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1.
This study compared the body composition (fillet yield, chemical composition and lipid quality of fillets) and sensory quality of captured wild (by gillnet in August 2011) with experimentally raised farmed (reared in concrete flow‐through raceways, average water temperature 10 ± 3°C) whitefish, Coregonus macrophthalmus, from Lake Constance. The study was conducted in 2011 using 28 wild and 24 farmed market‐sized fish of approximately equal total lengths (25.1 ± 1.21 and 25.6 ± 1.28 cm). Farmed female Coregonus macrophthalmus exhibited a 3.3% lower fillet yield resulting from larger gonads and a shallower body shape. The protein contents of farmed and wild fillets were equal (17.5% vs. 17.4%), but farmed fish fillets contained less moisture (76.1% vs.77.4%), less ash (1.2% vs. 1.6%), and more lipid (5.1% vs. 4.1%) than wild‐caught specimens. Levels of monounsaturated fatty acids (MUFA) were higher in farmed fish (42.0 vs. 31.0 g/100 g lipid), as well as the levels of polyunsaturated fatty acids (PUFA; 26.0 vs. 19.7 g/100 g lipid), in particular 22:6n?3 (docosahexaenoic acid, DHA; 7.3 vs. 2.1 g/100 g lipid). Conversely, wild fish fillets contained significantly more 20:4n?6 (arachidonic acid, AA; 1.6 vs. 0.4 g/100 g lipid) and 20:5n?3 (eicosapentaenoic acid, EPA; 4.1 vs. 3.2 g/100 g lipid). Sensory evaluation of odour, colour, texture and flavour by an experienced six‐person panel revealed a significant preference for the colour (79% vs. 21%) of farmed fish fillets. In conclusion, farmed whitefish can be strong competitors to wild whitefish in terms of product quality, with higher levels of healthy fatty acids and a more attractive fillet colour. Farmed Coregonus macrophthalmus thus represents a promising and pragmatic approach, compensating for the current capture decline in the whitefish fisheries of Lake Constance.  相似文献   

2.
Aims:  Zero‐valent iron (ZVI) filters may provide an efficient method to mitigate the contamination of produce crops through irrigation water. Methods:  A field‐scale system was utilized to evaluate the effectiveness of a biosand filter (S), a biosand filter with ZVI incorporated (ZVI) and a control (C, no treatment) in decontaminating irrigation water. An inoculum of c. 8·5 log CFU 100 ml?1 of Escherichia coli O157:H12 was introduced to all three column treatments in 20‐l doses. Filtered waters were subsequently overhead irrigated to ‘Tyee’ spinach plants. Water, spinach plant and soil samples were obtained on days 0, 1, 4, 6, 8, 10, 13 and 15 and analysed for E. coli O157:H12 populations. Results:  ZVI filters inactivated c. 6 log CFU 100 ml?1E. coli O157:H12 during filtration on day 0, significantly (P < 0·05) more than S filter (0·49 CFU 100 ml?1) when compared to control on day 0 (8·3 log CFU 100 ml?1). On day 0, spinach plants irrigated with ZVI‐filtered water had significantly lower E. coli O157 counts (0·13 log CFU g?1) than spinach irrigated with either S‐filtered (4·37 log CFU g?1) or control (5·23 log CFU g?1) water. Soils irrigated with ZVI‐filtered water contained E. coli O157:H12 populations below the detection limit (2 log CFU g?1), while those irrigated with S‐filtered water (3·56 log CFU g?1) were significantly lower than those irrigated with control (4·64 log CFU g?1). Conclusions:  ZVI biosand filters were more effective in reducing E. coli O157:H12 populations in irrigation water than sand filters. Significance and Impact of the Study:  Zero‐valent ion treatment may be a cost‐effective mitigation step to help small farmers reduce risk of foodborne E. coli infections associated with contamination of leafy greens.  相似文献   

