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 15 毫秒
1.
Linseed cake (LC), a byproduct of linseed oil extraction, is used as a functional filler for production of biodegradable composites. To determine the influence of residual linseed crude oil contained in lignocellulosic filler on the properties of the poly(lactic acid) (PLA)-based composites with 5–30% filler content, two types of LC were analyzed: a defatted and an unmodified one. Complex analysis of the composites' properties change was conducted in relation to their structure modification caused by the addition of a waste filler. It was found that the addition of LC resulted in simultaneous plasticization and improved crystallization of PLA. Lignocellulosic particles and crude linseed oil contained in the LC powder provided a modifying effect, influencing the level of crystallinity and mechanical and thermomechanical properties. Using LC may thus overcome one of the main drawbacks of PLA, which is brittleness and low crystallinity. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47152.  相似文献   

2.
The fatty acid composition of developing soybean (Glycine max [L.] Merrill) seeds was evaluated in the mutant line, A6, and its parent, FA8077. Seeds of both lines were harvested at 2-day intervals from 15 to 39 days after flowering (DAF) and at 4-day intervals from 39 DAF until maturity. Significant differences between the two lines were observed for stearic and oleic acid percentages at 19 DAF. The maximum difference between the lines was at 25 DAF, when A6 had 45.4% and FA8077 had 4.1% stearic acid. The increase in stearic acid percentage in A6 was accompanied by a decrease in oleic acid to 16.8% at 25 DAF, compared with 53.7% oleic acid for FA8077. The two lines did not differ in development of palmitic, linoleic and linolenic acids. The protein and oil content of mature seeds were similar for the two lines.  相似文献   

3.
Dimethyl and ethylene acetals of polyformylated unsaturated fatty esters were prepared, characterized, and evaluated as polyvinyl chloride plasticizers. Dimethyl acetals were prepared with trimethyl orthoformate as a water scavenger in the acid catalyzed acetalation reaction. With ethylene acetals, water was removed azeotropically. Although the acetals prepared were mixtures, molecular distillation gave diacetal esters of 80–90% purity and triacetal esters of 80–95% purity. The samples were characterized by gas liquid chromatography and by IR and NMR spectra. Compared to di-2-ethylhexyl phthalate as a plasticizer for polyvinyl chloride, the triacetal esters (both dimethyl and ethylene acetals) gave less migration and at least equivalent volatility characteristics; the triacetals also gave equivalent compatibility and strength, but somewhat less desirable low temperature and heat stability properties. The diacetal esters also had good compatibility, equivalent strength, somewhat better low temperature, but less desirable migration and volatility properties. Presented at the AOCS Meeting, Chicago, Illinois, September 1973. ARS, USDA.  相似文献   

4.
Conjugated linoleic acid (CLA) shows potential benefits in a number of medical conditions, making it a possible target for incorporation into a functional food. Until recently, clinical trials were conducted with various mixtures of CLA isomers, encapsulated as the free acid. The purpose of this study was to examine a mixture of two specific CLA isomers (9c,11t and 10t,12c), incorporated into a functional food either as triacylglycerol, free fatty acid or fatty acid ethyl ester. Differences in absorption between the lipid forms and between the isomers were investigated. The palatability of the different functional‐food formulations was also studied. Significantly less CLA was absorbed into chylomicrons over six hours when fed as fatty acid ethyl ester than when either the triacylglycerol or free fatty acid forms were fed. Further work is recommended, to examine fatty acid ethyl ester absorption over longer periods of time. Most subjects reported that the fatty acid formulation had poor taste characteristics. We conclude that CLA as triacylglycerol is the most suitable form for incorporation into a functional food and that the 9c,11t and 10t,12c CLA isomers are absorbed similarly into chylomicrons.  相似文献   

