Nitrate-N determination in leafy vegetables: Study of the effects of cooking and freezing

Nitrate upon reduction to nitrite can cause methaemoglobinaemia or act as precursor in the endogenous formation of carcinogenic nitrosamines. The leafy vegetables are the major vehicle for the entry of nitrate into the human system. The present study was conducted to establish a flow injection analysis (FIA) technique to investigate the nitrate-N contents of four commonly consumed fresh leafy vegetables (Chinese cabbage, celery, lettuce and English cabbage) from market in Fiji. Two extraction techniques (activated carbon and alkaline extraction) were assessed to extract nitrate-N and the activated carbon extraction was preferred over alkaline extraction and applied. The recoveries of spiked nitrate-N in vegetable matrices ranged from 90.40% to 112.80% in activated carbon extraction with an average of 100.62%. The effects of cooking (boiling, baking and frying) and deep-freezing on the nitrate-N contents were also studied. Nitrate contents in selected leafy vegetables were determined by FIA coupled with Greiss protocol involving sulfanilamide and N-(1-naphthyl)ethylenediamine dihydrochloride as color reagents. Nitrate was determined in the linear range from 1.0 to 20.0 mg L⁻¹ with the method detection limit of 0.042 mg L⁻¹ (0.34 mg kg⁻¹). The results of the study show that nitrate contents in fresh leafy vegetables ranged from 1297 to 5658 mg kg⁻¹. Boiling reduces nitrate content by 47–56% whereas frying in Soya bean oil elevates nitrate content by as much as 159–307%. No significant change was observed in nitrate content after baking. The deep-freezing of the selected leafy vegetables shows that nitrate-N content fluctuates slightly from the original nitrate-N values over the seven day period. The FIA throughput was 38 samples h⁻¹.     

Flow injection assessment of nitrate contents in fresh and cooked fruits and vegetables grown in Fiji

Nitrates form part of the essential chemistry of soils and plants. Thus, plant roots are able to absorb nitrate directly from the soil. It has been discovered that human nitrate intake is mainly from vegetables. Vegetables play an important role in human nutrition since they are an outstanding source for vitamins, minerals, and biologically active compounds. In risk assessment of nitrate contents, this study reports the nitrate levels of 8 commonly consumed fruits and vegetables grown in Fiji, tomato (Lycopersicon esculentum), eggplant (Solanum melongena), capsicum (Capsicum annuum var. grossum), breadfruit (Artocarpus altilis), long bean (Vigna sesquipedalis), jackfruit (A. heterophyllus), pumpkin (Cucurbita pepo), and cucumber (Cucumis sativus). The effects of different types of cooking methods, baking, boiling, and frying, have also been studied. The validated flow injection analysis technique has been used to quantify the nitrate-N levels in the chosen products following nitrate extraction using the activated carbon technique. The mean values of nitrate levels in fresh products ranged from 25.83 to 281.02 mg NO(3) (-) kg(-1) . The study shows that boiling reduced nitrate contents by 65.37% to 25.25%. The frying in soy bean oil elevated nitrate contents from 354.79% to 86.69%, but after baking, nitrate contents remained almost constant with slight increasing trend in the case of tomato (19.97%). The nitrate levels published in the literature for the same types of fruits and vegetables studied have also been reviewed and compared. The average nitrate-N values were comparable or lower than overseas data, but did not present unpredictably high values, that is, they were below the risk level.     

Flavonols (kaempeferol,quercetin, myricetin) contents of selected fruits,vegetables and medicinal plants

