Analysis of acrylamide,a carcinogen formed in heated foodstuffs

Reaction products (adducts) of acrylamide with N termini of hemoglobin (Hb) are regularly observed in persons without known exposure. The average Hb adduct level measured in Swedish adults is preliminarily estimated to correspond to a daily intake approaching 100 microg of acrylamide. Because this uptake rate could be associated with a considerable cancer risk, it was considered important to identify its origin. It was hypothesized that acrylamide was formed at elevated temperatures in cooking, which was indicated in earlier studies of rats fed fried animal feed. This paper reports the analysis of acrylamide formed during heating of different human foodstuffs. Acrylamide levels in foodstuffs were analyzed by an improved gas chromatographic-mass spectrometric (GC-MS) method after bromination of acrylamide and by a new method for measurement of the underivatized acrylamide by liquid chromatography-mass spectrometry (LC-MS), using the MS/MS mode. For both methods the reproducibility, given as coefficient of variation, was approximately 5%, and the recovery close to 100%. For the GC-MS method the achieved detection level of acrylamide was 5 microg/kg and for the LC-MS/MS method, 10 microg/kg. The analytic values obtained with the LC-MS/MS method were 0.99 (0.95-1.04; 95% confidence interval) of the GC-MS values. The LC-MS/MS method is simpler and preferable for most routine analyses. Taken together, the various analytic data should be considered as proof of the identity of acrylamide. Studies with laboratory-heated foods revealed a temperature dependence of acrylamide formation. Moderate levels of acrylamide (5-50 microg/kg) were measured in heated protein-rich foods and higher contents (150-4000 microg/kg) in carbohydrate-rich foods, such as potato, beetroot, and also certain heated commercial potato products and crispbread. Acrylamide could not be detected in unheated control or boiled foods (<5 microg/kg). Consumption habits indicate that the acrylamide levels in the studied heated foods could lead to a daily intake of a few tens of micrograms.     

Rugged LC-MS/MS survey analysis for acrylamide in foods

The described liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the detection of acrylamide in food entails aqueous room temperature extraction, SPE cleanup, and analysis by LC-MS/MS. The method is applicable to a wide variety of foods. [(13)C(3)]acrylamide is the internal standard. The limit of quantitation is 10 ppb (microg/kg). Data were obtained in duplicate from >450 products representing >35 different food types. The variability in analyte levels in certain food types suggests that it may be possible to reduce acrylamide levels in those foods.     

Investigations of factors that influence the acrylamide content of heated foodstuffs

The acrylamide content of heated foodstuffs should be considered to be the net result of complex reactions leading to the formation and elimination/degradation of this compound. The present study, involving primarily homogenized potato heated in an oven, was designed to characterize parameters that influence these reactions, including the heating temperature, duration of heating, pH, and concentrations of various components. Higher temperature (200 degrees C) combined with prolonged heating times produced reduced levels of acrylamide, due to elimination/degradation processes. At certain concentrations the presence of asparagine or monosaccharides (in particular, fructose and also glucose and glyceraldehyde) was found to increase the net content of acrylamide. Addition of other free amino acids or a protein-rich food component strongly reduced the acrylamide content, probably by promoting competing reactions and/or covalently binding acrylamide formed. The dependence on pH of the acrylamide content exhibited a maximum around pH 8; in particular, lower pH was shown to enhance elimination and decelerate formation of acrylamide. In contrast, the effects of additions of antioxidants or peroxides on acrylamide content were small or nonexistent.     

Postharvest UV-C-irradiated grapes as a potential source for producing stilbene-enriched red wines

The use of postharvest controlled irradiation by UV pulses is proposed as a potential method to produce stilbene-enriched red wine. "Monastrell" grapes were UV-C-irradiated to increase stilbene content. The main inducible stilbenes were resveratrol and piceatannol, which are molecules with reported health-beneficial activities. The evolution of both compounds was followed in the different steps of an "analytical" traditional maceration wine-making process. The final wine made from UV-C-irradiated grapes was enriched about 2- and 1.5-fold in resveratrol and piceatannol, respectively, when compared to the control wine. In addition, no difference was detected regarding the standard enological parameters (color, acidity, etc.). It is strongly suggested that, with the use of more susceptible wine grapes to induce bioactive stilbenes upon UV-C irradiation, the stilbene-enrichment of wine can be much higher.     

