Chemical characterization of Opuntia dillenii and Opuntia ficus indica fruits

The chemical compositions (moisture, °Brix, total fibre, protein, fat, ash, pH, acidity, ascorbic acid, total phenolics, Na, K, Ca, Mg, Fe, Cu, Zn, Mn, Ni and Cr) were determined in fruits belonging to two species of prickly pear, Opuntia ficus indica and Opuntia dillenii, from Tenerife Island. The chemical compositions of the two species were clearly different. However, no important differences were observed between orange and green prickly pears within the specie O. ficus indica. An important contribution to the intakes of fibre, ascorbic acid, Mn, Cr and total phenolics is provided by the consumption of prickly pears, particularly from fruits of O. dillenii. Applying factor and/or discriminant analysis, the prickly pear samples were differentiated according to the species, altitude and region of cultivation in the island.     

Effects of trace element supplementation on milk yield and composition in camels

Objective of the study was to determine milk yield and quality (fat, protein, mineral content) of camels reared in north-east Africa, supplemented with trace elements for the first nine months of lactation. Twelve multiparous lactating camels were divided into two groups: control and treated (trace element supplemented). Addition of trace elements did not affect milk production and milk fat and protein content (respectively 3.09 vs. 3.51 kg d⁻¹; 2.86 vs. 2.56%; 3.31 vs. 3.19%, treatment vs. control). Calcium and zinc contents of milk were significantly higher in treated animals (1.20 vs. 0.94 g L⁻¹ and 3.16 vs. 2.52 mg L⁻¹; P<0.01). Mineral status of lactating camels and of their calves was assessed by analysis of plasma. Camel control diet was deficient in copper and supplementation did not allow reaching, neither in milk nor in plasma, the threshold values. Results suggest that oral trace element supplementation could increase zinc excretion in camels’ milk, despite the low levels of zinc in plasma.     

Mineral and trace element content of various vegetarian foodstuffs available in Belgium

 Atomic absorption spectrometry was used to determine mineral (Na, K, Ca and Mg) and trace element content (Zn, Fe, Cu and Si) of various vegetarian foodstuffs in Belgium. Thirty-five commercially available products were analysed after a wet-acid destruction in a closed-vessel destruction bomb. Various important sources of the minerals and trace elements were identified. Since data for vegetarian foods in Belgium are non-existent, the concentration values are compared with the scarce literature data and particularly with levels found in the same products available in The Netherlands. Received: 2 June 1998 / Revised version: 5 October 1998     

Evaluation of trace and toxic element concentrations in Paris polyphylla from China with empirical and chemometric approaches

Trace and toxic elements in Paris polyphylla samples were determined by flame and graphite furnace atomic absorption spectrometry following microwave-assisted acid digestion, based on a mixture of nitric acid and hydrogen peroxide. The whole procedure, including sample preparation, digestion and measurements, was successfully validated against CRM GBW07603 (bush twigs and leaves). In order to get a better insight into the elemental patterns, common chemometric approaches to data evaluation, such as principal component analysis (PCA) and hierarchical cluster analysis (HCA), were used as classification techniques. Five significant groups classified by PCA were attributed partly to significant influential sources. HCA revealed five groups of P. polyphylla samples based on their trace and toxic element concentrations.     

Multi-element analysis of mineral and trace elements in medicinal herbs and their infusions

