Aluminium determination in food matrices IUPAC check sample survey of analytical performance

Summary Aluminium has been determined by 24 laboratories in the context of a check sample survey. Samples studied were two duplicate diets, one of which was spiked with 15.87mg Al/kg, and two blind duplicate milk powders. Target values for the duplicate diets were 11.80 and 27.90 mg Al/kg, respectively, and 15.65 mg Al/kg for the milk powders. Participants were requested to make only single determinations per sample. A two-step approach was used to assess the raw data. In the first step, those data were excluded that were outside a ±50% range of the duplicate diet spike and the target value for milk powder. Likewise, only one single data set per participant was accepted and results were ruled out stemming from procedures that have a detection limit of >5 mg Al/kg. The remaining data were evaluated both statistically and in the context of the method performance parameters available. Best scores for aluminium were from laboratories applying wet-pressurized digestion in combination with electrothermal atomic absorption spectrometry. Results for laboratories applying dry-ashing for sample decomposition were unreliable. The overall performance for aluminium is very disappointing given the relatively high aluminium levels of the samples studied. Out of 24 laboratories 11 have one or more major problems with their aluminium determination. They should dramatically improve or replace their methodology for this element.

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Aluminiumbestimmungen in Lebensmittelproben IUPAC-Ringprobenversuch der analytischen Ausführung

Zusammenfassung Im Rahmen eines Ringprobenversuches bestimmten 24 Labors Aluminium. Gemeinschaftlich untersuchte Proben: zwei Ganztagskostproben, von denen eine mit 15,87 mg Al/kg angereichert war und zwei getarnte Milchpulverdoppelproben. Sollwerte für die Ganztagskostproben waren 11,80 bzw. 27,90 mg Al/kg und 15,65 mg Al/kg für die Milchpulverproben. Teilnehmer wurden um Einzelbestimmungen je Probe gebeten. Die rohen Daten wurden in einem Zwei-Schritt-Verfahren ausgewertet. Im ersten Schritt wurden diejenige Daten ausgeklammert, die außerhalb des ±50%-Bereiches der Anreicherung oder des Sollwertes lagen. Pro Teilnehmer wurde nur ein Satz von Einzelwerten akzeptiert; Ergebnisse wurden verworfen, die mit einer Methode, deren Bestimmungsgrenze >5 mg Al/kg war, erhalten worden sind. Die verbleibenden Daten wurden statistisch ausgewertet. Am besten schnitten die Labors ab, die einen Naßaufschluß unter Druck in Kombination mit elektrothermischer Atomabsorptionsspektrometrie benutzten. Labors, die Trockenveraschung als Probenaufschluß benutzten, erzielten unzuverlässige Ergebnisse. Die Qualität der Analysendaten ist, im Anbetracht des Aluminiumgehaltes der Proben, sehr enttäuschend. Elf der 24 Labors hatten mehr oder minder große Probleme mit ihrer Aluminiumbestimniung und sollten diese entscheidend verbessern oder durch eine andere Arbeitsweise ersetzen.

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This study was carried out under the sponsorship of the IUPAC Commisision on Food Chemistry     

Aluminium content in milk powders by inductively-coupled argon plasma--optical emission spectrometry.

Forty-four brands of milk powders and simulated milk powders were analysed for aluminium content using Inductively Coupled Plasma Spectroscopy (ICP-OES) technique. The samples covered the full range of infant food items available in Singapore--full-cream milk formula, infant formula, fortified infant formula and milk-free soy protein formula. ICP-OES technique was employed for the analysis. Most samples analysed were found to contain less than 1 mg aluminium per kg powder. The highest aluminium content found was 15.0 mg aluminium per kg powder in a milk-free soy protein formula. The study found that ICP-OES is a convenient and accurate technique for trace metal analysis. However, considerable care needs to be exercised in the selection of emission lines of the metal under analysis to avoid error caused by emission from other metal present in the sample.     

