Comparison of isoflavones composition in seed,embryo, cotyledon and seed coat of cooked-with-rice and vegetable soybean (Glycine max L.) varieties

In order to study the content and composition of isoflavones retained in soybean seed component, obtained each component part the embryo, cotyledon and seed coat tissues of nine different soybean varieties were analyzed for 12 isoflavones using high performance liquid chromatography with photo diode array detector (HPLC-PDA) and were compared to each other. A total average concentration of isoflavone was 2887 μg g⁻¹ in embryo, 575 μg g⁻¹ in whole seed, 325 μg g⁻¹ in cotyledon, and 33 μg g⁻¹ in seed coat. With respect to each tissue of soybean varieties, isoflavone content was highest in Geomjeongkong 2 embryo (5701 μg g⁻¹), Geomjeongolkong whole seed (1321 μg g⁻¹), Heugcheongkong cotyledon (951 μg g⁻¹), and Keunolkong seed coat (56 μg g⁻¹). Isoflavone was least present in Keunolkong embryo (341 μg g⁻¹), Hwaeomputkong whole seed (175 μg g⁻¹), Seonheukkong cotyledon (81 μg g⁻¹), and Seoklyangputkong seed coat (5 μg g⁻¹). Overall, embryo and seed coat of all nine varieties contained isoflavones at the highest and lowest level, respectively. Isoflavones accumulated in the order of malonylglycoside, glycoside, acetylglycoside, and aglycon, among which malonylglycoside was the most abundant form ranging from 66% to 79% of the total isoflavone content in all three tissues. The embryo of cooked-with-rice soybean with black seed coat appears to be the best source of isoflavone.     

Residue levels of food-grade antioxidants in postharvest treated in-pod peanuts during five months of storage

In order to investigate residue levels of butylated hydroxyanisole (BHA), propyl paraben (PP) and butylated hydroxytoluene (BHT) during storage, eight-hundred kilograms of bulk peanuts were treated with the following antioxidant emulsions: BHA (1802 μg g⁻¹), BHA–PP (1802 μg g⁻¹ + 1802 μg g⁻¹) M1 and BHA–PP–BHT mixtures (1802 μg g⁻¹ + 901 μg g⁻¹ + 2204 μg g⁻¹) M2 and (1802 μg g⁻¹ + 1802 μg g⁻¹ + 2204 μg g⁻¹) M3. Residues were determined in peanut pod and seed tissues at 1-month intervals during the storage. While the reduction levels of BHA and PP in pods at the end of the storage period ranged from 66% to 76%, BHT levels were decreased extensively (86%). Twenty-four hours after peanuts were treated, antioxidant emulsions effectively seeped into the seeds and low levels of these chemicals were detected during the assay. Residues of PP in seeds were lower (62%) than the other antioxidants. Although the doses used were higher than those approved for food-grade antioxidants in stored peanuts, the residue levels in seeds (32.8–0.02 μg g⁻¹) did not exceed the maximum residue limits during the storage period.     

Selective determination of copper and iron in various food samples by the solid phase extraction

The solid phase extraction method developed using N-benzoyl-N-phenylhydroxylamine as a chelating reagent and Amberlite XAD-1180 as an adsorbent was used for the determination of Cu(II) and Fe(III) in various food samples by flame atomic absorption spectrometry. The samples were digested by using nitric acid and hydrogen peroxide. The Cu concentrations ranged from 1.01 to 5.81 μg g⁻¹ in cereals, from 0.40 to 9.67 μg g⁻¹ in vegetable and fruits and from 0.37 to 0.70 μg g⁻¹ in infusions while the Fe concentrations ranged from 7.48 to 34.3 μg g⁻¹ in cereals, from 5.74 to 260 μg g⁻¹ in vegetable and fruits, from 1.63 to 5.12 μg g⁻¹ in infusions and from 0.24 to 1.56 mg L⁻¹ in beverage samples. The Cu and Fe concentrations found were compared with the results obtained from the other food studies in the world.     

