Acorn (<Emphasis Type="Italic">Quercus</Emphasis> spp.) fruit lipids: Saponifiable and unsaponifiable fractions: A detailed study

The composition of the oils extracted from the acorn fruit of three species of Mediterranean oaks, Quercus ilex L., Q. suber L., and Q. faginea L., was characterized. Both major and minor components, including FA, TG, sterols, methyl sterols, triterpenic and aliphatic alcohols, tocopherols, and hydrocarbons, were identified by standard methods and MS. High-resolution GLC and HPLC were used for quantification. The FA profile, together with the equivalent carbon numbers and TG carbon numbers, was compared with data for other edible vegetable oils. Oil yield, expressed as wet weight, was 5% (w/w). Sterol content was remarkable for the three species (8,563–11,420 mg/kg), with β-sitosterol being the most abundant (80%). Oils were also high in tocopherol, with a wide variation between species (165–456 mg/kg) but with γ-tocopherol predominating in all three oils (90% of the total tocopherol content). Also, high terpenic alcohol contents were found (1527–2984 mg/kg), with dammaradienol and β-amyrin being the most abundant (33–60% of the total alcohol content). Bioactive properties and industrial applications of this underutilized native product are also discussed.     

富含OPO、OPL和LPL的结构脂质促进C57BL/6小鼠脂质代谢

该研究通过酶法合成一种富含1,3-二油酸-2-棕榈酸甘油三酯（OPO）、1-油酸-2-棕榈酸-3-亚油酸甘油三酯（OPL）和1,3-二亚油酸-2-棕榈酸甘油三酯（LPL）结构脂质（SL）,并研究其对小鼠脂质代谢的影响。选取21只健康的C57BL/6J型实验小鼠均分为3组,喂食无脂纯合日粮,并以灌胃形式分别给予小鼠相同剂量的大豆油,InFat CC（一种富含OPO的产品）和SL（富含OPO、OPL和LPL）。喂养期间观察小鼠体重和摄食量的变化,并检测小鼠血清和肝脏中相关的脂质指标。实验表明,喂养富含OPO、OPL和LPL结构脂质（SL）的小鼠平均体重（24.97 g）低于大豆油（27.29 g）和InFat CC组（26.54 g）小鼠,SL组小鼠肝脏中的总胆固醇TC（0.05 mmol/g prot）、总甘油三酯TG（0.14 mmol/g prot）和脂肪酸合成酶（FAS）质量分数（0.13 mg/g肝脏）与大豆油和InFatCC组相比显著降低（P<0.05）。该研究表明SL能够通过促进肝脏脂质代谢来控制小鼠体重增加,为结构脂质的膳食应用提供理论依据。     

Comparative study of resistant starch from minor millets on intestinal responses,blood glucose,serum cholesterol and triglycerides in rats

Native starch (NS) extracted from rice and five different minor millets, when subjected to five autoclaving and cooling cycles, contained higher amounts of resistant starch (RS) than NS. Both NS and treated starch (TS) were fed to groups of rats for 2 weeks. In rice and all the minor millets, rats fed with treated starch showed a six-fold (TS alone) or nearly 18-fold (TS with antibiotics) increase in faecal wet weight than rats fed with NS. Increase in faecal volumes paralleled increases in faecal weight. Rats fed with diet (both NS and TS) from Echinochloa frumentacea had the lowest blood glucose, serum cholesterol and triglycerides than the rice and other minor millets. ©1997 SCI     

Interesterification and hydrolysis catalyzed by fatty acid‐modified lipases

Native lipases often exhibit poor interesterification activity. We previously developed a fatty acid modification method to improve the activity of lipases. In this study, we applied this fatty acid modification method to several lipases and evaluated their interesterification and hydrolytic activities. The resulting interesterification activity was strongly dependent on the modifying fatty acid used. Of the saturated fatty acids tested, stearic acid modification substantially improved the interesterification activity of three lipases. Hydrolytic activity was affected slightly by the modifying fatty acid used. Substrate specificity of the modified lipase with triglycerides was also investigated and it was found that fatty acid modification changed the substrate specificity of some lipases.     

