Effect of nitrogen fertiliser on the nitrate contents of field vegetables grown in Britain

The nitrate and percentage organic nitrogen contents of 14 vegetable and two arable crops were measured after they had been grown with different levels of N-fertiliser. Foliage crops always contained substantial quantities of nitrate which increased with increase in the rate of N-fertiliser application. Grain of legumes and cereals, storage roots of carrots, parsnips and sugar beet, and onion bulbs and leeks contained no detectable amounts of nitrate even when N-fertiliser application rates were very high. Storage roots of red beet, swede and white turnip contained more than 3 mg NON g^?1 dry weight when grown with exceptionally high levels of fertiliser-N but contained very little when grown with the optimum amount of fertiliser-N or less. An equation was developed that linked NON to percentage organic-N for those parts of plants that could accumulate nitrate. It gave good fits to the data from seven crop species grown at a range of different levels of N-nutrition. It is estimated from the foregoing data and a survey of household food consumption that the average British person consumes about 60 mg NON week^?1 in field vegetables. If N-fertilisers were withheld consumption would be about 30 mg and if excess were applied it would be about 120 mg NON week^?1.     

The extraction of radiolabelled inorganic sulphate from blood plasma

A study was conducted into factors governing the efficiency of the ion exchange method for extracting ³⁵S-labelled inorganic sulphate (SO) from blood plasma, using Dowex′1-X8 ion exchange resin. The study compared effects of trichloroacetic acid (TCA) strength as protein precipitant, different HCl strengths as resin eluent, sodium citrate/HCl (SC/HCl) versus HCl as eluents, and evaluated ultrafiltrated (UF) plasma upon the adsorption and recovery of added ³⁵SO. Both adsorption and release of ³⁵SO from the resin were inhibited by the presence of TCA, and HCl was not as effective as 1 M SC/2 M HCl in releasing ³⁵SO adsorbed to resin. The rates of ³⁵SO adsorbed onto resin and recovered were markedly increased by using UF plasma and 1 M SC/2 M HCl as eluent, with the values being 96.3 ± 0.11% and 91.1 ± 0.39%, respectively, where 1 g resin was used. Therefore, the use of UF for deproteinising and 1 M SC/2M HCl as eluent are recommended for extracting ³⁵SO from blood plasma when Dowex′1-X8 resin is used as the ion exchanger.     

Acceptability of diets containing olive oil fried sardines (Sardina pilchardus) in the prevention of dietary hypercholesterolaemia in rats

Garlic (Allium sativum L) bulb explants produced undifferentiated white globular callus when grown on MS medium having 2,4-dichlorophenoxy-acetic acid (2,4-D) and Kinetin (Kn). Such callus when grown on medium having indole-3-yl-acetic acid (IAA) and/or Kn developed into the differentiating callus which had comparatively more allicin than that of undifferentiated callus. The effect of sucrose, NH/NO ratios and hormone concentrations on growth and allicin development in the callus was investigated. There was a significant increase in allicin development in callus when grown for up to 4 weeks on medium (a) having sucrose at 3% and 5% levels; (b) having NH and NO ratios at 2:1 and 1;1; and (c) with Kn alone at a concentration of 0.5 mg litre^?1, which produced a tenfold increase in allicin content.     

Quantity/intensity relations in soils and the potassium nutrition of the strawberry plant (Fragaria SP)

In glasshouse pot experiments over two years, the strawberry plant used potassium primarily from sources which were in instantaneous equilibrium with the soil solution. Leaf potassium concentration at flowering and fruiting was highly correlated with the initial equilibrium potassium activity ratio (AR) of the soil, and a linear relationship existed between 1/Leaf-K and 1/AR Yield of fruit was less well correlated with AR than with the quantity of labile potassium in the soil. the gradient of the straight line part of the quantity/intensity (Q/I) graph was increased for 2 of the 5 soils after the period of intensive cropping; this could be related to an increase in the amount of exchangeable calcium+magnesium in the soil.     