Non-chromatographic speciation of inorganic arsenic in mushrooms by hydride generation atomic fluorescence spectrometry

A non-chromatographic speciation method has been developed for the determination of inorganic arsenic in cultivated and wild mushroom samples from different origins. The ultrasound-assisted extraction of the toxic arsenic species As (III) and As (V) was performed for 10 min with 1 mol l⁻¹ H₃PO₄ and 0.1% (m/v) Triton X-100. After phase separation the residue was washed with 0.1% (w/v) EDTA and centrifuged. As (III) and As (V) were determined by hydride generation atomic fluorescence spectrometry. Speciation was made using proportional equations corresponding to two different measurement conditions, (i) directly feeding sample extracts diluted with HCl and (ii) after reduction with KI and ascorbic acid for 30 min. The limits of detection of the method were 6.3 and 5.0 ng g⁻¹ for As (III) and As (V), respectively. Recovery percentages varied between 91% and 108% for As (III) and from 90% to 109% for As (V) indicating that As species interconversion was avoided. As (III) concentrations from 264 to 81 μg g⁻¹ and As (V) concentrations from 246 to 59 μg g⁻¹ were found in Spanish cultivated mushrooms. For Chinese wild mushrooms As (III) varied between 624 and 117 μg g⁻¹ and As (V) from 380 to less than 5 μg g⁻¹. The accuracy of the method was checked by the determination of total As (from the sum of As (III) and As (V)) in a tomato leaves reference sample, with good agreement with the certified value.     

Effect of foliar application of selenium on its uptake and speciation in carrot

Carrot (Daucus carota) shoots were enriched by selenium using foliar application. Solutions of sodium selenite or sodium selenate at 10 and 100 μg Se ml⁻¹, were sprayed on the carrot leaves and the selenium content and uptake rate of selenium were estimated by ICP–MS analysis. Anion and cation exchange HPLC were tailored to and applied for the separation of selenium species in proteolytic extracts of the biological tissues using detection by ICP–MS or ESI–MS/MS. Foliar application of solutions of selenite or selenate at 100 μg Se ml⁻¹ resulted in a selenium concentration of up to 2 μg Se g⁻¹ (dry mass) in the carrot root whereas the selenium concentration in the controls was below the limit of detection at 0.045 μg Se g⁻¹ (dry mass). Selenate-enriched carrot leaves accumulated as much as 80 μg Se g⁻¹ (dry mass), while the selenite-enriched leaves contained approximately 50 μg Se g⁻¹ (dry mass). The speciation analyses showed that inorganic selenium was present in both roots and leaves. The predominant metabolised organic forms of selenium in the roots were selenomethionine and γ-glutamyl-selenomethyl-selenocysteine, regardless of which of the inorganic species were used for foliar application. Only selenomethionine was detected in the carrot leaves. The identity of selenomethionine contained in carrot roots and leaves was successfully confirmed by HPLC–ESI–MS/MS.     

Solid phase extraction with flame atomic absorption spectrometry for determination of traces of Ca,K, Mg and Na in quality control of white sugar

A fast and straightforward pre-concentration procedure based on solid phase extraction with a strongly acidic cation-exchanger Dowex 50 W × 8–400 was proposed to determine traces of Ca, K, Mg and Na in white sugar samples by means of flame atomic absorption spectrometry. For this purpose, 20% (m/v) white sugar solutions (100 ml) were driven through resin beds at 10 ml min⁻¹ to retain Ca, K, Mg and Na ions and to separate sucrose that passed through unretained. Thereafter, columns were rinsed with water and elements of interest were recovered prior to measurements using 5 ml of a 2 mol l⁻¹ HCl solution. Detection limits of 0.04, 0.05, 0.02 and 0.01 μg g⁻¹ for Ca, K, Mg and Na, respectively, and precision of measurements within 1–3% were achieved. The proposed method enabled to determine Ca, K, Mg and Na in samples of white sugar within corresponding ranges: 0.66–0.99 μg g⁻¹ (Ca), 2.9–12.2 μg g⁻¹ (K), 0.53–1.57 μg g⁻¹ (Mg) and 0.06–0.30 μg g⁻¹ (Na). Accuracy of this sample pre-treatment procedure and analysis method was assessed by performing spikes and recovery experiments. Recoveries of added Ca, K, Mg and Na were found to be within 97–102%, demonstrating good reliability of results.     

