Digestion and absorption of free and esterified fish oil fatty acids in rats

This study was designed to test the hypotheses that digestibility and post-absorption metabolism of fish oil are influenced by impaired lipolysis and by the stereospecific composition of its triacylglycerols. Male Wistar rats were fed nonpurified diets containing one of the following fat sources: 9% native fish oil (NFO), 9% autorandomized fish oil (RFO), 8.1% fish oil-derived free fatty acids (FO-FFA) plus 0.9% glycerol, or 9% soybean oil (SO) as a reference fat. In a 24-day balance study, apparent digestibility of total dietary fat averaged 93.1% in the SO, NFO and RFO groups, and 90.9% in the FO-FFA group. Randomization of fish oil had no effect on apparent digestibility of individual fatty acids. In rats fed FO-FFA, apparent absorption of saturated and monounsaturated fatty acids was lower when compared to the NFO and RFO groups. Feeding the FO-FFA diet tended to increase plasma triglyceride content. The hypocholesterolemic effect of polyunsaturated n−3 fatty acids was not influenced by the dietary source. Similar effects on fatty acid profiles of plasma and liver phospholipids were caused by the NFO, RFO and the FO-FFA diets. We conclude that once polyunsaturated n−3 fatty acids are absorbed, their effect on lipid metabolism is not determined by the dietary source.     

Peroxidation reactions in plant membranes: Effects of free fatty acids

Free fatty acids accumulate in plant membranes after exposure of plants to environmental stress, such as freezing and desiccation. Fatty acid accumulation has been linked to various biophysical changes and to the occurrence of lipid peroxidation, but the relationships appear complex and inconsistent. The interactions between oxygen free radicals, free fatty acids and lipid peroxidation in plant membranes were examined further by studying peroxidation reactions in a model membrane system composed of a complex mixture of plant phospholipids, including various free fatty acids. Multilamellar liposomes were treated with oxygen free radicals generated from iron ascorbate. Increased concentrations of free palmitic acid up to 10 mol% (fatty acid/phospholipid) reduced the production of aldehydes detected by the thiobarbituric acid assay, but enhanced the production of fluorescent products. By contrast, increased concentrations of free linolenic acid increased aldehyde production and reduced the formation of fluorescent products. The two free fatty acids both enhanced the susceptibility of phospholipids to degradation as shown by the reduced recovery of esterified polyunsaturated fatty acids (linoleic and linolenic). The free radical reactions with or without free fatty acid additions catalyzed the selective degradation of phospholipids in the order phosphatidylethanolamine > phosphatidylcholine > phosphatidylinositol > phosphatidylglycerol. Selective degradation of phospholipids is often observed after periods of environmental stress or during senescence of plants, and has been cited as evidence for the involvement of phospholipases in these degenerative processes. The results indicate that selectivity is not a criterion for eliminating the involvement of oxygen free radicals in these degenerative processes. Furthermore, the results suggest that modifications of lipid composition during a plant's acclimation to adverse environments may determine the types of free radical reactions that occur due to stress.     

Production of free fatty acids in safflower seeds by fungi

In 1975, free fatty acids (FFA) reached 0.50% in hand-sampled seeds (achenes) from the Sacramento Valley but never exceeded 0.10% in samples from the San Joaquin Valley. High levels of FFA in safflower seeds from the Sacramento Valley were attributed to seed-borne fungi, especiallyAlternaria sp., having a lipolytic action on safflower oil. Greenhouse inoculations on representative safflower cultivars reduced yields and oil content while increasing FFA. In vitro experiments using safflower oil-potato dextrose agar medium showed that theAlternaria species and four other fungi isolated from safflower had lipolytic activity. TheAlternaria sp. produced 3.90% FFA after 20 days of growth on this medium. Separation of the FFA by thin layer chromatography and characterization by gas liquid chromatography indicated that fatty acids are released by all five fungi in proportions similar to those in safflower oil. Presented in part at the AOCS Meeting, New York, May 1977.     

Rapid colorimetric determination of free fatty acids

In 1964, a method was described for the determination of free fatty acids (FFAs) in vegetable oil. This paper describes an expansion of that work, improving the sensitivity and reproducibility of the method, as well as examination of solubilities of the copper soaps as a function of chain length and unsaturation. Involvement of the micellar structure was reviewed. Finally, a procedure is described that permits very rapid determination of FFA at the 2.0–14.0 μmol (0.5–4.0 mg oleic acid) level, and the results with several oils are given. Particular attention was given to evaluation of solvent systems which would extract the copper complexes. Presented in part at the AOCS Meeting in San Francisco, April 1969. Technical Paper No. 4036, Oregon Agricultural Experiment Station.     

