Aroma compounds and sensory characteristics of Arneis Terre Alfieri DOC wines: the concentration of polyfunctional thiols and their evolution in relation to different ageing conditions

Arneis is an Italian autochthonous white grape cultivar. This study involved investigating the chemicophysical, aromatic composition and sensory evaluation of Arneis wine in relation to different oenological practices during winemaking and ageing. For the first time, polyfunctional thiols related aromas were identified above their perception threshold in Arneis wine. Moreover, citrus, grapefruit and tropical fruit notes characterized this wine during the first month of ageing, thus suggesting a strong correlation between chemical and sensory results. The concentration of thiols decreased rapidly during the first month of ageing, together with the tropical fruit notes. In particular, the perception of the grapefruit note of the wine decreased in association with the 3-mercaptohexyl acetate content in both the barrel and stainless steel (ST) aged wines. Moreover, the ageing technique clearly affected wine composition and sensory profile; barrel aged wines were characterized both by vanilla and honey notes, and a weaker perception of thiols despite containing a similar concentration to ST aged wines. Within this study, the ability of glutathione to decrease the oxidation of volatile thiols in Arneis wine was confirmed, but under experimental conditions employed, the addition of reduced glutathione did not lead to any statistically significant differences in sensory results.     

Fertiliser requirements of potatoes in relation to kind of soil and soil analysis

Responses of maincrop potatoes to N, P and K fertilisers were measured in 119 experiments done by Soil Scientists of the National Agricultural Advisory Service in the years 1955-62. The experimental sites were spread over 13 soil groups, most of which corresponded to particular soil series. Average crop responses to P and K are given for each soil group. The amount of response was related to soil texture and to content of soluble P or K in the soil. For a given content of soluble P in the soil, crops on loamy sand and sandy loam soils gave a larger response to the first level of P fertiliser (0.5 cwt P₂O₅ per acre) than did those on silty loams, clay loams and clays; but the additional response to the second level of P fertiliser and, consequently to the optimum dressings of P, was greater for crops grown on the heavier-textured soils. P response was also related to depth of freely drained soil, sites with impeded drainage giving larger responses to P than freely drained sites. The proportion of soils poor in K, crop responses to K and optimum dressings of K fertiliser were all greater for the loamy sands and sandy loams than for the silty loam, clay loam and clay soils. The optimum dressings of N and K for almost all the soil groups were less than the average amounts currently used on maincrop potatoes in Great Britain; however, the seasons seem to have been relatively unfavourable to N and K responses. For P, the average amounts used were less than the optimum for most of the silty loam, clay loam and clay soils but more than the optimum for most soils of lighter texture.     

The availability to pasture plants of native and applied soil cobalt in relation to extractable soil cobalt and other soil properties

In pot trials using a range of soils from South-East Scotland, plant cobalt concentrations were significantly correlated with the amounts of cobalt extracted from soil with 0.05 M calcium chloride. Plant cobalt concentrations were also correlated with soil pH, showing a decrease with increasing soil pH. There were no significant correlations between plant cobalt concentrations and 0.5 M acetic acid-extractable cobalt, 0.04 M EDTA-exttactable cobalt, isotopically exchangeable cobalt or total soil cobalt. Uptake of cobalt by ryegrass from cobalt added to the soil was inversely related to both the ability of the soil to sorb cobalt and to soil pH.     

Speciation of Se in Bertholletia excelsa (Brazil nut): A hard nut to crack?

A separation method based on ion-pairing liquid chromatography was combined with both elemental (inductively coupled plasma mass spectrometry (ICP-MS)) and molecular (electrospray tandem mass spectrometry (ES-MS-MS)) mass spectrometry in order to unravel the identity of the Se-species present in the complex matrix of Brazil nuts rich in Se. Via enzymatic digestion, Se-species were released from the matrix. Subsequently the species were separated and the Se was monitored on-line by ICP-MS. By HPLC–ES-MS-MS, the species were identified based on their molecular mass and their specific product ions. The main compound was identified as Se-Methionine. Another compound was identified as Se-Cystine, partly on the basis of the isotopic pattern of Se. This research was further extended to the analyses of in vitro gastrointestinal digests of the Brazil nuts. These digests were analyzed for their Se-content and screened for the presence of the different Se-species by HPLC–ICP-MS. In both the gastric and the intestinal digests, we were able to identify the Se-species as Se-Methionine and Se-Cystine by HPLC–ES-MS-MS. By coupling HPLC to both elemental and molecular mass spectrometry, the species present in Brazil nuts and supposedly extractable by our body were fully characterized.     

