consent was obtained. The Municipal Ethical Committee of Copenhagen and Frederiksberg and the National Institute of Radiation Hygiene, Denmark, approved the research protocol (KF) 01–100/97.

Written report blueprint.

The subjects were given three test meals: a basic meal without meat (A) and two basic meals that as well independent 75 g (raw weight) of pork cooked to unlike temperatures (B and C). The meat was cooked at seventy, 95 or 120°C and two of the three meat meals were randomly assigned to each bailiwick. Two of the meals were served in the lodge ABBA on iv sequent days and the remaining repast was served 5 wk later on two consecutive days: CC. The order of serving was randomized amidst the three types of meals given to each subject. Iron absorption was measured by the dual characterization extrinsic tag method (10). The two different meals in the outset period were labeled with 55Atomic number 26 and 59Atomic number 26, respectively, and the repast served in the 2nd period was labeled with 59Fe. The retentiveness of 59Fe was measured in a whole-body counter at baseline and 17 or 18 d after intake of the last meal in each period. The day after the whole-trunk counting in the first period, a claret sample was drawn, and the activity of 55Fe and 59Fe determined for the estimation of the 55Fe whole-trunk retention. A reference dose of 59Fe was given on 2 consecutive mornings subsequently the whole-body counting of the second menstruum, and 59Fe retentivity was measured by whole-torso counting xiv d later. The measurements of 59Iron in the whole-body counter from the repast in the second menstruation and from the reference dose were corrected for residual 59Fe. Iron excretion from the torso was causeless to be zero betwixt the three whole-torso countings.

Composition and training of the meals.

In the evening preceding all examination mornings, subjects consumed a standard meal in their homes prepared as described earlier (11). The bones exam repast was described in particular previously as well as the preparation and serving (xi) and consisted of rice, tomato sauce, pea puree and a wheat curl; the salt content was lower in the nowadays study (1 one thousand) than in the previously described basic repast (11). For preparation of meat patties, sixteen loins (longissimus dorsi) were obtained from a local slaughterhouse and trimmed of visible fat and connective tissue. The meat was minced through stainless steel blades in a meat grinder and 150 ± 0.five g portions were packed in hermetically sealed aluminum cans (inner sealing: aluminum pigmented epoxy phenol 7 g/yard2; weld protection: white polyester sealing; approved for food contact: Food and Drug Administration §175–300, U.s.a.). The cans were stored at –twenty°C and thawed overnight at 4°C earlier utilise. An integrating temperature-measuring device no. cmc 821 (Ellab A/South, Copenhagen, Kingdom of denmark) with a temperature probe was used to measure the temperature in the centre of the cans. The cans were exposed to one of three heat treatments: a minimal microbiologically safe heat treatment in circulating water at 70°C for lx min with a concluding center temperature of 69°C, a medium heat treatment in circulating water at 95°C for 60 min to a final center temperature of 94°C, and a maximal heat handling in an autoclave at 120°C. The content of the cans was divided into two equal portions corresponding to 75 g of meat (raw weight) and one was used for the absorption study. The nonheme fe content of the meals was determined and adapted to the amount present in the meal with meat heat treated at seventy°C by addition of 0.05 mg (120°C oestrus treatment) and 0.26 mg (basic meal) atomic number 26 equally ferrous sulfate (Struers KEBO lab A/S, Albertslund, Denmark) in ultra pure water.

Isotope labeling and serving procedure.

All meals were extrinsically labeled by the addition of 1 mL of radioisotope solution (FeCl3 in 0.1 mol HCl/Fifty) a minimum of 16 h before serving. Each dose in the commencement period contained 55 kBq 55FeCl3 or 38 kBq 59FeCl3 (Amersham, Buckinghamshire, United kingdom) and 19 kBq 59Fe in the 2d catamenia. The test meals were served in the morning with 300 mL of ultra pure water.

Restrictions.

The examination meals were served in the morning afterward subjects had fasted for 12 h. Intake of a maximum 0.5 Fifty h2o was allowed overnight. Moderate or hard physical activity or the intake of any alcohol or medication was not allowed during the 36 h earlier intake of the exam meal. Later consuming the examination meals, the subjects were not immune to eat or drink for 4 h and intake of alcohol was prohibited for the adjacent 48 h. The subjects filled in a questionnaire in connexion with each examination meal to ensure that they adhered to all procedures.