5.
In this study, the Transesterification Double Step Process (TDSP) for the production of biodiesel from vegetable oil was modified to yield a shorter reaction time and products with improved quality. TDSP consists in a two step transesterification procedure which starts with a basic catalysis, followed by an acidic catalysis. The process modifications included a reduction in the concentration of catalysts, a reduction in the reaction time of the first step and the direct mixing of methanol/acid solution, without cooling the system between the first and second step. A comparison between washed and unwashed biodiesel demonstrates that the final washing and drying procedure is necessary for satisfactory results. The products were analyzed by 1H-NMR and nineteen different biodiesel analyses specific for international quality certification. The modified procedure resulted in a high conversion index (97% for waste cooking oil and soybean oil and 98% for linseed oil) and high yield (87 ± 5% for waste cooking oil, 92 ± 3% for soybean and 93 ± 3% for linseed oil). The biodiesel produced by the modified TDSP met ASTM, EN ISO and ABNT standards before the addition of stabilizer.  相似文献   

6.
Synthesis of Poly(methyl methacrylate), PMMA‐multigraft copolymers derived from linseed oil, soybean oil, and linoleic acid PMMA‐g‐polymeric oil/oily acid‐g‐poly(3‐hydroxy alkanoate) (PHA), and their protein adsorption and bacterial adherence have been described. Polymeric oil/oily acid peroxides [polymeric soybean oil peroxide (PSB), polymeric linseed oil peroxide (PLO), and polymeric linoleic acid peroxide (PLina)] initiated the copolymerization of MMA and unsaturated PHA‐soya to yield PMMA–PLO–PHA, PMMA–PSB–PHA, and PMMA–PLina–PHA multigraft copolymers. PMMA–PLina–PHA multigraft copolymers were completely soluble while PMMA–PSB–PHA and PMMA–PLO–PHA multigraft copolymers were partially crosslinked. Crosslinked parts of the PLO‐ and PSB‐multigraft copolymers were isolated by the sol gel analysis and characterized by swelling measurements in CHCl3. Soluble part of the PLO‐ and PSB‐multigraft copolymers and completely soluble PLina‐multigraft copolymers were obtained and characterized by spectroscopic, thermal, gel permeation chromatography (GPC), and scanning electron microscopy (SEM) techniques. In the mechanical properties of the PHA–PLina–PMMA, the elongation at break is reduced up to ~ 9%, more or less preserving the high stress values at its break point (48%) when compared to PLina‐g‐PMMA. The solvent casting film surfaces were studied by means of adsorption of blood proteins and bacterial adhesion. Insertion of the PHA into the multigraft copolymers caused the dramatic increase in bacterial adhesion on the polymer surfaces. PHA insertion into the graft copolymers also increased the protein adsorption. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007  相似文献   

7.
Dietary deficiencies of nutrients critical for foetal/infant brain development and function are increasingly being reported in scientific literature. Maternal supplementation with these nutrients within safe intake recommendations during pregnancy and while breast‐feeding has the potential to prevent many brain and central nervous system abnormalities and could enhance brain development and function in their children.  相似文献   

8.
In this study, extractions of rapeseed, linseed, safflowerseed and tobaccoseed have been conducted with a new extractor which has been developed for the extraction of vegetable tannins and which was later applied to sugar beets and sugar cane. Using the optimal conditions of the new extractor for oilseeds, that is, 315μ particle size and 62 C temperature, technical hexane has been employed, and the variations of the rate and distribution of oil extraction from solid materials have been determined. Optimal extraction periods with the new extractor were found to be 88 min for rapeseed, 90 min for linseed, 118 min for safflowerseed and 90 min for tobaccoseed. The same seeds have been extracted with the Soxhlet extractor for a period of 10 hr. Soxhlet extractor yields compared to Gülbaran yields with the new extractor were found to be only 98.18% for rapeseed, 98.15% for linseed, 97.79% for safflowerseed and 97.39% for tobaccoseed.  相似文献   

9.
Epoxidized linseed oil-free fatty acids were reacted with aniline and three isomers of toluidine, anisidine, and chloroaniline in such a manner that the carboxylic groups remained free. The prepared adducts were evaluated as antioxidants and antirads for styrene butadiene rubber (SBR) vulcanizates. It was found that 2 phr of orthotoluidine, paraanisidine, orthochloroaniline, and aniline adducts were the best antioxidants and/or antirads. © 1993 John Wiley & Sons, Inc.  相似文献   

