Extending the frying-life of oils is of commercial and economic importance. Due to this fact, assessment on the thermal stability of frying oils could provide considerable savings to the food processors. In this study, the physico-chemical properties of five palm products mainly palm oil, single-fractionated palm olein, double-fractionated palm olein, red palm olein and palm-based shortening during 80 hours of heating at 180°C were investigated. Heating properties of these products were then compared with that of high oleic sunflower oil, which was used as reference oil. The indices applied in evaluating the quality changes of oils were free fatty acid, smoke point, p-anisidine value, tocols, polar and polymer compounds. Three palm products i.e. palm oil, single-fractionated palm olein and double-fractionated palm olein were identified to be the most stable in terms of lower formation of free fatty acid, polar and polymer compounds as well as preserving higher smoke point and tocols content compared to the other three oils. The low intensity of hydrolytic and oxidative changes due to prolonged heating, suggests that these palm products are inherently suitable for frying purposes.
The optimal dietary n-6/n-3 ratio has not been fully elucidated. To investigate the influence of the dietary n-6/n-3 ratio on this ratio in the body and on liver β-oxidation peroxisomal activity, rats were fed diets containing fat at an n-6/n-3 ratio of 1 to 16 for 4 weeks. To investigate whether elevation of the liver peroxisomal β-oxidation activity increases the n-6/n-3 ratio in the body, rats were fed a diet containing a peroxisome-activating agent, bezafibrate, for 2 weeks, and its influence on the liver n-6/n-3 ratio was examined. The slope of the regression line between the dietary and liver total lipid n-6/n-3 ratios was significantly smaller when the dietary n-6/n-3 ratio was 4 or greater than when it was smaller than 4. Peroxisomal β-oxidation and acyl CoA oxidase activities were significantly lower in rats fed a diet with an n-6/n-3 ratio of 16 than in those fed a diet with a ratio of 1. The peroxisomal β-oxidation activity in the bezafibrate-supplemented group was significantly higher than that in the control group. The serum and liver total lipid n-6/n-3 ratios were significantly higher in the 0.015% bezafibrate-supplemented group than in the control group. These findings suggest that the liver n-6/n-3 ratio might be controlled via peroxisomal β-oxidation in rats.
The aggregation behaviors of three stereoisomers of tetramethylammonium N-dodecanoyl phenylalanylphenylalaninate in dilute aqueous solution were investigated. From surface tension, fluorescence intensity using probes, and heat of dilution measurements, it was suggested that the critical aggregation concentration was the same between the enantiomers, but was obviously different between the diastereomers. It was also found that these surfactants formed large aggregates at lower concentrations. These large aggregates were then transformed to micelles at higher concentrations similarly to the potassium N-acyl phenylalaninate system. Furthermore, the fluorescence intensity of auramine increased strikingly in the N-dodecanoyl-L-phenylalanyl-L-phenylalanine (homo-chiral dipeptide-type surfactant) system. The fluorescence intensity of auramine in the aggregate of homo-chiral dipeptide-type surfactant was 20 times larger than that in the hetero-chiral dipeptide-type surfactant.
We have prepared a viscous bicontinuous microemulsion consisting of water / [20 wt% POE-GIS + 30 wt% PEPTME + 47.5 wt% POE/POP-PDMS + 2.5 wt% OA)] / DMPS system. A pseudoternary phase diagram was constructed for the mixture, and the bicontinuous microemulsion phase was characterized by means of rheometry and freeze-fracture transmission electron microscopy (FF-TEM).
In this study, we examined the effects of Pleurotus nebrodensis on systolic blood pressure of spontaneously hypertensive rats. Single-dose and continuous-dose tests with sample diets made from the fruit body of the mushroom, P. nebrodensis were carried out on SHR and control rats. Sample diets included 6% dry powder of fruit body (6% dry powder), hot water extract, polysaccharide fraction, protein fraction, dialyzable fraction and non-dialyzable fraction. Polysaccharide and protein fractions were obtained by hot water extraction. The protein fraction was separated to the dialyzable fraction and non-dialyzable fraction by dialysis. In the single-dose test, protein fraction, hot water extract and polysaccharide fraction decreased systolic blood pressure. Blood pressure was lowered after administration for 2 h, and it returned to the pre-administration blood pressure after 48 h. In the continuous-dose test, spontaneously hypertensive rats were fed each of the diets for 16 weeks. The 6% dry powder group showed significantly inhibited elevation of blood pressure compared with the control group and there was no influence on total cholesterol and triglyceride levels. The non-dialyzable fraction showed suppression of increase in blood pressure from the start of the continuous oral administration. Effects on the rennin angiotensin system and renal function were also indicated. The antihypertensive action effect of P. nebrodensis can be expected to not only prevent but also to improve hypertension.
Male Wistar rats, age 10 weeks, were fed for 11 weeks a commercial powdered diet (no fat) containing 7 wt% fresh frying oil and 0.1 wt% gluten heated in oil at 180°C for 10 h followed by filtration. The animals appeared to grow normally and had the same serum levels of glucose, triacylglycerol, phospholipids, and cholesterol as those of a control group fed a diet containing 7 wt% fresh oil. However, aspartate aminotransferase (AST), and alanine aminotransferase (ALT) were significantly higher in the test group, and many dark-red patches due to bleeding were observed on the livers of this group. In contrast, rats fed for 11 weeks a diet containing 7 wt% of oil obtained by filtration after the heating described above did not show any damage to the liver or kidneys and showed no gross symptoms. Rats fed a diet containing 7 wt% fresh frying oil and 0.1 wt% gluten heated in a tube at 180°C for 10 h did not show any differences from the control group. Analyses of low-molecular-weight compounds in the filtered oil revealed that gluten obviously reduced the level of all the low-molecular-weight compounds (except ethanol) of the oil heated at 180°C for 10 h. Thus, it was suggested that gluten reacted with/adsorbed thermally oxidized oil/decomposition products and kept the cytotoxic low-molecular-weight compounds in the chemical structure even after filtration.
The association between coffee consumption and its antioxidant effects has not been elucidated in detail. In experimental animals, we used biomarkers to investigate the relationship between coffee consumption and its effects on oxidative stress. We propose a method in which both the free and ester forms of hydroperoxides and ketones as well as the hydroxides of linoleic acid are measured as total hydroxyoctadecadienoic acid (tHODE). Mice were divided into 6 groups: animals in 5 of these groups were fed a vitamin E-depleted diet [VE(-) group], whereas those in the 6th (control) group were fed a diet containing 0.002 wt% vitamin E [VE(+) group]. Different VE(-) groups were also administered coffee or drinking water that contained a coffee component-chlorogenic acid, caffeic acid, or caffeine-for 1 month. It was clearly demonstrated that the liver levels of tHODE in the VE(-) groups increased compared to the VE(+) group but that coffee consumption reduced these elevated levels to that of the control. Interestingly, the plasma and liver levels of the HODE stereoisomer ratio (Z,E/E,E), which is a measure of antioxidant capacity in vivo, were highest among the groups studied. These data, together with the values for antioxidant levels in vivo, indicate that the efficacy of antioxidants in vivo can be evaluated reasonably well based on the tHODE level and its stereoisomer ratio, and that the antioxidant capacity of coffee is superior to that of its individual components.