Trace element levels in honeys from different regions of Turkey

A survey of 25 honey samples from different botanical origin, collected all over the Turkey was conducted to assess their trace element contents. The aim of this study was to determine the levels of cadmium (Cd), lead (Pb), iron (Fe), manganese (Mn), copper (Cu), nickel (Ni), chromium (Cr), zinc (Zn), aluminium (Al) and selenium (Se) in honey samples from different regions of Turkey. Trace element contents were determined by a flame and graphite furnace atomic absorption spectrometry technique after dry-ashing, microwave digestion and wet-digestion. The accuracy of the method was corrected by the standard reference material, NIST-SRM 1515 Apple leaves. The contents of trace elements in honey samples were in the range of 0.23–2.41 μg g⁻¹, 0.32–4.56 μg g⁻¹, 1.1–12.7 μg g⁻¹, 1.8–10.2 μg g⁻¹, 8.4–105.8 μg kg⁻¹, 2.6–29.9 μg kg⁻¹, 2.4–37.9 μg kg⁻¹, 0.9–17.9 μg kg⁻¹, 83–325 μg kg⁻¹ and 38–113 μg kg⁻¹ for Cu, Mn, Zn, Fe, Pb, Ni, Cr, Cd, Al and Se, respectively. Iron was the most abundant element while cadmium was the lowest element in the Turkish honeys surveyed. The results showed that trace element concentrations in the honeys from different regions were generally correlated with the degree of trace element contamination of the environment.     

Analysis of potential adulteration in herbal medicines and dietary supplements for the weight control by capillary electrophoresis

Four different phytopharmaceutical dosage forms for use in weight control programs were analyzed. Two different ground herbal blends and their correspondent infusions, a capsule and a tincture were investigated for the presence of compounds used as adulterants in these products. A capillary electrophoresis (CE) method was developed and validated. The optimized experimental conditions were: BGE, sodium tetraborate buffer 20 mM, pH 9.2, voltage applied 30 kV, capillary temperature 25 °C, injection sample at 0.5 Psi during 5 s. Ephedrine, norephedrine, caffeine and furosemide were baseline separated in less than 7 min; the migration times were found to be 2.65, 2.90, 3.75 and 6.58 min, respectively. The analysis showed in sample 3 concentrations of 0.45 ± 0.03 mg g⁻¹ (ephedrine), 0.33 ± 0.02 mg g⁻¹ (norephedrine), 1.09 ± 0.41 mg g⁻¹ (caffeine) and 0.80 ± 0.17 mg g⁻¹ (furosemide). Caffeine content in samples 1, 2 and 4 was 0.61 ± 0.06 mg g⁻¹, 15.66 ± 1.05 mg g⁻¹ and 2.27 ± 0.13 mg ml⁻¹, respectively. Linearity was obtained in the concentration range of 1–1000 μg ml⁻¹. Limits of detection (LOD) and quantification (LOQ) were determined as 0.42 μg ml⁻¹ and 1.40 μg ml⁻¹ (ephedrine), 0.47 μg ml⁻¹ and 1.40 μg ml⁻¹ (norephedrine), 0.12 μg ml⁻¹ and 0.48 μg ml⁻¹ (caffeine), 0.22 μg ml⁻¹ and 0.73 μg ml⁻¹ (furosemide).     