Twelve mineral and trace elements (Al, B, Ba, Fe, Zn, Mn, Mg, K, Na, P, Cu, Sr, and Ca) were determined in the herbs and their infusions consumed for medical purposes in Poland such as chamomile (Matricaria chamomilla L.), peppermint (Mentha xpiperita), melissa (Melissa officinalis), sage (Salvia officinalis), nettle (Urtica dioica), linden (Tilia vulgaris) and St. John's wort (Hypericum calycinum). Dry digestion procedure for total concentration and wet digestion procedure for infusions were applied under optimized conditions for dissolution of medicinal herbs. Element concentrations in herbs and their infusions were determined by ICP-OES. The accuracy and precision were verified against NCS DC 73349 - bush branches and leaves certified reference material. The result of total concentrations of elements in herb leaves shows that all herbs contain most of the elements, except K and P, in the μg/g range, and that elemental concentrations varied widely. Moreover, on the basis of experimental results for the extraction efficiencies, the elements in herb infusions were classified into three specific groups: highly-extractable (>55%) including K; moderately-extractable (20-55%) including Mg, Na, P, B, Zn and Cu and poorly-extractable (<20%) including Al, Fe, Mn, Ba, Ca and Sr. The results of analysis were evaluated statistically using ANOVA one-way and three-way analysis of variance, variance correlation test and Spearman's test.     

Chemometric approach to evaluate trace metal concentrations in some spices and herbs

Herbs (mint, thyme and rosemary) and spices (black pepper, chili pepper, cinnamon, cumin, sweet red pepper and turmeric) were analysed using atomic spectrometry and then subjected to chemometric evaluation in an attempt to classify them using their trace metallic analyte concentrations (As, Ba, Ca, Cd, Co, Cr, Cu, Fe, Mg, Mn, Ni, Sr and Zn). Trace metals in acid digests of these materials were determined using both inductively coupled plasma-atomic emission spectrometry and inductively coupled plasma-mass spectrometry. The chemometric techniques of principal component analysis (PCA), linear discriminant analysis (LDA) and cluster analysis (CA) were used for the classification studies. These herbs and spices were classified into five groups by PCA and CA. When the results of these techniques were compared with those from LDA, it was found that all group members determined by PCA and CA are in the predicted group that 100.0% of original grouped cases correctly classified by LDA.     

Verifying the geographical origin of beef: The application of multi-element isotope and trace element analysis

Beef samples originating from the major cattle producing regions of the world (Europe, USA, South America, Australia and New Zealand) have been analysed using IRMS and ICP-MS. C and N isotope composition of the beef defatted dry mass and H and O isotope composition of the corresponding lipid fractions were determined. It was observed that intensive maize and/or C₄ pasture feeding, during cattle production, gave rise to significant differences in the ¹³C content of beef produced in Brazil and the USA versus British beef fed predominantly on C₃ pasture and fodder. The mean δ²H‰ and δ¹⁸O‰ values of beef lipid correlated well with the latitude of production regions and the relationship between the H and O isotopic contents were found to parallel the Meteoric Water Line. These findings support the hypothesis that the systematic global variations in the ²H and ¹⁸O content of precipitation are transferred through drinking water and feed into beef lipid. Multi-element concentrations determined in the beef were combined with the stable isotope data and submitted to multivariate analysis. Six key variables (δ¹³C‰ (defatted dry mass), Sr, Fe, δ²H‰ (lipid), Rb and Se) were identified by canonical discriminant analysis as providing the maximum discrimination between beef samples on the basis of the broad geographical areas (Europe, South America and Australasia). It was concluded that the methodology in its current state can be used to provide reliable origin information, but this is dependent upon the countries under investigation.     

Evaluation of trace metal concentrations in some herbs and herbal teas by principal component analysis

Sixteen trace metallic analytes (Ba, Ca, Ce, Co, Cr, Cu, Fe, K, La, Mg, Mn, Na, Ni, P, Sr and Zn) in acid digests of herbal teas were determined and the data subjected to chemometric evaluation in an attempt to classify the herbal tea samples. Nettle, Senna, Camomile, Peppermint, Lemon Balm, Sage, Hollyhock, Linden, Lavender, Blackberry, Ginger, Galangal, Cinnamon, Green tea, Black tea, Rosehip, Thyme and Rose were used as plant materials in this study. Trace metals in these plants were determined by using inductively coupled plasma-atomic emission spectrometry and inductively coupled plasma-mass spectrometry. Principal component analysis (PCA), linear discriminant analysis (LDA) and cluster analysis (CA) were used as classification techniques. About 18 plants were classified into 5 groups by PCA and all group members determined by PCA are in the predicted group that 100.0% of original grouped cases correctly classified by LDA. Very similar grouping was obtained using CA.     