Content and Bioaccessibility of Aluminium in Duplicate Diets from Southern Spain

Aluminium is found naturally in foods and beverages, but levels increase notably during processing, packaging, storage, and cooking, as a consequence of its presence in food additives and the wide use of aluminium utensils and vessels. Dietary intake of Al was estimated in 2 population groups in southern Spain (families and university students) in a duplicate diet sampling study. Diets were sampled for 7 consecutive days, and Al was determined in acid‐mineralized samples with electrothermal atomization‐atomic absorption spectrometry (ETA‐AAS). Mean values for Al intake were 2.93 and 1.01 mg/d in families and students, respectively, ranging from 0.12 to 10.00 mg/d. Assuming an average adult weight of 60 kg, the mean dietary exposures to aluminium were 0.34 and 0.12 mg/kg body weight/week in these groups, which amounted to 17% and 6% of the 2 mg/kg body weight estimated as the tolerable weekly intake by the Joint FAO/WHO Expert Committee on Food Additives. Bioaccessibility of dietary Al tested with in vitro studies ranged from 0.30 to 17.26% (absorbable fraction). The highest aluminium intakes were observed in subjects consuming diets with a low adherence to the Mediterranean diet, which were associated to high consumption of processed and canned food. On the contrary, subjects consuming diets with a high adherence to the Mediterranean diet patterns showed the lowest Al intakes. The present findings are useful for giving both a reliable estimate of total aluminium dietary intake and tolerable intake levels according to usual dietary habits.     

Aluminium in foodstuffs and diets in Sweden.

The levels of aluminium have been determined in a number of individual foodstuffs on the Swedish market and in 24 h duplicate diets collected by women living in the Stockholm area. The results show that the levels in most foods are very low and that the level in vegetables can vary by a factor 10. Beverages from aluminium cans were found to have aluminium levels not markedly different from those in glass bottles. Based on the results of the analysis of individual foods, the average Swedish daily diet was calculated to contain about 0.6 mg aluminium, whereas the mean content of the collected duplicate diets was 13 mg. A cake made from a mix containing aluminium phosphate in the baking soda was identified as the most important contributor of aluminium to the duplicate diets. Tea and aluminium utensils were estimated to increase the aluminium content of the diets by approximately 4 and 2 mg/day, respectively. The results also indicate that a considerable amount of aluminium must be introduced from other sources.     

The oral nitrate and nitrite intake in The Netherlands: evaluation of the results obtained by HPIC analysis of duplicate 24-hour diet samples collected in 1994.

In spring and autumn of 1994 duplicates of 24-h diets were collected from 123 respondents. One of the goals of this study was to determine the amount of nitrite and nitrate in the duplicates of 24-h diets to establish the oral daily intake of these analytes. For this purpose an HPIC/UV method for the determination of nitrate and nitrite in duplicate diets was developed and validated. The sample preparation procedure was derived from the in-house method used for the determination of nitrate and nitrite in human blood plasma. The sample is diluted with water, deproteinized with Carrez reagent, followed by chromatographic clean-up on an SPE C18-column. Both the nitrate and the nitrite results are quantitative. The recovery for nitrite was on average 104% (n = 21, spiking levels: 0.84-95 mg/kg) and for nitrate on average 103% (N = 21, spiking levels: 1.8-404 mg/kg). Samples of duplicates of 24-h diets were analysed according to the method developed. The median intake of nitrite calculated from the samples collected in spring 1994 was 0.6 mg/person day (range < 0.1-6.1 mg/person/day). For the samples collected in autumn 1994 these figures were < 0.2 mg/person/day (range < 0.1-16 mg/person/day). The mean intake of nitrate was 73 mg/person/day (range 7-322 mg/person/day) in spring 1994 and 87 mg/person/day (range 1-310 mg/person/day) in autumn 1994. The overall mean intake of nitrate in 1994 was 80 mg/person/day. The daily intake for nitrate was higher than that found in the duplicate diet study carried out in 1984/1985, when an average daily intake of 52 mg/person was measured. The intake of nitrite was also higher than found in the duplicate diets collected in 1984/1985. The findings of the study are discussed in the context of the ADI for nitrate and nitrite as well as the outcome of other recent European intake studies.     