A study of the solution properties of selected binary mixtures of bulk and intense sweeteners in relation to their psychophysical characteristics

The solution properties of binary mixtures of two bulk sweeteners (sucrose and maltitol) and three intense sweeteners (acesulfame K, aspartame and sodium cyclamate) were studied. The parameters measured were apparent specific volumes, isentropic compressibilities and compressibility hydration numbers. An attempt has been made to correlate the solution properties of some of the mixtures with their sweetness responses. Both specific volume and isentropic compressibility data have been used to interpret the possibility of synergism or suppression in the mixtures in terms of the affinity of the solutes for the surrounding solvent structure, and hence the effectiveness of transport of the molecules to their appropriate receptor sites. However, an understanding of the nature and stereochemistry of the individual components in the mixtures is necessary for predicting the packing characteristics of molecules in water and their accession to receptor sites. The intense sweeteners seem to play an important role in modifying the structure of water in solution. Although there is no clear proof of how this affects perception, fine differences in solution behaviour can be observed with isentropic apparent specific compressibility measurements. The study supports the idea that receptors lie at different depths in the lingual epithelium, and also that in two-component systems, one species may alter the packing efficiency of the other in solution sufficiently to effect a change in taste quality or intensity.     

Zinc bioavailability in wheat grain in relation to phosphorus fertiliser,crop sequence and mycorrhizal fungi

BACKGROUND: While human diets are often deficient in zinc (Zn), the impacts of crop management on Zn in cereal grains are rarely examined. In this study the effect of phosphorus (P) fertiliser and crop sequence (wheat following canola, linola, fallow or pasture) on wheat grain Zn concentration and bioavailability for humans was investigated. RESULTS: The Zn concentration of wheat grain decreased by 33–39% in response to P fertiliser. It was also 30–40% lower for crops following canola and fallow than for those following linola and pasture. P fertiliser decreased the colonisation of arbuscular mycorrhizal fungi (AMF) in wheat roots, and canola and fallow led to lower colonisation than linola and pasture. Since AMF are known to assist in soil uptake of immobile nutrients such as Zn, it is hypothesised that P fertiliser and crop sequence affected grain Zn concentration through AMF. P fertiliser also increased the concentrations of grain P by 17% and grain phytic acid (PA) by 19%, but had little effect on the concentrations of calcium (Ca), iron (Fe) and polyphenols. Other impacts of crop sequence were slightly higher concentrations in grain of P after pasture and Fe after canola. The bioavailability of grain Zn, as shown by the PA:Zn and Ca × PA:Zn molar ratios, mostly reflected Zn concentration and was low in all treatments. After milling, the PA:Zn molar ratio suggested low Zn bioavailability for flour from wheat grown with P fertiliser after canola or fallow. CONCLUSION: Crop management can affect the bioavailability of Zn in wheat grain, with practices leading to high yields potentially leading to low Zn bioavailability. Copyright © 2008 Society of Chemical Industry     

Speciation, characterization, and mobility of As, Se, and Hg in flue gas desulphurization residues

Flue gas from coal combustion contains significant amounts of volatile toxic trace elements such as arsenic (As), selenium (Se), and mercury (Hg). The capture of these elements in the flue gas desulphurization (FGD) scrubber unit has resulted in generation of a metal-laden residue. With increasing reuse of the FGD residues in beneficial applications, it is important to determine metal speciation and mobilityto understand the environmental impact of its reuse. In this paper, we report the solid phase speciation of As, Se, and Hg in FGD residues using X-ray absorption spectroscopy (XAS), X-ray fluorescence spectroscopy (XRF), and sequential chemical extraction (SCE) techniques. The SCE results combined with XRF data indicated a strong possibility of As association with iron oxides, whereas Se was distributed among all geochemical phases. Hg appeared to be mainly distributed in the strong-complexed phase. XRF images also suggested a strong association of Hg with Fe oxide materials within FGD residues. XAS analysis indicated that As existed in its oxidized state (As(V)), whereas Se and Hg was observed in primarily reduced states as selenite (Se(IV)) and Hg(I), respectively. The results from the SCE and variable pH leaching tests indicated that the labile fractions of As, Se, and Hg were fairly low and thus suggestive of their stability in the FGD residues. However, the presence of a fine fraction enriched in metal content in the FGD residue suggested that size fractionation is important in assessing the environmental risks associated with their reuse.     