城市污泥的蚯蚓分解处理技术研究进展

城市污泥成分复杂,其中有机质、N、P、K含量丰富,Ca、Mg、Fe等矿物营养成分含量较高,此外还有许多重金属（Zn、Cu、Cd、Cr、Pb、Ni、Hg、As、Sn等）、有机有害成分以及病原菌。本文分析了国内外关于污泥处理处置的主要方法及其优缺点,重点讨论了一种新兴城市污泥处理技术,即城市污泥的蚯蚓分解处理技术（Vermicomposting）,利用蚯蚓处理城市污泥,不仅可以将污泥中的重金属富集于蚯蚓体内、去除病原菌、转移消化有机有害物,而且可将城市污泥转化为富含营养物质的有机肥,是一种无害化处理城市污泥的有效途径。最后,总结了目前城市污泥蚯蚓分解处理技术研究中存在的问题,并展望了其研究发展趋势。     

Labile soil organic matter as a potential nitrogen source in golf greens

The loss of fertilizer N from golf greens can be high depending upon management (irrigation schedule, N source, rate and timing of fertilizer application) as well as soil conditions. Although soil organic matter (SOM) is acknowledged as a major source of N and other nutrients, its potential as an N source seems to be neglected in the management of golf greens. The susceptibility of SOM to degradation is one indication of how active a role SOM plays as a nutrient source. An extraction method developed by Olk et al. [Geoderma 65 (1995) 195] distinguishes humic acid fractions by their binding to dominant stabilizing soil cations and separates them into calcium-bound (CaHA) and non calcium-bound or mobile (MHA) fractions. Mobile humic acid is a relatively young, N-rich HA fraction that does not appear to form stable complexes with Ca. The MHA could therefore play a greater role in nutrient availability than CaHA. We determined C and N distributions within SOM extracted from these two HA fractions in 11 golf greens ranging in age from 4 to 28 yr. Because SOM in golf greens is recently formed, and MHA is an N-rich fraction representing an early stage of SOM evolution, we hypothesized that the MHA fraction would account for a larger proportion of soil organic N than CaHA. The amounts of both HA-C and HA-N increased significantly with green age. MHA accounted for a larger proportion (20-27%) of total soil C than CaHA-C (8-14%). MHA was also enriched in N compared to CaHA with consistently smaller C-to-N ratios. Thus, the greater abundance of MHA and its higher N concentration accounted for a larger proportion of soil organic N (24-45%). The equivalence of MHA-N ranged between 250 kg N ha⁻¹ for a 4 yr-old green and 775 kg N ha⁻¹ for a 21 yr-old green. Thus, soils of established greens contain significant quantities of labile SOM rich in N that could through mineralization supply part of the fertilizer N requirement of turf grass. A greater understanding of the dynamics of this resource is needed if we are to manage golf greens for optimal use without negative consequences to the environment.     

Iron derivatives from casein hydrolysates as a potential source in the treatment of iron deficiency

