The contribution of lead in water to dietary lead intakes

Preliminary experiments have been carried out to determine the uptake of lead from both hard and soft waters used in the preparation of food and beverages. Lead concentrations in water for the range of 0.05-0.5 mg litre^?1 were used to prepare composite groups representing root vegetables, other vegetables and beverages whose composition reflected per capita consumption of these foods in the UK. The uptake of lead from water was highest for the composite group of other vegetables which comprises 70% by weight of green vegetables. For each of the composite groups and the particular water samples used there was little relative difference in uptake whether foods were prepared in hard or soft water. Calculations of the contribution made by lead in water used for preparation of foods and beverages to the total dietary lead intake indicates that at levels of lead of 0.02 mg litre^?1, the contribution is about 10% but this can rise to about 40% as lead levels in the water approach 0.1 mg litre^?1.     

Preliminary studies on acidity-astringency interactions in model solutions and wines

Intensity of astringency in model solutions and wines varying in total acid and total phenols was evaluated by paired comparisons by 10 trained judges. Model solutions consisted of tannic (500, 1000, 2000 mg litre^?1) and tartaric (0, 2, 4, 6 g litre^?1) acids dissolved in aqueous solutions of ethanol (120 ml litre^?1) and sucrose (5 g litre^?1). Wine solutions were prepared by addition of citric acid (0, 0.5, 1, 2, 3 g litre^?1 as tartaric acid) to a high phenol-red wine (2645 mg litre^?1 GAE) and a moderate phenol-white wine (800 mg litre^?1 GAE). At all three levels of tannic acid, astringency of model solutions increased significantly (P<0.001) with tartaric acid concentration. Astringency of white wine also increased significantly (P<0.05) with citric acid concentration. A negative linear relation was found between relative astringency and pH at a given tannin level for both model solutions and white wine. As pH was reduced, more phenolic molecules were in the phenol form thereby increasing the likelihood of hydrogen bonding between hydroxyl groups of wine tannins and ketoimide groups of mouth proteins. The preliminary hypothesis that hydrogen bonding is the main reaction involved in the formation of protein-tannin complexes resulting in the sensation of astringency was reinforced.     

Hydroxycinnamates of Vitis vinifera: Sensory assessment in relation to bitterness in white wines

The bitter and astringent taste properties of hydroxycinnamoyl tartaric acids have been responsible for incorrect speculation that these compounds influence the taste of wine. The sensory contribution of the major hydroxycinnamates found in wine was evaluated by duo—trio difference tests in model wine solutions and in white wine. The major hydroxycinnamate compound, trans-caffeoyl tartaric acid, was not detectable when added at the highest level at which it has been found in wine, 150 mg litre^?1. Similarly, no significant difference in taste was produced when caffeic acid and p-coumaric acid were added at 120 mg litre^?1 and 30 mg litre^?1, respectively. Trans-2-S-glutathionyl caffeoyl tartaric acid, a product of oxidase activity in must, was not detectable at 50 mg litre^?1. It was concluded that the hydroxycinnamates do not play any direct role in the taste of wines.     

Effect of drought and irrigation on the fate of nitrogen applied to cut permanent grass swards in lysimeters: Leaching losses