Dissolution of various sources of gypsum in aqueous solutions and in soil

The dissolution of six sources of gypsum in water and 0.01 M CaCl₂ was examined in the presence and absence of soil. The gypsum samples included: analytical grade (AR), three sources of flue-gas desulphurisation (FGD) gypsum, phosphogypsum (PG), and mined gypsum (MG). Dissolution in aqueous solutions was monitored by measuring the concentration of calcium (Ca²⁺) and sulphate (SO) ions. In soils which adsorb small amounts of SO^?2₄, dissolution was estimated from the increase in the concentration of Ca²⁺ and SO in gypsum-treated soil over the control soil. However, in soils which adsorb significant amounts of SO, measurement of solution SO concentration underestimates the extent of dissolution. Gypsum dissolution was larger in water (15.20 mmol litre^?1) than in 0.01 M CaCl₂ (11.12 mmol litre^?1), and this was attributed to the Ca²⁺ common-ion effect. The rate of dissolution decreased in the order: AR > FGD > PG > MG. Dissolution was 2 to 10 times faster for powdered (< 500 .m) gypsum than for the discs obtained by pelletising. The differences in the rate of dissolution between the gypsum sources and between powder and disc samples were related to both surface area and the presence of CaCO₃, impurity. The rate of dissolution was 3 to 8 times faster in the presence than in the absence of soil. Whereas the dissolution of gypsum in the presence of soil followed first order reaction kinetics, it followed second order kinetics in the absence of soil. This difference in reaction kinetics resulted from the continuous removal of Ca2+ and SO by the soil.     

The relative merits of the presence of hull on the nutritional qualities of the African yam bean flour

The flour from three colour cultivars of hulled and dehulled seeds of the African yam bean (AYB) (Sphenostylis stenocarpa) was analysed for anatomical fractions; proximate, mineral, fatty and amino acids composition. The seed hull varied between 8.25% and 9.14%. Na, K. Ca, Mn, Fe, Zn are preferably found in the hulled samples. Essential fatty acids as well as essential amino acids are more enriched in the hulled samples than in the endosperm. Correlation coefficient results showed that proximate composition (r, r, r), mineral composition (r, r, r), fatty acids (r, r, r), fatty acids saturation (r, r, r) and amino acids (r, r, r) were significant at α = 0.05 in the samples shown in parentheses with values having high positive correlation coefficients ranging from 0.82 to 1.00. These results showed that dehulling of African yam bean seeds will lead to reduction in the nutritional qualities of the AYB.     

Intrinsic viscosities and apparent specific volumes of amino acids and sugars. ‘Effective size’ and taste of sapid molecules

Intrinsic viscosities ([η]) and apparent specijic volumes (V) are compared for a number of amino acids and simple sugars and their derivatives. While the sugars and their derivatives fit within a narrow range for both parametevs ([η])=2.27–2.61 cm³ g^?1; V=0.60–4.69 cm³ g^?1), the amino acids cover a much wider band ([η]) = 1.29–4.20 cm³ g^?1; V=0.562–0.712 cm³ g^?1). The intrinsic viscosity value of any particular amino acid is always greater than the corresponding apparent specijc volume, and ranges (at 10 mg g^?1) between two and seven times the value of the apparent specific volume. For the sugars and sugar derivatives, on the other hand, the intrinsic viscosities are always three to four times greater than the values of the corresponding apparent specijic volumes. When concentration is increased, all apparent specific volumes increase but they remain relatively constant if they are expressed as parachors (Vγ^1/4). Differences between the sugars and amino acids originate in the greater structural diversification of the latter molecules which in turn accords with their greater range of taste qualities.     