The properties of an Fe(3+)-peptide complex containing 5.6% Fe, obtained by the reaction of ferric chloride with an enzymatic hydrolysate of casein, are described. The major site of iron binding corresponds primarily to the carboxylate groups and to a lesser extent to the peptide bonds. The Fe(3+)-peptide complex is insoluble at acid pH and completely soluble at neutral to alkaline pH. When soluble, the Fe(3+) is tightly bound to the complex peptide mixture but can be displaced and complexed by a low molecular weight ligand such as cysteine. Its efficacy in relation to iron sulfate was compared in rats. Both iron sources were administrated in Milli-Q water by gastric gavage to male Wistar rats (180-200 g) after an 18 h fast with water ad libitum. Fe(3+) from the Fe(3+)-peptide complex was transferred to the blood in a dose-dependent manner (1-8 mg of Fe/kg), and the serum iron levels were significantly higher (p < 0.001) than in a similar group of rats treated with iron sulfate. In the comparative kinetics experiments, the rats received 4 mg of Fe/kg. Both iron sources presented maximum absorption, as indicated by the elevation of serum iron levels, 30 min after administration, and the AUC(0)(-->2h) of the Fe(3+)-peptide complex was significantly higher (p < 0.05) than that observed with iron sulfate. The simultaneous administration of free peptides (0-192 mg) with the Fe(3+)-peptide complex or iron sulfate did not modify the extent of absorption of iron from both sources, suggesting that the absorption is due to the complex formed and probably not to exchange reactions in the gastrointestinal tract. In the hemoglobin repletion experiments carried out on newly weaned rats with anemia induced by a low-iron diet, supplementation of the diet with the the Fe(3+)-peptide complex was as efficient as supplementation with iron sulfate in the conversion from diet to hemoglobin iron. These results, taken together, suggest that the Fe(3+)-peptide complex is a potential compound for use as an iron source in biological situations.     

Effectiveness of ionizing radiation in reducing furan and acrylamide levels in foods

Furan and acrylamide are two possible carcinogens commonly found in many thermally processed foods. The possibility of using ionizing radiation to reduce the levels of thermally induced furan and acrylamide in water and selected foods was investigated. Aqueous furan solutions, and foods (frankfurters, sausages, infant sweet potatoes) that contained furan were irradiated to various doses of gamma-rays. Water and oil spiked with acrylamide and potato chips (a known acrylamide-containing food) were also irradiated. In addition, possible irradiation-induced formation of acrylamide in glucose and asparagine solutions was analyzed. Results showed that irradiation at 1.0 kGy destroyed almost all furan in water. In frankfurters, sausages, and infant sweet potatoes, the rate of irradiation-induced destruction of furan was much lower than the rate in water, although significant reductions in furan levels were observed in all foods. Irradiation at 2.5-3.5 kGy, doses that can inactivate 5-log of most common pathogens, reduced furan levels in the food samples by 25-40%. Similarly to furan, acrylamide in water was also sensitive to irradiation. After 1.5 kGy of irradiation, most of the acrylamide was degraded. Irradiation, however, had a very limited effect on acrylamide levels in oil and in potato chips, even at a dose of 10 kGy. No detectable acrylamide was formed in the mixture of asparagine and glucose upon irradiation. These results suggest that a low dose of irradiation easily destroys furan and acrylamide in water. In real foods, however, the reduction of furan was less effective than in water, whereas the reduction in acrylamide was minimal.     

Thermally generated 3-aminopropionamide as a transient intermediate in the formation of acrylamide

On the basis of the recent findings that "biogenic amines" can also be formed during thermal food processing from their parent amino acids in a Strecker-type reaction, the formation of 3-aminopropionamide, the biogenic amine of asparagine, was investigated in model systems as well as in thermally processed Gouda cheese. The results of model studies revealed that, besides acrylamide, 3-aminopropionamide was also formed in amounts of 0.1-0.4 mol % when asparagine was reacted in the presence of either glucose or 2-oxopropionic acid. Results of a second series of model experiments in which [(13)C(4)(15)N(2)]-asparagine ([(13)C(4)(15)N(2)]-Asn) and unlabeled 3-aminopropionamide were reacted together in the presence of glucose revealed a >12-fold higher efficacy of 3-aminopropionamide in acrylamide generation as compared to asparagine. Both [(13)C(3)(15)N(2)]-3-aminopropionamide and [(13)C(3)(15)N(1)]-acrylamide were formed during [(13)C(4)(15)N(2)]-Asn degradation in a ratio of about 1:4, supporting the idea that 3-aminopropionamide is a transient intermediate in acrylamide formation. In this study, 3-aminopropionamide was identified and quantified for the first time in foods, namely, in Gouda cheese. Although the fresh cheese contained low amounts of 3-aminopropionamide, its concentrations were much increased to approximately 1300 mug/kg after thermal processing. In isotope labeling studies, performed by administering to the cheese [(13)C(4)(15)N(2)]-Asn in a ratio of 1:2 as compared to the "natural" concentrations of asparagine, similar ratios of unlabeled/labeled 3-aminopropionamide and unlabeled/labeled acrylamide were determined. Thus, 3-aminopropionamide could be verified as a transient intermediate of acrylamide formation during food processing.     

