We previously reported that the feeding of soybean phospholipids to fish increased the storage stability of n-3 polyunsaturated fatty acids (PUFA)-rich fish fillets. In this study, we examined the storage stability of lipids extracted from fish fed a diet containing soybean phospholipids and fish oil. Rainbow trout were divided into two groups, and were fed an either 2.5% soybean phospholipids (test) or no phospholipids (control) containing diet for 4 weeks. Lipids were extracted from fish fillets after the feeding period, and were subjected to an oxidation test. Lipids extracted from the fillets of fish in the test group exhibited lower values of oxygen absorption than those in the control group, and the degradation of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) was inhibited. Higher percentages of DHA and EPA were bound to phosphatidylcholine and phosphatidylethanolamine in the extracted lipids in the test group than in the control group. These results indicate that the oxidative stability of lipids extracted from fish fed soybean phospholipids is high, and that the higher percentages of DHA and EPA in PC and PE may have resulted in the higher stability of the lipids extracted from fish fillet.
We have previously reported that a soy oil-containing experimental diet (fat-free AIN93G containing oil thermally processed with soybean protein followed by filtration), inhibited body weight increases without any adverse effects when given ad libitum to male Wistar rats for 12 weeks. In the present paper, the mechanism of weight-loss promoting effects was investigated. Fasted 10-week-old rats were fed a slurry composed of AIN93G (fat-free), Cr2O3 (marker), water, and 7 wt% soy oil or fresh oil (control) and sacrificed at 20, 60, 90, 120, 150, 210, 270 or 360 min. The stomach, small intestine, cecum, colon and feces were then collected to determine the distribution of the slurry in the digestive tract. The results indicated that the content was transferred faster from stomach to small intestine in the soy oil group than in the control group. Fecal excretion (derived from a commercial standard diet ingested before slurry administration) in the soy oil group was significantly higher than in the control group. Digestive enzyme activities, lipase, sucrose, and maltose, were not inhibited by soy oil. In addition, feces collected in the 12-week feeding experiment were more in the dry weight and contained higher levels of nitrogen and water in the soy oil group than in the control group, revealing that an increased amount of nutrition was continuously excreted in the former group. The above-described findings suggest that soy oil stimulated peristalsis of the gastrointestinal tract and that colon contents are actively excreted, resulting in safe and steady body weight decreases.
We have studied the rheological properties of mixtures of polyoxyethylene (10 mol) phytosterol (PhyEO10) and polyoxyethylene (10 mol) cholesterol (ChEO10) mixed in different ratios along with tetraethylene glycol monododecyl ether (C12EO4) surfactants in water. Addition of C12EO4 to the aqueous solution of a mixture of (PhyEO10 + ChEO10) results in one-dimensional micellar growth and formation of viscoelastic solution of entangled wormlike micelles. Steady-shear rheological measurements show the Newtonian flow behavior at low shear-rate region and non-Newtonian flow behavior at higher shear-rate for viscous samples. The dynamic rheological data of the viscoelastic samples indicate the plateau modulus (Go) increases monotonically with C12EO4 concentration and relaxation time (τR) display a maximum at a composition corresponding to the viscosity maximum. The prepared viscoelastic sample in mixed nonionic surfactant systems has potential applications in cosmetic formulation.
The evaluation of textile detergency was carried out using artificially soiled multifiber adjacent fabric (MFF) composed of six different warp regions. The MFF soiled with model water-soluble, oily or particulate contaminant was cleaned in water, water/ethanol (1/1 in volume ratio), ethanol and n-decane with the stirring as a mechanical action. The detergency of the each fiber region was determined from the change in surface reflectance of the corresponding region due to cleaning. The soil removal was strongly dependent on contaminant, fiber and liquid species, indicating that the detergency was dominated by the dissolution of the contaminant into the washing liquid and the affinity between the contaminant and the fiber surface. The addition of alkali and surfactant to water or the solubilization of water into n-decane considerably increased the soil removal. The experimental results were not in contradiction with common and well-known knowledge about textile washing. Therefore, the artificially soiled MFF can be utilized for the detergency evaluation for textiles.
