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1.
Profiles of triacylglycerols (TAG) and fatty acids were compared in soybean oil thermally oxidized at 180 °C for 60 min or methylene blue photosensitized for 10 h. Headspace oxygen in thermally oxidized and photosensitized soybean oil decreased significantly (p < 0.05) as oxidation time increased. Relative contents of linoleic and linolenic acids decreased and those of oleic acid increased during oxidation. In both thermal and photosensitized oxidation, TAG with lower than 44 equivalent carbon number including dilinoleoyllinolenoylglycerol (LLLn, 40), trilinolein (LLL, 42), oleoyllinoleoyllinolenoylglycerol (OLLn, 42), dilinoleoyloleoylglycerol (LLO, 44), and dilinoleoylpalmitoylglycerol (PLL, 44) significantly decreased, while those with dioleoyllinoleoylglycerol (OOL, 46) increased significantly in relative peak areas (p < 0.05). Photosensitized oxidation decreased TAG containing linoleic and linolenic acids significantly faster than thermal oxidation in soybean oil (p < 0.05), which may be due to the singlet oxygen reaction. Photosensitized soybean oils can be differentiated from thermally oxidized samples using the distributions of TAG by principal component analysis.  相似文献   

2.
Domestic (Bombyx mori) and wild (tussah, Antheraea pernyi) silk fabrics were treated with diluted NaOH solutions by the pad/batch method. The equillbrium moisture regain of tussah silk fibers increased steadily with alkaline treatment, while that of B. mori did not change. B. mori tensile strenght and elongation at break were slightly impaired. The average molecular orientation and crystallinity of both kinds of silk remained unchanged. Differential scanning calorimetry (DSC) and thermomechanical analysis(TMA) showed that the thermal behavior of B. mori silk was almost unaffected, while that of tussah exhibited slight changes in the temperature range 250–300°C. By dynamic mechanical measurements (DMA) it was elucidated that both storage and loss moduli of B. mori silk fibers decreased following NaOH treatment. On the other hand, tussah silk exhibited a noticeable upward shift of the major loss peak. Alkali-treated tussah silk fibers, dyed with an acid dyestuff, attained a lower degree of dye-bath exhaustion. © 1995 John Wiley & Sons, Inc.  相似文献   

3.
Chemical Characteristics and Fatty Acid Profile of Foxtail Millet Bran Oil   总被引:3,自引:0,他引:3  
Chemical characteristics of a sample of foxtail millet bran and its oil, focusing on the approximate composition of foxtail millet bran and the fatty acid profile, physicochemical properties and tocopherol composition of foxtail millet bran oil, are presented in this work. The results indicate that the millet bran constituted 9.39 ± 0.17% crude oil, 12.48 ± 0.41% crude protein, and 51.69 ± 2.14% crude fiber. The specific gravity, refractive index, saponification value, and unsaponifiable matter content of millet bran oil were 0.9185 ± 0.0003 g/cm3 ( d2020 ) \left( {d_{20}^{20} } \right) , 1.4676 ± 0.0002 ( nD40 ) \left( {n_{D}^{40} } \right) , 186.29 ± 0.51 mg KOH/g, and 3.62 ± 0.19 g/100 g, respectively. The tocopherol content was 64.83 ± 0.83 mg/100 g oil, which consisted mainly of γ-tocopherol (48.79 ± 0.46 mg/100 g oil) and α-tocopherol (15.53 ± 0.31 mg/100 g oil). The millet bran oil was rich in linoleic acid (66.5%) and oleic acid (13.0%). The saturated fatty acids included palmitic acid (6.4%) and stearic acid (6.3%). The major fatty acid in the sn-2 position of the millet oil was linoleic acid (71.2%). The dominant triacylglycerols, calculated according to the 1,3-random-2-random hypothesis, were trilinoleate (LLL, 29.3%) and dilinoleoyl-monoolein (LLO, 17.2%). This work might be useful for developing applications for millet bran and its oil.  相似文献   

