首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 31 毫秒
1.
Recent legislation in the European Union (EC/2065/2001) requires that seafood must provide the consumer with information that describes geographical origin and production method. The present studies aimed to establish methods, based on chemical and stable isotopic analysis, that could reliably differentiate between wild and farmed European sea bass (Dicentrarchus labrax). The study measured fatty acid and isotopic compositions (delta13C and delta18O) of total flesh oil, delta15N of the glycerol/choline fraction, and compound-specific analysis of fatty acids (delta13C) by isotope ratio mass spectrometry. The sample set comprised 10 wild and 10 farmed sea bass from England (wild) and Scotland or Greece (farmed). Discrimination was achieved using fatty acid composition with 18:0, 18:2n-6, 20:4n-6, and 22:6n-3 providing the highest contributions for discrimination. Principal component analysis of the data set provided good discrimination between farmed and wild sea bass where factor 1 and factor 2 accounted for 60% of the variation in the data.  相似文献   

2.
The stable isotope ratios ((13)C/(12)C and (15)N/(14)N) of casein measured by isotope ratio mass spectrometry (IRMS) and some free amino acid ratios (His/Pro, Ile/Pro, Met/Pro, and Thr/Pro) determined by HPLC in samples of ewes' milk cheese from Sardinia, Sicily, and Apulia were found to be parameters independent of ripening time. Multivariate data treatments performed by applying both unsupervised (principal component analysis and cluster analysis) and supervised [linear discriminant analysis (LDA)] methods revealed good discrimination possibilities for the cheeses according to place of origin. In this respect, particularly significant were the variables Ile/Pro, Thr/Pro, (13)C/(12)C, and (15) N/(14)N ratios on which basis 100% discrimination and classification of the samples by LDA was obtained.  相似文献   

3.
To gain information about the geographical origin of oil samples, measurements of delta(13)C and delta(18)O of the whole oil and some of its fractions have been performed on samples coming from fruits of Olea europaea L. produced in Greece, Morocco, Spain, Italy, Tunisia, and Turkey. The results obtained by applying statistical procedures have given pieces of evidence that oil samples have shown the trend to cluster according to the different climatic areas of growing environment of fruits. Some confusion has been observed for samples coming from neighboring countries having similar climates.  相似文献   

4.
The stable isotopes of hydrogen, carbon, nitrogen, and oxygen provide insights into a heterotrophic organism's diet and geographic origin. Although the contribution of food delta (2)H and delta (18)O to the final tissue signal will not vary for constrained diets, it will for animals eating varied diets, that is, humans. This study surveyed the isotopic range in one portion of the American diet, fast food meals. Hamburger patties, buns, and French fries from national chain restaurants across the United States and from local restaurants (Salt Lake City, UT, and Charleston, SC) were analyzed for delta (2)H, delta (13)C, delta (15)N (patties only) and delta (18)O values. Patties and buns from local Utah restaurants were more depleted for delta (2)H, delta (13)C, and delta (18)O values than samples from other restaurants. There were no significant differences in delta values among French fries. All three components of the fast food meal displayed significant linear delta (2)H versus delta (18)O relationships (delta (2)H = 7.8delta (18)O - 237 per thousand, delta (2)H = 5.9delta (18)O - 258 per thousand, and delta (2)H = 3.3delta (18)O - 231 per thousand for patties, buns, and fries, respectively). The findings show that significant predictable variation exists in the stable isotopic composition of fast food meals. It is proposed that the variation in delta (13)C values of hamburger (beef) patties is indicative of differences in cattle-rearing practices, whereas delta (2)H and delta (18)O values are evidence of geographic variation in food sources. Although the patterns support the concept of a "continental" supermarket diet, there appears to be a strong regional component within the diet.  相似文献   

5.
The authenticity and geographical origin of wines produced in Slovenia were investigated by a combination of IRMS and SNIF-NMR methods. A total of 102 grape samples of selected wines were carefully collected in three different wine-growing regions of Slovenia in 1996, 1997, and 1998. The stable isotope data were evaluated using principal component analysis (PCA) and linear discriminant analysis (LDA). The isotopic ratios to discriminate between coastal and continental regions are the deuterium/hydrogen isotopic ratio of the methylene site in the ethanol molecule (D/H)(II) and delta(13)C values; including also delta(18)O values in the PCA and LDA made possible separation between the two continental regions Drava and Sava. It was found that delta(18)O values are modified by the meteorological events during grape ripening and harvest. The usefulness of isotopic parameters for detecting adulteration or watering and to assess the geographical origin of wines is improved only when they are used concurrently.  相似文献   