Nitrogen losses were measured in water draining from cut permanent grass swards growing in monolith lysimeters containing clay loam (Salop series) or silt loam (Bromyard series) soils. The swards were cut at 6-week intervals during the summer and were fertilised with calcium nitrate at rates of 0 and 400 kg N ha^?1 in each of five successive years (1977–81); in the first year the fertiliser was labelled with ¹⁵N. Four differing rainfall regimes were imposed from spring to autumn in each year. Mean annual losses of nitrogen by leaching from unfertilised swards were 3.8 kg N ha^?1 with mean nitrate-N concentrations in the water of about 1 mg N litre^?1. In fertilised lysimeters where rainfall distribution was that of the long-term average the mean annual total nitrogen losses were 41 kg N ha^?1 in the Salop soil and 15 kg N ha^?1 for the Bromyard soil; mean nitrate-N concentrations were 11.6 mg N litre^?1 and 5.1 mg N litre^?1, respectively. Losses of nitrogen and nitrate concentrations were similar to these quantities when irrigation increased the rainfall total to 120% of average. Where a drought was imposed for 2 weeks before and after each cut, mean nitrate-N concentrations increased to 20.3 mg N litre^?1 on Salop soil and 13.1 mg N litre^?1 on Bromyard soils; total annual nitrogen losses were 74 kg N ha and 33 kg N ha^?1, respectively. The largest losses were recorded when the drought period extended for four weeks before each cut and mean nitrate-N concentrations increases to 28.8 mg N litre^?1 on Salop soil and 34 mg N litre^?1 on Bromyard soil, with total annual nitrogen losses of 104 kg N ha^?1 and 109 kg N ha^?1, respectively. Losses of nitrogen derived from the fertiliser labelled with ¹⁵N were 7.3–8.4% of that applied in the Salop soil (29–33 kg N ha^?1), with little effect by the differing rainfall distributions. On the Bromyard soil, losses were 3.7% (14 kg N ha^?1) of the applied fertiliser in lysimeters not subjected to droughts. When the period of the drought extended before and after each cut, losses were 8.2% (32 kg N ha^?1) and increased to 17.9% (70 kg N ha^?1) when the drought period occurred entirely before each cut. Fertiliser nitrogen contributed 48–69% of the total nitrogen in drainage water from both soils in the first year.     

Content of selenium, total and inorganic arsenic and bioaccessibility of arsenic in children diets of Mexico

BACKGROUND: The aim of this study was to evaluate the intake of selenium, total and inorganic arsenic and the bioaccessibility of arsenic in diets of Mexican schoolchildren using an in vitro method. RESULTS: Total and inorganic arsenic concentrations in the diets ranged from 0.05 to 1.15 mg kg^?1 dry weight (DW) and from 0.023 to 0.088 mg kg^?1 DW respectively, while selenium levels were between 0.08 and 0.20 mg kg^?1 DW. Daily intake of total and inorganic arsenic ranged from 0.15 to 10.49 µg day^?1 kg^?1 body weight (BW) and from 0.06 to 1.11 µg day^?1 kg^?1 BW respectively, while that of selenium varied from 0.29 to 2.63 µg day^?1 kg^?1 BW. Bioaccessibility of total and inorganic arsenic ranged from 4 to 97% (mean 44 ± 21.5%) and from 33 to 97% (mean 71 ± 22.5%) respectively. CONCLUSION: Inorganic arsenic levels in the diets were low. Therefore there appears to be a low risk of adverse effects resulting from excess inorganic arsenic intake from these diets. Copyright © 2011 Society of Chemical Industry     

Effects of explant source,culture medium: Strength and growth regulators on the in-vitro propagation of three Jamaican yams: (Dioscorea cayenensis,D trifida and d rotundata)

Explants of tuber, meristem and vines from three widely cultivated yam species in Jamaica—D cayenensis, D rotundata and D trifida—were examined for their responses to mineral media strength, inorganic ammonium and growth regulator supplements. Tuber pieces (5mm³) showed some positive growth responses but did not produce in-vitro plantlets on all the media tested. Meristem tips of D trifida grew rapidly on basal media (BM) supplemented with either 0.1 mglitre^?1 6-benzylamino purine (BAP) and 0.01 mg litre^?1indole butyric acid or 0.2 mg litre^?1 BAP and 1.0 mg litre^?1 naphthalene acetic acid (NAA) producing plantlets by 28 weeks. The nodal explants grew rapidly with plantlets obtained from all the cultivars within 4 weeks. Use of young, vigorously growing vines of 8 weeks or less, as explant source, gave low contamination levels (16–25%) in culture when sterilised for 30 min in 200 g litre^?1 NaOCl in the case of D trifida and 300 g litre^?1 NaOCl in the case of D cayenesis prior to culturing. Initiation of growth was optimal when explants were taken from monopodial vines grown in October or January and placed on BM supplemented with 0.5 mg litre^?1 BAP (BM0.5BAP). Addition of 0.5 mg litre^?1 kinetin to the BM or 0.05 mg litre^?1 NAA to BM0.5BAP depressed shoot production, while 5.0 mg litre^?1 kinetin increased swelling of the nodal region in explants from sympodial shoots and from vines grown in March. The results suggest that nodal segments excised from young, fast growing vines of these species are the best explant source for the purpose of commercial micropropagation.     