4.
HPLC analysis of Echium plantagineum seed oil shows a complex triacylglycerol (TAG) profile. TAG species were separated on an analytical scale by HPLC and their fatty acid (FA) composition is reported. GLC analyses showed that some TAG fractions reached a stearidonic acid (SDA, 18:4n‐3) percentage significantly higher than that in the original oil. TAG separation on a bigger scale was also essayed, by means of a gravimetric normal‐phase chromatographic column, using silver ion‐silica gel as stationary phase. Gradient elution with solvents of increasing polarity was applied, allowing the separation of valuable TAG species containing γ‐linolenic acid (GLA, 18:3n‐6), α‐linolenic acid (ALA, 18:3n‐3) and SDA as the main constituents (more than 85% of the total FA). An enzymatic hydrolysis reaction showed the distribution of FA in the isolated species of TAG. SDA was the major FA in the sn‐2 position (more than 50% of total FA), followed by ALA (19%) and GLA (18.5%).  相似文献   

5.
Fluorescence and circular dichroism (CD) data suggest that the major pheromone-binding protein (PBP) from the wild silkmoth, Antheraea polyphemus, ApolPBP1, undergoes a pH-dependent conformational change similar to that previously observed for the PBP from the silkworm moth, Bombyx mori, BmorPBP. All three constituents of the sex pheromone, E6,Z11-16Ac, E6,Z11-16Ald, and E4,Z9-14Ac, bound to ApolPBP1 with apparent high affinity at high pH, but reduced binding at low pH when tested individually in a “cold binding assay.” In competitive assays, however, ApolPBP1 showed considerable preference for the major constituent of the sex pheromone, E6,Z11-16Ac. These data suggest that specificity of PBPs contributes at least in part to the remarkable selectivity of moth's olfactory system.  相似文献   

6.
The present research deals with the chemical esterification of the sn-2- position of sn-1,3-diacylglycerol (sn-1,3-DAG) with 9cis,11trans (c9,t11) and 10trans,12cis (t10,c12) conjugated linoleic acid (CLA) isomers to obtain structured triacylglycerols (TAG); the sn-1,3-DAG substrates were produced from extra virgin olive oil by means of enzymatic reactions while CLA isomers were obtained using a three-step procedure based on alkaline hydrolysis of sunflower oil, urea purification of linoleic acid (LA) and alkaline isomerization of LA. The results showed good levels of CLA incorporation in structured TAG at the tested temperatures: 37.5% at 4 °C and 39.1% at 14 °C. To evaluate the incorporation of CLA isomers in sn-2- position of sn-1,3-DAG structural analysis of the newly synthesized TAG was carried out using an enzymatic and a chemical method. The results of the structural analysis also showed up the occurrence of acyl migration. The pancreatic lipase method allowed the direct determination of the fatty acid composition of TAG sn-2- position but this enzymatic method showed different results (p < 0.05) in respect to the chemical one; this occurrence could be due to an acylic specificity of the lipase. High incorporation of CLA isomers in sn-2- position of TAG was observed, 77.0% at 4 °C and 81.5% at 14 °C, considering the results of the chemical procedure.  相似文献   

7.
Mechanical tests were performed on single brins of Bombyx mori silkworm silk, to obtain values of elastic modulus (E), yield strength, tensile breaking strength, and shear modulus (G). Specimen cross‐sectional areas, needed to convert tensile loads into stresses, were derived from diameter measurements performed by scanning electron microscopy. Results are compared with existing literature values for partially degummed silkworm baves. The tensile modulus (16 ± 1 GPa) and yield strength (230 ± 10 MPa) of B. mori brin are significantly higher than the literature values reported for bave. The difference is attributed principally to the presence of sericin in bave, contributing to sample cross‐section but adding little to the fiber's ability to resist tensile deformation. The two brins in bave are found to contribute equally and independently to the tensile load‐bearing ability of the material. Measurements performed with a torsional pendulum can be combined with tensile load‐extension data to obtain a value of E/ that is not sensitive to sample cross‐sectional dimensions or, therefore, to the presence of sericin. The value of E measured for brin can be used together with this result to obtain G = 3.0 ± 0.8 GPa and E/G = 5.3 ± 0.3 for brin. The latter value indicates a mechanical, and therefore microstructural, anisotropy comparable to that of nylon. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 1270–1277, 2000  相似文献   