3.
The Ball–Berry (BB) model of stomatal conductance (gs) is frequently coupled with a model of assimilation to estimate water and carbon exchanges in plant canopies. The empirical slope (m) and ‘residual’ gs (g0) parameters of the BB model influence transpiration estimates, but the time‐intensive nature of measurement limits species‐specific data on seasonal and stress responses. We measured m and g0 seasonally and under different water availability for maize and sunflower. The statistical method used to estimate parameters impacted values nominally when inter‐plant variability was low, but had substantial impact with larger inter‐plant variability. Values for maize (m = 4.53 ± 0.65; g0 = 0.017 ± 0.016 mol m?2 s?1) were 40% higher than other published values. In maize, we found no seasonal changes in m or g0, supporting the use of constant seasonal values, but water stress reduced both parameters. In sunflower, inter‐plant variability of m and g0 was large (m = 8.84 ± 3.77; g0 = 0.354 ± 0.226 mol m?2 s?1), presenting a challenge to clear interpretation of seasonal and water stress responses – m values were stable seasonally, even as g0 values trended downward, and m values trended downward with water stress while g0 values declined substantially.  相似文献   

4.
The objective of this study was to determine the effectiveness of the spray‐drying process on the inactivation of Salmonella choleraesuis and Salmonella typhimurium spiked in liquid porcine plasma and to test the additive effect of immediate postdrying storage. Commercial spray‐dried porcine plasma was sterilized by irradiation and then reconstituted (1:9) with sterile water. Aliquots of reconstituted plasma were inoculated with either S. choleraesuis or S. typhimurium, subjected to spray‐drying at an inlet temperature of 200°C and an outlet temperature of either 71 or 80°C, and each spray‐drying temperature combinations were subjected to either 0, 30 or 60 s of residence time (RT) as a simulation of residence time typical of commercial dryers. Spray‐dried samples were stored at either 4·0 ± 3·0°C or 23·0 ± 0·3°C for 15 days. Bacterial counts of each Salmonella spp., were completed for all samples. For both Salmonella spp., spray‐drying at both outlet temperatures reduced bacterial counts about 3 logs at RT 0 s, while there was about a 5·5 log reduction at RT 60 s. Storage of all dried samples at either 4·0 ± 3·0°C or 23·0 ± 0·3°C for 15 days eliminate all detectable bacterial counts of both Salmonella spp.

Significance and Impact of the Study

Safety of raw materials from animal origin like spray‐dried porcine plasma (SDPP) may be a concern for the swine industry. Spray‐drying process and postdrying storage are good inactivation steps to reduce the bacterial load of Salmonella choleraesuis and Salmonella typhimurium. For both Salmonella spp., spray‐drying at 71°C or 80°C outlet temperatures reduced bacterial counts about 3 log at residence time (RT) 0 s, while there was about a 5.5 log reduction at RT 60 s. Storage of all dried samples at either 4.0 ± 3.0°C or 23.0 ± 0.3°C for 15 days was effective for eliminating detectable bacterial counts of both Salmonella spp.  相似文献   

5.
Aims: To prepare commercially acceptable formulations of Bacillus subtilis CPA‐8 by spray‐drying with long storage life and retained efficacy to control peach and nectarine brown rot caused by Monilinia spp. Methods and Results: CPA‐8 24‐h‐ and 72‐h‐old cultures were spray dried using 10% skimmed milk, 10% skimmed milk plus 10% MgSO4, 10% MgSO4 and 20% MgSO4 as carriers/protectants. All carriers/protectants gave good percentages of powder recovery (28–38%) and moisture content (7–13%). CPA‐8 survival varied considerably among spray‐dried 24‐h‐ and 72‐h‐old cultures. Seventy‐two hours culture spray dried formulations showed the highest survival (28–32%) with final concentration products of 1·6–3·3 × 109 CFU g?1, while viability of 24‐h‐old formulations was lower than 1%. Spray‐dried 72‐h‐old formulations were selected to subsequent evaluation. Rehydration of cells with water provided a good recovery of CPA‐8 dried cells, similar to other complex rehydration media tested. Spray‐dried formulations stored at 4 ± 1 and 20 ± 1°C showed good shelf life during 6 months, and viability was maintained or slightly decreased by 0·2–0·3‐log. CPA‐8 formulations after 4‐ and 6 months storage were effective in controlling brown rot caused by Monilinia spp. on nectarines and peaches resulting in a 90–100% reduction in disease incidence. Conclusions: Stable and effective formulations of biocontrol agent B. subtilis CPA‐8 could be obtained by spray‐drying. Significance and Impact of the Study: New shelf‐stable and effective formulations of a biocontrol agent have been obtained by spray‐drying to control brown rot on peach.  相似文献   

