983 resultados para Freezing and processing


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The present study aims to find the effect of freezing Time on the quality of Cobia (Rastrelliger kanagurta) and Indian Squid in commercial scale during freezing and subsequent frozen storage (−18◦C). Total time for freezing was significantly different (P<0.05) between the Cobia and Indian squid samples. The difference in the freezing time could be attributed to the varied quality of the 2 samples. Upon freezing, the moisture content decreased in Indian Squide samples compared to Cobia freezer where protein content decreased in both the samples. Upon freezing and during frozen storage, lipid oxidation products (peroxide value, and free fatty acid value) and volatile bases (total volatile base nitrogen) showed an increasing trend in both the samples with values slightly higher in Indian squid samples compared to cobia frozen samples. The total plate counts showed a significantly (P<0.05) decreasing trend in both the samples. K value did not show any significant (P<0.05) difference between the samples whereas the histamine formation was significantly (P<0.05) increased in Indian squid frozen samples compared to cobia samples. The taste and overall acceptability was significantly different (P<0.05) in cobia samples compared to Indian squid frozen samples on 5th month. Both samples were in acceptable condition up to 5 month but the Cobia frozen samples quality was slightly better than the air blast frozen samples.

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The main aim of this research was to identify fatty acids composition of Caspian sea of White fish Rutilus frisi kutum tissue and their changes during one year cold storage (-18Ċ).The secondary aim was to determine the changes of moisture, ash, protein, fat, and to investigate the effects of storage time on peroxide, TBAi, FFA, and extractability of myofibrillar proteins of the fish tissue during one year cold storage (-18 Ċ). 10 samples of (Rutilus frisi kutum) were randomly collected from Anzali landings. The samples were frozen at -30 Ċ and kept in cold storage at -18Ċ for one year. According to time table, the samples were examined. The results showed that 27 fatty acids were identified. The unsaturated fatty acids (UFA) and saturated fatty acids (SFA) were 74/09 and 21/63 %, respectively, in fresh tissue. So that DHA (C22:6) oleic acid (C18:1c) had high amounts (15/07 ,20/57 ) among the UFA and palmitic acid (C16:0) was the most (13/09 %) among the SFA. The effects of freezing and cold storage on fish tissue showed that UFA and SFA contents have reached to 58/79 and 22/17 %, respectively, at the end of cold storage. It indicated that these compound change to each other during frozen storage. Also ω-3 and ω-6 series of fatty acids was 24/22 and 15/56% in fresh tissue, but their contents decreased to 8/68 and 5/11% at the end of period. Among the fatty acids C22:6, C18:1c and C16:0 had the most changes. The changes of fatty acids were significantly at 95% level expected for C18:0. Results showed that moisture, ash, protein, and fat contents were 75/9±0/03, 1/28±0/012, 21/8±0/2, and 4/1±0/01 % respectively, in fresh tissue. The moisture, ash, protein, and fat contents were 72/3±0/04, 1/83±0/05, 1/91±0/01 and 19/9±0/01 % respectively, at the end of storage period. Lipid damage was measured on the basis of free fatty acids (FFA), peroxide value (PV), and Thiobarbituric acid index (TBA-i). PV, TBARS and FFA concentration of frozen Caspian Sea white fish stored at -18 Ċ the temporal variation of these three variables were statistically significant (p<0.001). Results of White fish myofibrillar proteins showed aggregation of bound reduced for stored at 12 months. SDS-PAGE analysis revealed that, the intensity of the myosin heavy chain and actin bound was reduced with increasing storage time. SDS-PAGE patterns showed that myosin heavy chain was much more susceptible to hydrolysis than actin. Key words: Rutilus frisi kutum, frozen storage, ω-3, ω-6, protein myofibrillar