Analysis of food limerick.

Duplicate portions of the test meals were homogenized, freeze dried and analyzed for total atomic number 26, nonheme- and heme fe and nitrogen (Table i), ascorbic acrid, phytic acid, calcium (Ca) and zinc (Zn). Total iron (Atomic number 26), Ca and Zn were adamant by atomic absorption spectrometry (Spektr-AA 200, Varian, Mulgrave Victoria, Australia) after moisture-ashing in a MES 1000 Microwave Solvent Extraction system with 65% suprapure nitric acid (CEM, Matthews, NC). The standard Reference Material 1548a typical diet was used as reference for Iron (35.iii μg/g ± 3.eight), Ca (1.97 mg/g ± 0.11) and Zn (24.half dozen μthou/g ± 1.79) (National Institute of Standards and Technology, Gaithersburg, MD), and the analyzed values were: 37.six ± 2.7 μg/g (north = 4), 2.0 ± 0.06 mg/g (northward = four) and 28.3 ± 0.9 μg/1000 (n = iv). Phytic acid analysis was performed by HPLC as described earlier (12). Nitrogen assay was carried out on NA 1500 Automatic Nitrogen Analyzer (Carlo Erba Instruments, Milan, Italia) (13). Nitrogen measurements of Standard Reference Material 1548a (described above) was performed equally the control: 29.7 ± 0.3 (reference value: 30.three ± 3.1). A conversion cistron for nitrogen to protein of half dozen.25 was used. Nonheme iron was determined spectrophotometrically past the Ferrozine method (14) using iron standard no. 109972 (Merck, Darmstadt, Federal republic of germany) as a reference material. Heme iron was analyzed past a modified protocol (xv) of the acidified acetone extraction method originally described by Hornsey (16). Vitamin C analysis was performed by HPLC under the conditions reported previously (17). Sulfhydryl groups were determined spectrophotometrically at 405 nm in 0.v% SDS in Tris-glycine buffer after the addition of Ellman's reagent (18).

Tabular array one

Composition of test meals

Basic meal Meat meals
Heat handling
70°C 95°C 120°C
Total protein (g) 12.4 28.i 27.0 27.5
Nonheme iron (mg)1 ii.7 2.7 2.7 2.7
Heme atomic number 26 (mg)2 — 0.15 0.07 0.08
Cysteine (mg) — 171 166 138
Basic repast Meat meals
Heat treatment
lxx°C 95°C 120°C
Total protein (g) 12.4 28.1 27.0 27.v
Nonheme iron (mg)1 ii.7 2.7 two.7 ii.7
Heme atomic number 26 (mg)two — 0.15 0.07 0.08
Cysteine (mg) — 171 166 138

1

Afterward addition of 0.26 mg of nonheme atomic number 26 to the basic meal and 0.05 mg to the 120°C meat meal.

2

Heme fe in 75 g raw meat: 0.xviii mg.

TABLE 1

Composition of exam meals

Basic meal Meat meals
Heat treatment
70°C 95°C 120°C
Total protein (g) 12.4 28.1 27.0 27.5
Nonheme iron (mg)1 2.7 2.vii 2.seven 2.seven
Heme fe (mg)ii — 0.15 0.07 0.08
Cysteine (mg) — 171 166 138
Basic meal Meat meals
Heat treatment
70°C 95°C 120°C
Full protein (g) 12.4 28.one 27.0 27.five
Nonheme iron (mg)1 2.7 ii.seven 2.7 ii.7
Heme iron (mg)2 — 0.15 0.07 0.08
Cysteine (mg) — 171 166 138

1

After addition of 0.26 mg of nonheme iron to the basic repast and 0.05 mg to the 120°C meat meal.

two

Heme fe in 75 chiliad raw meat: 0.18 mg.

Electrophoresis.

Meat samples (i.2 g) were prepared as described previously (19) before loading onto a precast 10% NuPAGE Bis-Tris gel (Invitrogen, Paisley, United kingdom of great britain and northern ireland). Proteins were separated by a standard SDS-PAGE procedure using constant voltage (200 V), iii-(N-morpholino) propane sulfonic acid, pH 7.seven as running buffer and a broad range protein standard (# 161-0372, Bio-Rad, Hercules, CA). Poly peptide bands were visualized using 0.two% Coomassie Brilliant Blue R-250.