Artichoke (Cynara scolymus L.) byproducts as a potential source of health-promoting antioxidant phenolics

The present study reports a fast, economical, and feasible way to extract antioxidant phenolics from artichoke byproducts: raw artichoke (RA), blanched (thermally treated) artichoke (BA), and artichoke blanching waters (ABW). These byproducts represent a huge amount of discarded material in some industries. Two protocols, with possible industrial applicability, based on both methanol and water extractions were used. Phenolic contents (expressed as caffeic acid derivatives) (grams per 100 g of dry extract) were 15.4 and 9.9 for RA when extracted with methanol and water, respectively; 24.3 and 10.3 for BA when extracted with methanol and water, respectively; and finally, 11.3 g of phenolics/100 mL of ABW. Therefore, methanol extracts yielded more phenolics than water extracts, especially when BA byproducts were used. The higher amount of phenolics in BA could be due to the inactivation of polyphenol oxidase (PPO) at the industrial scale (due to blanching process), avoiding PPO-catalyzed oxidation of these phenolics, a phenomenon that could occur in RA byproducts. Artichoke extracts from industrial byproducts showed a high free radical scavenging activity (versus both DPPH* and ABTS*+ radicals) as well as capacity to inhibit lipid peroxidation (ferric thiocyanate method). According to these results, the use of artichoke extracts from industrial byproducts as possible ingredients to functionalize foodstuffs (to decrease lipid peroxidation and to increase health-promoting properties) is suggested.     

Carotenoid pigments in Rosa mosqueta hips, an alternative carotenoid source for foods

Carotenoid composition has been investigated in Rosa mosqueta hips (Rosa rubiginosa, Rosa eglanteria). Six major carotenoids were identified (beta-carotene, lycopene, rubixanthin, gazaniaxanthin, beta-cryptoxanthin, and zeaxanthin) together with other minor carotenoids (violaxanthin, antheraxanthin, and gamma-carotene). An average composition has been estimated as follows: beta-carotene (497.6 mg/kg of dry wt), lycopene (391.9 mg/kg of dry wt), rubixanthin (703.7 mg/kg of dry wt), gazaniaxanthin (289.2 mg/kg of dry wt), beta-cryptoxanthin (183.5 mg/kg of dry wt), zeaxanthin (266. 6 mg/kg of dry wt), and minor carotenoids (67.1 mg/kg of dry wt). Possible uses in food technology are outlined and discussed including the preparation of highly colored oleoresins as natural colorants of food and beverages and as provitamin A sources.     