辣根过氧化物酶催化去除水中染料的特性研究

首次采用辣根过氧化物酶催化降解直接黑38和偶氮荧光桃红染料,发现p H、反应温度、H2O2浓度对酶促反应有重要影响。辣根过氧化物酶可以在p H为3.0~9.0、温度25~65℃范围内有效去除直接黑38和偶氮荧光桃红。动力学实验结果表明,辣根过氧化物酶催化反应动力学符合一级反应动力学,并利用双倒数作图法测定了酶催化直接黑38动力学参数Km。     

Adsorption of soy oil free fatty acids by rice hull ash

Studies demonstrated that free fatty acids can be adsorbed from a soybean oil/hexane miscella by inorganic rice hull ash. A 1% dose was effective in diminishing free fatty acid concentrations but acid activation reduced the adsorption. Binding of free fatty acids followed a Freundlich isotherm with smaller doses of ash adsorbing more efficiently. Addition of isopropanol to the miscella promoted the adsorption, while water deactivation of the ash had no effect, possibly because water occupied sites not accessible to free fatty acids. Impaired adsorption behavior of ash heated above 700°C could have been due to disruption of the crystal form. The adsorption behavior of rice hull ash may be more fully understood with a better knowledge of adsorbent structure.     

Complex formation and reversible oxygenation of free fatty acids

Combined manometric and spectrophotometric studies reveal that prior to true oxidation unsaturated fatty acids undergo an oxygenation which is reversible in response to changes in oxygen pressure. The oxygenation seems to result from the oxygen molecule having a specific affinity for pairs of olefinic bonds.     

NMR measurement of free and esterified sterols

This short account describes a novel analytical technique for the determination of total, free and esterified sterols in olive oil developed in our laboratory. This methodology is based on ¹H and ³¹P NMR spectroscopy. The latter spectroscopic analysis requires first the derivatization of the sterolic hydroxyl groups with a phosphitylating reagent. This NMR method shows a number of advantages over conventional methods for sterols determination, amongst which speed and simplicity are the most beneficial ones. The possibility of applying the NMR spectroscopy to other food matrices is discussed.     

Use of acetyl chloride/methanol for assumed selective methylation of plasma nonesterified fatty acids results in significant methylation of esterified fatty acids

The albumin-bound nonesterified fatty acid pool in plasma, which represents a very small percentage of total plasma fatty acids, has previously been quantitated by a variety of methods. In the present study we determined that the nonesterified fatty acid concentrations in the plasma, quantitated by a popular method using acetyl chloride and methanol which is reported to be specific for methylation of nonesterified fatty acids in the presence of esterified fatty acids (i.e., without prior isolation of the plasma non-esterified fatty acids), were significantly overestimated due to cleavage and methylation of esterified fatty acids. Quantitation of the contaminating fatty acid from the esterified pool demonstrated that the amount of fatty acid cleaved from the esterified pool was enough to exceed the entire mass of nonesterified fatty acids. As an established method for comparison, we isolated nonesterified fatty acids from the plasma by thin-layer chromatography prior to methylation, using a number of simple precautions to limit oxidation. By performing all thin-layer chromatography steps in an atmosphere of nitrogen and by including fatty acid standards in the plasma with 0,1, 2 or 4 double bounds, we were able to accurately and reproducibly determine the concentration of nonesterified fatty acids in the plasma, including arachidonate. We demonstrated that no oxidation occurred in the thin-layer chromatographic isolation of homonesterified fatty acids and that the coefficients of variation for repeat measurements of the same sample were <11% using our reference method. Our data indicate that the use of acetyl chloride and methanol for assumed selective methylation of plasma nonesterified fatty acids results in significant methylation of esterified fatty acids.     

Determination of free fatty acids in palm oil by near-infrared reflectance spectroscopy

A near-infrared (NIR) spectroscopy calibration was developed for the determination of free fatty acids (FFA) in crude palm oil and its fractions based on the NIR reflectance approach. A range of FFA concentrations was prepared by hydrolyzing oil with 0.15% (w/w) lipase in an incubator at 60°C (200 rpm). Sample preparation was performed in Dutch cup, and the spectra were measured in duplicate for each sample. The optimized calibration models were constructed with multiple linear regression analysis based on C=O overtone regions from 1850–2050 nm. The best wavelength combinations were 1882, 2010, and 2040 nm. Multiple correlation coefficients squared (R ²) were: 0.994 for crude palm oil, 0.961 for refined-bleached-deodorized (RBD) palm olein, and 0.971 for RBD palm oil. Calibrations were validated with an independent set of 8–10 samples. R ² of validation were 0.997, 0.943, and 0.945, respectively. The developed method was rapid, with a total analysis time of 5 min, and environmentally friendly, and its accuracy was generally good for raw-material quality control.     