The concentrations of flavonols (kaempeferol, quercetin, myricetin) were determined in 22 plant materials (9 vegetables, 5 fruits, and 8 medicinal plant organs). The materials were extracted with acidified methanol (methanol/HCl, 100:1, v/v) and analyzed by reverse phase high-performance liquid chromatographic (RP-HPLC) with UV detection. The total flavonols contents varied significantly (P < 0.05) among vegetables, fruits and medicinal plant organs ranged from 0 to 1720.5, 459.9 to 3575.4, and 2.42 to 6125.6 mg kg⁻¹ of dry matter, respectively. Among vegetables, spinach and cauliflower exhibited the highest amounts of flavonols (1720.5 and 1603.9 mg kg⁻¹, respectively), however, no flavonols were detected in garlic. Within fruits, highest level of flavonols was observed in strawberry (3575.4 mg kg⁻¹), whereas, the lowest in apple fruit (459.9 mg kg⁻¹). Of the medicinal plant organs, moringa and aloe vera leaves contained the highest contents of flavonols (6125.6 and 1636.04 mg kg⁻¹), respectively, whereas, lowest was present in barks (2.42–274.07 mg kg⁻¹). Overall, leafy green vegetables, soft fruits and medicinal plant leaves exhibited higher levels of flavonols.     

Metal content determination in four fish species from the Adriatic Sea

Concentrations of As, Cd, Cu, Hg and Pb were measured by atomic absorption spectrometry (AAS) in muscle tissues of four fish species: anchovy (Engraulis encrasicholus), mackerel (Scomber japonicus), red mullet (Mullus surmuletus) and picarel (Spicara smaris) from the Croatian waters of the Adriatic Sea during 2008 and 2009. Metal levels measured in anchovy were in the following ranges (mg kg⁻¹): As 0.01–54.8, Cd 0.001–0.02, Cu 0.001–6.29, Hg 0.001–0.52 and Pb 0.001–0.34 mg kg⁻¹. Metal ranges in red mullet were (mg kg⁻¹): As 0.01–70.9, Cd 0.002–0.85, Cu 0.001–57.3, Hg 0.001–2.07 and Pb 0.001–0.27 mg kg⁻¹. Metal level ranges measured in mackerel were (mg kg⁻¹): As 0.01–36.4, Cd 0.001–0.1, Cu 0.001–15.9, Hg 0.001–0.78 and Pb 0.002–0.24 mg kg⁻¹. In picarel, metal level ranges were (mg kg⁻¹): As 0.01–54.6, Cd 0.001–0.1, Cu 0.08–32.9, Hg 0.001–0.207 and Pb 0.001–0.46 mg kg⁻¹. Significant differences in metal concentrations were found among fish species. The results presented on metal contents in the examined species give an indication of the environmental conditions. Concentrations of Cd, Cu, Hg and Pb obtained were far below the established values by the European Community regulations. However, arsenic levels found in red mullet were higher than the recommended legal limits for human consumption and as such may present a human health issue.     

Trace element content of Boletus tomentipes mushroom collected from Yunnan,China

The contents of As, Cd, Cr, Cu, Fe, Hg, Mg, Mn, Ni, Pb, and Zn in eleven fruiting bodies of Boletus tomentipes were determined. The results showed the values of the studied elements decreased in the order: Mg (208–279 mg kg⁻¹) > Fe (106–137 mg kg⁻¹) > Mn (29.5–46.8. mg kg⁻¹) > Zn (18.7–23.1 mg kg⁻¹), > Cu (11.4–15.8 mg kg⁻¹) > Cr (3.36–4.78 mg kg⁻¹) > Pb (1.38–3.88 mg kg⁻¹) > Ni (1.68–3.01 mg kg⁻¹) > Cd (0.16–0.32 mg kg⁻¹) > As (0.10–0.24 mg kg⁻¹) > Hg (<0.06 mg kg⁻¹).     

HPLC–MS identification and quantification of flavonol glycosides in 28 wild and cultivated berry species