Winter legumes as a nitrogen source for no-tillage cotton

Winter legumes can serve dual purposes in no-tillage cropping systems. They can provide a no-tillage mulch, and supply a considerable quantity of N for thesummer crops. Cotton (Gossypium hirsutum L.) was no-tillage planted into crimson clover (Trifolium incarnatum L.), common vetch (Vicia sativa L.), and fallowed soil for two years to determine the effects of winter legume mulches on growth, yield, and N fertilizer requirements. The legumes were allowed to mature and reseed prior to planting cotton. The winter legumes produced no measurable changes in soil organic matter, N, or bulk density, but water infiltration was more rapid in the legume plots than in the fallowed soil. In the fallow system, 34 kg ha^?1 N fertilizer was required for near maximum yields. In the clover plots, yields without N fertilizer were higher than when N (34 and 68 kg ha^?1) was applied. In the vetch plots, cotton yields were highest without N fertilizer the first year, but yields were increased with 34 kg ha^?1 N the second year because of a poor vetch seed crop and a subsequently poor legume stand. In the clover plots, a 20–30% cotton seedling mortality occurred in one year, but this stand reduction apparently did not affect cotton yields. Winter legume mulches can provide the N needs for no-tillage cotton without causing an excessive and detrimental quantity of N in sandy soils naturally low in soil N (0.04%). Unless the reseeding legume systems are maintained for at least 3 years, the legumes do not, however, provide an economical N source for cotton when N fertilizer requirementsare low (34 kg ha^?1 in this study). A possible disadvantage of the system for reseeding legumes is that cotton planting is delayed 4–6 weeks beyond the normal planting date, which can reduce yields in some years.     

Marine sponge: a potential source for methoxylated polybrominated diphenyl ethers in the Asia-Pacific food web

Marine sponges collected in Palau, Micronesia, were investigated for hydroxylated or methoxylated analogues of brominated diphenyl ethers (BDEs), brominated dibenzo-p-dioxin (BDD), and brominated biphenyls. The neutral fractions of Haliclona sp. and Callyspongia sp. contained 2'-methoxy-2,3',4,5'-tetraBDE, 6-methoxy-2,2',4,4'-tetraBDE, 2',6-dimethoxy-2,3',4,5-tetraBDE 2,2'-dimethoxy-3,3',5,5'-tetrabromobiphenyl, several methoxy-triBDEs, and dimethoxy-penta-/hexaBDEs. The methoxylated BDEs in sponges were strikingly similar to those of local fish living in the western Pacific Ocean. The total concentrations of these compounds (ΣMeO-PBDE) in both sponges were 63.5 μg/g extractable organic matter (EOM) for Haliclona sp. and 36.5 μg/g EOM for Callyspongia sp., which were about 2 orders of magnitude higher than the levels seen in tropical coral reef fish (unicornfish or surgeonfish) (280-290 ng/g lipid) and groupers (550 ng/g lipid) from Okinawan coastal waters. The phenolic fractions of both sponges contained hydroxy-methoxy tetra-/pentaBDEs as well as hydroxy-tetraBDD, in addition to the corresponding phenolic tetraBDE analogues. Although the total concentrations of phenolic products (27-80 μg/g EOM) in both sponges fell within a range comparable to the methoxylated products, ΣOH-PBDE in local fish were trace level (less than 10 ng/g lipid of) or undetectable. This survey indicates that marine sponges are a possible source of the MeO-PBDE analogues that biomagnify via the food chain to the higher trophic organisms in the western Pacific, whereas the distribution of the corresponding hydroxylated analogues is limited.     

Legume cover crops as a nitrogen source for pecan

Crimson clover (Trifolium incarnatum L.) plus hairy vetch ( Vicia villosa Roth), red clover (Trifolium pratense L.), white clover (Trifolium repens L.), red clover plus white clover, and bermudagrass (Cynodon dactylon [L.] Pers.) were evaluated as cover crops for pecans. Crimson clover plus hairy vetch supplied the equivalent of 101 to 159 kg nitrogen (N)/ha. Red clover plus white clover supplied up to 132 kg N/ha. Either white clover or red clover alone were less effective in supplying N than when grown together. Soil Kjeldahl‐N was usually not affected or increased using the legumes compared to fertilized bermudagrass sod. Soil nitrate (NO₃) concentrations during October were occasionally higher in unfertilized legume plots than in bermudagrass plots with March‐applied N.     

Cassava latex as a source of linamarase for determination of linamarin

A major constraint in the enzymatic assays for determination of linamarin in cassava is the preparation of purified linamarase. Cassava latex, which exhibits high linamarase activity, was tried as an alternate source of the enzyme. Enzyme yield from latex was compared with that from rind and leaf. Preparations from latex had significantly higher linamarase activity (approximately 300-fold) compared to leaf and rind. The purification of the enzyme was easier since homogenization of large quantities of tissues could be avoided. A 1 g amount of latex could yield enough enzyme for >3000 assays.     