Conclusion of iron status.

Restrictions on intake and exercise were as before the test meals (see to a higher place). Blood samples were fatigued from the cubital vein later on x min remainder in a supine position. Serum ferritin analysis was performed past a ii-site fluoroimmunometric assay using Delfia flourometer 1232 with Delfia Ferritin kit (kit B069-101, Wallac Oy, Turku, Finland) on venous blood (3.0 mL) collected in plain tubes (Vacutainer organization, Becton Dickinson, Franklin Lakes, NJ) with advisable reference serums (WHO NIBSC-ferritin, Blanche Lane, South Mimms, UK). Intra- and interassay CV were 2.ane% (n = 12) and 5.0% (northward = 17), respectively. Hemoglobin analysis was carried out on a Sysmex KX-21 automated hematology Analyser (Sysmex GMBH, Norderstedt, Germany) on venous claret (iv.5 mL) collected in tubes containing dissolved EDTA (Benson Dickinson) using appropriate control (EIGHTCHECK-3WP, lot no. 91160123, Sysmex GMBH). Intra- and interassay CV were 0.7% (n = twenty) and 1.iii% (n = 16), respectively.

Determination of nonheme iron absorption.

Claret (∼60 mL) was drawn from each subject for the determination of 55Fe and 59Fe action using heparin as the anticoagulant. Simultaneous decision of 55Fe and 59Iron in blood was performed as described in detail (20). 59Fe whole-body retentivity was measured as described (xi). Each subject area received 110 kBq 55Fe and 152 kBq 59Fe in total from the four meals and two reference doses; thus, they were calculated to receive a maximum radiations dose of 0.7 mSv. To correct for interindividual differences in iron status, iron absorption from a standardized reference dose was measured on two consecutive mornings after an overnight fast. Each reference dose contained 3 mg iron every bit ferrosulfate (Struers KEBO Lab A/Southward) and xxx mg L(+)ascorbic acrid (Merck) in a 10 mL solution of 0.01 mol/50 HCl. After intake of the reference dose, the vial was rinsed twice with ultra pure h2o, which was too consumed. The same restriction protocol as stated above for the examination meals was used.

Expression of iron assimilation.

To make comparison of the results to other information possible, atomic number 26 assimilation was expressed equally unadjusted assimilation (ane) and assimilation adapted to 40% from the reference dose (2) because these are common ways to express iron absorption information. 1) Absorption of 59Iron was determined directly from 59Fe whole-trunk retention. 55Fe assimilation was calculated from retention in blood, based on the assumption that the fraction of 55Iron and 59Atomic number 26 in the blood is similar (10):

\[^{55}\mathrm{Fe\ absorption}\ (\%){=}\ \frac{(^{55}\mathrm{Fe\ activity\ in\ blood})}{(^{59}\mathrm{Fe\ activity\ in\ claret})}{\times}^{59}\mathrm{Fe\ whole\ body\ retention}\ (\%)\]

2) The absorption data were adjusted to 40% absorption from the reference dose because this is assumed to equal absorption in subjects with depleted atomic number 26 stores (21):

\[\mathrm{Abs\ adjusted\ to}\ 40\%\ \mathrm{from\ reference\ dose}{=}\ \frac{\mathrm{Abs\ from\ meal}\ (\%)}{\mathrm{Abs\ from\ reference\ dose}\ (\%)}{\times}40\ (\%)\]

where Abs is nonheme fe absorption. Finally, the difference betwixt iron absorption from the meat repast and the basic repast was estimated.

Statistical analyses.