Differentiation of potato cultivars experimentally cultivated based on their chemical composition and by applying linear discriminant analysis

Moisture, starch, amylose, fibre, proteins, ascorbic acid, total phenol compounds, acidity, pH, ash and mineral and trace elements were determined in 10 potato cultivars from Canary Islands experimentally cultivated. Six of the cultivars were also cultivated in two locations, to ascertain the impact of different soil types on the parameters measured. There were differences between cultivars in both, physicochemical parameters and mineral and trace elements analysed. There were significant differences in the mean values obtained for all the parameters considered, except for ascorbic acid, between both locations. Application of linear discriminant analysis allowed to classify the potato samples according to the cultivar, and according to growing location.     

Investigation by ICP-MS of trace element levels in vegetable edible oils produced in Spain

The content of trace elements (Ag, As, Ba, Be, Cd, Co, Cr, Cu, Fe, Hg, Mn, Mo, Ni, Pb, Sb, Ti, Tl and V) in edible oils (virgin olive, olive, pomace-olive, sunflower, soybean and corn) from Spain was determined, using inductively-coupled plasma-mass spectrometry (ICP-MS) after microwave digestion, employing only nitric acid in this step. The method has been validated by using both an oil reference material and recovery experiments over different oil samples, obtaining satisfactory results in all cases. Inter-day repeatabilities lower than 10% were observed for all of the analysed elements in the different kinds of oil samples. Studying the content of trace elements, in order to detect tendencies in the samples of the same type of oil, principal components analysis was used. Promising groupings were observed using a model with two principal components and retaining 75.3% of the variance.     

Gross composition,amino acid,phytic acid and trace element contents of thirteen cowpea cultivars and their nutritional significance

Thirteen cultivars of cowpea (Vigna unguiculata (L) Walp) were analysed for their proximate composition, amino acid, trace element and phytic acid contents. Crude protein values ranged from 206·8 to 283·8 g kg^?1 DM. The mean contents (g kg^?1) of other major nutrients were ether extract, 18·6; ash, 38·8; total dietary fibre, 121·8 and carbohydrates, 573·4. When compared with the provisional amino acid scoring pattern of FAO, all cultivars were low in methionine and high in lysine, isoleucine, leucine and phenylalanine plus tyrosine. Values for threonine and valine were variable compared with the pattern. The range of values for the chemical score was 0·61–0·74. Phytic acid values ranged from 5·10 to 10·27 g kg^?1, and the phytate: zinc molar ratios were all higher than that (15:1) above which zinc deficiency can be induced. Most of the trace elements showed wide variation in their occurrence among the cultivars. The values for zinc and iron showed less variation. The toxic elements mercury and selenium were present in varying amounts in more than half of the cultivars while tin was found in only one variety.     

中药渣袋栽平菇中微量元素的分析

对中药渣袋栽平菇中微量元素进行研究,用湿法消解样品,原子吸收分光光度法进行微量元素的测定.结果表明:该方法灵敏度高,检出限低,精密度、准确度好;药渣袋栽平菇中微量元素Cu、Zn、Fe、Mn平均含量分别为:9.199mg/kg、113.9mg/kg、102.9mg/kg、8.095mg/kg,与对照组比较无明显差别.     