Oxidation and transformation of elemental sulphur in soils

The oxidation of ³⁵S-S⁰ (³⁵S-S⁰, sulphur flowers) added to four cultivated soils was well described using first-order kinetics. The half-life (t_l/2) of ³⁵S-S⁰ ranged from 12 days in a paddy soil to 176 days in an Ultisol. During the early phase of oxidation, a large proportion of the oxidised S was incorporated into organic fractions. After the first week any additional ³⁵S-S⁰ oxidised remained primarily as SO-S in most of the test soils. The amount of KH₂PO₄- extractable ³⁵S-SO-S as a percentage of total oxidised ³⁵S-S was at a maximum when approximately half of the added ³⁵S-S⁰ was oxidised. By the end of the 56-day incubation period, with the exception of the Ultisol, 54–70% of the oxidised ³⁵S-S in the test soils was present as ³⁵S-SO-S. The remaining oxidised S is presumed to have been converted into organic matter fractions. This ³⁵S-organic-S could be fractionated into the 0.1 M KH₂PO₄-extractable organic- S (5–13% of total oxidised ³⁵S-S) and the 0.01 M NaOH-extractable organic-S (14–23% of total oxidised ³⁵S-S). With the exception of the Ultisol where the undetermined organic S was about 36%, the amounts of unaccounted for S (not directly measured), in all soils were very small (typically less than 4%).     

Interaction between cow slurry and 15N-labelled calcium nitrate as fertilisers for ryegrass production

A field-plot experiment with ryegrass was carried out to study the interaction between ¹⁵N-labelled calcium nitrate at 0, 25 and 50 kg N ha^?1 and cow slurry supplying 0, 33 and 68 kg NH-N ha^?1. Treatments were applied on a single occasion to a site where first-cut silage had just been removed. The effects of the treatments on dry matter yield, nitrogen offtake and % utilisation of calcium nitrate were measured in two cuts of herbage taken after 5 and 17 weeks. Increases in dry matter yield due to slurry were smaller at the 50 kg N ha^?1 rate of calcium nitrate than at the 0 and 25 kg N ha^?1 rates, possibly due to non-linearity of the yield response curve. Nitrogen offtake data indicated that the two sources of nitrogen were taken up additively by the ryegrass. Rate of calcium nitrate application or slurry treatment had no significant effect on the % utilisation of calcium nitrate in either cut. The average values for % utilisation of calcium nitrate over all treatments were 50 and 7% at cuts 1 and 2, respectively. There was no evidence for enhanced rates of denitrification in the presence of slurry. Recovery values of nitrogen (estimated by difference) were lower for NH-N in slurry than for calcium nitrate. Volatilisation of ammonia from surface-spread slurry is the most likely reason for the low efficiency of NH-N in slurry.     

Kinetics of coffee infusion: a comparative study on the extraction kinetics of mineral ions and caffeine from several types of medium roasted coffees

A comparative study of the equilibrium concentrations, rates of infusion and intra‐bean diffusion coefficients of caffeine, P (as H₂PO ), K⁺, Mg²⁺ and Mn²⁺ in Milli‐Q‐Water at 80 °C was carried out. Medium roasted coffees of particle size range 1.70–2.00 mm from six different countries—Special Kenya (Kenya), Santos (Brazil), Blue Mountain Java (Sumatra), Mocha (Ethiopia), Zimbabwe (Zimbabwe) and South African Grown (South Africa)—were used in the investigation. High‐performance liquid chromatography was used for the analyses of caffeine, and inductively coupled plasma atomic emission spectrometry for the chosen elements. The equilibrium concentrations of all the species and the trend were found to be independent of the various coffee beans. The order of the rate of infusion was found to be K⁺ > caffeine > P (as H₂PO) > Mg²⁺ > Mn²⁺. Examination of the rate constants clearly indicated that P (as H₂PO), Mg²⁺ and Mn²⁺ cannot be used for identification of the coffee origin, but the values for caffeine and K⁺ can be used. Diffusion coefficients of caffeine and mineral ions were calculated in two separate ways using rate constants and half‐lives of infusion. These were then compared with known diffusion coefficients of the same species in water for determination of hindrance factors. The hindrance factor for caffeine was found to be much smaller than the corresponding factors recorded at 25.5 °C. In general the hindrance factors in the bean were all of the order of 10, with Mn²⁺ being the most hindered species. This is an indication that the infusion of the various species through the coffee bean is a hindered process. This is because of the association of caffeine and mineral ions with other coffee solubles and the physical restraint within the bean matrix. © 2000 Society of Chemical Industry     

Reducing gaseous losses of nitrogen from cattle slurry applied to grassland by the use of additives