Berries and red fruits are rich dietary sources of polyphenols with reported health benefits. More than 50 different flavonols (glycosides of quercetin, myricetin, kaempferol, isorhamnetin, syringetin and laricitrin) have been detected and quantified with HPLC–MSⁿ in fruits of blueberry, bilberry, cranberry, lingonberry, eastern shadbush, Japanese wineberry, black mulberry, chokeberry, red, black and white currants, jostaberry, red and white gooseberry, hardy kiwifruit, goji berry, rowan, dog rose, Chinese and midland hawthorn, wild and cultivated species of blackberry, raspberry, strawberry and elderberry. The phenolic constituents and contents varied considerably among the analyzed berry species. Elderberry contained the highest amount of total flavonols (450–568 mg kg⁻¹ FW), followed by berry species, containing more than 200 mg kg⁻¹ FW of total: chokeberry (267 mg kg⁻¹), eastern shadbush (261 mg kg⁻¹), wild grown blackberry (260 mg kg⁻¹), rowanberry (232 mg kg⁻¹), american cranberry (213 mg kg⁻¹) and blackcurrants (204 mg kg⁻¹). Strawberry (10.5 mg kg⁻¹) and white currants (4.5 mg kg⁻¹) contained the lowest amount of total flavonols. Quercetins represent the highest percentage (46–100%) among flavonols in most analyzed berries. In wild strawberry and gooseberry the prevailing flavonols belong to the group of isorhamnetins (50–62%) and kaempferols, which represent the major part of flavonols in currants (49–66%). Myricetin glycosides could only be detected in chokeberry, rowanberry and species from the Grossulariaceae, and Adoxaceae family and Vaccinium genus. Wild strawberry and blackberry contained from 3- to 5-fold higher total flavonols than the cultivated one.     

Principal phenolic phytochemicals and antioxidant activities of three Chinese medicinal plants

The principal antioxidant components and content of cinnamon (Cinnamomum cassia), turmeric (Curcuma longa) and golden thread (Coptidis rhizoma) extracts were determined using high performance liquid chromatography (HPLC) with UV detection. In general, C. cassia, C. longa and C. rhizoma extracts from domestic Taiwan were rich in cinnamaldehyde, curcumin, and berberin, respectively. The contents of cinnamaldehyde, curcumin, and berberin in the acetone extracts were 1911, 2029, and 840 mg l⁻¹, respectively. The Folin–Ciocalteu method was used to measure the total phenolic concentrations of extracts, which had the content of 9.6 (C. cassia), 2.6 (C. longa), and 4.3 (C. rhizoma) mM l⁻¹. In addition, DPPH radical-scavenging, ferric-reducing antioxidant power (FRAP), and ferric thiocyanate (FTC) assays were employed to measure antioxidant activities. The C. cassia fresh extracts had higher antioxidant activities which were 84–90% (DPPH), 17–33 μmol l⁻¹ (FRAP), and 53–82% (FTC). The activities of C. longa fresh extracts were 22–44% (DPPH), 7–11 μmol l⁻¹ (FRAP), and 53–81% (FTC) while C. rhizoma were 53–64% (DPPH), 18–26 μmol l⁻¹ (FRAP), and 59–82% (FTC).     

Determination of minor carbohydrates in carrot (Daucus carota L.) by GC–MS

Minor carbohydrates present in carrot (Daucus carota L.) have been studied by GC–MS analysis of their trimethylsilyl derivatives because of their remarkable role in a variety of biological functions. Scyllo-inositol and sedoheptulose (d-altro-2-heptulose), identified for the first time in this paper were present in all the carrots analysed in concentrations ranging 1.5–5.8 and 1.4–24.6 mg g⁻¹ dried weight, respectively. Other minor carbohydrates detected in carrot were myo- inositol (2.2–9.8 mg g⁻¹) and mannitol (traces-1.3 mg g⁻¹). Whereas small amounts (close to 2 mg g⁻¹) of scyllo-inositol were experimentally determined in other vegetables from the Apiaceae family (parsley, coriander and fennel), sedoheptulose was only detected at trace levels.     

