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Role of continuous phase protein on the oxidative stability of fish oil-in-water emulsions 总被引：4，自引：0，他引：4
Whey protein isolate (WPI), soy protein isolate (SPI), and sodium caseinate (CAS) can inhibit lipid oxidation when they produce a positive charge at the interface of emulsion droplets. However, when proteins are used to stabilize oil-in-water emulsions, only a fraction of them actually absorb to the emulsion droplets, with the rest remaining in the continuous phase. The impact of these continuous phase proteins on the oxidative stability of protein-stabilized emulsions is not well understood. WPI-stabilized menhaden oil-in-water emulsions were prepared by high-pressure homogenization. In some experiments WPI was removed from the continuous phase of the emulsions through repeated centrifugation and resuspension of the emulsion droplets (washed emulsion). Unwashed emulsions were more oxidatively stable than washed emulsions at pH 7.0, suggesting that continuous phase proteins were antioxidative. The oxidative stability of emulsions containing different kinds of protein in the continuous phase decreased in the order SPI > CAS > WPI, as determined by both hydroperoxide and headspace propanal formation. Iron-binding studies showed that the chelating ability of the proteins decreased in the order CAS > SPI > WPI. The free sulfhydryls of both WPI and SPI were involved in their antioxidant activity. This research shows that continuous phase proteins could be an effective means of protecting omega-3 fatty acids from oxidative deterioration. 相似文献
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Characterization of the antioxidant activity of sugars and polyhydric alcohols in fish oil emulsions
Polyols have been incorporated into fish oil emulsions as a means for the inhibition of lipid oxidation and suppression of fishy flavor. However, the role of sugars and polyhydric alcohols as antioxidants has not been clearly established. Selected polyols were evaluated for their performance as antioxidants and modifiers of oxidation pathways in a model system. Oil/water (O/W) emulsions were prepared with freshly steam-deodorized menhaden oil. A layer of emulsion in aluminum pans held at 5 degrees C was exposed to 2550 lx fluorescent lights for 24 h before peroxide values and volatile flavor compounds were analyzed by GC headspace entrainment procedure. Antioxidant activity was confirmed for fructose, sucrose, raffinose, sorbitol, or mannitol when incorporated at 16% of the aqueous phase into model fish oil-in-water emulsions. Peroxide values were suppressed 10-18% in treated samples compared to control samples. Viscosity data did not exclude possible contributions from a restricted oxygen diffusion mechanism in the antioxidant activity, but revealed that emulsion viscosity did not govern fish oil oxidation rates. Combining polyols with phenolic antioxidants (alpha-tocopherol, BHT, or TBHQ) frequently diminished the antioxidant activity compared to that for individual phenolic antioxidants, which was interpreted as indicating that the H-donating activity of phenolic antioxidants was hindered by the H-bonding activity of polyols. A viscosity-based inhibition of the retroaldol conversion of (E,Z)-2,6-nonadienal to (Z)-4-heptenal with a high fructose concentration (67%) was attributed to a restriction of molecular mobility of reactants, but the conversion was only slightly inhibited by the concentration of fructose (16%) used in experimental emulsions. The data supported a hypothesis that either or both free radical scavenging and transition state metal chelation activities were provided by polyols in fish oil emulsions. Also, polyols retarded the water-requiring retroaldol decomposition of (E,Z)-2,6-nonadienal to (Z)-4-heptenal in the model systems and the reaction may be involved in some suppression of fishy flavors in emulsions. 相似文献
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Ali Reza Homayounimehr Habibollah Dadras Abdolhamid Shoushtari Seyyed Ali Pourbakhsh 《Tropical animal health and production》2010,42(6):1291-1297
To determine the genetic relationship of Iranian viruses, the haemagglutinin (HA) genes from ten isolates of H9N2 viruses
isolated from commercial chickens in Iran during 1998–2002 were amplified and sequenced. Sequence analysis and phylogenetic
studies were conducted by comparing each isolate with those of the available H9N2 strains at GenBank. All these ten isolates
had the same sequence –R-S-S-R/G-L– of proteolytic cleavage site of the HA. Nucleotide sequence comparisons of HA gene from
Iranian isolates showed 95.2–99.1% identity within the group. Five isolates had leucine (L) at position 226 instead of glutamine
(Q). Phylogenetic analysis showed that all our isolates belonged to the G1-like sublineage. Also these isolates showed some
degree of homology with other H9N2 isolates e.g., 94.3–96.9% with qu/HK/G1/97, 96.1–98.6% with pa/Chiba/1/97, 95.6–98.2% with
pa/Narita/92A/98, and 94.0–96.3% with HK/1073/99. On the basis of phylogenetic and molecular characterization evidence, we
concluded that the H9N2 subtype influenza viruses circulating in chicken flocks in Iran since 1998–2002 had a common origin.