Aluminium content of some foods and food products in the USA, with aluminium food additives.

The primary objective was to determine the aluminium (Al) content of selected foods and food products in the USA which contain Al as an approved food additive. Intake of Al from the labeled serving size of each food product was calculated. The samples were acid or base digested and analysed for Al using electrothermal atomic absorption spectrometry. Quality control (QC) samples, with matrices matching the samples, were generated and used to verify the Al determinations. Food product Al content ranged from <1-27,000 mg kg(-1). Cheese in a serving of frozen pizzas had up to 14 mg of Al, from basic sodium aluminium phosphate; whereas the same amount of cheese in a ready-to-eat restaurant pizza provided 0.03-0.09 mg. Many single serving packets of non-dairy creamer had approximately 50-600 mg Al kg(-1) as sodium aluminosilicate, providing up to 1.5 mg Al per serving. Many single serving packets of salt also had sodium aluminosilicate as an additive, but the Al content was less than in single-serving non-dairy creamer packets. Acidic sodium aluminium phosphate was present in many food products, pancakes and waffles. Baking powder, some pancake/waffle mixes and frozen products, and ready-to-eat pancakes provided the most Al of the foods tested; up to 180 mg/serving. Many products provide a significant amount of Al compared to the typical intake of 3-12 mg/day reported from dietary Al studies conducted in many countries.     

Collaborative test of the fluorimetric determination of selenium in a test solution, milk powder and bovine liver

Results are reported for an inter-laboratory test conducted to assess precision (repeatability, reproducibility) and accuracy of a collaborative method for the fluorimetric determination of selenium (Se). The seven participating laboratories analysed one test solution, four samples of milk powder and two samples of freeze-dried bovine liver. Each set of samples comprised three duplicates: two colorant-disguised milk powders and one code disguised freeze-dried bovine liver. Two of the milk powders were enriched with 90.7 micrograms/kg Se as seleno-DL-methionine. One set of results had to be rejected because the laboratory involved did not adhere to the collaborative method. Results from a second laboratory contained both stragglers and outliers. The five remaining laboratories performed the method satisfactory. Results from these laboratories were statistically evaluated according to ISO 5725. The average coefficient of variation within a laboratory (repeatability) was 4.8% and between laboratories (reproducibility) 6.0% for the milk powder and bovine liver samples. Recovery for the test solution, target value 120 micrograms Se/1, was 96% and the average recovery for the Se enriched milk powder was 88%. The mean result for the milk powder was 98.9 micrograms/kg (n = 10), coefficient of variation (CV) 6.7%, and for Se enriched milk powder 178.3 micrograms/kg, coefficient of variation (CV) 3.6%. For freeze-dried bovine liver, these results were 238.4 micrograms/kg and 4.1% respectively.     

Dietary intakes of some essential and non-essential trace elements, nitrate, nitrite and N-nitrosamines, by Dutch adults: estimated via a 24-hour duplicate portion study

Duplicate portions of 24-hour diets of 110 adults have been analyzed for aluminium, cadmium, copper, lead, manganese, mercury, zinc, nitrate, nitrite and volatile N-nitrosamines. The mean daily intake of copper (1.2 mg) is only about 50% of recommended values; mean daily intakes for manganese (3.3 mg) and zinc (8.4 mg) are adequate and marginal respectively with respect to recommended amounts. For the non-essential elements Al, Cd, Hg and Pb, mean daily intakes of 3.1 mg, 0.01 mg, 0.002 mg and 0.034 mg were found, respectively. For Cd this amounts to 17% of the acceptable daily amount, for Al, Hg and Pb 5%, 5% and 8%, respectively. Since 1976-1978 the dietary intake of lead has been reduced by a factor three; for the other six elements daily dietary intakes are almost the same as in 1976-1978. Average nitrate intake was 52 mg NO3-/day, about 25% of the ADI. Only 16 diets contained a measurable amount of nitrite. The highest daily intake (0.7 mg NO2-) is less than 10% of the ADI. Volatile N-nitrosamines were detectable in two duplicate diets (NDMA and NPIP). It is estimated that the daily dietary intake of volatile N-nitrosamines is around 0.1 microgram or less.     