Losses of nitrogen (N) through ammonia (NH₃) volatilisation and denitrification were determined following the application of cattle slurry to grassland in autumn or spring. Denitrification was examined on two contrasting soils. A system of small wind tunnels was used to measure NH₃ loss and an acetylene inhibition technique for denitrification. Between 31 and 84% of the ammonium N (NH-N) applied in slurry was lost through NH₃ volatilisation. Acidifying the slurry to pH c 5.5 prior to application reduced these losses to between 14 and 57%. On a freely drained loam soil, denitrification from unacidified slurry applied in the autumn at 80 m³ ha^?1 was continuous throughout the winter, with the maximum rate of 0.91 kg N ha^?1 day^?1 occurring a few weeks after slurry application. The total denitrification losses were equivalent to about 29% of the NH-N applied for this treatment and 41% for the acidified slurry. The nitrification inhibitor dicyandiamide reduced the amount of N lost through denitrification by 70% when applied with the slurry at 25 kg ha^?1, by 55% at 20 kg ha^?1 and by 30% at 15 kg ha^?1. The nitrification inhibitor nitrapyrin did not appreciably reduce denitrification. Denitrification losses were consistently small from slurry applied to the freely drained loam soil in spring, or to a poorly drained, silty clay in autumn or spring. Neither nitrification inhibitor was of benefit in these situations.     

Ion chromatographic determination of inorganic anions in vinegar samples

An ion chromatographic procedure (IC) with chemical suppression is described for the simultaneous determination of the anions Cl^?, NO, HPO and SO at ppm levels in vinegar samples. The moderately strong eluent composed of NaHCO₃/Na₂CO₃ was chosen and sample pretreatment was required to reduce the influence of acetate on the chloride peak. The results obtained by IC were compared to those from standard methods.     

Analysis of proanthocyanidins in coffee pulp

Data are presented for the condensed tannins content of pulp prepared immediately from die cherries of three cultivars of freshly harvested coffee beans, and for the pulp after drying. The data have been interpreted with reference to purified quebracho profisetinidins (3.13–6.17% on a dry basis (db)) and to the E% values of the anthocyanin pigments formed by oxidative depolymerisation (0.60–1.19% db). Pulp from a yellow-fruited cultivar was significantly richer (P < 0.001) than pulp from the associated red-fruited cultivar. In contrast to previous reports the presence has been established of condensed tannin in the pulp at the time the cherry was harvested although an increase was observed on subsequent drying. Prodelphinidins could not be detected, but the presence of procyanidins was confirmed. Analysis of procyanidin dimer-rich and procyanidin oligomer-rich fractions suggested that while dimers dominate in undried pulp, dimers may be converted to oligomers during drying. Measurements of haemoglobin precipitation (relative astringency) were generally consistent with increased tannin content/polymerisation after drying but little interaction with methylene blue was detectable in any sample.     

Colour score as a guide for estimating the protein value of corn gluten feed

BACKGROUND: Dry corn gluten feed (CGF) is a raw material commonly included in compound feeds, particularly for ruminant animals. Its colour can vary from yellow–light brown to dark brown. A general assumption is that darker CGF has a low nutritive value for animals due to heat‐damaged protein. This study aims to evaluate the use of colour as a practical guide for estimating CGF protein value. RESULTS: Results indicate great variability in the physical and nutritional properties among 28 sources of CGF. Principal component factor analysis was used to reduce a large number of variables into fewer numbers of factors. First factor aggregated 1/Z and acid detergent insoluble N content in opposition to X, Y, e^L, and L. Second factor aggregated a, a*, neutral detergent fibre and soluble crude protein (CP) contents in opposition to ash and CP contents, and digestible N and in vitro organic matter digestibility. Multiple regression analysis also showed that physical appearance (colour) was related to nutritional properties, stronger relationships being found between a, a* and L scores and digestible N. CONCLUSION: Colour could potentially be used to quickly predict the nutritive value of CGF, particularly digestible N, a key parameter when formulating rations. Copyright © 2011 Society of Chemical Industry     

Effect of Various lons on the Kinetics of Retrogradation of Concentrated Wheat Starch Gels

The effect of various ions on the mode and kinetics of concentrated wheat starch gels retrogradation was investigated. The anions SCN^-, I^-, NO, Br⁻, F⁻ and SO, and the cations K⁺, Li⁺ and Na⁺ were tested at 0,4-M concentration. Teh results, based on the Avrami theory, indicated that the mechanism of starch crystallization is instantaneous nucleation followed by rod-like growth of crystals regardless the ion present. The retrogradation rate for the halogens anions increased in the following order: I⁻, Br⁻, CI⁻ and F⁻. The retrogradation rate for the cations increased in the following order: K⁺, Li⁺ and Na⁺. The results obtained were dependent of the charge distribution of the anions studied.     

