Isao Niiya

Effects of highly hydrogenated soybean oil and cholesterol on plasma, liver cholesterol, and fecal steroids in rats

We investigated the relationship between dietary highly hydrogenated soybean oil (HSO) and cholesterol transport in rats. In the first study, to examine the effects of cholesterol transport of different concentrations of HSO in dietary oil, rats were given one of the three diets containing 0, 25, or 50% HSO in dietary oil with cholesterol (5 g/kg diet) or a diet without HSO and cholesterol for 22 d. Feeding the high concentration of HSO prevented the increase in plasma total cholesterol, hepatic total lipids, and cholesterol and the decrease in high-density lipoprotein-cholesterol, which were caused by dietary cholesterol. Moreover, HSO increased the fecal excretion, fecal lipids, and steroids in a dose-dependent manner. In the second study, to examine the effects on cholesterol transport of redistribution of stearic acid in the triacylglycerol species contained in HSO, rats were given one of the six diets containing HSO (distearoylmonoacylglycerol and tristearoylglycerol)-rich, monostearoylglycerol-rich, or palmitic acid-rich oil with/without cholesterol (5 g/kg diet), for 30 d. Whereas the accumulation of cholesterol in the body was reduced, cholesterol excretion was enhanced effectively in rats given the HSO-rich diet compared with rats given the monostearoylglycerol-rich diet. These results suggested that not only the high concentration of stearic acid but also its uneven distribution in HSO-triacylglycerol contributed to the reduction in intestinal cholesterol absorption in rats.

Highly hydrogenated dietary soybean oil modifies the responses to polychlorinated biphenyls in rats.

The effects of dietary highly hydrogenated soybean oil (HSO) upon the changes caused by dietary polychlorinated biphenyls (PCBs) were examined in rats. Six groups of rats were fed the following diets for 30 d: a 20% soybean oil-containing diet (control diet), a diet in which a half of soybean oil was substituted with HSO (HSO-A diet), a diet in which cellulose powder was replaced with HSO (HSO-B diet) and these diets supplemented with 100 ppm PCBs (control+PCBs, HSO-A+PCBs and HSO-B+PCBs diets). Hepatic concentration of PCBs and relative liver weight were markedly decreased in rats fed with the HSO-A+PCBs diet compared with those fed with the other diets containing PCBs. Liver lipids and liver cholesterol were considerably decreased with a reciprocal increase in fecal sterol excretion by rats fed the HSO-A+PCBs and the HSO-B+PCBs diets compared with those fed with the control+PCBs diet. The fatty acid composition in hepatic phospholipids showed an independent increase of the saturated fatty acid content induced by dietary HSO and PCBs. Dietary PCBs also caused decreases in the amounts of monounsaturated and n-3 polyunsaturated fatty acids. These results suggest that dietary HSO prevents accumulation of PCBs in the liver and promotes the excretion of lipids stimulated by PCBs, accompanied by a change in fatty acid metabolism.

Nutrition of Tocotrienols and Lipid Metabolism

Lymphatic absorption of α-tocotrienols (α-Toc3) given as a mixture of Toc 3 and α-tocopherol (α-Toc) was significantly higher than in γ-Toc 3, δ-Toc 3 and α-Toc in rats. This was confirmed when the rate of absorption of individual Toc 3 was measured. Approximately 50 to 60% of the absorbed Toc 3 and α-Toc was transported as chylomicrons in lymph. More α-Toc was excreted into feces than α-Toc 3 when these were given to rats, but the content in the liver markedly higher in the former than in the latter. Either α-Toc or Toc 3 concentrate contain α-, γ-, and δ-Toc 3 and α-Toc (dietary level; 0.13% α-Toc or 0.07% Toc 3 and 0.06% α-Toc) did not reduce systolic blood pressure of SHR when 0.5% salt solution was given as drinking water, whereas they suppressed an increase in blood pressure with age when the dietary was increased to 0.2% and no saline was given. The effect of Toc 3 concentrate and α-Toc, in particular the former, on aortic production of PGI2 was diverse depending on their dietary level whereas no effect was observed on the degree of maximum platelet aggregation induced by ADP. Although the activity of liver microsomal Δ5- and Δ6- desaturates was not influenced by Toc3 concentrate and α-Toc, they repressed conversion of the linoleic acid to arachidonic acid. These results suggest that Toc 3 have diverse nutritional and physiological impacts on various parameters, and their effects are not necessary the same as those of α-Toc.