6.
Aims: To assess the effectiveness of sequential treatments of radish seeds with aqueous chlorine dioxide (ClO2) and dry heat in reducing the number of Escherichia coli O157:H7. Methods and Results: Radish seeds containing E. coli O157:H7 at 5·5 log CFU g?1 were treated with 500 μg ml?1 ClO2 for 5 min and subsequently heated at 60°C and 23% relative humidity for up to 48 h. Escherichia coli O157:H7 decreased by more than 4·8 log CFU g?1 after 12 h dry‐heat treatment. The pathogen was inactivated after 48 h dry‐heat treatment, but the germination rate of treated seeds was substantially reduced from 91·2 ± 5·0% to 68·7 ± 12·3%. Conclusions: Escherichia coli O157:H7 on radish seeds can be effectively reduced by sequential treatments with ClO2 and dry heat. To eliminate E. coli O157:H7 on radish seeds without decreasing the germination rate, partial drying of seeds at ambient temperature before dry‐heat treatment should be investigated, and conditions for drying and dry‐heat treatment should be optimized. Significance and Impact of the study: This study showed that sequential treatment with ClO2 and dry‐heat was effective in inactivating large numbers of E. coli O157:H7 on radish seeds. These findings will be useful when developing sanitizing strategies for seeds without compromising germination rates.  相似文献   

7.
Glutathione‐S‐transferases (GSTs) have a function in xenobiotic metabolism. They are a significant multifunctional family with a wide variety of catalytic activities. In the current study, we determined in vitro inhibition effects of 2,4‐dichlorophenoxyacetic acid dimethylamine salt (2,4‐D DMA), haloxyfop‐P‐methyl, glyphosate isopropylamine, dichlorvos, and λ‐cyhalothrin on purified GST. For this purpose, GST were purified from Van Lake fish (Chalcalburnus tarichii Pallas) liver with 29.25 EU mg?1 specific activity and 10.76% yield using GSH–agarose affinity chromatographic method. The pesticides were tested at various concentrations on in vitro GST activity. Ki constants were calculated as 0.17 ± 0.01, 0.25 ± 0.05, 3.72 ± 0.32, 0.42 ± 0.06, and 0.025 ± 0.004 mM, for 2,4‐D DMA, haloxyfop‐P‐methyl, glyphosate isopropylamine, dichlorvos, and λ‐cyhalothrin, respectively. λ‐Cyhalothrin showed a better inhibitory effect compared to the other pesticides. The inhibition mechanisms of λ‐cyhalothrin were competitive, while the other pesticides were noncompetitive.  相似文献   

8.
Aims: Greenhouse and field trials were conducted under different agronomic practices and inoculum doses of environmental Escherichia coli and attenuated E. coli O157:H7, to comparatively determine whether these factors influence their survival on leaves and within the rhizosphere. Methods and Results: Hydroponic conditions: E. coli spray‐inoculated at log 4 CFU ml?1 was recovered from leaf surfaces at a mean population of 1·6 log CFU g?1 at 15 days. E. coli O157:H7 sprayed at log 2 or 4 CFU ml?1 levelled off on spinach leaf surfaces at a mean average population of 1·4 log CFU g?1 after 14 days, regardless of initial dose. Quantitative recovery was inconsistent across leaf developmental age. Field conditions: Average populations of E. coli O157:H7 spray‐inoculated at log 1·45 or 3·4 CFU m?2 levelled off at log 1·2 CFU g?1 over a 14‐day period. Pathogen recovery from leaves was inconsistent when compared to regularly positive detection on basal shoot tissue. Pathogen recovery from soil was inconsistent among sampling locations. Moisture content varied up to 40% DW and was associated with 50% (P < 0·05) decrease in positive locations for E. coli O157:H7 but not for E. coli. Conclusions: Overall, similar populations of environmental E. coli and E. coli O157:H7 were recovered from plants despite differences in inoculum dose and agronomic conditions. Strain source had a significant impact on the quantitative level and duration of survival on leaves and in soil. Water availability appeared to be the determinant factor in survival of E. coli and E. coli O157:H7; however, E. coli showed greater environmental fitness. Significance and Impact of the Study: Persistence of surrogate, indicator E. coli and E. coli O157:H7, irrespective of variable growing conditions in spinach is predominantly limited by water availability, strain source and localization within the plant. These findings are anticipated to ultimately be adopted into routine and investigative pathogen testing protocols and mechanical harvest practices of spinach.  相似文献   