Rapid methods for determination of free fatty acids contents in fatty oils

Rapid qualitative and quantitative methods for determining the free fatty acid (FFA) contents in common oils and fats are reported. Qualitative method is based on the type of color developed in the presence of BDH indicators (Universal and “678”) when a known excess of alkali is added to an alcoholic solution of oil or fat. By this method, low (0.0–0.25), medium (0.26–0.99) and high (1.0 and above) FFA levels in fatty oils may be distinguished. Quantitative method is a simplified modification of the usual procedure of determining the FFA contents of oils and fats by titration against standard alkali solution in the presence of BDH Universal or “678” indicator. The results of the rapid methods agree well with those of the standard AOCS method.     

HRP催化淀粉与酚类接枝聚合物的合成研究

以辣根过氧化物酶(HRP)/H2O2为催化体系,催化降解淀粉和3,5-二羟基苯甲酸(3,5-DBA)进行自由基接枝共聚反应,合成了淀粉和酚类接枝共聚物。探讨了温度和pH对酶活力的影响以及接枝条件对接枝共聚反应的影响。通过FTIR、1HNMR和GPC对接枝改性淀粉的化学结构进行了表征。产物用作皮革鞣剂时,显示了良好的应用性能。     

An automatized method for determination of free fatty acids

An automated colorimetric method is described for determining free fatty acids (FFA) in vegetable oils using the flow injection analysis (FIA) technique. In this procedure, an almost linear relationship exists between the peak height and the FFA concentration. Liquid samples can be poured directly into the sample cups on the sampler for an automatic analysis of the FFA content. The dynamic range of this method is from 0.01 to almost 5%. Samples with higher FFA content must be diluted before analysis. The sample capacity is 12–20 injections/hr. No evidence of the existence of the earlier proposed cage-like complex (Cu(II)(FFA)₂)₂ in the organic phase was observed in this study.     

Germanium recovery using polyphenol microspheres prepared by horseradish peroxidase reaction

BACKGROUND: The formation of polyphenol microspheres by the polymerization of 3‐methylcatechol was performed in a methanol/phosphate buffer solution using horseradish peroxidase (HRP), without the use of a surfactant or a water/oil interface, to be used for germanium recovery. RESULTS: The polyphenol microspheres were of diameter 1 mm. The functional group density of phenol group in the polymer was approximately 15 mol kg^?1 determined by the Folin‐Denis method. In batchwise experiments, the amount of germanium adsorbed was 0.23 mol kg^?1. CONCLUSION: Because germanium is a rare metal, a system for its recovery is required. Using the proposed system, continuous recovery of germanium can be achieved using multilayered microspheres. Copyright © 2011 Society of Chemical Industry     

The determination of specific free fatty acids in peanut oil by gas chromatography

Peanut oil is dissolved in 2,2,4-trimethylpentane standard. The free acids are extracted into N,N-dimethylformamide as their sodium salts and treated with methyl iodide. The resulting methyl esters are analyzed by gas chromatography. A typical result for oleic acid is about 200 ppm with a relative standard deviation of 6%. An average recovery of 95% is obtained from a sample spiked with an additional 200 ppm of oleic acid. Evidence is presented that the procedure does not give high values as a result of sample hydrolysis.     

辣根过氧化物酶降解苯酚废水催化特性研究

采用辣根过氧化物酶催化降解苯酚,研究了辣根过氧化物酶浓度、pH值、反应温度对苯酚去除率的影响。结果表明,辣根过氧化物酶生物催化体系对苯酚有良好的降解效果。当温度为30℃,pH值为6时,在苯酚、H2O2、辣根过氧化物酶浓度分别为1 mmol/L,1.2 mmol/L,0.5μg/mL条件下,反应25 min,可以获得70%左右的苯酚去除率。利用双倒数作图法测定了不同酶浓度的催化动力学参数,动力学参数Kcat,Kcat/Km表明,苯酚的去除率和催化反应速率随着酶浓度的增加而增大;辣根过氧化物酶的催化效率与催化体系中酶和底物浓度有关,过高的底物浓度会降低酶的催化效率。