The results of this study indicated that all Iranian viruses have the potential to emerge as highly pathogenic influenza virus,
and considering the homology of these isolates with human H9N2 strains, it seems that the potential of these avian influenza
isolates to infect human should not be overlooked. 相似文献
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The aim of this study was to investigate production of single cell protein (SCP) using Lactobacillus acidophilus and Aspergillus niger in stickwater from fish meal factories. Stickwater was used as substrate for L. acidophilus and A. niger and compared with standard medium as control. The maximum chemical oxygen demand reduction by L. acidophilus was achieved at 55.4 and 86.4% and that by A. niger at 74.1 and 97.7% in the control treatment and stickwater, respectively. The maximum protein obtained by L. acidophilus was at 71.13 and 68.37% and that by A. niger at 51.36 and 48.66% for the control and stickwater, respectively. The amount of RNA by L. acidophilus was also found to be at 15.27 and 15.04% and that by A. niger at 9.36 and 9.09% for the control and stickwater, respectively. By substitution of stickwater and control treatment, in both cultures, maximum and minimum amounts of glutamic acid and methionine were obtained. According to the results of this study, the substitution of stickwater (as carbon source) was adequate for the production of SCP. The chemical score of the SCP in the biomass of both L. acidophilus and A. niger in stickwater indicates that the amino acid profile of SCP fulfils adult human nutritional requirements, except for methionine. In addition, the chemical score of the SCP shows that lysine, methionine, and phenylalanine are the most limiting amino acids and that other amino acids are present at levels exceeding the requirements of juvenile common carp. 相似文献
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Selected sugars (fructose, sucrose, or raffinose) and polyhydric alcohols (sorbitol or mannitol) were equilibrated directly with bulk fish oil (10% by weight, excess) and exposed to fluorescent lighting (2550 Lx) for 24 h at 5 degrees C. Data for room temperature-equilibrated samples revealed that polyols functioned as antioxidants in fish oil. Increased times and temperatures of equilibration (to 90-110 degrees C, 1-2 mmHg, to 2 h) greatly enhanced the antioxidant activity of polyols in fish oil exposed to light. Under accelerated oxidation conditions (60 degrees C) in the dark, dispersed sorbitol in bulk fish oil greatly suppressed the peroxide value, primarily by chelating transition metals, while fructose showed a limited antioxidant activity. Sugars with a lower molecular weight and smaller numbers of equatorial OH groups exhibited a higher rate of permeation of sugars into fish oil triacylglycerols and hence rendered greater antioxidant activities. The treatment of bulk fish oils with polyols and then using the oils in the preparation of emulsions greatly reduced their antioxidant activities as compared to those observed for treated bulk oils. The introduction of polyols dissolved in propylene glycol into bulk fish oils at 90 degrees C (0.025% polyol, 0.25 h of equilibration) provided a similar antioxidant activity to that imparted by the introduction of polyols into the oil by equilibrating excess polyols (10% by weight) with them at 90-110 degrees C for 2 h. However, regardless of the method of the introduction of polyols to bulk fish oil, an elevated temperature (90 degrees C) exposure during fish oil treatment was required to induce a notable antioxidant activity. 相似文献
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Najmeh Ahangari Amirhossein Sahebkar Mohsen Azimi-Nezhad Hamideh Ghazizadeh Mohsen Moohebati Mahmoud Ebrahimi Habibollah Esmaeili Gordon A. Ferns Alireza Pasdar Majid Ghayour Mobarhan 《Iranian Biomedical Journal》2021,25(5):374
Background:FH, a hereditary disorder, is caused by pathogenic variants in the LDLR, APOB, and PCSK9 genes. This study has assessed genetic variants in a family, clinically diagnosed with FH. Methods:A family was recruited from MASHAD study in Iran with possible FH based on the Simon Broom criteria. The DNA sample of an affected individual (proband) was analyzed using WES, followed by bioinformatics and segregation analyses. Results:A novel splice site variant (c.345-2A>G) was detected in the LDLRAP1 gene, which was segregated in all affected family members. Moreover, HMGCR rs3846662 g.23092A>G was found to be homozygous (G/G) in the proband, probably leading to reduced response to simvastatin and pravastatin. Conclusion:LDLRAP1 c.345-2A>G could alter the PTB, which acts as an important part of biological pathways related to lipid metabolism. Key Words: Genetic research, LDLRAP1, Hypercholesterolemia, Hydroxymethylglutaryl-CoA Reductase Inhibitors 相似文献
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