State diagram of salmon (Salmo salar) gelatin films

BACKGROUND: A state diagram presents different physical states of a biomaterial as a function of solid content and temperature. Despite their technological interest, little information is available on protein systems such as gelatin/water mixtures. The objective of this work was to develop state diagrams of salmon gelatin (SG) and bovine gelatin (BG) in order to determine maximal freeze concentration parameters (T′_g, T′_m and X_s′) and to relate possible differences to their biochemical characteristics. RESULTS: Biochemical characterisation of SG showed lower molecular weight and iminoacid concentration compared with BG. Likewise, the glass transition temperature (T_g) was lower for SG at X_s > 0.8, which was associated with its lower molecular weight. Unexpectedly, the depression of freezing temperature (T_f) was greater for SG at X_s > 0.1, which was associated with its higher ash content. Isothermal annealing produced effective values of T′_g ≈ ? 52 °C, T′_m ≈ ? 46 °C and X′_s ≈ 0.6 for both gelatins. Interestingly, the enthalpy change associated with T′_m (ΔH) was significantly higher for SG than for BG after annealing, indicating a higher proportion of ice present at about ? 50 °C. CONCLUSION: Maximal freeze concentration parameters were similar between the two gelatins, though differences in biochemical properties were evident. The results show that there are likely different ways of interaction of SG and BG with water. Copyright © 2011 Society of Chemical Industry     

The rheological properties of diluted solutions of 11 S-globulin isolated from soybeans by using selective thermal denaturation of 2 S- and 7 S-globulins

A simple and effective method of isolating 11 S-globulin (glycinin) from soybeans has been developed, which is based on the use of selective thermal denaturation of other components in globulin fraction. Glycinin content in the final preparation accounts for 97%, and its yield constitute about 1 g per 100 g of defatted flour (about 7% of glycinin content in flour). According to differential scanning microcalorimetry, the isolated preparation in terms of thermodynamics is identical with glycinin isolated by the method of THANH-SHIBASAKI with chromatography on hydroxyl apatite. The steady state viscosity of diluted solutions of the preparation was studied in four solvents: A - phosphate buffer pH 7.6, ionic strength 0.5; B - water pH 7.1, ionic strength below 0.001; C - 8 M guanidin - HCl; D - 8 M guanidine - HCl, containing 0.001 M 2-mercaptoethanol. Dependences of steady state viscosity on protein concentration (0.5 – 7.0 g/dl) and temperature (1 60 °C) were obtained. A study was also made on the fractional composition of the preparation in the indicated solvents by the sedimentation velocity method. According to the data of sedimentation velocity and viscosimetry, the molecular weights of various glycinin forms were determined. The values obtained are consistent with the published data. Analysis of the hydrodynamic properties of dodecameric and hexameric glycinin forms shows that they are similar to spheres of equal density, but of different size. In the investigated range of concentrations and temperatures, the intermolecular interactions play an insignificant role in the rheology of glycinin solutions (parameter of excluded volume according to MOONEY K α 0; excess effective activation enthalpy in viscous flow H. Only in water of about 4′ C, which is close to the temperature of glycinin precipitation, the role of intermolecular interactions is significant; this follows from the value H α 11 ± 7 kJ/mole.     