8.
The objective of this work was to synthesize a structured lipid (SL) enriched in stearidonic acid (SDA, C18:4 ω-3), from modified soybean oil (MSO) originally containing ~25% SDA. Low temperature crystallization (LTC) of MSO triacylglycerols (TAG) and free fatty acids (FFA) was performed. The TAG and FFA crystallization products (LTC-TAG and LTC-FFA, respectively) had SDA contents of 48.72 and 60.78%, respectively. Enzymatic acidolysis between MSO and LTC-FFA was studied utilizing Novozym 435 and Lipozyme TL IM as biocatalysts. Substrate molar ratio, incubation time, solvent, and enzyme load were explored. Equilibrium was reached at 96 and 48 h for Novozym 435 and Lipozyme TL IM-catalyzed reactions, respectively. The best conditions from these studies were also applied to the acidolysis of LTC-TAG and LTC-FFA. Utilizing Lipozyme TL IM and solvent free conditions, SLs with SDA contents of 37.61 ± 1.00% (20.86 ± 6.48% at sn-2 position) and 53.46 ± 1.85% SDA (36.37 ± 3.14% at sn-2 position) were obtained from the acidolysis reaction between MSO and LTC-FFA, and LTC-TAG and LTC-FFA, respectively. Compared to the original SDA content of MSO, this process leads to a 52 and 116% increase in SDA content, respectively.  相似文献   

9.
The stabilities of tocochromanols including α‐tocopherol, α‐tocotrienol, γ‐tocopherol, γ‐tocotrienol, and δ‐tocotrienol in grape seed oil, palm oil, or stripped soybean oil with added tocotrienol mixtures (SOTT) were determined under relative humidity (RH) 0, 32, 75, and 93% at 25 °C for 8 months of storage. Stability of tocochromanols was significantly influenced by the presence of moisture and other tocochromanols. Tocochromanol stability in grape seed oil was high at RH 75%, whereas palm oil had significantly lower tocochromanol content at RH 75% compared to those under other RH (p < 0.05). Tocochromanol stability in SOTT was high at RH 0%. δ‐Tocotrienol had the highest stability followed by α‐tocotrienol, γ‐tocotrienol, and α‐tocopherol in SOTT. Moisture content in palm oil was the lowest while that in SOTT was the highest at the same RH. Oxidative stability of palm oil was the highest followed by grape seed oil and SOTT based on conjugated dienoic acid content and p‐anisidine values. Moisture in oils affects the stability of tocochromanols and oxidative stability in vegetable oils.  相似文献   

10.
The quality characteristics and bioactive microconstituents of virgin olive oil produced by Mavrolia cv, an Olea europaea variety grown in Southern Peloponnesus, Greece, are reported for the first time. The oil samples of Mavrolia cv. studied fell within the limits established for the extra virgin olive oil (EVOO) category and were characterized by higher levels of campesterol (88.7 ± 14.8 vs. 56.1 ± 6.1 mg kg−1 oil) and β-sitosterol (1692.6 ± 100.3 vs. 1356.2 ± 85 mg kg−1 oil) and relatively lower oxidative stability (19.35 ± 2.62 vs. 37.44 ± 1.97 h) compared to Koroneiki cv. The lower oxidative stability was positively correlated to significantly lower polyphenols (88.95 ± 2.33 vs. 233.75 ± 34.29) and α-tocopherol (517.2 ± 6.50 vs. 655.37 ± 17.78) and to higher polyunsaturated fatty acids content (9.27 ± 0.35 vs. 6.41 ± 0.38). Tyrosol, ferulic acid and protocatechuic acid contents were significantly higher in Mavrolia cv. samples compared to Koroneiki cv. (218.80 ± 44.8 vs. 83.7 ± 23.1, 1.82 ± 0.11 vs. 0.97 ± 0.31, and 1.55 ± 0.39 vs. 0.35 ± 0.60 mg kg−1, respectively). Also, the bitter and pungent attributes were found in lower intensities compared to Koroneiki cv. EVOO for the same period (1.9 vs. 2.5 and 2.3 vs. 3.9, respectively). The ripe fruity intensity with walnut olfactory attribute of the Mavrolia cv., was also light to medium.  相似文献   