The determination of dimethyl sulphoxide in aqueous solution

A method for the determination of dimethyl sulphoxide (DMSO) in aqueous extracts is described. DMSO is reduced using stannous chloride and hydrochloric acid to dimethyl sulphide which can be measured by gas-liquid chromatography. Other sulphur compounds, including S-methyl methionine, have no effect on the assay. Levels of DMSO in solution higher than 10 μg litre^?1 can be readily determined. In samples of brewery wort the levels of DMSO were within the range of 261-411 μg DMSO litre^?1 and repeated determinations on two samples of beer gave mean values of 417 and 627 μg DMSO litre^?1 with coefficients of variation of 13.7 and 11.8% respectively.     

Levels of histamine and other biogenic amines in high-quality red wines

Biogenic amines in wine may impair sensory wine quality and cause adverse health effects in susceptible individuals. In this study, histamine and other biogenic amines were determined by HPLC after amine derivatisation to dansyl chloride conjugates in 100 selected high-quality red wines made from seven different cultivars. Amine levels varied considerably between different wines. The most abundant amines were putrescine (median?=?19.4?mg?l^?1, range?=?2.9–122), histamine (7.2?mg?l^?1, 0.5–26.9), and tyramine (3.5?mg?l^?1, 1.1–10.7), whereas lower levels were found for isoamylamine (median?=?0.25?mg?l^?1), phenylethylamine (0.16?mg?l^?1), cadaverine (0.58?mg?l^?1), spermidine (1.8?mg?l^?1) and tryptamine (0.06?mg?l^?1). Positive correlations were observed between isoamylamine and phenylethylamine, and between histamine, putrescine and tyramine levels. Amine concentrations were similar in all wine cultivars except Pinot noir and St. Laurent wines, which showed significantly higher tryptamine and cadaverine levels. The results indicate that levels of histamine and other biogenic amines may vary considerably between red wines independent of grape variety and that high amounts can also be found in high-rated wines. Adopting a legal histamine threshold level of 10?mg?l^?1 in the European Union, as formerly introduced in other countries, would have excluded 34% of the investigated wines from the market.     

Post-harvest application of diphenylamine and ethoxyquin for the control of superficial scald on Bramley's seedling apples

Recent changes in the antioxidant regulations in the UK and the need to evaluate the effectiveness of scald control chemicals in the presence of other post-harvest chemicals led to a comparative study of the effects of diphenylamine (DPA) and ethoxyquin on scald development in Bramley's Seedling apples. A range of concentrations (1000–4000 mg litre^?1 a.i.) of DPA completely controlled scald on Bramley apples kept in controlled atmosphere storage for 241 days; ethoxyquin at equivalent rates was less effective. Only partial control of scald was achieved with 500 mg litre^?1 a.i. DPA. None of the treatments injured the fruit. Control of scald by 2000 mg litre^?1 a.i. DPA or ethoxyquin was not impaired by adding thiophanate-methyl (l g litre^?1 a.i.) or calcium chloride (10 g litre^?1) although the measure of control was reduced when both fungicide and calcium chloride were added. Calcium chloride caused lenticel injury which was aggravated by adding ethoxyquin but reduced by incorporating DPA. The concentrations of ethoxyquin and DPA residues on the fruit immediately after treatment were within the limits required by UK legislation (see reference 1) of 3 mg kg^?1 and 10 mg kg^?1, respectively, even where 4000 mg litre^?1 had been applied. An initial residue concentration of 2.3 mg kg^?1 DPA was associated with complete control of scald. Residue levels, particularly of DPA, declined rapidly during the first month of storage.     