Contents of biologically active polyamines in chicken meat,liver, heart and skin after slaughter and their changes during meat storage and cooking

Dietary polyamines, putrescine, spermidine (SPD) and spermine (SPM), participate in an array of important physiological roles, including tumour growth. Thus, reliable information on polyamine content in foods has been needed. We therefore determined polyamine contents in chilled chicken meat and giblets (n = 20) and skin (n = 10) 24 h after slaughter. The polyamines were determined, after extraction with perchloric acid, as dansyl derivatives, using an HPLC method. Mean SPD values were 4.8, 10.2, 11.4, 48.7 and 12.1 mg kg⁻¹ and SPM values were 36.8, 38.0, 24.3, 133 and 82.7 mg kg⁻¹ in breast, thigh, skin, liver and heart, respectively. Significant statistical correlations between SPD and SPM contents were observed in breast, thigh, skin and liver, whereas correlations were insignificant in heart. An increase of SPD and SPM was apparent in breasts and thighs stored at −18 °C for 6 months; however, it was significant only for SPM in thighs. The losses of both SPD and SPM were statistically insignificant during storage of aerobically packaged breasts up to 9 days at +2 °C. A significant decrease of SPM to about 60% of the initial contents was observed in both vacuum-packaged and in modified atmosphere (20% CO₂ and 80% O₂)-stored breasts on day 21 at +2 °C. For both SPD and SPM, roasting, grilling and frying of fresh breasts caused losses of about 40–60% of the initial contents (higher than boiling and stewing). Similarly, losses of SPM, due to roasting of breasts frozen for 3 or 6 months, were higher than those caused by stewing. Putrescine was detected only sporadically and at levels close to the detection limit of 1.0 mg kg⁻¹ (fresh matter).     

Chemical composition of cultivated seaweed Ulva clathrata (Roth) C. Agardh

Samples of cultivated Ulva clathrata were collected from a medium scale system (MSS, 1.5 × 1.5 m tank), or from a large scale system (LSS, 0.8 ha earthen pond). MSS samples were dried directly while the LSS sample was washed in freshwater and pressed before drying. Crude protein content ranged 20–26%, essential amino acids accounting for 32–36% of crude protein. The main analysed monosaccharides were rhamnose (36–40%), uronic acids (27–29%), xylose (10–13%) and glucose (10–16%). Some notable variations between MSS and LSS samples were observed for total dietary fibre (26% vs 41%), saturated fatty acids (31% vs 51%), PUFAS (33% vs 13%), carotenoids (358 vs 169 mg kg⁻¹ dw) and for Ca (9 vs 19 g kg⁻¹), Fe (0.6 vs 4.2 g kg⁻¹), Cu (44 vs 14 mg kg⁻¹), Zn (93 vs 17 mg kg⁻¹) and As (2 vs 9 mg kg⁻¹). The chemical composition of U. clathrata indicates that it has a good potential for its use in human and animal food.     

Elemental composition of cephalopods from Portuguese continental waters

Essential and contaminant elements concentrations were determined in the muscle tissue of octopus (Octopus vulgaris), squid (Loligo vulgaris) and cuttlefish (Sepia officinalis), caught off the Portuguese coast in 2004–2005. As expected, the largest concentrations found correspond to Cl, S, K, Na, P and Mg (average values between 629 mg (100 g)⁻¹, for Cl, and 435 mg kg⁻¹, for Mg, in octopus and squid, respectively). Above average concentrations of Zn, Cu, Fe and Sr were also found. The highest total Hg concentration was found in cuttlefish (0.36 mg kg⁻¹); however, this value did not exceed the recommended limit proposed by EU (0.5 mg kg⁻¹). Lead levels observed in all samples were always significantly lower than the EU limit (1.0 mg kg⁻¹). Regarding Cd, the 1.0 mg kg⁻¹ limit was only exceeded in two octopus samples. It may be concluded that the cephalopods studied do not constitute cause for concern, in terms of toxic elements, and could be safely used for daily intake of essential elements. Nevertheless, the squid contribution for elemental DI is minor in comparison to the other two species.     