Crop composition in relation to soil pH and root cation-exchange capacity

Using a granitic soil limed to give pH values from 4–5 to 7–5, variation in the mineral composition of oats, barley, wheat, swede and potato was examined in relation to soil pH and the possible effect of root cation-exchange capacity (CEC). An increase in soil pH caused increases in root CEC, total cation (Ca+Mg+K+Na) and N contents of the monocotyledon crops but produced no change in root CEC and no consistent variation in total cations or N of the dicotyledon crops. Distinctly different cation translocation patterns were found between monocotyledons (low CEC) and dicotyledons (high CEC). The former favour translocation of monovalent cations, thus leaving their roots richer in divalent cations, while the opposite process takes place in swedes, but not in potatoes. This feature may be related to differences in the number of exchange sites in the roots and other tissues of these two classes of plant. Little change in P content was noted in tops of swedes or potatoes, but it increased with soil pH in cereal tops. Liming had variable effects on the contents of Fe, Mn and Cu. The Fe content of cereal tops altered little but both swede and potato tops had higher contents at high pH. The rate of reduction in the Mn content of the tops of all crops, except barley, increased above pH 6·0 or 6·5; little change in the Cu content of cereal or potato tops was noted, but levels in swede tops and potato tubers fell sharply on liming.     

Uptake of heavy metals by vegetable plants grown on contaminated soil and their bioavailability in the human gastrointestinal tract.

Lettuce, spinach, radish and carrot were grown on compost that had previously been contaminated at different concentrations of Cd, Cu, Mn, Pb and Zn. Control plants of each vegetable were also grown on unadulterated compost. The experiment was carried out under greenhouse conditions. Mature plants were harvested and their roots and leaves collected. Soil samples from each growing pot and plant materials were acid digested and analysed to determine total metal concentration. Flame-Atomic Absorption Spectroscopy (FAAS) was employed to determine metal concentrations in soil and plant samples (Mn and Zn), while Cd, Cu and Pb in plant materials were analysed by Differential Pulse Anodic Stripping Voltammetry (DP-ASV). Soil (BCR 146R and GBW 07310) and plant (tea leaves, INCT-TL-1) certified reference materials were used to assess accuracy and precision. The edible part of plants, i.e. the leaves of lettuce and spinach and the roots of radish and carrot, were also extracted using an in vitro gastrointestinal (GI) extraction to assess metal bioavailability. The results showed that the uptake of Cd, Cu, Mn and Zn by plants corresponded to the increasing level of soil contamination, while the uptake of Pb was low. Soil-to-plant transfer factor (TF) values decreased from Mn > Zn > Cd > Cu > Pb. Moreover, it was observed from this investigation that individual plant types greatly differ in their metal uptake, e.g. spinach accumulated a high content of Mn and Zn, while relatively lower concentrations were found for Cu and Pb in their tissues. From the in vitro gastrointestinal (GI) study, results indicate that metal bioavailability varied widely from element to element and according to different plant types. The greatest extent of metal releasing was found in lettuce (Mn, 63.7%), radish (Cu, 62.5%), radish (Cd, 54.9%), radish (Mn, 45.8%) and in lettuce (Zn, 45.2%).     

Macro- and micro-nutrients and their bioavailability in polish herbal medicaments

Several polish herbal medicaments were studied to determine trace elements and their bioavailable forms by the use of the ICP-AES method. The contents of Al, B, Ba, Bi, Ca, Cd, Cr, Cu, Fe, Mg, Mn, Ni, P, Pb, Se, Si, Ti, V and Zn were determined. The total concentrations were measured in samples mineralised with concentrated nitric acid and hydrogen peroxide in a microwave system. The one-step extraction was applied, using, as extractants: deionised water, diluted hydrochloric acid and buffer solution containing pepsin. Efficiencies of the leaching versus time were investigated. The extraction efficiencies were analysed, taking into account bioavailability of elements under conditions simulating digestion processes in the alimentary system. The contents of the examined elements in prescribed amounts of medication, were compared to the nutritional requirements and daily permissible dose. The results are considered in terms of the utility of the natural herbal medicaments as a source of minerals indispensable for proper functioning of the human organism. Some points of merit (precision of measurements, accuracy by Standard Reference Material analysis) are also considered.     