Effect of root zone pH and form and concentration of nitrogen on accumulation of quality‐related components in green tea

Green tea quality is greatly influenced by concentrations of free amino acids, polyphenols (mainly catechins) and caffeine. The present study investigated the principal relationship between selected nutritional factors (form and concentration of N supply, root zone pH) and accumulation of these quality‐related components of tea (Camellia sinensis (L.)) plants. Tea plants were hydroponically cultured with NH , NO and NH NO at pH 4.0, 5.0 and 6.0 in one experiment and supplied with varying N concentrations (0.75, 2.0 and 4.5 mmol L^?1, NH /NO^?₃ = 3:1) in another experiment. Concentrations of free amino acids were considerably higher in NH ‐ than in NO ‐fed plants. This was attributed to the much greater absorption of NH compared with NO . Furthermore, the relative allocation of absorbed N to free amino acids, particularly theanine and glutamine, was substantially increased by NH nutrition, suggesting that NH was more readily assimilated than NO into theanine. The concentration of caffeine was increased in NH ‐ and (NH NO )‐supplied plants, whereas concentrations of catechins were reduced in (NH NO )‐fed plants. Root zone pH did not influence concentrations of most free amino acids in young shoots, with the exception of theanine, which increased at low pH (4.0) irrespective of N form; this likely stemmed from an accumulation effect, as growth decreased more strongly than N absorption. Raising the N supply increased plant N allocation to free amino acids. The increase was most striking for arginine, while theanine was only marginally affected. This may have adverse consequences for green tea quality, as less favourable taste characteristics have been attributed to arginine. Copyright © 2007 Society of Chemical Industry     

A Survey of Nitrate and Nitrite Concentrations in Conventional and Organic‐Labeled Raw Vegetables at Retail

A national survey of the nitrate () and nitrite ( ) concentrations in raw and highly consumed vegetables available at retail in the United States was conducted. A total of 194 samples of fresh broccoli, cabbage, celery, lettuce, and spinach categorized as conventional or organic by label were collected from 5 major cities in different geographic regions of the United States and analyzed to determine and concentrations. There were no differences in the mean values of conventional compared with organic vegetables taken from the 5 metropolitan areas. However, significant differences in mean pairwise comparisons between some conventional and organic vegetables for content were observed. The mean concentration of both conventional and organic vegetables ranged between 0.1 and 1.2 mg/kg of fresh weight (FW) with the exception of conventional spinach that contained 8.0 mg/kg FW. Mean contents of conventional broccoli, cabbage, celery, lettuce, and spinach were 394, 418, 1496, 851, and 2797 mg/kg FW, respectively, while their organic‐labeled counterparts averaged 204, 552, 912, 844, and 1318 mg/kg FW. In most cases, organic vegetables were numerically lower in content than their conventional counterparts. Based on survey results, the finding that low levels were observed in some organic vegetables in different cities may warrant further study to determine if true differences exist, due to production practices, seasonal differences, and the magnitudes of those differences. Furthermore, the geographic differences in content of vegetables may flaw estimates of daily and exposure.     

Properties and Heterologous Expression of the Glucose Transporter GHT1 from Schizosaccharomyces pombe

Genomic DNA of the Schizosaccharomyces pombe glucose transporter, GHT1, was obtained by complementation of the glucose transport deficient Sz. pombe strain YGS-5. Here we describe the GHT1 gene that encodes a protein of 565 amino acids with a corresponding molecular mass of 62·5 kDa. This eukaryotic glucose transporter contains 12 putative transmembrane segments and is homologous to the HXT multigene family of S. cerevisiae with several amino acid motifs of this sugar transporter family. It is also homologous to other sugar carriers from human, mouse and Escherichia coli. The function of the Ght1 protein as a glucose transporter was proved both by homologous and heterologous expression in the Sz. pombe mutant YGS-5 and in the S. cerevisiae hxt mutant RE700A, respectively. Both transformed yeast strains transported d -glucose with substrate specificity similar to that in Sz. pombe wild-type cells. Moreover, the cells of the two transformed yeast strains accumulated 2-deoxy-d -glucose, a non-metabolizable d -glucose analogue, with an efficiency similar to Sz. pombe wild-type cells. The ability of the S. cerevisiae mutant RE700A to accumulate 2DG in an Δμdependent manner after transformation with GHT1 provides evidence that the Sz. pombe transporter catalyses an energy-dependent uptake of glucose. The sequence of GHT1 was deposited at EMBL, Outstation EBI, Accession Number X91218. ©1997 John Wiley & Sons, Ltd.