10.
Carbon black (CB) and precipitated silica are two major reinforcing fillers in rubbers. CB/silica hybrid filler is also widely used in rubbers to provide balanced properties. CB/silica‐hybrid‐filler‐filled styrene‐butadiene rubber (SBR) containing naphthenic oil (NO), soybean oil (SO) and norbornylized SO (NSO) was investigated. The swelling and curing behavior and rheological, mechanical, thermal, aging and dynamic properties were studied and compared with earlier reported data on CB‐ or silica‐filled SBR. NSO provides better scorch safety and faster cure than SO. Compared with NO, the addition of SO and NSO enhances the thermal stability and aging resistance of SBR vulcanizates. SBR/NSO vulcanizates with hybrid filler exhibit a higher tensile and tear strength than SBR/NO and SBR/SO vulcanizates. A synergistic effect in the abrasion resistance of vulcanizates containing the hybrid filler is observed. An increase of sulfur content in the hybrid‐filler‐filled SBR/NSO vulcanizates provides further improvement in abrasion resistance, wet traction and rolling resistance. © 2017 Society of Chemical Industry  相似文献   

11.
Active films (AFs) using poly(lactic acid) (PLA) as a polymeric matrix containing various propolis concentrations (5, 8.5, and 13%) as the active agent (AA) were developed using a casting method. The purpose was to determine the effects of the incorporation of AA on the physical properties of the films and to evaluate the antioxidant and antimicrobial activities. Tensile strength and elastic modulus of the AFs decreased relative to the control (PLA without AA). Introducing the active substances from propolis into the PLA also affected its thermal properties (glass transition). Adding AAs to the polymer generated more opacity with a green-yellowish color compared to the control. In addition, AFs exhibited reduced water vapor permeability as the AA concentration increased. Biodegradation assay showed that the AFs degraded faster than the control. AFs exhibited antioxidant activity, which was measured as the ability to scavenge free radicals (2,2-diphenyl-1-picrylhydrazyl and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonate)), due to the presence of bioactive compounds (phenolics). Antimicrobial activity was evaluated against Escherichia coli and showed a reduction over 4-log cycles. Therefore, incorporation of propolis is a useful strategy for the development of active packaging with antioxidant and antimicrobial effects, which increase the shelf life of food products. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47090.  相似文献   

12.

Background

Although animal and human studies have demonstrated interactions between dietary choline and fetal alcohol spectrum disorders, dietary choline deficiency in pregnancy is common in the US and worldwide. We sought to develop and validate a quantitative food frequency questionnaire (QFFQ) to estimate usual daily choline intake in pregnant mothers.

Methods

A panel of nutrition experts developed a Choline-QFFQ food item list, including sources with high choline content and the most commonly consumed choline-containing foods in the target population. A data base for choline content of each item was compiled. For reliability and validity testing in a prospective longitudinal cohort, 123 heavy drinking Cape Coloured pregnant women and 83 abstaining/light-drinking controls were recruited at their first antenatal clinic visit. At 3 prenatal study visits, each gravida was interviewed about alcohol, smoking, and drug use, and administered a 24-hour recall interview and the Choline-QFFQ.

Results

Across all visits and assessments, > 78% of heavy drinkers and controls reported choline intake below the Dietary Reference Intakes adequate intake level (450 mg/day). Women reported a decrease in choline intake over time on the QFFQ. Reliability of the QFFQ across visits was good-to-acceptable for 2 of 4 group-level tests and 4 of 5 individual-level tests for both drinkers and controls. When compared with 24-hr recall data, validity of the QFFQ was good-to-acceptable for 3 of 4 individual-level tests and 3 of 5 group-level tests. For controls, validity was good-to-acceptable for all 4 individual-level tests and all 5 group-level tests.

Conclusions

To our knowledge, this is the first quantitative choline food frequency screening questionnaire to be developed and validated for use with both heavy and non-drinking pregnant women and the first to be used in the Cape Coloured community in South Africa. Given the high prevalence of inadequate choline intake and the growing evidence that maternal choline supplementation can mitigate some of the adverse effects of prenatal alcohol exposure, this tool may be useful for both research and future clinical outreach programs.
  相似文献   