Replacement of corn silage with shredded beet pulp and dietary starch concentration: Effects on performance,milk fat output,and body reserves of mid-lactation dairy cows

We aimed to evaluate the interaction between dietary starch concentration, varied by replacing wheat bran with dry ground corn, and replacement of corn silage (CS) with shredded beet pulp (BP) on production, milk fat output, milk fatty acid profile, and body reserves in dairy cows. Sixty-four Holstein dairy cows (140 ± 26 d in milk) were randomly assigned to 8 pens (8 animals per pen). Treatments were arranged in a 2 × 2 factorial arrangement with 2 concentrations of starch and 2 sources of fiber and were allotted to 8 pens (2 pens per treatment). Treatments were (1) 15% dry ground corn and 24% CS, (2) 15% dry ground corn and 24% BP replacing CS, (3) 30% dry ground corn and 24% CS, and (4) 30% dry ground corn and 24% BP replacing CS. The trial lasted for 47 d and final 7 d of experimental period was used for data and sample collection. Cows fed the BP-based diets had greater dry matter intake than those offered the CS-based diets, whereas no effects were observed with starch concentration. Milk yield increased by 1.8 kg/d with BP-based diets compared with CS-based diets and by 2.5 kg/d when cows received the high-starch compared with low-starch diets. Interactions between dietary starch concentration and forage substitution were detected for milk fat concentration and yield as BP inclusion lowered milk fat output with high-starch diet. Milk trans-18:1 concentration was lower with 15% dry ground corn and 24% CS compared with other diets. In conclusion, the effects of dietary starch concentration (22 and 32% dry matter) and forage substitution on production responses were independent except for milk fat output and milk trans 18:1 isomers. Substituting CS with BP is effective at increasing milk yield regardless of starch concentration; however, milk fat yield is lower when BP is used with high-starch concentration.     

Aluminium in foodstuffs and diets in Sweden

Summary The levels of aluminium have been determined in a number of individual foodstuffs on the Swedish market and in 24 h duplicate diets collected by women living in the Stockholm area. The results show that the levels in most foods are very low and that the level in vegetables can vary by a factor 10. Beverages from aluminium cans were found to have aluminium levels not markedly different from those in glass bottles. Based on the results of the analysis of individual foods, the average Swedish daily diet was calculated to contain about 0.6 mg aluminium, whereas the mean content of the collected duplicate diets was 13 mg. A cake made from a mix containing aluminium phosphate in the baking soda was identified as the most important contributor of aluminium to the duplicate diets. Tea and aluminium utensils were estimated to increase the aluminium content of the diets by approximately 4 and 2 mg/day, respectively. The results also indicate that a considerable amount of aluminium must be introduced from other sources.

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Aluminium in Lebensmitteln und in Nahrung in Schweden

Zusammenfassung Die Menge an Aluminium wurde in einer Anzahl von Lebensmittelrohstoffen, Grundnahrungsmitteln und von Duplikaten der Mahlzeiten von in Stockholm lebenden Frauen bestimmt. Die Resultate ergaben, daß die Aluminiumkonzentrationen in den meisten der Einzelprodukte sehr niedrig waren; bei Gemüse z. B. variierten diese je nach Art bis zum Faktor 10 und bei Getränken in Aluminiumdosen zeigten sich kaum Unterschiede zu jenen in Glasflaschen. Berechnet man den Aluminiumgehalt der durchschnittlichen täglichen Mahlzeit aus jenen in einzelnen Komponenten enthaltenen Mengen, aus denen sich die Mahlzeiten zusammensetzen, so kommt man auf 0,5 mg, während die experimentellen Bestimmungen einen Durchschnittswert von 13 mg ergaben. Einen wichtigen Beitrag zu dem hohen Aluminiumgehalt liefert das zur Zubereitung eines Kuchens verwendete Aluminiumphosphat enthaltende Backpulver. Tee und Aluminiumbestecke sind weitere Al-Lieferanten und erhöhen die tägliche Menge auf 24 mg. Aus dem Analysenergebnis ergibt sich die Schlußfolgerung, daß noch andere derzeit noch nicht identifizierte Quellen einen nennenswerten Beitrag zur Aluminiumzufuhr leisten müssen.