Fish and food safety: Determination of formaldehyde in 12 fish species by SPME extraction and GC–MS analysis

The formaldehyde (FA) content in different fish products was evaluated using a solid phase microextraction (SPME)-GC–MS method based on fiber derivatisation with pentafluorobenzyl-hydroxyl-amine hydrochloride. LOD and LOQ values of 17 and 28 μg kg⁻¹, respectively were calculated. Fish quality was assessed by the analysis of 12 species (sea-fish, freshwater-fish and crustaceans), revealing variable FA levels. Fresh, deep frozen, canned, boiled and roasted fish were analysed; cooking always produced a decrease in the analyte content. Fish belonging to the Gadidae family were the samples with the highest FA concentration (from 6.4 ± 1.2 mg kg⁻¹ to 293 ± 26 mg kg⁻¹), in four cases out of 14 exceeding the value of 60 mg kg⁻¹ proposed by the Italian Ministry of Health. Storage on ice was also investigated, showing moderate FA production also at temperature around 0 °C. FA contents lower than 22 mg kg⁻¹ were finally found in all the other samples.     

Study of flavonoids in aqueous spinach extract using positive electrospray ionisation tandem quadrupole mass spectrometry

The presence of three flavonols (quercetin, kaempferol, myricetin) and two flavones (apigenin, luteolin) were investigated in the extract of fresh spinach leaves. Aqueous spinach extracts were prepared with a leaf/water ratio of 1:2 at 80 °C for 30 min stirring. Ferric ammonium sulphate method was used for measuring total polyphenols in the extracts and expressed as catechins and tannic acid equivalents. The flavonoids glycosides in the extract were hydrolysed to their aglycons with 1.2 M HCl in boiling 50% water methanol solution. The resulting aglycons were identified and quantified by a C18 reverse phase high-performance liquid chromatography (RP-HPLC). Furthermore, the results were confirmed by HPLC coupled to an electrospray ionisation tandem triple-quadrupole mass spectrometer ESI-MS performing low-energy collision induced dissociation (CID-MS/MS) in the collision cell (HPLC-ESI-MS/MS). Analyses were made in the multiple reaction monitory (MRM) mode. Results showed that total polyphenols contents in fresh spinach leaves were 270 mg kg⁻¹ and 390 mg kg⁻¹ as tannic acid and catechin equivalents, respectively, in which, major flavonoids aglycons were apigenin (170 mg kg⁻¹), quercetin (50 mg kg⁻¹) and kaempferol (30 mg kg⁻¹).     

Comparison of the cell wall composition for flesh and skin from five different plums

Cell walls were isolated from flesh and skin of five plum varieties corresponding to three species (Prunus domestica L., Prunus salicina Lindl. and Prunus insititia Lindl.) using the alcohol-insoluble solids (AIS) procedure. Yields varied from 83 to 114 g kg⁻¹ dry weight in the flesh and from 192 to 361 g kg⁻¹ dry weight in the skins. Their main sugars were uronic acid (224–322 mg g⁻¹ AIS), cellulosic glucose (139–170 mg g⁻¹ AIS), galactose and arabinose. Galactose and arabinose ratio were variable between the varieties. The degrees of methylation were high (62–84).     

Chemical characterization of a traditional honey-based Sardinian product: Abbamele

The first chemical characterization of abbamele, a traditional honey decoction from Sardinia (Italy) is hereby reported. Water content (from 17.7% to 27.7%), electrical conductivity (from 0.19 to 0.81 mS cm⁻¹), pH (from 3.21 to 3.92), free acidity (from 26.1 to 87.6 meq kg⁻¹), invertase activity (from 0 to 1.02 U kg⁻¹), 5-(hydroxymethyl)-2-furaldehyde, HMF (from 881 to 4776 mg kg⁻¹), total polyphenols (from 188 to 984 mg kg⁻¹) and free amino acid contents of thirteen abbamele samples, from industrial and traditional producers, were obtained in an attempt to compare this traditional product with honey and to study the relationship between its main features and the production procedures. The long thermal treatment involved in the production of abbamele has been identified as the main cause of very low (or absent) invertase activity and free amino acid content as well as the very high content of HMF.     