Impact of trace element addition on degradation efficiency of volatile fatty acids, oleic acid and phenyl acetate and on microbial populations in a biogas digester

The effect of trace element addition on anaerobic digestion of food industry- and household waste was studied using two semi-continuous lab-scale reactors, one (R30+) was supplied with Fe, Co and Ni, while the other (R30) acted as a control. Tracer analysis illustrated that methane production from acetate proceeded through syntrophic acetate oxidation (SAO) in both digesters. The effect of the trace elements was also evaluated in batch assays to determine the capacity of the microorganisms of the two digesters to degrade acetate, phenyl acetate, oleic acid or propionate, butyrate and valerate provided as a cocktail. The trace elements addition improved the performance of the process giving higher methane yields during start-up and early operation and lower levels of mainly acetate and propionate in the R30+ reactor. The batch assay showed that material from R30+ gave effects on methane production from all substrates tested. Phenyl acetate was observed to inhibit methane formation in the R30 but not in the R30+ assay. A real-time PCR analysis targeting methanogens on the order level as well as three SAO bacteria showed an increase in Methanosarcinales in the R30+ reactor over time, even though SAO continuously was the dominating pathway for methane production. Possibly, this increase explains the low VFA-levels and higher degradation rates observed in the R30+ batch incubations. These results show that the added trace elements affected the ability of the microflora to degrade VFAs as well as oleic acid and phenyl acetate in a community, where acetate utilization is dominated by SAO.     

Non-essential and essential trace element concentrations in meat from cattle reared under organic,intensive or conventional production systems

We evaluated if differences in non-essential and essential trace element accumulation in beef-cattle reared under different systems (including organic, conventional and intensive management) were reflected in the meat derived from these animals. Diaphragm muscle from 166 calves from nine farms were analysed. Muscle cadmium concentrations were low (<10 µg/kg wet weight) and muscle arsenic, mercury and lead levels were below the limits of detection (<12, 2 and 3 µg/kg, respectively) in most (77–97%) samples; there were no significant differences between farms. Essential trace element concentrations in muscle were generally within adequate physiological ranges and, although they varied significantly between farms, this was not apparently related to management practices. There were no significant correlations in element concentrations between muscle and liver or kidney (organ concentrations that better reflect exposure), except for cobalt (positive association) and zinc (negative association). Non-essential and essential trace element concentrations in muscle in the studied animals did not generally reflect differences in exposure. This is particularly relevant for animals reared in systems (such as organic farms) where cattle are exposed to higher levels of non-essential elements (probably due to soil ingestion when grazing) but also can suffer from mineral deficiencies.     

Preparation and use of reference materials for quality assurance in inorganic trace analysis

A general preparation and certification scheme used in the Institute of Nuclear Chemistry and Technology (INCT) for the preparation and use of certified reference materials (CRMs) for inorganic trace analysis is presented and contrasted with approaches used by other CRM producers. 'Definitive' and 'very accurate' methods have a role, based on a combination of neutron activation and quantitative and selective post-irradiation isolation of an indicator radionuclide by column chromatography. Natural matrix CRMs of biological origin including the typical food products are reviewed and the need is identified for new well-characterized materials that would also be suitable for micro-analytical techniques such as PIXE, EDXRF, SS-AAS, etc. There are various approaches to studying homogeneity and its relationship with particle size distribution of a material, and the many problems associated with reliable particle size measurements of CRMs by various techniques are illustrated using real examples. There is an equation relating Ingamells' sampling constant to the mass of single particle of a powder material and this theoretical approach has been compared with experimental results obtained for some CRMs.     

Chemometric evaluation of trace metal concentrations in some nuts and seeds

Seventeen trace metals in acid digests of nuts and seeds were determined using inductively coupled plasma-atomic emission spectrometry and inductively coupled plasma-mass spectrometry. The data were subjected to chemometric evaluation using principal component analysis (PCA), linear discriminant analysis (LDA) and cluster analysis (CA) in an attempt to classify the samples. Hazelnuts (raw and dry roasted), almonds (raw and dry roasted), sunflower seeds (black and white), peanuts (raw and dry roasted), cashew nuts, Brazil nuts, walnuts, chickpeas (raw and dry roasted), pumpkin seeds (raw and dry roasted), and pistachio nuts were used as samples. The samples were classified into seven groups by PCA and CA. All group members determined using PCA and CA were found by LDA to be correctly classified in the predicted groups. Interestingly, the chemometric evaluation indicated that the raw and roasted nuts are very close to each other even though some originated from different countries.     