Ane discipline had a very high nonheme iron absorption from the bones repast: 29.6% compared with the mean absorption of one.8%, and the statistical analyses were carried out with this information prepare included and excluded. Serum ferritin and assimilation information were converted to logarithms before statistical analyses and the results reconverted to antilogarithms. Data used for statistical analysis were normally distributed with variance homogeneity tested by plots and histograms of residuals. The Shapiro-Wilk'southward exam for normal distribution was performed. Data are presented as estimates of least-squares ways with 95% conviction intervals (22). Nonheme atomic number 26 absorption from meals was compared by linear mixed models with log (nonheme iron assimilation) equally the dependent variable, repast (bones meal, meat meal: 70, 95 or 120°C cooking temperature) and absorption from reference dose as contained stock-still variables and subject as random effect: log (nonheme iron absorption)i = μ + α (meali) + β × referencei + [subjecti] + εi. Reference dose adjusted data were estimated with the following model: log (nonheme atomic number 26 absorption)i = μ + α (meali) + [subject areai] + εi. Differences of to the lowest degree-squares ways were performed post hoc. Mixed linear models were performed with the Statistical Analysis Systems statistical software bundle version 8.1 (SAS Constitute, Cary, NC).

RESULTS

All subjects had low serum ferritin (ix.7–41.3 μ1000/50) and normal hemoglobin concentrations (119.2–137.0 1000/50), and there were no differences among the iii groups with respect to these iron status parameters (Table ii). Similarly, nonheme iron absorption from the reference dose did not differ significantly among the groups: 26.4 (twenty.6–33.nine)%, 25.8 (19.7–33.7)% and 32.0 (24.7–41.5)% in the group given meat cooked at 70, 95 and 120°C, respectively. The bones meal contained 33 mg of vitamin C and 219 mg (198 μmol) of phytic acrid. The two highest cooking temperatures reduced the heme atomic number 26 content of the meat to 50% that of the lowest temperature (Table 1). The cysteine content decreased with increasing cooking temperature (Table 1). The largest proteins such as myosin tended to polymerize at the college cooking temperatures and were retained in the well (Fig. one, lanes iv and 5), whereas the lower molecular proteins such as actin did not polymerize.

Effigy 1

SDS-PAGE (10% NuPAGE Bis-Tris gel) of the meat when raw and when cooked at different temperatures.

SDS-Page (ten% NuPAGE Bis-Tris gel) of the meat when raw and when cooked at dissimilar temperatures.

Effigy 1

SDS-PAGE (10% NuPAGE Bis-Tris gel) of the meat when raw and when cooked at different temperatures.

SDS-PAGE (x% NuPAGE Bis-Tris gel) of the meat when raw and when cooked at different temperatures.

Table ii

Nonheme iron absorption (%) and iron status data in women given a bones meal with cooked meat added 1

Oestrus handling of meat
70°C 95°C 120°C
Subjects,2 n 15 13 14
Serum ferritin, μg/L 23.ii 24.6 24.vii
(xviii.eight–28.7) (19.six–30.9) (19.9–30.eight)
Hemoglobin, grand/Fifty 124 127 126
(121–127) (124–131) (123–129)
Difference in absorption between meat repast and basic meal,iii % 0.nine 0.7 2.0*
(0.5–4.0) (0.four–3.9) (1.3–3.one)
Heat treatment of meat
70°C 95°C 120°C
Subjects,2 n 15 13 14
Serum ferritin, μg/50 23.ii 24.6 24.7
(xviii.viii–28.7) (nineteen.vi–30.9) (19.9–30.8)
Hemoglobin, g/L 124 127 126
(121–127) (124–131) (123–129)
Difference in absorption betwixt meat repast and bones repast,3 % 0.ix 0.7 2.0*
(0.5–4.0) (0.4–3.9) (1.3–iii.1)

1

Least-squares means (LSMeans), 95% confidence interval in parentheses.

2

Each subject field was served two of iii meat meals (n = 21 in total).

3

Unadjusted data.

*

P < 0.001.

Table two

Nonheme iron assimilation (%) and iron condition data in women given a basic meal with cooked meat added ane

Estrus treatment of meat
70°C 95°C 120°C
Subjects,2 n 15 13 xiv
Serum ferritin, μg/50 23.ii 24.6 24.7
(18.8–28.seven) (19.6–xxx.nine) (19.9–30.8)
Hemoglobin, thou/L 124 127 126
(121–127) (124–131) (123–129)
Difference in absorption betwixt meat meal and basic repast,3 % 0.ix 0.7 ii.0*
(0.five–iv.0) (0.iv–3.nine) (1.iii–3.1)
Rut handling of meat
seventy°C 95°C 120°C
Subjects,two northward fifteen 13 14
Serum ferritin, μg/50 23.ii 24.6 24.seven
(18.viii–28.7) (19.six–30.9) (xix.9–30.8)
Hemoglobin, g/L 124 127 126
(121–127) (124–131) (123–129)
Difference in absorption between meat meal and basic meal,iii % 0.ix 0.7 2.0*
(0.5–iv.0) (0.four–3.nine) (1.iii–3.1)

1

Least-squares means (LSMeans), 95% confidence interval in parentheses.