Physicochemical properties of potato and cassava starches and their mutants in relation to their structural properties

Physicochemical properties [swelling power (SP), pasting behaviour and retrogradation] of five wild type (wt), five amylose free (amf), four high-amylose (ha) potato starches (ps) and one wt and amf cassava starch (cs) were investigated. While swelling of wtps occurred in two phases, amfps showed a very fast swelling and no gel of swollen granules was observed at higher temperatures (>90 °C). Haps underwent only restricted swelling. SP of cassava starches were lower than those of potato starches. Wtps leached mainly amylose (AM) during heating at low temperatures. Molecules of higher molecular weight (MW) leached out at higher temperatures. Longer amylopectin (AP) chains [degree of polymerisation (DP) > 18] inhibited swelling while short chains (DP < 14) favoured swelling. Starch pasting behaviour of 5.0 and 8.0% starch suspensions was studied using Rapid Visco Analyser (RVA). For 5.0% suspensions, increased levels of high-MW AP and decreased levels of AM molecules led to higher peak viscosity. Longer AP chains (DP > 18) depressed peak viscosity, while short chains (DP < 14) increased peak viscosity for both concentrations. At 8.0%, peak viscosity increased with starch granule size. After 1 day of storage of gelatinised starch suspensions, wtps and especially amfps showed only limited AP retrogradation. In contrast, the high enthalpies of retrograded AP (ΔH_retro) and peak and conclusion temperatures of retrogradation (T_p,retro and T_c,retro) of haps suggested partial cocrystallisation between AM and AP. Chains with DP 18–25 seemed to be more liable to AP retrogradation. Wtcs and amfcs did not retrograde at room temperature.     

Phosphate soil tests and their suitability to assess the phosphate status of soil

Some phosphate soil tests (P-tests) are evaluated for their suitability to assess the phosphate status (P-status) of contrasting soils. A P-test at best only provides a relative estimate of the soil P-status, which may be thought of as the ability of a soil to release P either to a crop, or more specifically to a given plant root for a given period under optimum conditions with respect to all other growth factors. A P-test gives no direct information on the crop response to added P. The P-tests were evaluated on the basis of data from 29 published papers where the anion exchange resin method was among the P-tests used, and where plant P-uptake in pot experiments had been used as the evaluation basis. The evaluations ranked the P-tests in three groups: best group: anion-exchange resin method, intermediate group: water, and sodium bicarbonate methods, worst group: all ‘acid’ methods: acetate buffer, lactate buffer, citric acid, Bray-1, Truog and Bondorff methods.     

Solid-phase microextraction to predict bioavailability and accumulation of organic micropollutants in terrestrial organisms after exposure to a field-contaminated soil

The risk posed by soil contaminants strongly depends on their bioavailability. In this study, a partition-based sampling method was applied as a tool to estimate bioavailability in soil. The accumulation of organic micropollutants was measured in two earthworm species (Eisenia andrei and Aporrectodea caliginosa) and in 30-microm poly(dimethylsiloxane) (PDMS)-coated solid-phase micro extraction (SPME) fibers after exposure to two field-contaminated soils. Within 10 days, steady state in earthworms was reached, and within 20 days in the SPME fibers. Steady-state concentrations in both earthworm species were linearly related to concentrations in fibers over a 10,000-fold range of concentrations. Measured concentrations in earthworms were compared to levels calculated via equilibrium partitioning theory and total concentrations of contaminants in soil. In addition, freely dissolved concentrations of contaminants in pore water, derived from SPME measurements, were used to calculate concentrations in earthworms. Measured concentrations in earthworms were close to estimated concentrations from the SPME fiber measurements. Freely dissolved concentrations of contaminants in pore water, derived from SPME measurements, were used to calculate bioconcentration factors (BCF) in earthworms. A plot of log BCFs against the octanol-water partition coefficient (log Kow) was linear up to a log Kow of 8. These results show that measuring concentrations of hydrophobic chemicals in a PDMS-coated fiber represents a simple tool to estimate internal concentrations of chemicals in biota exposed to soil.     

Selenium speciation in the soil solution and its relevance to plant uptake

The relationship between soil and plant selenium has been investigated using two ⁷⁵SeO₃ spiked silt loam soils from the Hoosfield series with long-term equilibration pH values of 4.5 and 7. Lolium perenne plants were grown in the soils over a 15-week period, and seven harvests were made. Plant samples and soil solutions were assayed for radioactivity, and selenium compounds found in the soil solutions separated by high voltage paper electrophoresis. Throughout the 15-week experimental period selenium speciation was observed to change in soil solution. Samples collected at day 2 from pH 4.5 soil revealed that selenate accounted for 71% and selenite 8% of the soluble selenium compounds present, whereas for the pH 7 soil the relative percentages were 51 and 23% respectively. After 105 days selenate accounted for 22% and selenite 20% at pH 4.5, and 12 and 22% respectively at pH 7. The occurrence of selenoglutathione was noted in the soil solution and its concentration increased significantly with time. Statistically significant correlations (r=0.82) were found between the concentration of selenium in Lolium perenne at harvest and selenate selenium removed from the soil solution.     

