Reduction of persistent organic pollutants in fishmeal: a feasibility study

The dioxin, dioxin-like polychlorinated biphenyl (DL-PCB), fat, and dry matter partitioning during fishmeal production have been studied in pilot scale. Most of the dry matter and lipid content in the fishmeal could be ascribed to the press cake intermediate product. Dioxins and DL-PCBs are fat-soluble compounds, and the process partitioning is reflected by the fat partitioning data. Enzyme and heat treatment of the press cake and stickwater concentrate did not improve fat separation. Soybean oil extraction of the press cake reduced the dioxin and DL-PCB content by 97%. Less exchange of fatty acids was observed (56-72%). Combined with fat separation of the stickwater concentrate, the applied process conditions were able to give a fishmeal decontamination rate higher than hexane and isopropanol extraction of the fishmeal. Quantification of fat content based on chloroform/methanol extraction was found to be the best protocol to estimate fat partitioning and decontamination effects. The oil extraction process requires further optimization, but has several advantages compared to organic solvent extraction. These include easy implementation in an existing fishmeal processing line, use of a safe and nonflammable extraction medium, and expected lower investment and operation costs. A new integrated fishmeal and fish oil production and decontamination process line is proposed.     

UV treatment of fishmeal: a method to remove dioxins?

This study evaluates the use of UV on contaminated fishmeal and photodegradation of dioxins. Fishmeal samples were placed under UVA or UVB light for 2, 5, and 10 days. Subsequently, analysis of amino acid content, lipid oxidation marker, ethoxyquin content, dioxin, and polychlorinated biphenyl (PCB) profiling was carried out. Exposure of fishmeal for 5 days to UVB light resulted in the degradation of approximately 70% of the dioxin content, while UVA had little effect, only resulting in the degradation of 10% of the dioxin content. UVB did not affect the protein and amino acid content of fishmeal; however, lipid oxidation was triggered. Addition of ethoxyquin prevented oxidation but simultaneously slowed dioxin breakdown. Increasing UVB intensity resulted in a more efficient dioxin degradation of 90%. Exposure of fishmeal to UVB also resulted in an increase in PCBs. UVB light is shown to photodegrade dioxin in fishmeal, indicating the needs to further investigation of methods for application at industrial scale.     

Laboratory and on-farm studies on the bioaccumulation and elimination of dioxins from a contaminated mineral supplement fed to dairy cows

A dioxin-contaminated mineral supplement was used to study the bioaccumulation and elimination of dioxins in two dairy cows. The supplement was mixed into the total maintenance ration and fed to the cows for 40 days after which unfortified diets were fed for 40 additional days. Dioxins and coplanar polychlorinated biphenyls (PCBs) were measured twice a week in the milk and in selected tissues of the cows, one at death (day 10 of withdrawal) and one at slaughter (day 40 of withdrawal). The dioxins and PCBs were readily transferred into the milk, and at steady state, total toxic equivalents were concentrated 6-fold into the milk fat from the diet. Bioaccumulation was inversely related to chlorination number. The elimination of dioxins and PCBs in milk was biphasic. With the exception of 1,2,3,4,6,7,8-heptachlorodioxin and both octachlorinated congeners, dioxin and furan half-lives in milk were approximately 3-5 days for the alpha-phase and 35-50 days for the beta-phase. PCB-169 had a longer half-life: 11 (alpha) and 200 days (beta). When milk and feed samples from Minnesota farms that had used similar contaminated mineral supplements were analyzed, no elevated dioxin levels were found in milk. It appeared that although the dioxins from the mineral supplements have the potential to bioaccumulate, dilution into the total diet was sufficient to prevent a significant rise in the dioxin concentrations in the milk at these farms.     