Influence of temperature on heat transfer coefficient during moderate vacuum deep-fat frying

The objective of this study is to analyze the influence of temperature and reduced pressure on the convective heat transfer coefficient, h, during frying of products with different area/volume ratio. h was determined from surface temperature and moisture loss experimental data during frying of potato cylinders and “churros”, at different oil temperatures (100, 120 and 140 °C) and moderate vacuum (19.5–25.9 kPa). The results obtained during vacuum frying were compared with those obtained at atmospheric pressure, both for the same oil temperature (140 °C) and for the same thermal gradient (40 °C). During frying, h changes considerably, reaching a maximum between 700–1600 Wm⁻² K⁻¹ in vacuum frying and 800–2000 Wm⁻² K⁻¹ in atmospheric frying. To quantify the effect of oil temperature, pressure and size of the product on h, a parameter called “bubbling efficiency”, BE, was defined. BE relates the bubble departure radius and the area/volume ratio of the product. An equation (the derivative of the Gompertz function) was proposed to estimate the mean heat convective coefficients for each frying condition as a function of BE (R² = 0.957). The relation between h and BE shows a maximum corresponding to an optimal bubbling pattern. Most of the vacuum frying settings are outside this optimum, being affected by the insulation effect of bubbles covering the surface.     

Determination of metal contaminations in sea foods from Marmara,Aegean and Mediterranean seas: Twelve fish species

The concentrations of cadmium, cobalt, chromium, copper, iron, manganese, nickel, lead and zinc were determined by ICP-AES in muscles and livers of 12 fish species sampled from the Marmara, Aegean and Mediterranean seas of Turkey. Iron showed the highest levels in examined tissues of all fish species. Following Fe, Zn generally showed the second highest levels. Metal concentrations in edible parts of fish species were 0.02–0.37 mg kg⁻¹ for cadmium, 0.04–0.41 mg kg⁻¹ for cobalt, 0.04–1.75 mg kg⁻¹ for chromium, 0.32–6.48  mg kg⁻¹ for copper, 7.46–40.1 mg kg⁻¹ for iron, 0.10–0.99  mg kg⁻¹ for manganese, 0.02–3.97 mg kg⁻¹ for nickel, 0.33–0.86 mg kg⁻¹ for lead, 4.49–11.2 mg kg⁻¹ for zinc, respectively. All metal concentrations in livers were higher than those in muscles. In some stations, cadmium and chromium concentrations in both muscles and livers, and lead levels in livers of the examined species were higher than permissible safety levels for human uses.     

Effect of cross-linking on the resistance to enzymatic hydrolysis of waxy maize starch and low-methoxy pectin

Gelatinised waxy maize starch and low-methoxy pectin mixtures were solubilised/dispersed in water and cross-linked with sodium trimetaphosphate (STMP). The polysaccharides were subjected to α-amylase, β-amylase or amyloglucosidase (AMG) hydrolysis for different times, and at two starch to pectin combination ratios (3:2 and 2:3). The extent of hydrolysis by porcine pancreatic α-amylase of the cross-linked (gelatinised) starch was 54.8–58.9% in comparison with gelatinised starch (for different incubation times), corresponding to 52.3–58.9% and 51.3–55.3% of the starch in the uncross-linked (UL) 3:2 and 2:3 starch to pectin ratios (for the same hydrolysis times). Blends of individually cross-linked starch to pectin ratios (3:2 and 2:3) were hydrolysed to 66.2–67.0% and 65.4–71.8%, respectively, compared with the corresponding UL counterparts. When the gelatinised starch was incubated for 0.5–36 h with β-amylase, hydrolysis ranged from 9.2% to 26.2%, and from 5.4% to 12.2% when the starch was cross-linked (corresponding to 40.0–58.7% of the gelatinised starch). For starch to pectin ratios of 3:2 or 2:3 blended after cross-linking, or by simultaneous cross-linking, hydrolysis represented 2.3–3.4% and 0.3–0.6% for the 3:2 ratio but only 1.2–2.0% and 0–0.3% for the 2:3 ratio. Hydrolysis with AMG using a 0.1 mg ml⁻¹ enzyme concentration caused 51.8% hydrolysis of gelatinised starch, which was lowered to 35.2% (i.e. by 68%) after cross-linking. At a higher enzyme concentration (1 mg ml⁻¹), the comparable figures were 91.7% and 71.9% (a reduction of 78.4%). For the UL 3:2 starch to pectin ratio and 0.1 and 1 mg ml⁻¹ enzyme concentrations, there was 27.8% and 56.5% hydrolysis of the polysaccharide which translated to 24.3% (87.4%) and 45.8% (81.1%), respectively, after cross-linking. Comparable figures for the 2:3 ratio (for the 0.1 and 1 mg ml⁻¹ enzyme concentrations) were 20.2% and 36.5% hydrolysis of the UL samples and 18.2% (90.1%) and 32.5% (89.0%) hydrolysis, respectively, after cross-linking.     