Comparison of sterol composition between Tuber fermentation mycelia and natural fruiting bodies

Truffle, belonging to Tuber genera, is a nutritious and sterol-rich edible fungus, and sterol is a potential health beneficial compound. A comparison of Tuber sterol composition indicates that the total sterol contents in the fermentation mycelia (i.e., 10.5 mg g⁻¹) (n = 3) were approximately 3.2-5.6 times higher than that of the fruiting bodies (p < 0.05) with the addition of soybean flour into the basal fermentation media. Moreover, the phytosterol profile of fermentation mycelia could be significantly improved by adding soybean flour into the fermentation media. After the addition of soybean flour, stigmasterol and β-sitosterol appeared in the fermentation mycelia and the contents of total phytosterols (2279 μg g⁻¹) (n = 3), brassicasterol (943 μg g⁻¹) (n = 3), and campesterol (418 μg g⁻¹) (n = 3) were all increased significantly (p < 0.05). Moreover, the total contents of sterols and phytosterols in the fermentation mycelia cultured in the soybean media were much higher than those in the fruiting bodies (i.e., 1883-3240 and 479-1832 μg g⁻¹, respectively) (n = 3, p < 0.05). This work confirms the potentiality of Tuber fermentation mycelia as the alternative resource for its fruiting bodies from the viewpoint of sterols production.     

α-Tocopherol stereoisomers in beef as an indicator of vitamin E supplementation in cattle diets

These studies investigated the potential application of analysis of stereoisomers of α-tocopherol to discriminate between beef from animals raised at pasture or fed concentrates containing synthetic vitamin E. Muscle α-tocopherol levels were affected (P < 0.05) by diet with mean values of 2.63, 1.14, 2.43 and 1.77 μg g⁻¹ muscle for beef from animals receiving pasture only (P), a barley-based concentrate with synthetic vitamin E (C), winter silage followed by summer pasture (SiP) and winter silage followed by summer pasture with concentrate (SiPC), respectively. Stereoisomeric analysis of α-tocopherol permitted discrimination between beef from the P/SiP, C and SiPC animals. In a comparison of Irish and non-Irish beef, Brazilian beef had higher (P < 0.05) α-tocopherol (8.13 μg g⁻¹) than beef from Austria, England, France, Germany, the U.S. and Ireland (mean 2.51 μg g⁻¹). Stereoisomeric analysis of α-tocopherol in non-Irish beef revealed supplementation with synthetic vitamin E in all samples, including the samples marketed as pasture-fed beef.     

Simultaneous multi-channel hydride generation atomic fluorescence spectrometry determination of arsenic,bismuth, tellurium and selenium in tea leaves

A novel, rapid and sensitive method for the simultaneous multi-channel hydride generation atomic fluorescence spectrometry (HG-AFS) determination of total arsenic (As), total bismuth (Bi), total tellurium (Te) and total selenium (Se) in tea leaves was proposed. The operating parameters of self-made multi-channel HG-AFS were optimised, including negative high voltage of photo multiplier tube (PMT), the flow rates of carrier and shield gas, observation height and lamp currents. The conditions of hydride generation for As, Bi, Te and Se were studied in details. Under optimal conditions, the method detection limits (MDL) for As, Bi, Te and Se in tea leaves were 0.0152 μg g⁻¹, 0.0080 μg g⁻¹, 0.0022 μg g⁻¹ and 0.0068 μg g⁻¹, respectively. The proposed method was successfully applied to the simultaneous determination of As, Bi, Te and Se in various tea leaves and the spike recoveries were in the range of 90–103%. The accuracy of method was validated by analysing a tea certified reference material. The obtained values were consistent with the certified ones.     

Determination of diquat and paraquat in olive oil by ion-pair liquid chromatography–electrospray ionization mass spectrometry (MRM)

For the first time a method for determination of herbicides diquat (DQ) and paraquat (PQ) in olive oil was developed utilising liquid chromatography–electrospray ionization mass spectrometry (MRM). n-Hexane/10 mM HFBA aqueous solution partitioning was used as the extraction method. Separation was carried out in an Xterra C8 column (100 × 21 mm, 3 μm), using the gradient mode. Solvent A was a HFBA aqueous solution (5 mM, pH 2) and solvent B acetonitrile/methanol 75/25 (v/v). Peaks used for quantification were m/z = 157 (diquat) and m/z = 158 (paraquat). Detection limit found for both diquat and paraquat was 4 μg kg⁻¹. The method can also be applied for determination of chlormequat (CQ, quantification peak m/z = 58), the detection limit being 0.3 μg kg⁻¹. Such limits are clearly lower than the MCLs commonly applied to olive oil as reference criteria (5 times MCLs in olives). Good reproducibilities (day to day and run to run) were obtained.     