高敏连续分光光度法测定矿泉水中不同价态的痕量碲

本文继文献［１］之后，进一步将其发展为不经分离连续水相测定混合物中两种价态痕量碲（Ｔｅ）的方法，使用途更广，意义更大。所拟最佳手续不需萃取和浮选，至少可测定混合比例范围Ｔｅ（Ⅳ）：Ｔｅ（Ⅵ）＝１：５～５：１，ε_（６６０）高达５．６１×１０~５Ｌ·ｍｏｌ~（－１）·ｃｍ~１，Δλ高达２１０ｎｍ，并已用于测定我国多种矿泉水中痕量四价和六价碲，方法很灵敏，简便，准确，多方面优于国内外现行的方法。     

Comparative study of trace elements in certain fish, meat and meat products

Selenium, copper, nickel, zinc, cadmium, manganese, iron, copper and lead contents of certain fish, meat and meat products consumed in Turkey were determined using inductively coupled plasma-optical emission spectrometry (ICP-OES). The order of the elements in the meat, meat products and fish samples and their concentration ranges in μg 100 g⁻¹ was Fe (57.7–156.4) > Zn (20–159) > Ni (8.2–24) > Pb (11.5–13.5) > Cr (8.44–9.51) > Cu (7.18–10.01) > Cd (0.77–1.04) > Mn (3.98–10) > Se (1.32–4.6). The elemental concentrations of fish studied seemed to be close to the international standards. The highest trace element concentrations were obtained from past?rma, meat and sausage while the lowest value was observed in Trachurus trachurus (saurel). Iron concentrations in all samples were higher than the recommended values.     

Applicability of neutron activation analysis (NAA) in quantitative determination of some essential and toxic trace elements in food articles

Accurate and reliable data on microgram and nanogram quantities of some essential and toxic elements in most food articles are very scarce. Neutron activation analysis (NAA), with its essentially blankfree advantage, is a valuable approach in the field of determination of trace elements in different foodstuffs and diets. Accordingly, various radiochemical (RNAA) and instrumental (INAA) approaches have been developed in our laboratory for the elements As, Cd, Co, Cu, Hg, I, Mo, Ni, Sb, Se, Sn, Th, U, V, and others, and verified by the analysis of compositionally appropriate certified reference materials.This communication was presented as a poster at EURO FOOD CHEM VIII, Vienna, September 18–20, 1995, and was one of three such posters which were awarded as being outstanding     

Chemometric analysis of minerals and trace elements in raw cow milk from the community of Navarra,Spain

The concentrations of protein, fat, five minerals (Na, K, P, Ca and Mg) and nine trace elements (Fe, Zn, Cu, Mn, Se, Al, Cd, Cr and Pb) have been determined in 347 samples of raw cow milk from the community of Navarra, north Spain, using infrared analysis, atomic absorption spectrometry (flame and electrothermal atomisation) and inductively coupled plasma atomic emission spectroscopy. A preliminary chemometric study with the use of pattern recognition methods was carried out in order to characterise, classify and distinguish the different collected samples on the basis of their contents. Principal component analysis (PCA) has permitted the reduction of 16 variables to five principal components which interpret reasonably well the correlations of these studied variables. These variable associations may be attributed to intrinsic (lactogenesis) and other extrinsic factors, such as seasonal variation, animal feeding or geographical situation. Changes in these contents during different seasons were also assessed and consistently interpreted. Linear discriminant analysis (LDA) was used to explore cow milk samples, classifying according to season or geographical location, providing complementary information to PCA. This work shows that PCA and LDA are useful chemometric tools for the multivariate characterisation of raw cows’ milk.