2

Each bailiwick was served two of three meat meals (n = 21 in total).

3

Unadjusted data.

*

P < 0.001.

The absorption of nonheme iron from the bones meal (due north = 21) was i.eight (ane.3–1.7)% (unadjusted data) and 2.7 (1.8–three.9)% when adapted to 40% absorption from the reference dose. When 75 g of meat cooked at 70, 95 and 120°C was added to the bones meal, the unadjusted nonheme atomic number 26 absorption was ii.8 (1.8–4.0)%, 2.6 (one.6–3.9)% and iii.8% (ii.five–5.8)% and the reference dose adapted absorption was 3.eight (2.v–5.8)%, 3.six (2.4–5.vi)% and 5.5 (3.six–eight.2)%, respectively (P = 0.07). Thus, addition of meat cooked at 70, 95 and 120°C to the basic meal increased the assimilation past 0.9% (P = 0.06), 0.7% (P = 0.1) and two.0% (P < 0.001) respectively. When outlying data were omitted (see Statistical analyses), nonheme iron absorption increased by 0.8% (P = 0.03), 0.7% (P = 0.09) and two.0% (P < 0.001), respectively.

DISCUSSION

This study demonstrated that cooking 75 chiliad of pork meat at higher temperatures (95 and 120°C) did not impair nonheme iron absorption from a repast compared with cooking at 70°C. In addition, nonheme iron assimilation tended to increment at the highest cooking temperature compared with lower cooking temperatures. Because the loftier-molecular-weight meat proteins (e.1000., myosin) tend to polymerize to some extent at 95°C and completely at 120°C, this process of protein polymerization does not seem to impair nonheme iron assimilation. The absorption results suggest, rather, that polymerization actually increases nonheme fe assimilation; notwithstanding, this hypothesis remains to exist investigated. Disappearance of larger proteins has also been observed with chicken muscle cooked at 60–80°C (23). An additional explanation for the disappearance of high-molecular-weight meat proteins is the formation of gelatin when collagen is coagulated at high cooking temperatures (24).

The cysteine content of the meat decreased with increased cooking temperature in accord with previous findings (9) and was non correlated with the degree of nonheme iron absorption.

Heme atomic number 26 is better absorbed than nonheme iron (iv) and because the heme atomic number 26 content of meat was diminished by 50% at the highest cooking temperature, the issue of cooking on total iron absorption from meat has to be evaluated.

The lowest temperature was selected every bit a minimum for microbiological prophylactic, but is also relevant for the preparation of meats such as roasts. The medium temperature is realistic for meat cooked in water (e.g., stews) and the highest temperature relevant to canned meat production (25). Because cooking meat in water-based liquids is a widespread meat preparation method in developing countries such as Cambodia and Thailand (26,27) also every bit in adult countries [e.1000., Denmark (28)] and because consumption of canned cooked meat and meat products is common worldwide, the findings of the present study are relevant.

In conclusion, increasing cooking temperatures of meat does not impair nonheme fe absorption. There was a trend toward a higher assimilation when meat was cooked at 120°C. These findings exercise not support a specific office for SH groups produced from cysteine residues in the meat promoting nonheme iron absorption because the cysteine content of the meat decreased with increasing cooking temperature. In addition, the observed reduction of heme iron content by higher temperatures must be considered in evaluating total iron captivated.

We thank Hanne Lysdal Petersen, Res. Dept. Human being Nutr., Royal Vet. Agric. Univ., Frederiksberg, Susanne Svalling, Dept Clin. Physiol. Nucl. Med., National Univ. Infirmary, Copenhagen and Pia Madsen, Biochem. Nutr., Biocentrum DTU, Lyngby, for providing excellent technical assistance.