Nutrient contents of kale (Brassica oleraceae L. var. acephala DC.)

Fructose, glucose and sucrose, as the major soluble sugars and citric and malic acids, as the major organic acids, were identified and determined in kale (Brassica oleraceae L. var. acephala DC., black cabbage) leaves. Fructose was the predominant sugar (2011 mg 100 g⁻¹ dry wt) identified, followed by glucose (1056 mg 100 g⁻¹ dry wt) and sucrose (894 mg 100 g⁻¹ dry wt). The contents of citric and malic acids were at 2213 and 151 mg 100 g⁻¹ dry wt in the leaves. The 16:0, 18:2n − 6 and 18:3n − 3 fatty acids were the most abundant fatty acids in the leaves. Considering the level of these fatty acids, 18:3n − 3 was found to be the highest (85.3 μg g⁻¹ dry wt), contributing 54.0% of the total fatty acid content. Linoleic acid (18:2n − 6), being the second most abundant fatty acid was present at 18.6 μg g⁻¹ dry wt, contributing 11.8% of the total fatty acid content. In the seed oil of kale, 22:1n − 9 was the most abundant fatty acid (4198 μg g⁻¹ dry wt, 45.7%), with 18:2n − 6 (1199 μg g⁻¹ dry wt, 12.3%) and 18:1n − 9 (1408 μg g⁻¹ dry wt, 14.8%) being the second next most abundant fatty acids. The most abundant amino acid was glutamic acid (Glu) which was present at 33.2 mg g⁻¹ dry wt. Aspartic acid, which was the second most abundant amino acid, was present at 27.6 mg g⁻¹ dry wt and accounted for 10.2% of the total amino acid content of kale leaf. The amino acid content was assessed by comparing the percentages of the essential amino acids in kale leaf versus those of a World Health Organization (WHO) standard protein. The protein of kale leaf compares well with that of the WHO standard. Only one amino acid, lysine, had a score that fell below 100%; the lysine score of kale leaf was 95%. This study attempts to contribute to knowledge of the nutritional properties of the plant. These results may be useful for the evaluation of dietary information.     

Determination of lead and cadmium in food samples by the coprecipitation method

In this study, the coprecipitation method developed using a combination of 2-mercaptobenzothiazole (MBT) as a chelating reagent and copper as coprecipitate carrier was used for the determination of trace lead and cadmium in various food samples by graphite furnace atomic absorption spectrometry (GFAAS). The method was applied for the determination of Pb(II) and Cd(II) in salami, sausage, chicken, anchovy, spinach, cabbage, onion, dill, parsley, lettuce, tea and rice samples. The matrix modifiers were added as 50 μg NH₄H₂PO₄ + 3 μg Mg(NO₃)₂ for both Pb(II) and Cd(II). The signals were measured as peak area. The concentrations of Pb(II) and Cd(II) in the food samples were found to be in the range of 6.63 ng g⁻¹ (anchovy) −3.30 μg g⁻¹ (spinach) and 2.67 ng g⁻¹ (salami) −0.51 μg g⁻¹ (lettuce), respectively.     