Peanut roots as a source of resveratrol

A potent antioxidant, resveratrol (3,4',5-trihydroxystilbene), was extracted using 80% methanol from peanut roots (Arachis hypogaea L.), isolated with a solid-phase extraction column, purified by a semipreparative HPLC, and identified with 1H NMR and MS. The highest and lowest resveratrol contents in the peanut roots of 2000 fall and 2001 spring crops were 1.330 and 0.130 mg/g and 0.063 and 0.015 mg/g, respectively. When the dehydrated peanut root powders of spring and fall crops were combined and cooked with pork-fat patties (1%, w/w) and the separated oils were stored at 60 degrees C for conjugated diene hydroperoxide (CDHP) determination, CDHP contents of the control oils increased after 3 days of storage, whereas the contents in the peanut root-treated oils of spring and fall crops did not increase after 9 and 15 days of storage, respectively. It is of merit to find that peanut roots, usually left in the field as agricultural waste, contain resveratrol and bear potent antioxidative activity.     

Polyhalite as a sulfur source for fresh market tomato production in Brazil

Abstract

Polyhalite (PH), a naturally occurring multinutrient fertilizer containing potassium (K), calcium (Ca), magnesium (Mg), and sulfur (S), has improved tomato (Solanum lycopersicum L.) production in Brazil but a specific response by tomato to the S in PH is not confirmed. We compared four S sources – PH, sulfate of potash (SOP), sulfate of potash magnesia (SOPM), and single super phosphate (SSP) – applied at a target application rate of 40?kg?S?ha^?1 to fertilizers with no S (muriate of potash, MOP), and no K or S at commercial application rates in three commercial fields in Brazil with nitrogen (N), phosphorus (P), and K applied at recommended rates of 355, 500, and 200–300?kg?ha^?1, respectively. Consistent across locations, PH increased total yields over the control, MOP, and SSP, with SOP and SOPM higher than the control but not MOP or SSP. Only PH increased marketable yields compared to the control. Yields increased linearly with fruit numbers per plant which were higher for PH than the control or MOP, indicating higher fruit set in PH contributed to yield differences. While fertilizers increased leaf K and S concentrations and soil test K and SO₄–S, yield differences did not appear to be related solely to either K or S fertilization, nor to Mg fertilizers to which there was no response. Leaf and fruit Ca concentrations were higher in PH than the control and MOP at some locations suggesting Ca improved fruit set in PH. Results suggest tomato likely responded to the multinutrient content or solubility pattern of PH.     

Dwarf shrub litter as a food source for macro-decomposers in alpine pastureland

Dwarf shrub litter is thought to be of poor quality and palatability for macro-decomposers. In laboratory feeding experiments, however, it was found that this litter type represents a potential food source for earthworms and millipedes. Here we tested whether this is true under natural conditions by conducting a 1 year field experiment on an abandoned alpine pasture in Tyrol (Austria). As the natural isotopic signatures of plant litter do not allow discriminating between different plant species, dwarf shrub litter, artificially enriched in ¹⁵N, was offered in experimental plots to the macro-decomposer community. Both the earthworm Lumbricus rubellus and the millipede Cylindrojulus fulviceps fed on dwarf shrub litter as indicated by their increased δ¹⁵N signatures, but IsoError analysis indicated a clear preference for grass litter for all macro-decomposer species investigated.Soil δ¹⁵N signatures were only marginally affected by the experimental provision of ¹⁵N-enriched dwarf shrub litter, whereas litter from other, unlabelled, plants became enriched by the isotopic tracer to some extent. Except for one grass species, plants harvested at the end of the experiment were not enriched in ¹⁵N, suggesting that the N-uptake from decomposing litter material by plants on abandoned alpine pastureland is slow.