LITERATURE CITED

i.

United Nations Authoritative Committee on Coordination (ACC)Subcommittee on Diet (SCN)

(

1997

)

Tertiary Report on the World Nutrition Situation

World Health Organization

Geneva, Switzerland

.

2.

Milman

,

Northward.

&

Kirchhoff

,

Grand.

(

1992

)

Fe stores in 1359, 30- to 60-y-old Danish women: evaluation past serum ferritin and hemoglobin

.

Ann. Hematol.

64

:

22

–

27

.

3.

Dallman

,

P. R.

,

Siimes

,

K. A.

&

Stekel

,

A.

 (

1980

)

Iron deficiency in infancy and childhood

.

Am. J. Clin. Nutr.

33

:

86

–

118

.

4.

Hallberg

,

L.

,

Björn-Rasmussen

,

E.

,

Howard

,

L.

 &

Rossander

,

Fifty.

 (

1979

)

Dietary heme iron assimilation. A discussion of possible mechanisms for the absorption-promoting effect of meat and for the regulation of atomic number 26 absorption

.

Scand. J. Gastroenterol.

xiv

:

769

–

779

.

5.

Martinez-Torres

,

C.

&

Layrisse

,

M.

(

1971

)

Iron absorption from veal muscle

.

Am. J. Clin. Nutr.

24

:

531

–

540

.

six.

Melt

,

J. D.

&

Monsen

,

E. R.

(

1976

)

Food iron absorption in homo subjects. III. Comparison of the result of animal proteins on nonheme iron assimilation

.

Am. J. Clin. Nutr.

29

:

859

–

867

.

7.

Layrisse

,

Thousand.

,

Martinez-Torres

,

C.

,

Leets

,

I.

,

Taylor

,

P.

 &

Ramirez

,

J.

 (

1984

)

Event of histidine, cysteine, glutathione or beefiness on iron absorption in humans

.

J. Nutr.

114

:

217

–

223

.

eight.

Taylor

,

P. G.

,

Martinez-Torres

,

C.

,

Romano

,

E. L.

 &

Layrisse

,

M.

 (

1986

)

The outcome of cysteine-containing peptides released during meat digestion on iron assimilation in humans

.

Am. J. Clin. Nutr.

43

:

68

–

71

.

nine.

Hoffmann

,

K.

&

Hamm

,

R.

(

1978

)

Sulfhydryl and disulfide groups in meats

.

Adv. Food Res.

24

:

1

–

111

.

10.

Hallberg

,

50.

(

1980

)

Food iron absorption

.

Cook

,

J. D.

eds.

Methods in hematology

:

116

–

133

Churchill-Livingstone

London, Great britain

.

11.

Bæch

,

S. B.

,

Hansen

,

Thousand.

,

Bukhave

,

G.

,

Jensen

,

One thousand.

,

Sørensen

,

South. S.

,

Kristensen

,

Fifty.

,

Purslow

,

P. P.

,

Skibsted

,

L.

 &

Sandström

,

B.

 (

2003

)

Nonheme iron absorption from a phytate rich meal is enhanced past addition of small amounts of pork meat

.

Am. J. Clin. Nutr..

12.

Sandberg

,

A. S.

&

Ahderinne

,

R.

(

1986

)

HPLC method for determination of inositol tri-, tetra-, penta-, and hexaphosphates in foods and intestinal contents

.

J. Food Sci.

51

:

547

–

545

.

xiii.

Kirsten

,

Westward. J.

&

Hesselius

,

M. U.

(

1983

)

Rapid, automatic, high capacity dumas conclusion of nitrogen

.

Microchem. J.

28

:

529

–

547

.

14.

Ahn

,

D. U.

,

Wolfe

,

E. H.

&

Sim

,

J. Southward.

 (

1993

)

Three methods for determining nonheme atomic number 26 in turkey meat

.

J. Food Sci.

58

:

288

–

291

.

15.

Carpenter

,

C. E.

&

Clark

,

E.

(

1995

)

Evaluation of methods used in meat iron analysis and iron content of raw and cooked meats

.

J. Agric. Food Chem.

43

:

1824

–

1827

.

16.

Hornsey

,

H. C.

(

1956

)

The colour of cooked cured pork

.