Effect of phosphorus on the fruit yield and food value of two landraces of Trichosanthes cucumerina L.- Cucurbitaceae

Studies were conducted in the early season of 2002 and 2003 at the Teaching and Research Farm, Obafemi Awolowo University, Ile-Ife, Nigeria to evaluate the effect of phosphorus (P) on fruit yield and chemical composition of two landraces of Trichosanthes cucumerina L. For the purpose of the study, two landraces of T. cucumerina named Landrace I and Landrace II were used. The five levels of phosphorus evaluated were 0, 30, 60, 90 and 120 kg P₂O₅ ha⁻¹ using single super phosphate fertilizer (8% P). Statistical analysis showed that 90 kg P₂O₅ ha⁻¹ gave statistically significant higher fruit yield (16.4 tons ha⁻¹) compared to other P levels. The fruit yield of the two Landraces did not differ significantly. Except for crude protein content, the 90 kg P₂O₅ ha⁻¹ produced significantly higher ether extract (1.22 g 100 g⁻¹), crude fibre (1.93 g 100 g⁻¹), moisture content (90.5 g 100 g⁻¹), ash (0.90 g 100 g⁻¹), total sugars (0.81 g 100 g⁻¹) and ascorbic acid (28.7 mg 100 g⁻¹) than other P levels. The essential amino acids compositions were also significantly higher at 90 g 100 g⁻¹ compared to other lower P levels. Landrace I had significantly higher ether extract (0.90 g 100 g⁻¹) content than Landrace II (0.62 g 100 g⁻¹) while Landrace II in turn had significantly higher total sugar (0.76 g 100 g⁻¹) compared to Landrace I (0.61 g 100 g⁻¹). The essential amino acids composition is high and the oxalate composition is low. The high ascorbic acid and amino acid content together with a low oxalate composition suggested a strong basis for encouraging the cultivation of this indigenous fruit vegetable to augment nutrient requirement, improve diet and consequently alleviate poverty, preserve the biodiversity and increase the gene bank of neglected wild species of high quality nutrient sources.     

Synthesis and application of a new functionalized resin for use in an on-line,solid phase extraction system for the determination of trace elements in waters and reference cereal materials by flame atomic absorption spectrometry

The synthesis and characterization of the resin Amberlite XAD-4 functionalized with 2,6-pyridinedicarboxaldehyde and its application in an on-line system for the preconcentration of cadmium, cobalt, copper, lead and manganese prior to determination using flame atomic absorption spectrometry (FAAS) is proposed. Metal ions retained on the modified resin were eluted using 1.0 mol L⁻¹ HNO₃ solution and aspirated directly to the nebulizer–burner system of a FAAS instrument using a flow injection system. Detection limits (3σ) were determined to be 0.13 μg L⁻¹ for Cd, 0.29 μg L⁻¹ for Cu, 0.23 μg L⁻¹ for Mn, 0.58 μg L⁻¹ for Co and 2.19 μg L⁻¹ for Pb using a 10 mL of water sample loading volume. The limits of detection would be 100 times higher with units of μg kg⁻¹ for the solid samples in which their dilution ratios as (volume/weight) were 100. Enrichment factors ranged from 23.6 to 28.9 (for Co and Mn, respectively). The proposed method was successfully applied to determination of the analytes in natural water samples and certified reference materials.     

Effect of modifiers for As,Cu and Pb determinations in sugar-cane spirits by GF AAS

Palladium plus magnesium nitrates with and without Ir, Ru and W were evaluated for the simultaneous determination of As, Cu and Pb in cachaça by graphite furnace atomic absorption spectrometry. For 20 μL of sample, 5 μL Pd(NO₃)₂ and 3 μL Mg(NO₃)₂ dispensed together onto the Ir-coated platform of the THGA, analytical curves in the 0–30.0 μg L⁻¹ As, 0–1.50 mg L⁻¹ Cu and 0–60.0 μg L⁻¹ Pb were built up and typical linear correlation coefficients were always better than 0.999. The limit of detection was 1.30 μg L⁻¹ As, 140 μg L⁻¹ Cu and 0.90 μg L⁻¹ Pb. As, Cu and Pb contents in 10 cachaça samples agreed with those obtained by ICP-MS. Recoveries of spiked samples varied from 96% to 106% (As), 97% to 112% (Cu) and 92% to 108% (Pb). The relative standard deviation (n = 12) was typically 2.7%, 3.3% and 1.9%.     