11.
The desilked silkworm pupae (Bombyx mori L.) collected from Kollegala, Malavalli and Ramanagaram belt of Karnataka State (South India) were extracted with petroleum ether (60–80°C). The neutral lipids fraction was isolated and saponified. Saponifiable fraction was analysed for fatly acids and unsaponifiable fraction for sterols. The neutral lipids contain oleic, palmitic, palmitoleic, stearic, linoleic, I auric, myristic, C13:0-, linolenic and arachidic acids. Cholesterol, β-sitosterol and a trace of campesterol are found to be present in unsaponifiable fractions.  相似文献   

12.
Triacylglycerols (TAG) in viper bugloss oil were isolated from raw pressed oil by silicic acid column chromatography. The obtained blend of TAG was separated by silver ion thin‐layer chromatography (TLC Ag+) into nine fractions, varying in terms of unsaturation level and molecular polarity. The composition of TAG in viper bugloss oil was determined by HPLC coupled with a diode‐array detector and an evaporative light‐scattering detector. The results showed that the first three fractions were combinations of TAG containing palmitic, oleic and linoleic acids. Fractions 4 and 6 contained TAG of a similar acid composition as above, but with the addition of γ‐linolenic acid. The remaining fractions (7–9) were the most varied in acid composition. They were found to contain 26–39% palmitic acid, 12–15% oleic acid, 13–41% linoleic acid 8–24% γ‐linolenic acid, 1.5–5.5% α‐linolenic acid and 1–5% stearidonic acid. The analysis of fatty acid allocation in TAG of viper bugloss lipids revealed that linoleic acid (ranging from 2 to 100%) was the only acid found in all isolated fractions. In the investigated oil, the predominant TAG included: LnLnG (11.38%), LnLnSt (11.17%), LnGSt (7.71%), LnStSt (6.19%) and LnLnLn (5.44%). Almost 86% of the TAG contained α‐linolenic acid, while γ‐linolenic and stearidonic acids amounted to 49 and 38%, respectively.  相似文献   

13.
Linseed (Linum usitatissimum, L.) and camelina (Camelina sativa, L.) are ancient crops containing seed oils with a high potential for nutritional, medicinal, pharmaceutical and technical applications. In the present study, linseed and camelina oils of plant varieties grown under Central European climate conditions were examined with respect to their volatile and triacylglycerol (TAG) components. Solid‐phase microextraction was applied to the study of volatile compounds of several linseed and camelina oils, which have not been described prior to this publication. Hexanol (6.5–20.3% related to the total level of volatiles), trans‐2‐butenal (1.3–5.0%) and acetic acid (3.6–3.8%) could be identified as the main volatile compounds in the linseed oil samples. Trans‐2‐butenal (9.8%) and acetic acid (9.3%), accompanied by trans,trans‐3,5‐octadiene‐2‐one (3.8%) and trans,trans‐2,4‐heptadienal (3.6%), dominated the headspace of the examined camelina oil samples. TAG were analysed by MALDI‐RTOF‐MS and ESI‐IT‐MS, providing information about the total TAG composition of the oils as well as the fatty acid composition of the individual components. More than 20 TAG could be identified directly from whole linseed oil samples, mainly composed of linolenic (18:3), linoleic (18:2) and oleic (18:1) acid, and to a lesser degree of stearic (18:0) and palmitic (16:0) acid. While in linseed these TAG comprise more than 60% of the oils, Camelina sativa exhibited a wider range of more than 50 constituents, with a considerable amount (>35%) of TAG containing gadoleic (20:1) and eicosadienoic (20:2) acid.  相似文献   