In this work, novel SO3H type Gemini surfactants having semifluoroalkyl group (RfCH2CH-: Rf = C4F9, C6F13, C8F17) as hydrophobic group were successively synthesized by the radical addition of fluoroalkyl to 1,4-pentadiene using fluoroalkyl iodide and AIBN as initiator, and the following thiocyanization (-SCN), conversion to –SH, and oxidation to SO3H as hydrophilic group. Similarly, the common 1+1 type semifluoroalkyl surfactants having SO3H were synthesized. Surfactant properties of their sodium salts (cmc, γcmc, pC20, Γcmc, and A) were investigated by measuring surface tension. As expected, the cmc value of Gemini surfactant whose fluoroalkyl is C4F9 was more than one order of magnitude smaller than that of the corresponding 1+1 type. Other properties also showed the excellent efficiency of Gemini structure to reduce the surface tension.
Sophoroselipids (SL) are bolaform biosurafactants which are abundantly produced by microorganisms from renewable resources. In this study, four kinds of bolaform biosurfactants were produced, and these derivatives were chemoenzymatically synthesized from “acid form” diacetylated SL (SLdiAc), which are preferentially produced by Candida floricola TM 1502 which was newly found in our group. The effects of the structure of sugar moiety on their surface-active properties were investigated by surface tension measurement. After microbial production of SLdiAc from oleic acid/glucose, SLdiAc was converted into acetylated glucoselipid (GLAc). Among twelve species of glucosidases, pectinase and pectolyase including polygalacturonase were found to cleave the β-1,2-glycosidic linked disaccharide, especially pectolyase produced GLAc effectively at 40 °C and pH 4.0. The structure of the major component of purified GLAc was assigned as 17- [(β-D-glucopyranosyl)oxy]-cis-9-octadecenoate 6’-acetate by using NMR analyses, MALDI-TOF/MS and GC-MS. Glucoselipid (GL) without acetyl group was also enzymatically converted from SL obtained from alkaline hydrolysis of SLdiAc. Interestingly, the estimated CMC values of SLdiAc, SL, GLAc, GL indicated almost the same values despite their difference in hydrophilic structure. Although the difference in monosaccaride and disaccharide also did not affect γCMC, the presence of acetyl group on sugar moiety was found to lower the γCMC value slightly, suggesting that the acetyl group on produced bolaform biosurfactant is likely to play more important role to reduce the free energy of air/water interface.
Dietary cholesterol oxidation products (COPs) modulate various metabolic processes, particularly lipid metabolism. In this study, we observed that dietary COPs perturbed hepatic function, linoleic acid desaturation, and cholesterol catabolism in rats that were fed with diets containing 0.5% COPs for a short duration (7 days). The rats (age, 8 weeks) were fed American Institute of Nutrition (AIN)-purified diets containing 0.5% cholesterol or 0.5% COPs for 7 days. The glutamic oxaloacetic transaminase (GOT), glutamic pyruvic transaminase (GPT), and lactate dehydrogenase (LDH) levels were significantly high in rats fed with dietary COPs, but no such increase was observed in rats fed with dietary cholesterol, thereby indicating that dietary COPs may impair the hepatic function. The mRNA expression levels of Δ6 desaturase in the liver were significantly increased by dietary COPs, while these levels were significantly decreased by dietary cholesterol. However, the mRNA expression level of cholesterol 7α-hydroxylase (CYP7A1) in the liver was significantly decreased by dietary COPs and significantly increased by dietary cholesterol. Therefore, dietary COPs may modulate lipid metabolic processes such as linoleic acid desaturation and cholesterol catabolism even when they are consumed for a short duration. Hence, processed animal foods containing COPs should be consumed with caution.
Sphingolipids are ubiquitous in all eukaryotic organisms and known to be essential constituents of cellular membranes. Recently, various physiological functions of dietary sphingolipids, such as preventing cancer, improving skin barrier and contributing to central nervous system myelination have been demonstrated. To characterize the sphingolipids from fish as food components, tissue distribution of sphingomyelin and glycosylceramide (ceramide monohexoside, CMH) in fish were determined in this study. We established a rapid, accurate and effective method for separation, purification and determination of sphingolipids by using high-performance liquid chromatography with evaporative light-scattering detector (ELSD-HPLC). Sphingolipids were extracted and quantified from pacific saury (Cololabis saira). Sphingomyelin in different tissues of Cololabis saira ranged from 2.5 ± 0.2 mg/g to 27.6 ± 2.1 mg/g, the content in brain was the highest, followed by eyes, and CMH contents were less than 23.0 ± 2.4 mg/g in all tissues. These results revealed that fish contained CMH and sphingomyelin as same levels as most of the terrestrial organisms and suggested marine organisms could be used as a potential source of precious and useful complex lipids.