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The first aim of this research was to identify fatty acids, amino acids composition of Thunnus tonggol roe and their changes during cold storage (-18'C). The second aim was to determine the changes of moisture, protein, fat and ash contents of the roe during one year cold storage (-18'C). 60 samples of longtail tuna (Thunnus tonggol) ovaries were randomly collected form Bandar-e-Abbas landings. The samples were frozen at-30'C and kept in cold store at -18'C for one year. According to a time table, the samples were examined for identification of fatty acids, amino acids, moisture, protein, fat, ash, peroxide and T.V.N. and their changes were evaluated during this time. The results showed that 26 fatty acids were identified. The unsaturated fatty acids (UFA) and saturated fatty acids (SFA) were 62.33 and 37.6%, respectively, in fresh roe. So that, DHA (C22:6) and oleic acid (C18:1) had high amounts (24.79 and 21.88%) among the UFA and palmitic acid (C16:0) was the most content (22.75%) among the SFA. The PUFA/SFA was 0.91. Also, 17 amino acids were identified that essential amino acids (EAA) and nonessential amino acids (NE) were 10478 and 7562 mg/100g, respectively, and E/NE was 1.38. Among the EAA and NE, lysine (2110mg/100g) and aspartic acid (1924 mg/100g) were the most contents. Also, results showed that moisture, ash, protein and fat contents were 72.74, 1.8, 19.88 and 4.53%, respectively, in fresh roe. The effects of freezing and cold storage on the roes showed that UFA and SFA contents have reached to 49.83 and 48.07%, respectively, at the end of cold storage. It indicated that these compounds change to each other during frozen storage. Also, n-3 and n-6 series of fatty acids were 32.75 and 1.61% in fresh roe. But their contents decreased to 22.96 and 1.25% at the end of period. Among the fatty acids, 22:6 and C16:0 had the most changes. The changes of fatty acids were significantly at 95% level except for C15:1, C18:3(n-3) and C20:4(n-6). All of the amino acids decreased in frozen storage and their changes were significantly (P<0.05). EAA was 7818 mg/100g and E/NE was 1.27 at the end of storage period. Among the amino acids, leucine and lysine had the most changes. Moisture, ash, protein and fat contents were 70.13, 1.82, 19.4 and 6.51%, respectively, at the end of storage period. The peroxide value and T.V.N. increased during storage. So that, their contents have reached to 5.86 mg/kg and 26.37 mg/100 g, respectively, at the end of frozen storage. The best shelf life of Thunnus tonggol roe was 6 or 7 months, because of lipid oxidation and increasing of peroxide.

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At the fishing season, in 2000, samples of species persian sturgeon (A. persicus), Severjuga (A. stellatus) and Mullet (L. aurata), were caught from the southern coasts of Caspian Sea and were freezes and preserved in the cold storage for one year They have also become biometery. The tissue's fillet were identified in order to determined the Fatty Acids. This was done during one year, frequently, fresh, two weeks after freezing and then monthly, respectively. So, after the extraction of lipids from the tissues and methylation, was injected to the gas-liquid Chromatography. After calibration, identified Fatty Acids were compared with standards according to their Retention Times. Peroxid value, lipid content and humidity were controlled. The unsaturated Fatty acids had The most amount, and a plenty of Polyunsaturated Fatty acids (PUFA) were observed, so that linoleic (C18:2), a-linolenic (C18:3), Arashidonic (C20:4), EPA (C20:5) and DHA (C22:6) Fatty acids had high amounts. The w-3, PUFA were more in comparison with w-6. The effects of freezing and cold storing on the fish fatty acids , were evaluated by the statistical tests , like SPSS, Tukey, Homogenous and Anova, and showed that in some species, a group of Fatty acids, specially PUFA, had some variation. The peroxide value that indicates the lipid deterioration, increased during toring. So, the best term if preserving in the cold storage, were determined and their Nutrition value and Medical applications due to their consumption were investigated.

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The Ugandan fishery, heavily influenced by the emergence of global markets, is extremely dynamic. In recent years a major export trade, principally in Nile perch fillets from Lake Victoria, has expanded markedly. The growth of this factory based processing industry has had a marked impact on the pre-existing artisanal fishery, which has become increasingly dependent on supplying the export market instead of its traditional local small-scale markets. The industrial fishery developed as a response to the liberalisation of the management of the Ugandan economy and the consequent opening up of the export markets in North America and Europe. The emergence of the export industry has resulted in the creation of a dual structure in the fisheries sector, with the Nile perch catching and processing chain operating to European standards, whilst the artisanal sub-sector still utilises traditional methods. This dual structure is a potential source of disadvantage to the artisanal fishery which has command over fewer financial assets than the export fishery.

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We present a new online psycholinguistic resource for Greek based on analyses of written corpora combined with text processing technologies developed at the Institute for Language & Speech Processing (ILSP), Greece. The "ILSP PsychoLinguistic Resource" (IPLR) is a freely accessible service via a dedicated web page, at http://speech.ilsp.gr/iplr. IPLR provides analyses of user-submitted letter strings (words and nonwords) as well as frequency tables for important units and conditions such as syllables, bigrams, and neighbors, calculated over two word lists based on printed text corpora and their phonetic transcription. Online tools allow retrieval of words matching user-specified orthographic or phonetic patterns. All results and processing code (in the Python programming language) are freely available for noncommercial educational or research use. © 2010 Springer Science+Business Media B.V.