Effects of cooking on concentrations of polychlorinated dibenzo-p-dioxins and related compounds in fish and meat

We investigated the cooking-induced changes in concentrations of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (PCBs) (dioxins) using mackerel and beef. The concentrations of dioxins (29 congeners) were determined by isomer specific analyses and were compared between uncooked and cooked samples. The cooking procedures examined in this study included grilling as a fillet, boiling as a fillet, and boiling as tsumire (small, hand-rolled balls) for mackerel and boiling as a slice, broiling as a slice, and broiling as a hamburger for beef. Three trials were carried out for each cooking method. Generally, concentrations of dioxins were reduced in every cooking trial. When nondetected congener concentrations were assumed to be half the limit of detection for mackerel, the maximum percentage reductions of total concentrations given as 2,3,7,8-tetraCDD equivalents (TEQ) were 31% in grilling as a slice, 14% in boiling as a slice, and 21% in boiling as tsumire under the conditions of this study. In contrast, for beef, the reductions were 42% in boiling as a slice, 42% in broiling as a slice, and 44% in broiling as a hamburger. These results suggest that ordinary cooking processes with heating undoubtedly reduce the dioxin content in animal products, and the reductions estimated should be considered when dioxin intake is evaluated using contamination data for individual food items.     

Assessing the Potential of Organic Solvents on Total Petroleum Hydrocarbon Extraction from Diesel-Contaminated Soils

The total petroleum hydrocarbon (TPH) extraction potential of organic solvents including dichloromethane (DCM), pentane, hexane, methanol, ethanol, propanol, and acetone was investigated along with the effect of water content in solvents for their efficiency of extraction. The extent of TPH extraction was analyzed using various extraction schemes (i.e., solvent/solid ratio, treatment time, extraction method, solvent/water ratio) to better understand the physical and chemical factors controlling TPH release from contaminated soils. More TPH was extracted with increasing solvent/solid ratio and increasing time. The extent of TPH extracted also varied depending on the extraction method, solvent type, and solvent/water ratio, but was highest when using the total extraction method and 100% DCM. However, the efficiency of TPH extraction decreased dramatically with the increase in the water content in organic solvents. The results also showed that TPH extraction using DCM was the best option for achieving cost-effective, eco-friendly outcomes along with remediation goals. DCM used in solvent extraction to remediate diesel-contaminated soils showed low toxicity, low cost, high recycling potential, and high efficiency compared to the other solvents tested in this study.     

Survey of dioxin-like compounds in dairy feeds in the United States

The United States Environmental Protection Agency (USEPA) has completed a survey of dioxin-like compounds (including 17 dioxin and furan (CDD/F) congeners and 12 coplanar polychlorinated biphenyl (PCBs) congeners) in dairy feeds from 10 dairy research facilities around the United States, sampling the overall mixtures and the major and minor feed components. Low levels of dioxin were found in all feed mixtures with an average concentration of 0.05 pg/g (ppt) toxic equivalent (TEQ) dry weight. This is lower than previously found in dairy feeds by about a factor of 4. While it is possible that generally lower levels of dioxins in the environment in recent years may explain this result, examinations of the data suggest that the oven drying used to prepare the wet feed samples could have resulted in a loss of dioxins from the feed materials. The percentage of the total TEQ due to CDD/Fs was about four times that of PCBs. Leafy vegetations in the feed (the silages and the hays) had concentrations about twice as high as nonleafy, protected vegetation of the feeds (the ground or meal corn, cottonseed, and others). Minor components did not significantly influence the final feed mixture concentration of dioxin TEQ. However, in one of the feed mixtures, a minor component with a high concentration of 38.5 ppt TEQ effectively doubled the concentration of the overall feed mixture.     

Levels of polychlorinated biphenyls and pesticides in bluefish before and after cooking

Similar levels of polychlorinated biphenyls (PCBs), pesticides, and fat were found in 20 correlated uncooked and cooked (baked) bluefish fillets. Fillets averaged 2.5 ppm PCBs as Aroclor 1254 (whole basis) before cooking; after cooking, with the oil drippings and skin discarded, the average PCB level was 2.7 ppm. Although PCBs, lipophilic pesticides, and fat were lost along with oil drippings and skin that were discarded after cooking, the moisture loss in the fillets during cooking compensated for these weight losses almost completely. After the fillets were cooked and the oil drippings and skin were discarded, the PCB content of the fillets was 27% lower on the average.     