Thermostability of Silicone Oil Evaluated by Thermogravimetric Method

The thermostability of silicone oil and antioxidation effects of lard containing silicone oil were evaluated by thermogravimetric (TG) and Rancimat methods.In programmed TG for silicone oil alone, the initial temperature of weight loss shifted to the higher temperature side with increase in viscosity. In programmed TG of lard samples to which silicone oil had been added, slight elevation in the initial temperature of weight loss was noted for several samples.For isothermal TG, thermostability evaluated based on the initial time of decomposition for lard samples to which a silicone oil had been added was found similar to oxidative stability measured by the Rancimat method. Antioxidant effects determined by the two methods failed to show any definite relationship with the type or amount of silicone oil added.

Thermostability of Synthetic Antioxidants

By programmed thermogravimetry (TG), weight loss of 8 synthetic antioxidants was examined, and thermostability was determined from initial temperatures based on TG and decomposition time at 5 % by isothermal TG. Antioxidant content in residual substances was determined at 25 % weight loss by TG. The results obtained are summarized as follow : 1) For programmed TG, curves for synthetic antioxidants showed characteristic weight loss patterns depending on the type of antioxidant. Weight loss patterns were not influenced by atmospheric gas used (air and nitrogen).2) At 25 % weight loss by TG, phenolic antioxidant content in residual sabustances exceeded 90 % in both gases. Gallate content was less than that observed for phenolicis.3) Synthetic antioxidant thermostability increased in the order of NDGA>DG>OG>PG>THBP>TBHQ>BHA>BHT as determined from TG data.

Effect of Extracts from Sesame Seeds on the Stability of Fish Oil

Additive effects of extracts from sesame seeds for preventing the oxidation of fish oil (sardine oil) were examined by the Rancimat method at 80 °C under 20 L/h air flow or by an oven test at 5 and 20 °C. Extracts were obtained from raw and roasted sesame seeds using water, methanol and ethyl ether as extracting solvents. In the Rancimat test, the ethyl ether extract clearly inhibited fish oil oxidation while water and methanol extracts exerted no such effect. The ethyl ether extract suppressed peroxide formation in the oven test, but expressed greater antioxidant effect at 5 °C than 20 °C.

Sterols and fatty acids of a whisk fernPsilotum nudum

The sterols and fatty acids ofPsilotum nudum were investigated. The 4,4-dimethyl- and 4α-methylsterol fractions contained 24β-methyl-Δ25-unsaturated sterols,viz., cyclolaudenol and 24β-methyl-25-dehydrolophenol, respectively, as dominant sterols among the other components common in vascular plants. 24-Methylcholesterol (mixture of C-24 epimers) and sitosterol constituted the dominant sterols in the 4-demethylsterol fraction. This is the first identification of 24-methylene-5α-lanost-8-en-3β-ol, 24β-methyl-25-dehydrolophenol, codisterol, isofucosterol, 24-methylene-25-methylcholesterol and avenasterol in a fern. The major fatty acids were 16:0, 18:1, 18:2, 18:3 and 20:3. In addition, several C20 fatty acids with various unsaturation were found to be present in low concentrations.