6.
Multielemental (C, N, H, S) stable isotope ratio analysis was used as an analytical tool to verify the geographical origin of beef from several European and non-European countries. Beef samples were collected from nine different countries, and the (13)C/(12)C, (15)N/(14)N, (2)H/(1)H, and (34)S/(32)S ratios of defatted beef were measured using isotope ratio mass spectrometry (IRMS). There were highly significant differences in the mean isotopic values of the beef from different countries. The results of discriminant analysis showed that the four isotope ratios were significant for the discrimination of geographical origin and that 84.9% of the samples were correctly assigned to the country of origin (82.2% when cross-validated). Beef was also classified according to geographical origin when additional information on different feeding regimens used in Ireland was included, with 85.0% of the samples correctly allocated and 82.9% cross-validated using the isotopic signatures. All of the Irish beef samples verifiable as pasture-fed beef were correctly classified and then cross-validated.  相似文献   

7.
Fatty acid composition and stable isotope ratios of carbon (delta(13)C) and nitrogen (delta(15)N) were determined in muscle tissue of turbot (Psetta maxima). The multivariate analysis of the data was performed to evaluate their utility in discriminating wild and farmed fish. Wild (n=30) and farmed (n=30) turbot of different geographical origins (Denmark, The Netherlands, and Spain) were sampled from March 2006 to February 2007. The application of linear discriminant analysis (LDA) and soft independent modeling of class analogy (SIMCA) to analytical data demonstrated the combination of fatty acids and isotopic measurements to be a promising method to discriminate between wild and farmed fish and between wild fish of different geographical origin. In particular, IRMS (Isotope Ratio Mass Spectrometry) alone did not permit us to separate completely farmed from wild samples, resulting in some overlaps between Danish wild and Spanish farmed turbot. On the other hand, fatty acids alone differentiated between farmed and wild samples by 18:2n-6 but were not able to distinguish between the two groups of wild turbot. When applying LDA isotope ratios, 18:2n-6, 18:3n-3, and 20:4n-6 fatty acids were decisive to distinguish farmed from wild turbot of different geographical origin, while delta(15)N, 18:2n-6, and 20:1n-11 were chosen to classify wild samples from different fishing zones. In both cases, 18:2n-6 and delta(15)N were determinant for classification purposes. We would like to emphasize that IRMS produces rapid results and could be the most promising technique to distinguish wild fish of different origin. Similarly, fatty acid composition could be used to easily distinguish farmed from wild samples.  相似文献   

8.
Green coffee bean isotopes have been used to trace the effects of different climatic and geological characteristics associated with the Hawaii islands. Isotope ratio mass spectrometry (IRMS) and inductively coupled plasma mass spectrometry ((MC)-ICP-SFMS and ICP-QMS) were applied to determine the isotopic composition of carbon (δ13C), nitrogen (δ15N), sulfur (δ34S), and oxygen (δ18O), the isotope abundance of strontium (87Sr/86Sr), and the concentrations of 30 different elements in 47 green coffees. The coffees were produced in five Hawaii regions: Hawaii, Kauai, Maui, Molokai, and Oahu. Results indicate that coffee plant seed isotopes reflect interactions between the coffee plant and the local environment. Accordingly, the obtained analytical fingerprinting could be used to discriminate between the different Hawaii regions studied.  相似文献   

9.
On-line capillary gas chromatography-isotope ratio mass spectrometry was used in the combustion (HRGC-C-IRMS) and the pyrolysis (HRGC-P-IRMS) modes to determine delta(13)C(PDB), delta(2)H(SMOW), and delta(18)O(SMOW) data of estragole (1) and methyl eugenol (2) originating from various sources. For 1, similar delta(13)C values, i.e., ranging from -35.4 to -29.9 per thousand and from -36.4 to -28.8 per thousand for the product of synthetic and natural origins, respectively, were found. The delta(2)H values ranged from -155 to -3 per thousand for synthetic 1 and from -193 to -105 per thousand for 1 from natural origin, whereas the determination of delta(18)O data gave values from +1.8 to +24.8 per thousand and from +2.7 to +18.7 per thousand for 1 from synthetic and natural origins, respectively. As synthetic 2 is produced by methylation of natural eugenol, the IRMS techniques did not allow differentiation of synthetic 2 from the product of natural origin. The recorded data ranges were nearly identical, i.e., delta(13)C = -37.4 to -35.0 per thousand and -41.1 to -32.2 per thousand; delta(2)H = -155 to -126 per thousand and -217 to -107 per thousand; delta(18)O = +5.5 to +6.6 per thousand and +2.7 to +6.9 per thousand, each for 2 from synthetic and natural origins, respectively.  相似文献   