     

Evaluation of aluminium concentrations in samples of chocolate and beverages by electrothermal atomic absorption spectrometry

Samples of chocolate, cocoa, tea infusions, soft drinks and fruit juice have been examined by, electrothermal atomic absorption spectrometry (ETA-AAS) for the presence of aluminium (Al). Fruit juices and chocolate were analysed after an adequate sample preparation; the other products were evaluated directly. Sampling was performed in duplicate for 248 independent samples. The mean Al concentration in chocolate was 9.2 +/- 7.5 mg kg(-1), and individual values were correlated with the per cent of cocoa in samples (Y = 0.63 + 0.27X, r = 0.78, p < 0.0001). Al concentration in commercial tea infusions ranged from 0.9 to 3.3 mg l(-1) (mean = 1.80 +/- 65 mg l(-1), whereas in laboratory-prepared samples it was 2.7 +/- 0.93 mg l(-1). In soft drinks, the concentrations of Al were lower, ranging from 9.1 to 179 microg l(-1); the highest values were observed in samples of orange squash (mean = 114 +/- 56 microg l(-1)). Apricot juice showed the highest Al level (mean = 602 +/- 190 microg l(-1)), being statistically, different from that of pear (mean = 259 +/- 102 microg l(-1)), but not different from that of peach juice (mean = 486 +/- 269 microg kg(-1)). Toxicologically, the amount of Al deriving from the consumption of these products is far below the acceptable daily intake of 1 mg kg(-1) body weight indicated by the FAO/WHO, and it is a verv low percentage of the normal Al dietary intake.     

Effects of metabolizable protein supply and amino acid supplementation on nitrogen utilization, milk production, and ammonia emissions from manure in dairy cows

Two experiments were conducted with the objective of investigating the effects of rumen-protected methionine (RPMet) supplementation of metabolizable protein (MP)-deficient or MP-adequate but Met-deficient diets on dairy cow performance. Experiment (Exp.) 1 utilized 36 Holstein dairy cows blocked in 12 blocks of 3 cows each. Cows within block were assigned to one of the following dietary treatments: (1) MP-adequate diet [AMP; positive MP balance according to the National Research Council (2001) dairy model]; (2) an MP-deficient diet supplemented with 100g of rumen-protected Lys (RPLys)/cow per day (DMPL); and (3) DMPL supplemented with 24g of RPMet/cow per day (DMPLM). Experiment 2 utilized 120 Holstein cows assigned to 6 pens of 20 cows each. Pens (3 per treatment) were assigned to one of the following dietary treatments: (1) AMP diet supplemented with 76g of RPLys/cow per day (AMPL); and (2) AMPL (74g of RPLys/cow per day) supplemented with 24g of RPMet/cow per day (AMPLM). Each experiment lasted for 10wk (2-wk adaptation and 8-wk experimental periods) following a 2-wk covariate period (i.e., a total of 12wk). In Exp. 1, the MP-deficient diets decreased apparent total-tract nutrient digestibility but had no statistical effect on dry matter intake (DMI), milk yield, or milk fat percentage and yield. Compared with AMP, DMPL decreased milk protein content; both DMPL and DMPLM diets decreased milk protein yield. Urinary N losses and milk urea-N concentration were decreased by the MP-deficient diets compared with AMP. The ammonia emitting potential of manure from the MP-deficient diets was decreased by about 37% compared with that of AMP manure. Plasma Lys and Met concentrations were not affected by treatment, but concentrations of His, Thr, and Val were lower for the MP-deficient diets compared with AMP. In Exp. 2, the AMPLM diet had lower milk yield than AMPL due to numerically lower DMI; no other effects were observed in Exp. 2. In conclusion, feeding MP-deficient diets supplemented with RPLys and RPMet did not statistically decrease milk yield in dairy cows in Exp. 1. However, without RPMet supplementation, milk protein content was decreased compared with the MP-adequate diet. Other amino acids, possibly His, may limit milk production in MP-deficient, corn or corn silage-based diets. A summary of 97 individual cow data from trials in which MP-deficient diets were fed suggested the National Research Council (2001) model under-predicts milk yield in cows fed MP-deficient diets (MP balance of -20 to -666g/d) in a linear manner: milk yield under-prediction [National Research Council (2001) MP-allowable milk yield, kg/d - actual milk yield, kg/d] = 0.0991 (±0.0905) + 0.0230 (±0.0003) × MP balance, g/d (R(2)=0.99).     