J. Sci. Food Agric.

vii

:

534

–

540

.

17.

Kall

,

Thousand. A.

&

Andersen

,

C.

(

1999

)

Improved method for simultaneous determination of ascorbic acid and dehydroascorbic acid, isoascorbic acid and dehydroisoascorbic acid in food and biological samples

.

J. Chromatogr. Biomed. Sci. Appl.

730

:

101

–

111

.

18.

Beveridge

,

T.

,

Toma

,

S. J.

&

Nakai

,

Southward.

 (

1974

)

Conclusion of SH- and SS-groups in some nutrient proteins using Ellmans'due south reagent

.

J. Food Sci.

39

:

49

–

51

.

19.

Kristensen

,

50.

&

Purslow

,

P. P.

(

2001

)

The effect of ageing on the water-holding capacity of pork: function of cytoskeletal proteins

.

Meat Sci.

58

:

17

–

23

.

xx.

Bukhave

,

1000.

,

Sørensen

,

A. D.

&

Hansen

,

M.

 (

2001

)

A simplified method for decision of radioactive iron in whole-blood samples

.

J. Trace Elem. Med. Biol.

15

:

56

–

58

.

21.

Magnusson

,

B.

,

Bjorn-Rassmussen

,

E.

,

Hallberg

,

L.

 &

Rossander

,

L.

 (

1981

)

Iron absorption in relation to iron status. Model proposed to express results to food fe assimilation measurements

.

Scand. J. Haematol.

27

:

201

–

208

.

22.

Bland

,

J. M.

&

Altman

,

D. Chiliad.

(

1996

)

Transformations, means, and confidence intervals

.

Br. Med. J.

312

:

1079

.

23.

Murphy

,

R. Y.

&

Marks

,

B. P.

(

2000

)

Issue of meat temperature on proteins, texture, and cook loss for ground craven breast patties

.

Poult. Sci.

79

:

99

–

104

.

24.

Lawrie

,

R. A.

(

1998

)

The eating quality of meat

.

Lawrie

,

R. A.

eds.

Meat Science

:

212

–

257

Woodhead Publishing Express

Cambridge, UK

.

25.

Andersen

,

P. E.

&

Risum

,

J.

(

1982

)

Varmekonservering (Heat preservation)

.

Andersen

,

P. E.

Risum

,

J.

 eds.

Introduktion til levnedsmiddelteknologien, bind 1, konservering (Introduction to Food Applied science, Volume ane, Preservation)

:

186

–

233

Polyteknisk forlag (Polytechnical Publishing)

Lyngby, Denmark

.

26.

Mogensen

,

M. T.

(

2001

)

Varmekonservering (Oestrus preservation)

.

The Importance of Fish and Other Aquatic Animals for Food and Nutrition Security in the Lower Mekong Basin. Doctoral thesis

The Royal Veterinary and Agronomical Academy

Copenhagen, Denmark

.

27.

Prapertchob

,

P.

,

Kachamart

,

P.

,

Pakuthai

,

West.

,

Viratchakul

,

J.

,

Viratchakul

,

J.

,

Hornak

,

A.

,

Thiranggoon

,

P.

 &

Kamsrakaeo

,

P.

 (

1989

)

Varmekonservering (Estrus preservation)

.

Analysis of freshwater fish consumption and marine product marketing on Northeast Thailand. Summary Written report

Department of Fisheries, Ministry of Agriculture and Cooperatives and Envirocon International Limited

Thailand

.

28.

Fagt

,

Southward.

&

Trolle

,

Eastward.

(

2001

)

Varmekonservering (Heat preservation)

.

Udvikling i danskernes kost - forbrug, indkøb og vaner (Food supply 1955–1999. Development of food consumption, purchase and dietary habits). Report no. 10

Veterinær- og Fødevaredirektoratet (The Danish Veterinary and Food Assistants)

Søborg, Denmark

.

Writer notes

3

Present address: Department of Mathematics and Physics, The Purple Veterinary and Agricultural University, DK-1958 Frederiksberg, Denmark.

iv

Present address: Section Food Science, University of Guelph, Guelph, ON, Canada.

© 2003 The American Society for Nutritional Sciences

© 2003 The American Society for Nutritional Sciences