10.
Wine hydrogen and oxygen stable isotopes record the climatic conditions experienced by the grape vine and the isotopic composition of the vine's source water during berry development. As such, stable isotopes have been explored extensively for use in detecting wine adulteration or for independently verifying claims of origin. We present the results of a study designed to evaluate the relationships between wine water delta18O and spatial climate and precipitation delta18O patterns across the winegrape-growing regions of Washington, Oregon, and California. Retail wines produced from typically small vineyards across these regions were obtained from the 2002 vintage, and the delta18O of wine water was analyzed using a CO2 equilibration method. Significant correlations were observed between the measured wine water delta18O from 2002 and the long-term average precipitation delta18O and late season 2002 climate, based on a spatial join with continuous geographic information system (GIS) maps of these drivers. We then developed a regression model that was implemented spatially in a GIS. The GIS model is the first of its kind and allows spatially explicit predictions of wine delta18O across the region. Because high spatial resolution monthly climate layers are now available for many years, wine delta18O could be modeled for previous years. We therefore tested the model by executing it for specific years and comparing the model predictions with previously published results for wine delta18O from seven vintages from Napa and Livermore Valleys, California. With the exception of one year, an anomaly potentially related to the effects of El Ni?o on precipitation isotopic composition, the model predicted well the wine delta18O for both locations for all vintages and generally reflected the consistent enrichment of wine from Napa relative to Livermore. Our results suggest that wine water delta18O records both source water delta18O and climate during the late stages of winegrape ripening and that GIS models of wine water delta18O are useful tools for independently verifying claims of regional origin and vintage.  相似文献   

11.
Isotope parameters (δ(13)C(honey), δ(13)C(protein), δ(15)N) were determined for 271 honey samples of 7 types (black locust, multifloral, lime, chestnut, forest, spruce, and fir honeys) from 4 natural geographical regions of Slovenia. Carbon and nitrogen stable isotope ratios were measured to elucidate the applicability of this method in the identification of the botanical and geographical origin of honey and in honey adulteration. Only 2.2% of the samples were adulterated according to the internal standard carbon isotope ratio analysis method. Botanical origin did not have any major influence on the honey isotope profiles; only black locust honey showed higher δ(13)C values. Some differences were seen across different production years, indicating that the influence of season should be further tested. Statistical and multivariate analyses demonstrated differences among honeys of various geographical origins. Those from the Alpine region had low δ(13)C (-26.0‰) and δ(15)N values (1.1‰); those from the Mediterranean region, high δ(13)C (-24.6‰) and medium δ(15)N values (2.2‰); those from the Pannonian region, medium δ(13)C (-25.6‰) and high δ(15)N value (3.0‰); and those from the Dinaric region, medium δ(13)C (-25.7‰) and low δ(15)N values (1.4‰).  相似文献   

12.
By use of headspace SPME sampling and a PLOT column, on-line capillary gas chromatography-isotope ratio mass spectrometry was employed in the combustion (C) and the pyrolysis (P) modes (HRGC-C/P-IRMS) to determine the delta(13)C(VPDB) and delta(18)O(VSMOW) values of ethanol in authentic (n = 14) and commercial tequila samples (n = 15) as well as a number of other spirits (n = 23). Whereas with delta(13)C(VPDB) values ranging from -12.1 to -13.2 per thousand and from -12.5 to -14.8 per thousand similar variations were found for 100% agave and mixed tequilas, respectively, the delta(18)O(VSMOW) data differed slightly within these categories: ranges from +22.1 to +22.8 per thousand and +20.8 to +21.7 per thousand were determined for both the authentic 100% agave and mixed products, respectively. The data recorded for commercial tequilas were less homogeneous; delta(13)C(VPDB) data from -10.6 to -13.9 per thousand and delta(18)O(VSMOW) values from +15.5 to +22.7 per thousand were determined in tequilas of both categories. Owing to overlapping data, attempts to differentiate between white, rested, and aged tequilas within each of the two categories failed. In addition, discrimination of tequila samples from other spirits by means of delta(13)C(VPDB) and delta(18)O(VSMOW) data of ethanol was restricted to the products originating from C(3) as well as C(4)/CAM raw materials.  相似文献   