Determination of polychlorinated biphenyls in sediments, using sonication extraction and capillary column gas chromatography-electron capture detection with internal standard calibration

A sonication technique is presented for the extraction of polychlorinated biphenyls (PCBs) from sediments. In addition, a quantitation scheme is described which allows peak-specific and, in many cases, congener-specific determination of PCBs. PCBs are quantitated by capillary column gas chromatography-electron capture detection, with internal standard calibration. Results utilizing sonication extraction were compared with those obtained by Soxhlet and steam distillation extractions of 3 U.S. Environmental Protection Agency (EPA) quality control sediment samples and 3 lake sediments known to be contaminated with PCBs. Environmental lake sediments were extracted wet, with no drying prior to extraction. Recoveries by each technique varied depending on the sediment sample being extracted and degree of chlorination of PCB congeners. With proper selection of extraction solvent, the sonication technique can recover amounts of PCBs equivalent to and sometimes greater than recoveries by the Soxhlet or steam distillation techniques. A 24-h quiescent period in the extraction solvent between 2 sonications improved extraction efficiency for 2 freeze-dried sediments but did not affect results obtained for 3 environmentally contaminated sediments that were extracted without drying. Replacement of Soxhlet extraction with the sonication technique results in reduced sample preparation time, decreased volumes of solvents and sample, and substitution of common laboratory glassware in place of fragile, expensive Soxhlet glassware. Sonication extraction can also improve precision compared with Soxhlet extraction.     

Determination of polybrominated diphenyl ethers and polybrominated dibenzo-p-dioxins/dibenzofurans in marine products

Polybrominated diphenyl ethers (PBDEs) have been widely used as flame retardants in plastics and textile coatings, and these compounds have been recognized as ubiquitous environmental contaminants. Furthermore, it is considered a serious problem that polybrominated dibenzo-p-dioxins and dibenzofurans (PBDD/DFs), having toxicities similar to those of chlorinated dioxins, are generated by the manufacture of brominated flame retardants (BFRs) such as PBDEs, and formed by the combustion of substances containing BFRs. Several congeners of PBDD/DFs and PBDEs have been detected in the adipose tissue of the Japanese. Although food is suspected as an exposure source, little information is available regarding the levels of these brominated compounds in food, as compared with information regarding dioxin or polychlorinated biphenyls. It is necessary to investigate the levels of these brominated organic compounds in various foods and to estimate their influence in the case of human exposure. We developed an efficient method of analyzing PBDEs and PBDD/DFs contents in food samples using accelerated solvent extraction and determined the concentrations in several marine products such as raw fish, processed foods, and seaweed purchased in Japan. A recovery test (n = 5) using the method and involving dried fish showed acceptable recoveries of 57.7-78.5% (RSD 5.4-15.9%) for PBDEs and 50.0-56.4% (RSD 1.5-7.9%) for PBDD/DFs. In the analysis of marine product samples, several congeners of PBDEs were detected in raw fish, processed fish, and seaweed; the highest concentration of sigmaPBDEs was detected in yellowtail (1161 pg/g whole basis), followed by mackerel (553.5 pg/g whole basis). The most dominant congener present in these marine samples was 2,2',4,4'-tetraBDE (#47).     

初烤烟叶中烟碱和新植二烯的提取工艺研究

为探究云南烟油的成分以及烟碱和新植二烯的提取工艺,本试验以云南典型初烤烟叶为原料,通过超临界CO₂萃取、超声辅助萃取、索式回流萃取和溶剂萃取4种方法提取初烤烟叶中烟碱和新植二烯,采用气相色谱-质谱(GC-MS)分析萃取物组成,比较不同萃取方法和萃取溶剂下,烟叶萃取物得率及所得萃取物中烟碱和新植二烯的相对含量。结果表明,当以纯乙醇作为萃取剂时,4种萃取工艺烟油得率从高到低依次为索式回流萃取>超声辅助萃取>溶剂萃取>超临界CO₂萃取。不同提取工艺得到的烟油均检测出烟碱、新植二烯、正十六烷酸、(Z,Z,Z)-9,12,15-十八碳三烯酸、1,5,9-三甲基-12-(1-甲基乙基)-4,8,13-环四十三碳三烯-1,3-二醇、维生素E等主要成分,其中烟碱和新植二烯的相对含量依次为索式回流萃取(75.58%、2.85%)>超临界CO₂萃取(35.01%、26.80%)>超声辅助萃取(32.28%、28.24%)>溶剂萃取(9.56%、45.20%)。本研究结果为云南烟油中的成分以及烟碱和新植二烯的纯化工艺研究提供了一定的理论依据。     