13.
1.中老年人的皮肤特性 随着生活水平的普遍提高,中老年化妆品市场也在不断扩大.中老年女性的皮肤随着年龄的增长而不断变化.  相似文献   

14.
Since in recent years for certain age groups, the main cause of anemia is not iron deficiency, we intended to study the effect of iron, folic acid and vitamin B12 deficiencies on anemia prevalence in adolescents from Venezuela. One hundred adolescents aged between 12 and 19 years participated in the study. Each subject was interviewed about antecedents and habits and a physical examination and a 24-hour food recall questionnaire were performed. From a blood sample, hemoglobin and hematocrit concentrations were determined and serum was separated for quantification of ferritin, folic acid and vitamin B12 concentrations. Prevalence of anemia was 78% and for iron, folic acid and vitamin B12 deficiencies were 34.66, 90.9 and 18.18%, respectively. From anemic cases, 35.89% presented iron deficiency, while 91.02% presented folic acid deficiency. Only 19.23% of adolescents with anemia presented also vitamin B12 deficiency, but all the cases with vitamin B12 deficiency, were anemic. Simultaneous iron and folic acid deficiencies affected 30.76% of anemic cases. The high prevalence of deficiencies found in this work could be explained by insufficient intake and inadequate food habits. The prevalence of anemia was associated to folic acid deficiency rather than to iron deficiency, due to the high prevalence of folic acid deficiency. The high prevalence of nutritional deficiencies found in this work, especially regarding folic acid deficiency, require immediate interventions.  相似文献   

15.
Ghebremeskel K  Min Y  Crawford MA  Nam JH  Kim A  Koo JN  Suzuki H 《Lipids》2000,35(5):567-574
Relative fatty acid composition of plasma and red blood cell (RBC) choline phosphoglycerides (CPG), and RBC ethanolamine phosphoglycerides (EPG) of pregnant (n=40) and nonpregnant, nonlactating (n=40), healthy Korean women was compared. The two groups were of the same ethnic origin and comparable in age and parity. Levels of arachidonic (AA) and docosahexaenoic (DHA) acids were lower (P<0.05) and palmitic and oleic acids higher (P<0.0001) in plasma CPG of the pregnant women. Similarly, the RBC CPG and EPG of the pregnant women had lower AA and DHA (P<0.05) and higher palmitic and oleic acids (P<0.01). The reduction in DHA and total n−3 fatty acids in plasma CPG of the pregnant women was paralleled by an increase in docosatetraenoic (DTA) and docosapentaenoic (DPA) acids of the n−6 series and in DPA/DTA ratio. In the RBC phospholipids (CPG and EPG) of the pregnant women, DTA and DPA acids of the n−6 series and DPA/DTA ratio did not increase with the decrease of the n−3 metabolites (eicosapentaenoic acid, DPA, and DHA) and total n−3. Since pregnancy was the main identifiable variable between the two groups, the lower levels of AA and DHA in RBC CPG and EPG of the pregnant women suggest that the mothers were mobilizing membrane AA and DHA to meet the high fetal requirement for these nutrients. It may also suggest that RBC play a role as a potential store of AA and DHA and as a vehicle for the transport of these fatty acids from maternal circulation to the placenta to be utilized by the developing fetus.  相似文献   

16.
The objective of this study was to improve the content of docosahexaenoic acid (DHA) and obtain the blended oils used for different cooking methods (steaming, boiling, and stir-frying) by blending 0%–15% DHA algal oil into soybean oil. It was shown that the addition of DHA algal oil increased saturated fatty acid (SFA) (1.57%) but decreased monounsaturated fatty acid (MUFA) (0.76%) and polyunsaturated fatty acid (PUFA) (0.68%). Various cooking methods significantly changed the fatty acid (FA) compositions. Steaming is a more effective way to prevent DHA loss and the production of trans-fatty acid than boiling and stir-frying. Besides, a positive result from free fatty acid (FFA) and peroxide value also demonstrated that steaming was a better way to protect oils. Overall, the soybean oil blended with 3% DHA algal oil with better oxidative stability and could be recommended for daily application by steaming.  相似文献   