Effect of triacontanol on sprout growth in potatoes (Solanum tuberosum)

The effects of a 3-min dip in various concentrations (0–1–100 mg litre^?1) of a triacontanol emulsion on sprout growth from single-eye pieces of seed potato (Solanum tuberosum L) tubers were assessed after 10 days' growth in acid-washed sand. Treatment effects were compared with those resulting from immersion for 3 min in a mixture of gibberellic acid (6 mg litre^?1) and ethrel (4 mg litre^?1). Triacontanol dips were more effective than gibberellic acid and ethrel. Treatments increased the fresh weight of sprouts but had little effect on sprout number per tuber fragment. The optimum concentration of triacontanol was 10 mg litre^?1.     

Elements in rice from the Swedish market: 1. Cadmium,lead and arsenic (total and inorganic)

A survey of the levels of cadmium, lead and arsenic in different types of rice available on the Swedish retail market was carried out in 2001–03. The types of rice included long and short grain, brown, white, and parboiled white rice. The mean levels found were as follows: total As: 0.20 mg kg^?1, inorganic As: 0.11 mg kg^?1; Cd: 0.024 mg kg^?1; and Pb: 0.004 mg kg^?1. ICP-MS was used for the determination of As (total and inorganic) after acid digestion. Lead and cadmium were determined using graphite furnace atomic absorption spectrometry (GFAAS) after dry ashing. In countries where rice is a staple food, it may represent a significant contribution in relation to the provisional tolerable weekly intake for Cd and inorganic As.     

Contribution of water and cooked rice to an estimation of the dietary intake of inorganic arsenic in a rural village of West Bengal,India

Arsenic contamination of rice plants by arsenic-polluted irrigation groundwater could result in high arsenic concentrations in cooked rice. The main objective of the study was to estimate the total and inorganic arsenic intakes in a rural population of West Bengal, India, through both drinking water and cooked rice. Simulated cooking of rice with different levels of arsenic species in the cooking water was carried out. The presence of arsenic in the cooking water was provided by four arsenic species (arsenite, arsenate, methylarsonate or dimethylarsinate) and at three total arsenic concentrations (50,?250 or 500?µg?l^?1). The results show that the arsenic concentration in cooked rice is always higher than that in raw rice and range from 227 to 1642?µg?kg^?1. The cooking process did not change the arsenic speciation in rice. Cooked rice contributed a mean of 41% to the daily intake of inorganic arsenic. The daily inorganic arsenic intakes for water plus rice were 229, 1024 and 2000?µg?day^?1 for initial arsenic concentrations in the cooking water of 50, 250 and 500?µg?arsenic?l^?1, respectively, compared with the tolerable daily intake which is 150?µg?day^?1.     

Spectral evaluation of total phenolic components in Vitis vinifera: Grapes and wines

Whereas high levels of flavonoid extractives are responsible for the characteristic λ_Dmax at about 280 nm in the ultra-violet spectra of red wines, there is wide variability in the spectral features of natural white wines, in which the phenolic content is often minimal. For the latter, λ_Dmax may occur anywhere within the range 265–285nm, with relatively strong absorbance at 320 nm arising from the presence of hydroxycinnamate esters. Massive fining of many white wines and juices with polyvinylpyrrolidone (10% w/v) has shown residual non-phenolic u.v. absorbing constituents to be sufficiently uniform to enable direct spectral measurement of total hydroxycinnamates in white juices, white wines and rosés as (E₃₂₀-1.4) absorbance units. For white grape juices and white wines, total hydroxycinnamates are directly quantitated as mg litre^?1 ‘caffeic acid equivalents’ and total flavonoid extractives may also be estimated. Total phenolic components of red wines are accounted as (E₂₈₀-4) absorbance units. The spectral interpretations enable comparative estimation of flavonoid extractives in all natural wine types.     