14.
Karawila (Momordica charantia), also known as bitter gourd, is widely used as a food and a medicine in Asian countries. Representative samples of the seeds of the most abundant cultivar (MC43) in Sri Lanka were collected. The kernel represented 60 ± 4.7% of the seed by dry weight basis. The oil content of the dry kernel was 40.45 ± 3.12%. The seed oil was rich in α-eleosteric acid (50.04 ± 4.80%) and three other geometrical isomers of 9,11,13-octadecatrienoic acid that constituted 6.55%. The acid value, the saponification value and the iodine value were 2.73 ± 0.876, 190.70 ± 1.82 mg/g and 115.96 ± 3.46 cg/g, respectively. The set-to-touch drying time of 3 h observed for the seed oil of MC43 was significantly less than that of linseed oil (13 h). The presence of a high amount of conjugated octadecatrienoic acids, low acid value, high saponification value, moderate iodine value and the low set-to-touch drying time are promising indicators of the potential of karawila seed oil as a good drying oil for the paint and coating industry.  相似文献   

15.
The oxidative stability of soybean oil triacylglycerols (TAG) obtained from genetically modified soybeans was determined before and after chemical randomization. Soybean oil oxidative studies were carried out under static oxygen headspace at 60°C in the dark and oxidative deterioration was monitored by peroxide value, monometric and oligomeric oxidation products, and volatile compounds. Randomization of the soybean oil TAG improved the oxidative stability compared to the natural soybean oil TAG. Oxidative stability was improved by three factors. Factor one was the genetic modification of the fatty acid composition in which polyunsaturated acids (such as linolenic and linoleic acids) were decreased and in which monounsaturated fatty acids (such as oleic) and saturated acids (palmitic and stearic) were increased. Factor two was the TAG compositional modification with a decrease in linolenic and linoleic-containing TAG and an increase in TAG with stearic and palmitic acids in combination with oleic acid. Factor three was the TAG structure modification accomplished by an increase in saturated fatty acids and a decrease in linoleic and linolenic acids at the glycerol moiety carbon 2. Presented at the AOCS Annual Meeting & Expo, Chicago, IL, May 10–13, 1998.  相似文献   

16.
Kondo H  Hashizume K  Shibuya Y  Hase T  Murase T 《Lipids》2011,46(8):691-700
Diacylglycerol acyltransferase (DGAT) catalyzes the final step of triacylglycerol (TAG) synthesis, and is considered as a potential target to control hypertriglyceridemia or other metabolic disorders. In this study, we found that the extract of rose petals suppressed TAG synthesis in cultured cells, and that the extract showed DGAT inhibitory action in a dose-dependent manner. Fractionation of the rose extract revealed that the DGAT inhibitory substances in the extract were ellagitannins; among them rugosin B, and D, and eusupinin A inhibited DGAT activity by 96, 82, and 84% respectively, at 10 μM. These substances did not inhibit the activities of other hepatic microsomal enzymes, glucose-6-phosphatase and HMG-CoA reductase, or pancreatic lipase, suggesting that ellagitannins inhibit DGAT preferentially. In an oral fat load test using mice, postprandial plasma TAG increase was suppressed by rose extract; TAG levels 2 h after the fat load were significantly lower in mice administered a fat emulsion containing rose extract than in control mice (446.3 ± 33.1 vs 345.3 ± 25.0 mg/dL, control vs rose extract group; P < 0.05). These results suggest that rose ellagitannins or rose extract could be beneficial in controlling lipid metabolism and used to improve metabolic disorders.  相似文献   

17.
The liver oils of six shallow-water shark species, silky (Carcharhinus falciformis), thresher (Alopias superciliosus), oceanic whitetip (Carcharhinus longimanus), blue (Prionace glauca), hammerhead (Sphyrna lewini) and salmon (Lamna ditropis) were analyzed with particular attention to the regioisomeric composition of triacylglycerols (TAG). The TAG compositions were analyzed by using an HPLC-evaporative light scattering detector and each molecular species identified by HPLC-atmospheric pressure chemical ionization/mass spectrometry. Major lipid components of all sharks’ oils were TAG (~80 %) made up of omega-3 polyunsaturated fatty acids at 26–40 % and 20–25 % docosahexaenoic acid (DHA). Forty different molecular species were detected in the TAG fractions. TAG consisting of one palmitic acid, one DHA and one oleic acid (12.5–19.9 %) and TAG consisting of two palmitic acids and one DHA (8.4–15.4 %) were the predominant form while 30–50 % TAG molecular species were bound to one or more DHA. Distribution of fatty acids in the primary (sn-1 and sn-3) and secondary (sn-2) position of the glycerol backbones was examined by regiospecific analysis by using pancreatic lipase and it was found that DHA was preferentially positioned at sn-2. These findings greatly extend the utilization of shark liver oils in food productions and may have a significant impact on the future development of the fish oil industry.  相似文献   