Analysis of heterocyclic amines (HAs) in pan-fried pork meat and its gravy by liquid chromatography with diode array detection

Aminoazaarenes (heterocyclic amines, HAs) contents were investigated in pan-fried pork meat as well as in gravies generated during frying. The clean-up procedure included alkaline hydrolysis, tandem solid phase extraction on columns filled with Extrelut – diatomaceous earth, cation exchanger (propyl sulfonic acid) and chemically bounded phase – C₁₈. Identification and quantitative analysis of HAs fraction was carried out using a HPLC system with DAD-type detector. Separation was achieved by using TSK-gel ODS 80-T_M column and a mixture of 5% acetonitrile and 95% triethylamine phosphate buffer (pH 3.3) as a mobile phase. Six compounds were determined: 2-amino-1,6-dimethylimidazo[4,5-b]pyridine (DMIP), 2-amino-3-methylimidazo[4,5-f]quinoline (IQ), 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (8-MeIQx), 2-amino-3,4-dimethylimidazo[4,5-f]quinoline (MeIQ), 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline (4,8-DiMeIQx), 2-amino-1-methyl-6-phenyl-imidazo[4,5-b]pyridine (PhIP). Two types of dishes prepared at home according to common recipes used in Poland were investigated. The total content of aminoazaarenes determined in collar was 7.2 and in chop samples 18.0 ng g⁻¹ of cooked meat. The total contents of investigated HAs in gravy samples were 10.2 and 15.1 ng g⁻¹ of cooked meat for collars and chops, respectively.     

Antioxidant and micronutrient quality of fruit and root vegetables from the Indian subcontinent and their comparative performance with green leafy vegetables and fruits

Commonly consumed, fruit vegetables (12) and root vegetables (15) in the Indian subcontinent in cooked and uncooked states assessed for inhibition of thiobarbituric acid reactive substances (TBARS), superoxide radical scavenging activity (SOSA), ferrous iron chelating ability (FICA) and nine micronutrients, exhibited large variability in these parameters. SOSA and FICA were significantly associated (r = 0.803, p < 0.001) with each other. Inhibition of TBARS showed marginal correlation with both FICA (0.38, p < 0.05) and SOSA (0.29, p > 0.05). There were significant cooking losses for each of the assessed antioxidant capacity parameters (p < 0.05). Contents of ascorbic acid, per 100 g of cooked fruit and root vegetables were high (61.9 and 31.3% of recommended daily allowance (RDA)). However, both the food classes were not good sources of beta‐carotene, riboflavin and thiamine (1.66–5.26% RDA). When compared with our data on 30 cooked green leafy vegetables (GLV) and 30 fresh fruits, root vegetables showed significantly (p < 0.05) higher levels of zinc and selenium. Cooked root vegetables were comparable with cooked GLVs but uncooked GLVs gave the highest values for inhibition of TBARS (0.73 ± 0.21 mM vitamin E/100g). SOSA (40.7 ± 15.6 mM tannic acid/100g) and FICA (41.6 ± 14.9 mM EDTA/100g) were highest for uncooked fruit vegetables. Root vegetables had the highest levels of polyphenols (251.4 ± 107.3 mg/100g). For the present study, popular fruits and vegetables such as guava, spinach, bitter gourd (Momordica charantia), yam, ginger and beetroot, and also less common ones like bael (Aegle marmelos), kokum (Garcinia indica) and mango‐ginger (Curcuma ameda), showed potential in vitro to combat oxidative stress. Copyright © 2005 Society of Chemical Industry