Aluminium in food and daily dietary intake assessment from 15 food groups in Zhejiang Province,China

Aluminium was measured in 2580 samples of 15 food groups and dietary exposure was estimated. Samples were purchased and analysed during 2010 to 2014. High aluminium levels were found in jellyfish (mean 4862 mg/kg), laver (mean 455.2 mg/kg) and fried twisted cruller (mean 392.4 mg/kg). Dietary exposure to aluminium was estimated for Zhejiang residents. The average dietary exposure to aluminium via 15 food groups in Zhejiang Province was 1.15 mg/kg bw/week, which is below the provisional tolerable weekly intake of 2 mg/kg bw /week. Jellyfish is the main Al contributor, providing 37.6% of the daily intake via these 15 food groups. This study provided new information on aluminium levels and assessment of aluminium (Al) dietary exposure in Zhejiang Province of China.     

衍生化-富集-表面增强拉曼光谱法快速筛查奶粉中亚硝酸盐

目的 建立衍生化-富集-表面增强拉曼光谱法快速检测奶粉中亚硝酸盐的分析方法。方法 样品水溶液通过除蛋白、衍生化后，采用阳离子小柱PSY-001对衍生化合物进行富集，再使用表面增强拉曼光谱对样品中的亚硝酸盐含量进行定性检测。结果 7类不同奶粉，采用本研究所建立的方法进行检测，根据不同的批处理量，单个样品检测全过程只需3~15 min，定性检测限为0.4 mg/kg，远低于国家安全标准对亚硝酸盐的限量要求(2 mg/kg)。方法的灵敏度在96%～100%，特异性为100%，假阴性率为0%～4%，假阳性率为0%，相对准确度为98%～100%。结论 该方法操作简单、快速，易于掌握，适用于奶粉中亚硝酸盐的快速筛查。     

Invited review: production and digestion of supplemented dairy cows on pasture

Literature with data from dairy cows on pasture was reviewed to evaluate the effects of supplementation on intake, milk production and composition, and ruminal and postruminal digestion. Low dry matter intake (DMI) of pasture has been identified as a major factor limiting milk production by high producing dairy cows. Pasture DMI in grazing cows is a function of grazing time, biting rate, and bite mass. Concentrate supplementation did not affect biting rate (58 bites/min) or bite mass (0.47 g of DM/bite) but reduced grazing time 12 min/d per kilogram of concentrate compared with unsupplemented cows (574 min/d). Substitution rate, or the reduction in pasture DMI per kilogram of concentrate, is a factor which may explain the variation in milk response to supplementation. A negative relationship exists between substitution rate and milk response; the lower the substitution rate the higher the milk response to supplements. Milk production increases linearly as the amount of concentrate increases from 1.2 to 10 kg DM/d, with an overall milk response of 1 kg milk/kg concentrate. Compared with pasture-only diets, increasing the amount of concentrate supplementation up to 10 kg DM/d increased total DMI 24%, milk production 22%, and milk protein percentage 4%, but reduced milk fat percentage 6%. Compared with dry ground corn, supplementation with nonforage fiber sources or processed corn did not affect total DMI, milk production, or milk composition. Replacing ruminal degradable protein sources with ruminal undegradable protein sources in concentrates did not consistently affect milk production or composition. Forage supplementation did not affect production when substitution rate was high. Fat supplementation increased milk production by 6%, without affecting milk fat and protein content. Increasing concentrate from 1.1 to 10 kg DM/d reduced ruminal pH 0.08 and NH3-N concentration 6.59 mg/dl, compared with pasture-only diets. Replacing dry corn by high moisture corn, steam-flaked or steam-rolled corn, barley, or fiber-based concentrates reduced ruminal NH3-N concentration 4.36 mg/dl. Supplementation did not affect in situ pasture digestion, except for a reduction in rate of degradation when high amounts of concentrate were supplemented. Supplementation with energy concentrates reduced digestibility of neutral detergent fiber and intake of N but did not affect digestibility of organic matter or flow of microbial N.     