Production and analysis of ochratoxin A produced by Aspergillus ochraceus ITEM 5137 in submerged culture

A rapid simple and economical method was described for the determination of ochratoxin A produced by Aspergillusochraceus ITEM 5117 grown in a biofermenter in submerged culture. The ochratoxin A was determinate with RP-HPLC-FLD (reverse phase high performance liquid chromatography) with direct injection in the HPLC apparatus using a C18 column. The mycotoxin was completely resolved by using the mixture acetonitrile, water and acetic acid (49:49:2 v/v) as the mobile phase with a flow rate of 1.0 mL/min. Mean recoveries of ochratoxin A ranged from 95.36% to 103.15%. The limit of detection for ochratoxin A in medium was found to be 1 μg L⁻¹.     

Determination of phthalate esters in wine using solid-phase extraction and gas chromatography–mass spectrometry

A method for the determination of six phthalate esters in wine samples has been developed. The phthalates were extracted from wine samples with an optimised solid-phase extraction method on C18 column and quantification was achieved via gas chromatography coupled with a mass spectrometer. The method was linear between 0.015 and 5.000 μg mL⁻¹ for DMP, DEP and DEHP and between 0.018 and 5.000 μg mL⁻¹ for iBP, DBP and BBP. The LOQs of DMP, DEP and DEH were 0.024 μg mL⁻¹ while those of iBP, DBP and BBP were 0.029 μg mL⁻¹. The intra-day method repeatability was between 10% and 15% RSD, whereas the inter-day method repeatability was between 13% and 21% RSD. A survey was performed on white and red wines (n = 62) from the market, winemakers and an experimental pilot plant. All the analysed samples were phthalate contaminated. Commercial wine showed higher detection frequency and level of total phthalate, DBP and BBP than those produced in a pilot plant. iBP and DEHP concentrations were similar in all the groups of samples. iBP concentration was higher in red wines than in white ones.     

Effects of skin and grilling method on formation of heterocyclic amines in chicken pectoralis superficialis muscle

Mutagenic heterocyclic amines (HAs) originate in processed proteinaceous foods. The effects of the presence of skin (with vs. without) and of grilling method (two plate vs. infrared) on the content of HAs in grilled chicken pectoralis superficialis muscle (temperature, 220 °C) were investigated. HA precursors (creatine, creatinine, free amino acids and carbohydrates) and HAs of these raw and grilled breast muscles were determined. The muscles originated from 24 birds of either sex (provenance Ross; aged 40-45 days). The HA content was determined in homogenates of the upper and lower surface slices of the grilled muscles (T_i = 82 °C). A higher content of total free amino acids was seen for the muscle (27.1 mmol kg⁻¹ raw meat) than for the skin (21.7 mmol kg⁻¹ raw meat). The creatine, creatinine and carbohydrate levels in the skin were below the limits of detection. The contents of creatine (31.8-38.7 mmol kg⁻¹) and creatinine (0.24-0.33 mmol kg⁻¹) in the breast muscle were determined. Relatively high levels were seen for glucose (23 mmol kg⁻¹ raw meat) and fructose (10 mmol kg⁻¹ raw meat) in the muscle, with other sugars present at low levels (<2 mmol kg⁻¹ raw meat). For the chicken muscle grilled on a two-plate grill, the contents of total HAs (PhIP, MeIQx, DiMeIQx, Harman and Norharman) were lower with the skin in place than in the muscle grilled without the skin (3.5 μg kg⁻¹vs. 4.8 μg kg⁻¹). Also, during infrared grilling with the skin, lower amounts of HAs were formed than with grilling on the two-plate grill (2.4 μg kg⁻¹vs. 3.5 μg kg⁻¹). On average, the infrared-grilled samples with skin contained 3-fold more total HAs than similar samples without the skin (2.4 μg kg⁻¹vs. 0.8 μg kg⁻¹), with the highest levels seen for PhIP and MeIQx.