9.
A pharmacokinetic study of oxytetracycline (OTC) following a single (100 mg kg?1) or a multi‐dose (100 mg kg?1 for 5 days) oral administration was carried out in yellow catfish, Pelteobagrus fulvidraco. After oral administration at 25°C, a one‐compartment model was developed. The absorption half‐life (t1/2(ka)) was 3.92, 1.44, 2.75, and 3.34 h in plasma, muscle, liver, and kidney after the single dose, and 0.35, 0.22, 0.42, 0.32 h after the multi‐dose, respectively. The order of peak concentration (Cmax) was liver > kidney > plasma > muscle, at 3.48 μg g?1, 2.90 μg g?1, 1.46 μg ml?1, and 1.39 μg g?1 after the single dose, and 14.02 μg g?1, 8.51 μg g?1, 4.17 μg ml?1, and 3.84 μg g?1 after the multi‐dose, respectively. The elimination half‐lives (t1/2(ke)) of OTC in plasma, muscle, liver, and kidney were calculated to be 7.64, 26.29, 19.08, and 10.61 h after the single dose, and 47.54, 70.99, 49.87, and 47.73 h after the multi‐dose, respectively. The results suggest that OTC was absorbed faster after the multi‐dose than after the single dose, suggesting that OTC could be more efficacious after the multi‐dose and more effective in the control bacterial diseases in aquaculture, with the side effects of longer withdrawal periods.  相似文献   

10.
Aims: To select and evaluate an appropriate outer membrane (OM) permeabilizer to use in combination with the highly muralytic bacteriophage endolysin EL188 to inactivate (multi‐resistant) Pseudomonas aeruginosa. Methods and Results: We tested the combination of endolysin EL188 and several OM permeabilizing compounds on three selected Ps. aeruginosa strains with varying antibiotic resistance. We analysed OM permeabilization using the hydrophobic probe N‐phenylnaphtylamine and a recombinant fusion protein of a peptidoglycan binding domain and green fluorescent protein on the one hand and cell lysis assays on the other hand. Antibacterial assays showed that incubation of 106Ps. aeruginosa cells ml?1 in presence of 10 mmol l?1 ethylene diamine tetraacetic acid disodium salt dihydrate (EDTA) and 50 μg ml?1 endolysin EL188 led to a strain‐dependent inactivation between 3·01 ± 0·17 and 4·27 ± 0·11 log units in 30 min. Increasing the EL188 concentration to 250 μg ml?1 further increased the inactivation of the most antibiotic resistant strain Br667 (4·07 ± 0·09 log units). Conclusions: Ethylene diamine tetraacetic acid disodium salt dihydrate was selected as the most suitable component to combine with EL188 in order to reduce Ps. aeruginosa with up to 4 log units in a time interval of 30 min. Significance and Impact of the Study: This in vitro study demonstrates that the application range of bacteriophage encoded endolysins as ‘enzybiotics’ must not be limited to gram‐positive pathogens.  相似文献   