13.
The nanostructure of Mozzarella cheeses prepared from microfluidized milk was compared with that of control cheeses made from untreated milk. Milk heated to 10 or 54 degrees C and containing 1.0 or 3.2% fat was homogenized by microfluidization at 34 or 172 MPa prior to cheesemaking. The effects on the casein particles and fat globules in the cheese were determined by transmission electron microscopy after 1 day and 6 weeks of storage at 4 degrees C. The micrographs showed that electron-dense regions theorized to be casein submicelles rearranged from a homogeneous configuration to a pattern of clusters during the storage period. The nanostructure of the cheeses made from milk processed under the mildest conditions resembled the controls, but otherwise the fat droplets decreased in size and increased in number as the pressure and temperature were increased. The results indicate that both homogenization temperature and pressure affect the nanostructure of Mozzarella cheese.  相似文献   

14.
Purpose

This study aimed to understand the mechanisms of the variations in carbon (C) and nitrogen (N) pools and examine the possibility of differentiating the burning effects from seasonal and pre-existed N limitations in a native suburban forest ecosystem influenced by prescribed burning in subtropical Australia.

Materials and methods

Soil and litterfall samples were collected from two study sites from 1 to 23 months since last burnt. Soil labile C and N pools, soil C and N isotopic compositions (δ13C and δ15N), litterfall mass production (LM), and litterfall total C, total N, δ13C and δ15N were analysed. In-situ gas exchange measurements were also conducted during dry and wet seasons for Eucalyptus baileyana and E. planchoniana.

Results and discussion

The results indicated that labile C and N pools increased within the first few months after burning, with no correlations with climatic factors. Therefore, it was possible that the increase was due to the burning-induced factors such as the incorporation of ashes into the soil. The highest values of soil and litterfall δ15N, observed when the study was commenced at the experimental sites, and their high correlations with climatic factors were indicative of long-term N and water limitation. The 13C signals showed that soil N concentrations and climatic factors were also two of the main factors controlling litterfall and foliage properties mainly through the changes in photosynthetic capacity and stomatal conductance.

Conclusions

Long-term soil N availabilities and climatic factors were the two of the main driving factors of C and N cycling in the studied forest sites. Further studies are needed to compare soil and litterfall properties before and after burning to profoundly understand the effects of prescribed burning on soil labile C and N variations.

  相似文献   

15.
《Pedobiologia》2014,57(3):155-160
Animal dung is an important resource in natural, pastoral and agro-ecosystems. Labelling dung with stable isotopes offers a powerful technique to trace faeces-derived carbon and nutrients in soils and organisms, but the production of isotopically labelled animal excrements needs to be practicable and cost-effective. Here we present a simple method for producing solid rabbit faeces triple-labelled with 13C, 15N and 34S stable isotopes. The steps involved are: (1) fertilising cereal seedlings with isotopically enriched fertilizers (13C–15N urea and 34S sodium sulphate); (2) feeding these seedlings daily to a rabbit as supplementary forage for 6 days; and (3) collecting the accruing faeces and measuring the isotopic enrichment in bulk dung and the undigested fraction. The rabbit dung was clearly enriched in 13C, 15N and 34S compared to unlabelled start dung. The enrichments increased linearly with time and peaked on the last day of the labelling diet, but most were still detectable two days later, especially 15N. The undigested fraction (Neutral Detergent Fibre) had lower enrichments than the bulk material; this was especially marked for 34S. Data from a follow-up experiment, in which soil microcosms were fertilised with the dung, illustrated that the 15N enrichments were sufficient to track N incorporation into grass. Our method is simple, rapid and suitable to the small-scale production of labelled faeces. We present tracer recovery estimates for the sequence total tracer used ⇒ wheat biomass ⇒ animal dung and discuss ways of increasing the proportions recovered and of obtaining higher enrichments if required.  相似文献   