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La0.7Ca0.3MnO3 samples were prepared in nano- and polycrystalline forms by the sol-gel and solid state reaction methods, respectively, and structurally characterized by synchrotron X-ray diffraction. The magnetic properties determined by ac susceptibility and dc magnetization measurements are discussed. The magnetocaloric effect in this nanocrystalline manganite is spread over a broader temperature interval than in the polycrystalline case. The relative cooling power of the poly- and nanocrystalline manganites is used to evaluate a possible application for magnetic cooling below room temperature. © 2007 Springer-Verlag.

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This work demonstrates the condition optimization during liquid phase deposition (LPD) Of SiO2/GaAs films. LPD method is further applied to form Al2O3 films on semiconductors with poison-free materials. Proceeding at room temperature with inexpensive equipment, LPD of silica and alumina films is potentially serviceable in microelectronics and related spheres.

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This paper reviews our work on controlled growth of self-assembled semiconductor nanostructures, and their application in light-emission devices. High-power, long-life quantum dots (QD) lasers emitting at similar to 1 mu m, red-emitting QD lasers, and long-wavelength QD lasers on GaAs substrates have successfully been achieved by optimizing the growth conditions of QDs.

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The structural and photoluminescence (PL) properties of the InAs quantum dots (QDs) grown on a combined InAlAs and GaAs strained buffer layer have been investigated by AFM and PL measurements. The dependence of the critical thickness for the transition from 2D to 3D on the thickness of GaAs layer is demonstrated directly by RHEED. The effects of the introduced-InAlAs layer on the density and the aspect ratio of QDs have been discussed.

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Using a solution-based chemical method, we have prepared ZnS nanocrystals doped with high concentration of Mn2+. The X-ray diffraction analysis confirmed a zinc blende structure. The average size was about 3 nm. Photoluminescence spectrum showed room temperature emission in the visible spectrum, which consisted of the defect-related emission and the T-4(1)-(6)A(1) emission of Mn2+ ions. Compared with the undoped sample, the luminescence of the ZnS:Mn sample is enhanced by more than an order of magnitude, which indicated that the Mn2+ ions can efficiently boost the luminescence of ZnS nanocrystals.

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InAs quantum wires (QWRs) have been fabricated on the InP(001), which has been evidenced by TEM and polarized photoluminescence measurements (PPL). The monlayer-splitting peaks (MSPs) in the PL spectrum of InAs QWRs can be clearly observed at low temperature measurements. Supposing a peak-shift of MSP identical to that of bulk material, we obtain the thermal activation energies of up to 5 MSPs. The smaller thermal activation energies for the MSPs of higher energy lead to the fast red-shift of PL peak as a whole.

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In this paper, we investigated the Raman scattering and photoluminescence of Zn1-xMnxO nanowires synthesized by the vapor phase growth. The changes of E-2(High) and A(1(LO)) phonon frequency in Raman spectra indicate that the tensile stress increases while the free carrier concentration decreases with the increase of manganese. The Raman spectra exited by the different lasers exhibit the quantum confinement effect of Zn1-xMnxO nanowires. The photoluminescence spectra reveal that the near band emission is affected by the content of manganese obviously. The values Of I-UV/G decrease distinctly with the manganese increase also demonstrate that more stress introduced with the more substitution of Mn for Zn.

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The ball milling of Fe-24Mn and Fe-24Mn-6Si mixed powders has been performed by the high energy ball milling technique. By employing X-ray diffraction and Mossbauer measurements, the composition evolution during the milling process has been investigated. The results indicate the formation of paramagnetic Fe-Mn or Fe-Mn-Si alloys with a metastable fee phase as final products, which imply that the Fe and Mn proceed a co-diffusion mechanism through the surface of fragmented powders. The thermal stability and composition evolution of the as-milled alloys were discussed comparing with the bulk alloy. (C) 1999 Published by Elsevier Science S.A. All rights reserved.

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Digitization is the main feature of modern Information Science. Conjoining the digits and the coordinates, the relation between Information Science and high-dimensional space is consanguineous, and the information issues are transformed to the geometry problems in some high-dimensional spaces. From this basic idea, we propose Computational Information Geometry (CIG) to make information analysis and processing. Two kinds of applications of CIG are given, which are blurred image restoration and pattern recognition. Experimental results are satisfying. And in this paper, how to combine with groups of simple operators in some 2D planes to implement the geometrical computations in high-dimensional space is also introduced. Lots of the algorithms have been realized using software.