17.
Xuejun Liu  Shenlin Zhu  Huayang He 《Fuel》2008,87(7):1076-1082
In this study, physical and chemical characterizations of calcium methoxide were investigated to assess its performance as an excellent solid base catalyst using some instrumental methods, such as BET surface area measurement, scanning electron micrographs and particle size distribution. Then, it was used to catalyze transesterification of soybean oil to biodiesel with methanol. The effects of various factors such as mass ratio of catalyst to oil, reaction temperature and volume ratio of methanol to oil were studied to optimize the reaction conditions. The results showed that calcium methoxide has strong basicity and high catalytic activity as a heterogeneous solid base catalyst and it was obtained a 98% biodiesel yield within 2 h in this reaction. Besides, the recycling experiment results showed it had a long catalyst lifetime and could maintain activity even after being reused for 20 cycles.  相似文献   

18.
Experiments were conducted to evaluate heated unextracted soybean fractions as sources of soybean oil and protein for the growing chick. Heated dehulled unextracted soybean flakes produced growth rate and feed efficiency equal to that obtained with the combination of soybean oil meal and degummed soybean oil while heated ground unextracted soybeans were less satisfactory in this respect. The poorer results obtained with ground unextracted soybeans were shown to be related to a poorer absorbability of the oil in them. Flaking the soybeans markedly improved the absorbability of the oil by the chick, probably by causing a greater disruption of cellular structure than was obtained by the grinding of the soybeans. The metabolizable energy of ground unextracted soybeans was substantially less than that of unextracted soybean flakes. Most of the differences in metabolizable energy were accounted for by differences in absorbability of the oil. Soybean hulls at a level equivalent to that contained in soybeans were found to have no effect on growth rate and only a slight effect on feed efficiency. Autoclaving soybean oil did not lower its value for the chick. The relationship between the poorer growth obtained with ground unextracted soybeans and the low absorbability of the oil in them was discussed. To obtain maximum efficiency in the use of unextracted soybean products in chick rations, some such means as flaking must first be employed to increase the availability of the oil.  相似文献   

19.
Filter papers with covalently bound chelating groups are produced with the aim to enrich metal ions simultaneously for measurement by X-ray fluorescence spectrometry. The selectivity of the chelating groups to transition elements is of utmost importance. Some analytically important chelating groups dithiocarbamate-, 8-hydroxyquinoline-derivatives, and aminocarboxylic acid (EDTA analogue) are immobilized on cellulose filter papers. These filters are produced in a flow reactor, filled with commercially prefabricated analytical grade filter papers. They are synthesized in a three-step-reaction. First, an epoxyactivated cellulose is produced which in the second step is converted into an aminocellulose. This aminocellulose is the starting material for the dithiocarbamate-, the 8-hydroxyquinoline, and EDTA-analogue cellulose. The immobilization of 8-hydroxyquinoline or 8-hydroxyquinoline-5-sulfonic acid is accomplished through an aminomethylation. The analytically useful capacity of the various chelating filter papers is for dithiocarbamate, 8-hydroxyquinoline, 8-hydroxyquinoline-5-sulfonic acid, and EDTA-analogue derivatives 600, 700, 400, and 600 μmol/g, respectively.  相似文献   

20.
The concentration of plasma homocysteine was diminished by the oral use of vitamins B6 (300 mg/day), B12 (250 microg/day) and folic acid (10 mg/day), and the effect was studied in the lipids of patient with hiperlipoproteinemia secondary type IV, during 120 days, in 30 patients, 45 to 70 years old, with myocardial heart attack. They were divided in group A (n=15) without treatment with Lovastatin and group B (n=15) with Lovastatin. Basal homocysteine concentration was 17.4 +/- 1.0 micromol/L and 16.7 +/- 1.0 micromol/L for the groups A and B respectively, diminishing 24% at the end of the experimental time, in both groups. Total cholesterol decreased below 220 mg/dl, while the triglycerides diminished 25.4 mg/dl and 27.0 mg/dl in groups A and B respectively, by each micromol/L of homocysteine catabolissed. Low density lipoproteins (LDL) and very low density (VLDL) diminished significantly (p < 0.005), while the high-density (HDL) increased 1.0 mg/dl in group A and 1.15 mg/dl in group B, for each micromol/L of homocysteine metabolized, lowering the coronary risk factor in 28.5% group A and 35.9% group B. We concluded that these vitamins decreased plasma homocysteine concentration, promoting the lowering of lipids and lipoprotein concentratation in this type of patients; while Lovastatin doesn't reduce homocysteine, but it had a synergic effect with the vitamins, dicreasing the lipid concentration, in group B.  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