Vitamin B12 and its binding proteins in milk from cow and buffalo in relation to bioavailability of B12

Milk is an important source of highly bioavailable vitamin B₁₂ (cobalamin) in human nutrition. In most animal products, vitamin B₁₂ is strongly bound to various specific protein carriers. The 2 vitamin B₁₂-specific proteins, predominantly transcobalamin (TC) and haptocorrin (HC), were earlier found in milk from Holstein Friesian cows and in human or sow milk, respectively. As the type of vitamin B₁₂ binders may influence bioavailability of the vitamin, we examined vitamin B₁₂ carriers in pooled milk specimens derived from European and Indian cow and buffalo herds. The total endogenous vitamin B₁₂ concentration was comparable in all milk pools (≈3 nM), but the vitamin carriers varied considerably: TC + caseins in Danish cows, TC + HC in Indian cows and buffaloes, and mainly HC in Italian buffaloes. Danish cow milk contained half as much TC as vitamin B₁₂, and the surplus vitamin was all attached via a single coordination bond to abundantly available histidine residues of casein. The specific binding proteins in Indian cow milk (TC + HC) approximately matched the molar content of vitamin B₁₂. Milk from the 2 buffalo breeds contained more specific binders than vitamin B₁₂, and the surplus proteins included the unsaturated TC ≈ 3 nM (Indian stock), or both TC ≈ 4 nM and HC ≈ 23 nM (Italian stock). The abundant HC of the latter sample bound nearly all endogenous vitamin B₁₂. We tested (in vitro) the transfer of vitamin B₁₂ from milk proteins to human carriers, involved in the intestinal uptake. The bovine TC-vitamin B₁₂ complex rapidly dissociated at pH 2 (time of half reaction, τ_1/2 < 1 min, 37°C) and was susceptible to digestion with trypsin + chymotrypsin (pH 7.5). Transfer of vitamin B₁₂ from the precipitated bovine casein (pH 2) to human carriers proceeded with τ_1/2 ≈ 7 min (37°C) and τ_1/2 ≈ 35 min (20°C). Liberation of vitamin B₁₂ from buffalo HC was hampered because of its pH stability and slow proteolysis. Nutritional availability of vitamin B₁₂ is expected to be high in cow milk (with TC-vitamin B₁₂ and casein-vitamin B₁₂ complexes) but potentially constrained in buffalo milk (with HC-vitamin B₁₂). This especially concerns the Italian buffalo milk, where a high excess of HC was found. We speculate whether the isolated stock of Italian buffalo maintained the ancestral secretion of carriers (HC ≫ vitamin B₁₂, TC ≈ 0), whereas intensive crossbreeding of cows and buffaloes from other regions caused a change to TC ≤ vitamin B₁₂, with low or absent HC. The substitution of HC by less sturdy carriers is apparently more beneficial to human consumers as far as vitamin B₁₂ bioavailability is concerned.     

Comparison of soil Pb in vitro bioaccessibility and in vivo bioavailability with Pb pools from a sequential soil extraction

In this study, 15 soils ranging in Pb content from 32 to 6330 mg kg(-1) were subjected to in vitro gastrointestinal extractions with and without added powdered milk. Before and after treatment, Pb in the soils was fractionated according to a 7-step sequential extraction procedure. A subset of five soils and Pb acetate was used for a minipig dosing study. The amount of bioaccessible Pb determined with the in vitro system ranged from 3 to 20% without powdered milk and from 11 to 56% with powdered milk. The higher bioaccessibility of Pb in the in vitro model with addition of powdered milk was related to a depletion of Pb in the organic Pb pool and indicates that soluble milk constituents compete with soil organic ligands for Pb. The absolute and relative bioavailabilities of Pb in the minipig dosing experiment were not related to bioaccessible Pb determined in any of the two in vitro systems. However, relative bioavailabilities in liver, kidney, and total uptake were highly correlated to Pb in the third fraction of the sequential extraction that is attributed to easily reducible Mn oxides. These results indicate that reductive processes in the intestine may be more relevant for Pb absorption than the initial solubilization in the acidic stomach.