11.
Microalgae biofuel production can be feasible when a second function is added, such as wastewater treatment. Microalgae differ in uptake of phosphorus (P) and growth, making top performer identification fundamental. The objective of this screen was to identify dual‐purpose candidates capable of high rates of P removal and growth. Three freshwater – Chlorella sp., Monoraphidium minutum sp., and Scenedesmus sp. – and three marine – Nannochloropsis sp., N. limnetica sp., and Tetraselmis suecica sp. – species were batch cultured in 250 mL flasks over 16 days to quantitate total phosphorus (TP) removal and growth as a function of P loads (control, and 5, 10, and 15 mg L?1 enrichment of control). Experimental design used 100 μmol m?2 s?1 of light, a light/dark cycle of 14/10 h, and no CO2 enrichment. Phosphorus uptake was dependent on species, duration of exposure, and treatment, with significant interaction effects. Growth was dependant on species and treatment. Not all species showed increased P removal with increasing P addition, and no species demonstrated higher growth. Nannochloropsis sp and N. limnetica sp. performed poorly across all treatments. Two dual‐purpose candidates were identified. At the 10 mg L?1 treatment Monoraphidium minutum sp. removed 67.1% (6.66 mg L?1 ± 0.60 SE) of TP at day 8, 79.3% (7.86 mg L?1 ± 0.28 SE) at day 16, and biomass accumulation of 0.63 g L?1 ± 0.06 SE at day 16. At the same treatment Tetraselmis suecica sp. removed 79.4% (6.98 mg L?1 ± 0.24 SE) TP at day 8, 83.0% (7.30 mg L?1 ± 0.60 SE) at day 16, and biomass of 0.55 g L?1 ± 0.02 SE at day 16. These species merit further study using high‐density wastewater cultures and lipid profiling to assess suitability for a nutrient removal and biomass/biofuel production scheme.  相似文献   

12.
Herein, a new recipe is introduced for the preparation of hydrogen phosphate ion‐imprinted polymer nanoparticles (nano‐IIP) in acetonitrile/water (63.5:36.5) using phosphoric acid as the template. The nano‐IIP obtained was used as the recognition element of a carbon paste potentiometric sensor. The IIP electrode showed a Nernstian response to hydrogen phosphate anion; whereas, the non‐imprinted polymer (NIP)‐based electrode had no considerable sensitivity to the anion. The presence of both methacrylic acid and vinyl pyridine in the IIP structure, as well as optimization of the functional monomers‐template proportion, was found to be important to observe the sensing capability of the IIP electrode. The nano‐IIP electrode showed a dynamic linear range of 1 × 10?5‐1 × 10?1 mol L‐1, Nernstian slope of 30.6 ± (0.5) mV decade ?1, response time of 25 seconds, and detection limit of 4.0 × 10?6 mol L?1. The utility of the electrodes was checked by potentiometric titration of hydrogen phosphate with La3+ solution.  相似文献   

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14.
Schizochytrium mangrovei strain PQ 6 was investigated for coproduction of docosahexaenoic acid (C22: 6ω‐3, DHA ) and squalene using a 30‐L bioreactor with a working volume of 15 L under various batch and fed‐batch fermentation process regimes. The fed‐batch process was a more efficient cultivation strategy for achieving higher biomass production rich in DHA and squalene. The final biomass, total lipid, unsaponifiable lipid content, and DHA productivity were 105.25 g · L?1, 43.40% of dry cell weight, 8.58% total lipid, and 61.66 mg · g?1 · L?1, respectively, after a 96 h fed‐batch fermentation. The squalene content was highest at 48 h after feeding glucose (98.07 mg · g?1 of lipid). Differences in lipid accumulation during fermentation were correlated with changes in ultrastructure using transmission electron microscopy and Nile Red staining of cells. The results may be of relevance to industrial‐scale coproduction of DHA and squalene in heterotrophic marine microalgae such as Schizochytrium .  相似文献   

15.
Aims: The purposes of this study were to evaluate the efficacy of high pressure to inactivate Escherichia coli O157:H7 in ground beef at ambient and subzero treatment temperatures and to study the fate of surviving bacteria postprocess and during frozen storage. Methods and Results: Fresh ground beef was inoculated with a five‐strain cocktail of E. coli O157:H7 vacuum‐packaged, pressure‐treated at 400 MPa for 10 min at ?5 or 20°C and stored at ?20 or 4°C for 5–30 days. A 3‐log CFU g?1 reduction of E. coli O157:H7 in the initial inoculum of 1 × 106 CFU g?1 was observed immediately after pressure treatment at 20°C. During frozen storage, levels of E. coli O157:H7 declined to <1 × 102 CFU g?1 after 5 days. The physiological status of the surviving E. coli was affected by high pressure, sensitizing the cells to pH levels 3 and 4, bile salts at 5% and 10% and mild cooking temperatures of 55–65°C. Conclusions: High‐pressure processing (HPP) reduced E. coli O157:H7 in ground beef by 3 log CFU g?1 and caused substantial sublethal injury resulting in further log reductions of bacteria during frozen storage. Significance and Impact of the Study: HPP treatment of packaged ground beef has potential in the meat industry for postprocess control of pathogens such as E. coli O157:H7 with enhanced safety of the product.  相似文献   