Optimisation of the Amido Black assay for determination of the protein content of grape juices and wines

While the heat/chill stability of white wines cannot be predicted from the total protein concentration, this information is useful in assessing the effectiveness of fining treatments. We have adapted the Amido Black assay for use in grape juice and wine. The response of bovine serum albumin (BSA) was similar in water, model wine and model juice. The linear range of the assay (<100 mg l^?1) extends beyond protein concentrations typically found in grape juices and wines. The limit of quantification was 11.1 mg l^?1 for BSA in model wine and 7.6 mg l^?1 in model juice, while the limit of detection was found to be less than 3 mg l^?1 in either solution. In contrast to other methods of protein determination, this assay is not affected by common wine phenolic and pectic compounds or by glutathione. The mean response of BSA was similar in model juice and red and white grape juices. The mean response of BSA in red wine was lower than in white wine and model wine (p < 0.001), and there was considerable variation in response among wines. Protein concentrations determined using this method were reproducible (CV < 10%). This optimised assay can be used to monitor protein levels in grape juices and wines. © 2001 Society of Chemical Industry     

Automated analytical method for the determination of individual sugars in mixtures of glucose,fructose and sucrose

An automated colorimetric method, using p-hydroxybenzoic acid hydrazide and 2-thiobarbituric acid as colour reagents for the determination of total reducing sugars and fructose respectively, is described. The normal measurement range of reducing sugars is 50–1500 mg litre^?1, but with a simple modification of the autoanalyser arrangement it can be reduced to 1–30 mg litre^?1 or increased to 500–6000 mg litre^?1 without affecting the linearity of the calibration curve. Recovery of sugars by the known addition technique using this method range from 97 to 104%. The method is applicable for the joint determination of glucose, fructose and sucrose in fruits, vegetables and fermentation liquors.     

Formation of cyanide as a product of decomposition of cyanogenic glucosides in the treatment of elderberry fruit (Sambucus nigra)

Distribution of cyanogenic glucosides contained in elderberry fruit was investigated in the course of technological operations usually utilised for obtaining musts. The degree of glucoside hydrolysis was estimated by the amount of liberated hydrogen cyanide. After fermentation on skins the must contained 2.08 mg litre^?1 of hydrogen cyanide. Hydrogen cyanide in the must from depectinised fruit pulp was at a level of 2.31 mg litre^?1. After heat treatment the must contained 1.07 mg litre^?1 of hydrogen cyanide.     

Studies on the effect of protectants on Lactobacillus acidophilus strain dehydrated under controlled low-temperature vacuum dehydration and freeze-drying by using response surface methodology

Ca²⁺ (0–60 g litre^?1), glycerol (0–100 g litre^?1), and non-fat dry milk solids (NFDMS, 0–140 g litre^?1) were combined to study their effects on the survival of Lactobacillus acidophilus in controlled low-temperature vacuum dehydration and freeze-drying. A three-variable (each at three-levels) design method was used and analysed by fitting a quadratic response surface. These factors were found to be significantly effective on survival. Fitted quadratic regression equations were plotted using a graphing software package. Conditions for the best survival of freeze-drying was found to be Ca²⁺ 5.34 g litre^?1. NFDMS 100.8 g litre^?1, and glycerol 41.5 g litre^?1 and that of controlled low-temperature vacuum dehydration was Ca²⁺ 5.67 g litre^?1, NFDMS 107.1 g litre^?1, and glycerol 41.0 g litre^?1. Models obtained were tested using t-tests. Survival of freezing under different conditions was found to be not significantly different.     