Aluminium in food and daily dietary intake estimate in Greece

Aluminium content of foods, as well as dietary aluminium intake of the Greek adult population, was determined using graphite furnace atomic absorption spectroscopy after microwave sample digestion and food consumption data. Al content ranged from 0.02 to 741.2?mg?kg^?1, with spices, high-spice foods, cereal products, vegetables and pulses found to be high in Al. Differences in aluminium content were found between different food classes from Greece and those from some other countries. Aluminium intake of Greeks is 3.7?mg/day based on DAFNE Food Availability Databank, which uses data from the Household Budget Surveys. On the other hand, according to the per capita food consumption data collected by both national and international organisations, Al intake is 6.4?mg?day^?1. Greek adult population has an Al intake lower than the Provisional Tolerable Weekly Intake of 7?mg?kg^?1 body weight established by EFSA. Cereals and vegetables are the main Al contributors, providing 72.4% of daily intake.     

Quantitative effects of feed protein reduction and methionine on nitrogen use by cows and nitrogen emission from slurry

The effects on N use and N volatilization from slurry were investigated in 24 early-lactation Brown Swiss cows (32 kg/d milk) fed four diets with 128, 124, 147 and 175 g/kg DM of crude protein (CP). All diets were supplemented with 0.75 g/kg of rumen-protected Met except for one of the low-protein rations (128 g/kg of CP). The unsupplemented low-protein ration was calculated to be deficient in Met by approximately 20%. No significant treatment effects on performance, water intake and excretion, and slurry quantities were observed. Differences in N intake were closely reflected in the daily excretions of total and urea N via urine, and in urine N as a proportion of total excretory N. These values were higher for the unsupplemented low-protein ration than for the Met-supplemented low-protein ration. The treatment effects on fecal N excretion were generally smaller, and milk N excretion and N balance were not affected. Feed N utilization for milk N excretion increased with decreasing CP content from 27% for the high-protein group to about 35% for the two low-protein groups. Comparing the Met supplemented rations only, ammonia N emission from fresh slurry (excreta:water = 1:0.5) decreased from 231 to 160 and 55 microg/s per square meter of surface with 175, 147 and 124 g/kg of CP, respectively, and the corresponding total N losses during 7 wk of slurry storage declined from 89 to 57 and 25 g/d per cow. Regression analysis demonstrated the basic suitability of milk urea N excretion to estimate urine N excretion and, consequently, potential N emissions.     