16.
Stable carbon isotope ratio analysis (SCIRA) was used to determine the authenticity of commercial Australian orange juices. Thirty-five samples of Valencia (delta(13)C values from -23.8 to -24.7 ppt) and eight samples of Navel juices (delta(13)C values from -24.1 to -24.5 ppt) of known origin were used to establish a decision level before analysis. No significant seasonal variations in (13)C/(12)C ratio were observed. Variations in combustion temperature in the method were also found to be insignificant.  相似文献   

17.
Variability within the stable isotope ratios in various lipidic fractions and the fatty acid composition of muscle oil has been analyzed for a large sample (171 fish) of wild and farmed Atlantic salmon ( Salmo salar) from 32 origins within Europe, North America, and Tasmania. Sampling was extended over all seasons in 2 consecutive years and included fish raised by different practices, in order to maximize the range of variation present. It is shown that two readily measured parameters, delta 15N measured on choline and delta18 O measured on total oil, can be successfully used to discriminate between fish of authentic wild and farmed origin. However, the certainty of identification of mislabeling in market-derived fish is strengthened by including the percentage of linoleic acid C18:2n-6 in the lipidic fraction. Thus, several apparent misidentifications were found. The combination of these three analytical parameters and the size of the database generated makes the method practical for implementation in official laboratories as a tool of labeling verification.  相似文献   

18.
Stable isotope ratio analysis (SIRA) was used as an analytical tool to verify the preslaughter diet of beef cattle. Muscle and tail hair samples were collected from animals fed either pasture (P), a barley-based concentrate (C), silage followed by pasture (SiP), or silage followed by pasture with concentrate (SiPC) for 1 year (n = 25 animals per treatment). The (13)C/(12)C, (15)N/(14)N, (2)H/(1)H, and (34)S/(32)S isotope ratios in muscle clearly reflected those of the diets consumed by the animals. By applying a stepwise canonical discriminant analysis, a good discrimination of bovine meat according to dietary regimen was obtained. On the basis of the classification success rate, the (13)C/(12)C and (34)S/(32)S ratios in muscle were the best indicators for authentication of beef from animals consuming the different diets. Analysis of (13)C/(12)C and (15)N/(14)N in tail hair sections provided an archival record of changes to the diet of the cattle for periods of over 1 year preslaughter.  相似文献   

19.
为开展碳、氮、氢、氧(C、H、O、N)稳定同位素鉴别库尔勒香梨产地的可行性研究,明确新疆库尔勒香梨δ13C、δ15N、δ2H、δ18O值,本研究以甘肃香梨和陕西红香酥梨作为对照,采用稳定同位素比值质谱仪(IRMS)分析新疆库尔勒香梨与对照样品的δ13C、δ15N、δ2H、δ18O值,并采用正交校正的偏最小二乘判别分析(OPLS-DA) 鉴别新疆库尔勒香梨产地真实性。结果表明,新疆、甘肃两个产区香梨与陕西产区红香酥梨的δ13C、δ15N、δ2H、δ18O值存在显著差异(P<0.05)。新疆产区的66份库尔勒香梨判别准确率为95.45%;甘肃产区的20份香梨样品判别准确率为60%;陕西产区的23份红香酥梨样品判别准确率为95.65%。C、N、H、O 4种稳定同位素可有效鉴别新疆库尔勒香梨和陕西红香酥梨,但在新疆库尔勒香梨与甘肃香梨鉴别方面,误判率较高,如果能结合其他鉴别技术,则有可能出现较好的鉴别效果。本研究为库尔勒香梨产地真实性鉴别提供了科学依据。  相似文献   

20.
The determination of the geographical origin of dairy products is an ongoing issue. In this paper the effects of botanical diversity of two pastures on the hydrocarbon and fatty acid composition of cheese fat were studied, over 2 years of experimentation. Two areas in the Italian southwestern Alpine region, dominated by Trifolium alpinum (T) and Festuca nigrescens (F) vegetation, respectively, were chosen, and milk obtained from cows grazing on these pastures was used to produce a semihard traditional cheese. Cheese samples showed a significantly different composition of most linear hydrocarbons, odd-chain (C15, C17, and C17:1) and unsaturated (trans-11,cis-15-C18:2, C18:3, C20:4n-6, C20:4n-3, and 20:5n-3) fatty acids, according to pasture type. The ratio between C(29) and C(27) linear hydrocarbons, unlike the absolute content of the single molecules, showed a good discriminating ability between the two pastures and was little affected by the natural variability due to the climatic and environmental factors.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号