Levels and trends of polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (PCBs) in Spanish commercial fish and shellfish products, 1995-2003

The polychlorinated dibenzo-p-dioxin (PCDD), dibenzofuran (PCDF), and polychlorinated biphenyl (PCB) contents of 123 Spanish commercial salmon, tuna fish, sardine, oyster, mussel, and clam samples from 1995 to 2003 were investigated. A significant decrease of dioxin and non-ortho PCB concentrations in the studied species was found over the years. The decrease was greater in the case of dioxins than in that of non-ortho PCBs, especially during the early years of the study. PCB and PCDD/F concentrations in the years 2001-2003 were comparable to those reported in the literature for similar species collected after 1999. Mean PCB concentrations ranged from 3.46 ng/g of fresh weight (fw) in clams to 100 ng/g of fw in tuna fish. PCDD/F mean current levels ranged from 0.62 pg/g of fw in clams to 2.89 pg/g of fw in oysters. Toxic equivalent quantities (WHO-TEQ) ranged from 0.05 pg of WHO-TEQ(PCDD/Fs)/g of fw in clams to 0.5 pg of WHO-TEQ(PCDD/Fs)/g of fw in salmon (in the upper bound determination levels). When coplanar PCBs were included, the WHO-TEQ(PCDD/Fs+cop) (PCBs) values increased by a range of 1.7 times in oysters to 14.1 times in tuna fish. The decrease in dioxin concentrations suggests that efforts to control dioxin emissions and to reduce human exposure through foodstuffs are succeeding. The high contribution of PCBs to total WHO-TEQs in the fish and shellfish species investigated suggests that it is important to determine PCBs in foodstuffs, and especially in fish products, and they should be included in further research and future legislation.     

Extraction of Antioxidants from Wheat Bran Using Conventional Solvent and Microwave-Assisted Methods

Total phenolic and tocopherol contents and free radical scavenging capability of wheat bran extracted using conventional and microwave-assisted solvent extraction methods were studied. Three different solvents (methanol, acetone, and hexane) were used in the conventional solvent extraction. Methanol was the most effective solvent, producing higher extraction yield (4.86%), total phenolic compound content (241.3 μg of catechin equivalent/g of wheat bran), and free radical scavenging capability (0.042 μmol of trolox equivalent/g of wheat bran) than either acetone or hexane. However, there was no significant difference in the total tocopherol contents (13.6–14.8 μg/g of wheat bran) among the three different solvent extraction methods. Microwave-assisted solvent extraction using methanol significantly increased the total phenolic compound content to 467.5 and 489.5 μg of catechin equivalent; total tocopherol content to 18.7 and 19.5 μg; and free radical scavenging capability to 0.064 and 0.072 μmol of trolox equivalent/g of wheat bran at extraction temperatures of 100 and 120°C, respectively. However, extraction yields of conventional methanol solvent and microwave-assisted methanol extractions at different temperatures were not significantly different.     

Lunasin and Bowman-Birk protease inhibitor concentrations of protein extracts from enzyme-assisted aqueous extraction of soybeans