Aluminium levels of fish fillets baked and grilled in aluminium foil

During storage and preparation of food, aluminium foil is often used for wrapping heat-sensitive raw food for protection against direct heat, e.g. grilled or baked fish fillets. In this investigation the aluminium contents of grilled and baked fish fillets with and without ingredients wrapped in aluminium foil were determined. The selected fish species were mackerel (Scomber scombrus L.), a fatty species, ocean perch (Sebastes spp.), a medium fatty species, and cod (Gadus morhua) and saithe (Pollachius virens), two lean fish species. The wrapped fillets were baked for approximately 20 min at 200°C in an oven, either without ingredients or, alternatively, with vinegar and sodium chloride added. In another experiment one part of a fillet was grilled over charcoal without ingredients and the other part was grilled with onion rings and mixed spices added. All aluminium concentrations of both baked and grilled fillets wrapped in aluminium foil increased during heating. The increase in aluminium concentration ranged from a factor of 2 (baked saithe fillets without ingredients from 0.10 up to 0.21 mg/kg) to a factor of 68 (grilled mackerel fillets with ingredients from 0.07 up to 5.04 mg/kg). The aluminium contents of grilled fillets were higher than those of baked fillets. Presumably two factors were responsible for the higher aluminium contents in grilled fillets: first the higher temperature of preparation when grilling fillets and second the high aluminium content of mixed spices (63.5 mg Al/kg), which may be taken up in part by the grilled fillets. All results clearly showed that some aluminium migrated from the aluminium foil into the food. The aluminium migration seems to depend on several factors, e.g. the duration and the temperature of heating, the composition and the pH-value of food, the presence of any other substances (such as organic acids and salt) and complexing reactions that result in dissolution of the complexed metal. Considering the present state of knowledge and the suggested provisional tolerable daily intake of 1 mg Al/kg bodyweight per day of the [World Health Organisation, 1989], no risk to health of the consumer would to be expected from eating meals prepared in aluminium foil.     

Faster Measurement of Minerals in Milk Powders: Comparison of a High Power Wavelength Dispersive XRF System with ICP-AES and Potentiometry Reference Methods

A simple and quick (less than 5 min/pellet) method for the quantification of a series of macroelements (Na, Mg, P, Cl, K, and Ca) and trace elements (Fe, Cu and Zn) by wavelength dispersive X-ray fluorescence (WDXRF) has been established and validated for fortified milk powders, from a single production site. The calibration set of 23 samples was selected to uniformly cover the concentration ranges of each element. The validation set was composed of 32 samples. By using a high power WDXRF instrument, a counting time as short as 20 s for most of the analytes can be used to considerably decrease analysis time. Reference values obtained by inductively coupled plasma-atomic emission spectroscopy and by potentiometry for chloride were used to calibrate the WDXRF system. Subsequently, the WDXRF results were evaluated against those obtained from the reference methods. The results show good performance of the WDXRF method for routine analysis of milk powders including copper at low levels (<10 mg/kg). All the calibrations gave R ² > 0.98, while all validation work has been done using three replicates of each sample; the results have additionally been reassessed to check that only two replicates per sample would not lead to significant differences in terms of quality of data and could be considered for routine analysis to further decrease analysis time.     

Toxicity of moniliformin from Fusarium fujikuroi culture material to growing barrows.

In two studies, the effects of moniliformin (M)-contaminated diets from Fusarium fujikuroi culture material on growing barrows were evaluated. In the first study, six barrows (three replicates of two each, mean body weight = 17.8 kg) per group (four groups; 24 barrows total) were fed diets calculated to contain 0 mg M/kg feed (control); 25 mg M/kg feed; 50 mg M/kg feed; or 100 mg M/kg feed for 28 days. In the second study, the same experimental design and numbers of barrows (mean body weight = 15.3 kg) were used, and diets were formulated to contain 0 mg M/kg feed (control); 50 mg M/kg feed; 100 mg M/kg feed; or 200 mg M/kg feed. Diets of 100 mg or 200 mg M/kg feed reduced body weight, body weight gain, and feed consumption. Serum biochemical analytes were affected by 100 to 200 mg M/kg feed. Hematologic values were affected by 50, 100, and 200 mg M/kg feed. In the first study, one barrow in the 100 mg M-treated group died, and in the second study. one barrow died in the 100 mg M-treated group, and five barrows died in the 200 mg M-treated group. Relative heart weight was increased in the 200 mg M-treated barrows, yet tissues from organs collected from treatment groups were generally histologically unimpressive. The most consistent sign of M toxicity in barrows appeared to be death induced within 2 to 5 days by 100 to 200 mg M/kg feed.