Survey of sulfites in wine and various Turkish food and food products intended for export, 2007–2010

Surveys were carried out between 2007 and 2010 to determine the total levels of sulfites in 1245 samples of wines, dried apricots, dried vegetables, nuts, juices and purees, frozen foods and cereals containing dried fruit supplied by food inspectors and by food producers for testing or for export certification. Sulfite analysis of wine was carried out using the Ripper method with an LOQ of 5?mg?l^?1 and for dried and other foods the Monier-Williams distillation procedure was employed with an LOQ of 10?mg?kg^?1. In the survey all wines contained measurable sulfites, but with the exception of one sample of white wine they were otherwise below Turkish Food Codex limits of 160?mg?kg^?1 for red wine, 210?mg?kg^?1 to white wine and 235?mg?kg^?1 for sparkling wine. None of the cereal products, frozen foods, juices or purees contained sulfites above 10?mg?kg^?1. However, all dried apricot samples contained significant levels of sulfite with around 40% having levels exceeding the Turkish limit of 2000?mg?kg^?1. Significant levels of sulfite were found in other samples of dried fruit with even a fruit and nut bar containing 1395?mg?kg^?1 of sulfite, suggesting the dried fruit ingredients contained levels above regulatory limits.     

Influence of nitrogen form and concentration on the nitrate reductase activity of winter barley (Hordeum vulgare L cv Igri)

Winter barley (Hordeum vulgare L cv Igri) plants were grown for 5 weeks in a controlled environment room using a recirculating nutrient solution culture system at a root and shoot temperature of 10°C. When solution NO₃-N concentration was varied between 0 and 64 mg litre^?1, shoot endogenous and induced nitrate reductase activity (NRA_e and NRA_i respectively) increased asymptotically from zero in plants grown with O mg NO₃-N litre^?1 to a maximum activity in solutions containing ? 16 mg NO₃-N litre^?1. Shoot Nitrogen Response Index (NRI = NRA_i/NRA_e) showed an opposite trend decreasing from a maximum of 2.6 at 2 mg NO₃-N litre^?1 to a minimum approaching unity when ? 32 mg N litre^?1 was supplied. In a separate experiment, nitrogen form (NO₃-N, NH₄-N or a 1:1 mixture) had a marked influence on shoot NRA. Enzyme activity was negligible in tissue from plants absorbing NH₄-N, highest in NO₃-fed plants and intermediate in those supplied with both N forms. NRI, however, approached unity in all treatments. The results provide evidence to suggest that NRI may be used as an indicator of the N status of barley plants grown with varied N nutrition.     

Trace elements in Canadian field peas: a grain safety assurance perspective

Canada is a significant exporter of field peas and, thus, issues of food safety are important in all grain and food products within the international marketplace. Environmental contaminants, such as trace elements, may be present in all foods and, as a result, international standards have been established for a number of toxic trace elements, such as cadmium, lead, mercury and arsenic, in raw food commodities and food products. The Canadian Grain Commission has undertaken a baseline study of various trace elements in Canadian peas to ensure compliance with international food safety legislation. Mean total cadmium content was found to be 0.023 mg kg^?1; arsenic and lead mean values were below the method limit of quantification of 0.050 mg kg^?1 and the total mean mercury level was below the quantification level of 0.002 mg kg^?1. All measured values in the study were below the maximum residue levels (MRLs) established by the FAO and WHO in the Codex Alimentarius. The mean total selenium content was 0.331 mg kg^?1, with 56% of the measured values exceeding the MRL established by the People's Republic of China (PRC) of 0.3 mg kg^?1. No Codex MRL has been established for selenium as it is regarded as an essential trace element for human health and the PRC is currently reviewing its MRL for selenium in light of this fact. For those parts of the world where selenium-deficiency is of nutritional concern, the higher level of selenium in Canadian peas and their products may be of nutritional benefit.