Lunasin and Bowman-Birk protease inhibitor (BBI) are two soybean peptides to which health-promoting properties have been attributed. Concentrations of these peptides were determined in skim fractions produced by enzyme-assisted aqueous extraction processing (EAEP) of extruded full-fat soybean flakes (an alternative to extracting oil from soybeans with hexane) and compared with similar extracts from hexane-defatted soybean meal. Oil and protein were extracted by using countercurrent two-stage EAEP of soybeans at 1:6 solids-to-liquid ratio, 50 °C, pH 9.0, and 120 rpm for 1 h. Protein-rich skim fractions were produced from extruded full-fat soybean flakes using different enzyme strategies in EAEP: 0.5% protease (wt/g extruded flakes) used in both extraction stages; 0.5% protease used only in the second extraction stage; no enzyme used in either extraction stage. Countercurrent two-stage protein extraction of air-desolventized, hexane-defatted soybean flakes was used as a control. Protein extraction yields increased from 66% to 89-96% when using countercurrent two-stage EAEP with extruded full-fat flakes compared to 85% when using countercurrent two-stage protein extraction of air-desolventized, hexane-defatted soybean flakes. Extruding full-fat soybean flakes reduced BBI activity. Enzymatic hydrolysis reduced BBI contents of EAEP skims. Lunasin, however, was more resistant to both enzymatic hydrolysis and heat denaturation. Although using enzymes in both EAEP extraction stages yielded the highest protein and oil extractions, reducing enzyme use to only the second stage preserved much of the BBI and Lunasin.     

Determination of halogenated contaminants in human adipose tissue

A method has been developed for determination of organochlorine contaminants in human adipose tissue. After fat extraction from the tissue with acetone-hexane (15 + 85, v/v), organochlorines were fractionated from fat by gel permeation chromatography with methylene chloride-cyclohexane (1 + 1, v/v) as solvent. After Florisil column cleanup, the GPC extract was analyzed by capillary column gas chromatography using 2 columns of different polarity. Compound identity was confirmed by gas chromatography-mass spectrometry using selected ion monitoring. Recoveries for fortification levels of 10-500 ng/g were greater than 80% except for trichlorobenzene and hexachlorobutadiene (ca 60%).     

Quality Comparison of Rice Bran Oil Extracted with d‐Limonene and Hexane

d‐Limonene, a safe agricultural by‐product, was used to extract rice bran oil and compared against hexane, a petroleum product widely used as a solvent for extracting edible oil. The yield of crude rice bran oils extracted with both solvents in percentage by weight was obtained. The quality of crude rice bran oil was analyzed. The yield and quality of crude rice bran oil from the limonene‐based solvent extraction were almost equivalent to those from the hexane‐based operation. The optimum solvent‐to‐rice bran ratio and extraction time required for d‐limonene extraction of oil, based primarily on crude rice bran oil yield, have been determined to be 5:1 and 0.5 hr, respectively. Despite the absence of antioxidants during the limonene recovery step with vacuum evaporation, the quantity of the oxidation products in the recovered limonene was <1% (wt) of the original limonene solvent. The application of d‐limonene solvent as an alternative to hexane in edible oil extraction could potentially eliminate the safety, environmental, and health issues associated with the use of hexane.     

PCB 118 and Aryl Hydrocarbon Receptor Immunoassays for Screening Dioxins in Retail Fish

The efficacy of a combination of two enzyme-linked immunosorbent assay (ELISA) kits was examined for screening the toxic equivalent (TEQ) concentrations of dioxins in retail fish. The coplanar PCB-EIA system, which is a competitive immunoassay specific for polychlorinated biphenyl (PCB) 118, was tested as a screening method for mono- ortho PCBs. The Ah immunoassay (Ah-I), which is an ELISA-based aryl hydrocarbon receptor binding assay, was analyzed for its screening ability for non- ortho PCBs, polychlorinated dibenzo- p-dioxins (PCDDs), and dibenzofurans (PCDFs). Dilution and recovery tests using purified fish extracts revealed no major interference of the matrix in the PCB-EIA and suggested that the matrix effect was minimized in the Ah-I. Finally, the results for the fish samples ( n = 20) showed a strong correlation between this method and high-resolution gas chromatography coupled to high-resolution mass spectrometry for the determination of the TEQ concentrations of mono- ortho PCBs ( r = 0.99) and non- ortho PCBs and PCDD/Fs ( r = 0.97). These data indicate that our method is suitable for screening retail fish to determine the TEQ concentrations of dioxins.     