16.
A technique using 51chromium‐labelled erythrocytes was used to measure blood volume in Scyliorhinus canicula following long‐term and acute salinity transfers. Basal whole‐blood volume was 5·6 ± 0·2 ml 100 g?1 (mean ±s .e .), this increased (6·3 ± 0·2 ml 100 g?1) following +14 day acclimation to 80% sea water (SW) and decreased (4·6 ± 0·2 ml 100 g?1) following acclimation to 120% SW. These changes were shown to be primarily due to changes in plasma volume, with no significant changes in extrapolated red‐cell volume being demonstrated. Blood volume was also measured in the same animals during 10 h acute transfer to 100% SW. Plasma volume in S. canicula during acclimation from 80% SW was significantly reduced (4·5 ± 0·3 ml 100 g?1) after 6 h of transfer to 100% SW. Blood volume in animals during acclimation from 120% SW was significantly increased (4·8 ± 0·2 ml 100 g?1) after 4 h of acute transfer. The osmoregulatory implications of these different timeframes during hyposaline and hypersaline transfer are discussed, along with the importance of this in vivo technique as context for in vitro studies with haemo‐dynamic stimuli.  相似文献   

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Length–weight relationships and condition factors of wild, cultured, and cultured loose‐shell affected Penaeus monodon (2,609 specimens total) were studied from March to August 2007. The regression equation for healthy cultured shrimps was log W = ?1.811 + 2.721 log L (r2 = 0.71); log W = ?1.444 + 2.485 log L (r2 = 0.91) for wild shrimps; and log W = ?1.112 + 2.237 log L (r2 = 0.92) for loose‐shell affected shrimps. All shrimps showed negative allometric growth, although ancova indicated significant differences (P < 0.05) among them. This study presents the first known reference dealing with LWRs and condition factors of cultured, wild and loose‐shell affected P. monodon.  相似文献   

20.
The red seaweed Gracilariopsis is an important crop extensively cultivated in China for high‐quality raw agar. In the cultivation site at Nanao Island, Shantou, China, G. lemaneiformis experiences high variability in environmental conditions like seawater temperature. In this study, G. lemaneiformis was cultured at 12, 19, or 26°C for 3 weeks, to examine its photosynthetic acclimation to changing temperature. Growth rates were highest in G. lemaneiformis thalli grown at 19°C, and were reduced with either decreased or increased temperature. The irradiance‐saturated rate of photosynthesis (Pmax) decreased with decreasing temperature, but increased significantly with prolonged cultivation at lower temperatures, indicating the potential for photosynthesis acclimation to lower temperature. Moreover, Pmax increased with increasing temperature (~30 μmol O2 · g?1FW · h?1 at 12°C to 70 μmol O2 · g?1FW · h?1 at 26°C). The irradiance compensation point for photosynthesis (Ic) decreased significantly with increasing temperature (28 μmol photons · m?2 · s?1 at high temperature vs. 38 μmol photons · m?2 · s?1 at low temperature). Both the photosynthetic light‐ and carbon‐use efficiencies increased with increasing growth or temperatures (from 12°C to 26°C). The results suggested that the thermal acclimation of photosynthetic performance of G. lemaneiformis would have important ecophysiological implications in sea cultivation for improving photosynthesis at low temperature and maintaining high standing biomass during summer. Ongoing climate change (increasing atmospheric CO2 and global warming) may enhance biomass production in G. lemaneiformis mariculture through the improved photosynthetic performances in response to increasing temperature.  相似文献   

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