18.
The oil yield and composition of fatty acids, tocopherols, tocotrienols, sterols, carotenoids, and squalene in the seeds of three species—Hyptis suaveolens, Leonotis nepetifolia, Ocimum sanctum—belonging to the Lamiaceae family, are studied. The oil yields are 12.1%, 16.1%, and 29.0% in O. sanctum, H. suaveolens, and L. nepetifolia, respectively. The unsaturated fatty acids are a predominant group (86.8–92.1%) in all three investigated plants; however, the profile for each species is unique. The main fatty acid differs as follows: H. suaveolens—linoleic acid (85.8%), L. nepetifolia—oleic acid (58.3%), and O. sanctum—α‐linolenic (48.6%). γ‐Tocopherol accounts for over 97%, 90%, and 93% of the total tocochromanol content (sum of tocopherols and tocotrienols) in H. suaveolens, L. nepetifolia, and O. sanctum, respectively. Two tocotrienol homologues, α and γ, are detected only in L. nepetifolia. β‐Sitosterol is the main detected sterol (38–59%) in all three species. High levels of campesterol (18–20%), Δ5‐stigmasterol (9–21%), and Δ5‐avenasterol (7–12%) are also detected. Squalene is detected only in O. sanctum (45.8 mg/100 g oil). The content of sterols, tocochromanols, and carotenoids in the investigated Lamiaceae plant seed oils ranges between 279.5–576.3, 54.5–66.7, and 0.3–3.1 mg/100 g oil, respectively. Practical Applications: Lamiaceae plants are of medicinal interest due to the presence of a broad spectrum of bioactive molecules. The present study demonstrates that seeds of the species H. suaveolens, L. nepetifolia, and O. sanctum are rich sources of bioactive compounds of lipophilic nature. There is limited knowledge associated with the composition of tocopherols, tocotrienols, sterols, carotenoids, and squalene. The results of the studied medicinal plants may enhance future targeted applications in various sectors.  相似文献   

19.
The lipid profiles of the two most important New Zealand marine oil sources were investigated, with particular attention to the regioisomeric compositions of triacylglycerides (TAG), using 13C-nuclear magnetic resonance analysis. Oils from hoki (Macruronus novaezelandiae) and Greenshell™ mussel (Perna canaliculus) (GSM) were analyzed for their lipid content, lipid class and fatty acid profile. The regiospecific distribution of long chain (C ≥ 20) polyunsaturated fatty acids (LC-PUFA) between the sn-1,3 and sn-2 glycerol positions was calculated from 13C responses in the carbonyl region in the triacylglycerol fraction. Rendered hoki oil (RHO) produced from the viscera and filleting discards, had a similar lipid profile to that of hoki liver oil (HLO) confirming that the liver is the major source of oil in RHO. The regioisomeric distribution of fatty acids showed differences between the two oil sources. Docosahexaenoic acid (DHA) had a regioisomeric distributional preference to the sn-2 position in TAG from all the oils (59.2% HLO, 54.3% RHO and 63.4% GSM). Eicosapentaenoic acid (EPA) had a more even distribution along the triacylglycerol backbone in hoki TAG (29.1% HLO, 33.6% RHO) while there was a slight sn-2 positional preference in the GSM TAG (37.6%). This regioisomeric information is vital to distinguish LC-PUFA-rich marine oils from other marine sources for authentication purposes.  相似文献   

20.
Isolation and characterization of the naturally occurring sex attractants of the silkworm moth (Bombyx mori), gypsy moth (Porthetria dispar), cotton leafworm (Prodenia litura), American cockroach (Periplaneta americana), an introduced pine sawfly (Diprion similis), and mating attractants of the honey bee (Apis mellifera) and bumblebee (Bombus terrestris) are discussed.  相似文献   

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