Heavy Metals, Particularly Nickel, Contained in Cacao Beans and Chocolate

カカオ豆及びカカオ豆を主成分とする食品中のニッケル,鉄,銅,鉛及びヒ素などの重金属含量がどのように異なるかを調べた.試料にはカカオ豆26試料,カカオマス14試料,カカオ脂10試料,市販のチョコレート14試料(ブラック9,ホワイト5)及び粉末ココア4試料を用いた.また,参考試料としてシアナッツ5試料,ボルネオナッツ3試料及びコーヒー豆6試料についても分析した.(1) ニッケル含量はカカオ豆で平均5.12ppm,その胚乳部に相当するカカオマスでも平均4.81ppmとほとんど差がなかった.しかし分離脂肪のカカオ脂にはニッケルは0.13 ppmしか存在しなかった.鉄,銅の含量もカカオ豆(x: 112.4, 24.7ppm)とカカオマス(x: 82.5, 26.7ppm)の間ではほとんど差を示さないが,カカオ脂(x: 0.30, 0.04ppm)では著しく低かった.(2) 市販のカカオ加工食品では,ニッケル含量はブラックチョコートで平均1.09ppmとかなり高いが,ホワイトタイプでは主原料のカカオ脂と同様に微量にすぎなかった.これに対し,粉末ココアでは平均12.7ppmのニッケルが検出され,カカオマスよりさらに高いことを示した.この傾向は鉄及び銅の含量でも同様であり,ブラック,ホワイトチョコレート及び粉末ココアからそれぞれ平均24.4, 0.82及び362.5ppmの鉄及び5.36, 0.16及び43.9ppmの銅が検出された.(3) 参考試料としたハードバターの原料となるシアナッツ及びボルネオナッツからは,それぞれ平均0.58及び0.45ppmのニッケル, 85.4及び137.1ppmの鉄と0.72及び10.8ppmの銅を検出した.また,コーヒー豆からは平均0.55ppmのニッケル, 67.0ppmの鉄及び13.3ppmの銅を検出し,これを風味原料として使用するファットスプレッドではこれらの重金属の給源となり得ることが示された.なお,鉛はシアナッツ,ボルネオナッツ及びコーヒー豆の一部試料から0.1～0.3ppmの微量が検出されたにすぎず,ヒ素は全試料から検出されなかった.

Some Properties of Commercially Available Margarines and Cooking Fats in Germany

Commercial margarines, cooking fat and lard in Germany were assessed for quality, using 16 brands of margarine (including 4 of high linoleic type), 9 of low fat spread (including 4 of high linoleic type), 4 of dairy spread (compound type, 2 ; low fat butter, 2), 11 of cooking fat and 8 of lard, totaling 48.1) Lipid and water content averaged 80.0 and 19.4% in margarine, while 39.5 and 56.8% in low fat spread, respectively. The latter had about half calories of the former. Sorbic acid and stabilizers of emulsion were added to the low fat spread.2) Almost all margarine samples were fortified with vitamins A and D3, and vitamin B6, was also found in some cases. To all high linoleic products, α-tocopherol was added, and tocotrienols were detected in 6 brands of margarine, indicating blending palm oil to possibly be present.3) Cholesterol was detected only as a trace in products labelled vegetable oil on tha package, but Δ7-stigmastenol and avenasterol were detected in greater amounts in high linoleic products than in others.4) Since high linoleic margarines comprised of 64.351. 1% (57.7% in average) of c, c-18 : 2 fatty acid, and contained less trans fatty acids, they were considered “zero-trans” products. The ratios of α-tocopherol (mg) /polyunsaturated fatty acids (g) in these ranged from 1.45 to 0.63 (1.00 in average), indicating α-tocopherol to be sufficiently present.5) Various types of composition were present in cooking fat, most lard product were characteristically present in addition to onion and spices.6) SFC curves indicated the high linolleic type of margarines to be softer than others in the low temperature region. The dairy spread showed more SFC in the low temperature region, but less SFC in the higher region than margarines. SFC in cooking fat varied considerably according to type, and lard showed a SFC curve with a unique feature of a wide melting range.

Heavy Metals, Particularly Nickel Contained in Household Margarines

62 Brands of margarines (margarine ; “high grade” 35, “standard grade” 10 ; fat spread 17) for household use (including for school lunch) were examined for nickel, iron, copper and lead. As reference samples, 28 brands of analogous spreads containing natural foodstuffs (chocolate 7 ; peanut 11 ; soybean 2 ; almond 1 ; mustard 1 ; fruit 1 ; jams 5) were also analyzed.Nickel was found present up to only 0.05 ppm margarines samples and in 0.022.33 ppm in the analogouse spreads, though at higher levels in the chocolate, peanut and soybean spreads. Contents of iron and copper in the analogous spreads were higher than in the margarines (at 0.051.06 ppm and 0.05 ppm or less). Trace amount of lead could be found in all sample of the peanut and almond spreads and jams, but not found in all the margarines.Results from trans fatty acid analysis indicated hardened oil to be present in both nearly all margarines and analogous spreads except jams. For the chocolate and peanut spreads, the content of nickel was correlated with that of protein and copper. suggesting that the heavy metals in spreads originate in the cacao product or peanut rather than material fat containing hardened oil. Nickel and other heavy metals in household margarines are thus concluded to be present at a much lesser extent than in natural foods, such as chocolate, nuts and beans.