Pretreatment of Wet‐Milled Corn Fiber to Improve Recovery of Corn Fiber Oil and Phytosterols

The phytosterol‐containing oil in the corn fiber (corn fiber oil) has potential use as a natural low‐density lipoprotein (LDL) lowering nutraceutical but its low concentration (1–3%) makes it difficult and expensive to extract. Pretreatment of corn fiber with dilute acid or glucosidases removed nonlipid components of fiber, producing oil‐enriched fractions that should be more amenable to efficient and inexpensive oil extraction. Acid, as well as enzymes, significantly increased the content of corn fiber oil and its phytosterol compounds by hydrolyzing (and removing) the starch and nonstarch (cell wall) polysaccharides from the wet‐milled corn fiber. Dual treatment of the fiber with acid and enzyme greatly increased the concentrations of corn fiber oil and its phytosterol components, compared with acid or enzyme treatments alone. Depending on the treatment, the oil concentration in the residual solids increased from 0.3 to 10.8% (21–771% increase in conc.) and the total phytosterol concentration increased from 19.8 to 1256.2 mg/g of fiber (11–710% increase in conc.) compared with untreated fiber.     

Rapid and complete extraction of phenols from olive oil and determination by means of a coulometric electrode array system

Extraction methods to determine olive oil phenols are not exhaustive. A procedure to test their effectiveness, based on the treatment of the extracted oil with 2 N HCl followed by analysis of phenols in the aqueous phase, has been developed. It was concluded, using this test, that 15-40% of phenols remained unextracted when the liquid/liquid extraction method with 80% methanol was applied. Solid phase extraction (C(18) cartridge) succeeded in retaining most of the phenols in the cartridge, but the recovery yield from the sorbent material was low. However, a new extraction method, based on the use of N,N-dimethylformamide (DMF) as an extraction solvent, achieved a complete extraction of phenols from oils. The proposed method requires a lower amount of oil, solvents, energy, and labor than the traditional ones. Because of the low concentration of phenols in the DMF extract, the highly sensitive electrochemical detector (EC) technique was studied. All of the phenols detected by the traditional UV detectors were also detected by EC using a coulometric array system. A rapid and complete analytical methodology of phenols in olive oil has been proposed based on coupling DMF extraction and EC detection.     

Extractability of 2,4-D,Dicamba and MCPP from Soil

The adsorption of herbicides on soil colloids is a major factor determining their mobility, persistence, and activity in soils. Solvent extraction could be a viable option for removing sorbed contaminants in soils. This study evaluated the extractability of three herbicides: 2,4 dichlorophenoxy-acetic acid (2,4-D), 4-chloro-2-methylphenoxypropanoic acid (mecoprop acid or MCPP), and 3,6-dichloro-2-methoxybenzoic acid (dicamba). Three solvents (water, methanol, and iso-propanol) and three methods of extraction (column, batch, and soxhlet) were compared for their efficiencies in removing the herbicides from three soils (loamy sand, silt loam, and silty clay). Both linear and non-linear Freundlich isotherms were used to predict sorption intensity of herbicides on soils subjected to various extraction methods and conditions. High K_dand K_fr, and low N values were obtained for all herbicides in silty clay soil by batch extraction. Methanol was the best solvent removing approximately 97% of all added herbicides from the loamy sand either by column or soxhlet extraction method. Isopropanol ranked second by removing over 90% of all herbicides by soxhelet extraction from all three soils. However, water was ineffective in removing herbicides from any of the soils using any of the three extracting procedures used in this study. In general, the extent of herbicide removal depended on soil type, herbicide concentration, extraction procedure, solvent type and amount, and extraction time.     

用于浸油的大豆挤压膨化研究

研究了大豆挤压膨化系统诸参数（模孔孔径、挤压温度、物料含水率、螺杆转速）对大豆粗脂肪、豆粕残油率、蛋白质含量、及其氮可溶解指数、脲酶活性的影响规律和挤压膨化系统最佳参数。结果表明,只要系统参数选择合适,可使膨化后大豆粗脂肪基本不减少,粕残油小于１％,使原设备浸出能力增加１５０％。且膨化前后大豆粗蛋白含量基本不变,氨基酸没有损失,膨化后氮可溶解指数和脲酶活性均略有下降。同时省去目前大豆膨化浸油和传统浸油过程的破碎、软化、轧胚、蒸炒等工序。需增加粉碎、膨化工序。