A comparison of triglyceride oil hydrogenation in a downflow bubble column using slurry and fixed bed catalysts

The hydrogenation of the triglyceride oil, soya bean oil, has been studied in the temperature range 130–160 °C and in the pressure range 100–600 kPa using (i) a 5% w/w Pd/C slurry catalyst and (ii) a 3% w/w Pd/Al₂O₃ Raschig ring catalyst in a cocurrent downflow contactor (CDC) reactor. Separate studies of residence time distribution (RTD) were carried out in a modified CDC device in order to determine dispersion numbers and dispersion coefficients. The RTD measurements indicated that the overall flow was a mixture of well‐mixed and plug flow for the unpacked CDC, so that the entry section (0–30 cm from entrance) was perfectly mixed and the remainder of the column (30–130 cm) gave predominantly plug flow behaviour. The introduction of random packing in the form of 13 mm Raschig rings gave rise to increased back mixing in the lower part of the CDC and the overall dispersion number increased due to liquid and gas circulation around the packing elements. Kinetic studies revealed an initial rate reaction order of 1.24–1.26 with respect to hydrogen concentration both in slurry and fixed bed CDC reactors and is interpreted as a combination of a parallel pair of first and second order reactions during the initial stages of reaction. Mass transfer coefficients for gas absorption (k_La) and liquid–solid mass transport (k_s) were determined for both types of reactor. The k_La values lay in the range 1.0–3.33 s⁻¹ and the liquid–solid transport resistances (X_LS) were all <1%, so that the reaction was almost totally surface reaction rate controlled. Apparent energy of activation measurements gave values of E_A = 49 ± 6 kJ mol⁻¹, which is strongly indicative of surface reaction rate control involving the hydrogenation of an olefinic double bond. The selectivity in respect of linolenate (three double bonds) removal and linoleate (two double bonds) retention was high with, for palladium, relatively low trans‐isomer production (<30%). The overall selectivity was slightly, but significantly, better for the fixed bed CDC reactor and this is attributed to the greater degree of plug flow behaviour in the latter, despite the bed causing an increase in dispersion number. However, there is no reaction in the well‐mixed section of the fixed bed CDC reactor as there is in the slurry CDC reactor and this is likely to improve selectivity in a consecutive reaction sequence. © 2000 Society of Chemical Industry     

Possibility of improving the quality characteristics of olive‐pomace oil and enhancing its differentiation from refined olive‐pomace oil

An investigation was carried out to evaluate the oxidative and hydrolytic degradation of 37 olive‐pomace oils marketed in southern Italy and to compare the results with those obtained from 10 deodorised olive‐pomace oils representative of large stocks of oil obtained after the final step of refining. One aim of the research was to ascertain the quality characteristics of commercial olive‐pomace oils; another was to verify whether the legally prescribed addition of virgin olive oil to refined pomace oil, so that the final product may be classified commercially as olive‐pomace oil, was actually sufficient to justify upgrading. The analytical methods used were silica gel column chromatography and high‐performance size exclusion chromatography. The data obtained showed that the final retail olive‐pomace oils had a lower degree of oxidative degradation than the refined oils, as indicated by the lower values obtained when summing the proportions of triglyceride oligopolymers and oxidised triglycerides. Conversely, hydrolytic degradation, which was evaluated by determining diglycerides, proved to be the same in the two categories of oil. The proportions of virgin olive oil added are small, as indicated by the statistically indistinguishable values of triglyceride oligopolymers and free fatty acids obtained. The possibility of setting a limit to the amount of triglyceride oligopolymers present in the commercial category of olive‐pomace oil has been considered. This limit would ensure standardisation of the level of oxidation and, consequently, of the quality of marketed oils and would enhance differentiation between olive‐pomace oil and refined olive‐pomace oil. © 2000 Society of Chemical Industry     

芝麻油掺棕榈油鉴别方法的研究

以4种不同熔点棕榈油与4种芝麻油所配制的128个掺伪芝麻油样品为原料,分别采用全样脂肪酸组成分析法、Sn-2位脂肪酸组成分析法和甘三酯结构分析法对芝麻油中掺棕榈油的鉴别方法进行了研究。结果表明:在全样脂肪酸组成分析法中,当以棕榈酸为标准与芝麻油纯样和国标数据比较时,检出限分别为5%和15%。在Sn-2位脂肪酸组成分析法和甘三酯结构分析法中,当与芝麻油纯样数据比较,分别以亚油酸与棕榈酸含量比值(18:2/16:0)和β-POO(Sn-1-棕榈酸-2,3-二油酸甘油酯)含量为判断标准时,检出限分别为20%和12%。综合这3种方法的检出限高低及分析操作难易程度,初步得出结论:在芝麻油掺棕榈油的鉴别方法中,全样脂肪酸组成分析法是最好的鉴别方法,其余2种方法一般不优先采用,但可作为对上述方法的验证与补充。     

分子蒸馏分离提纯甘二酯中试工艺研究

研究了中试分子蒸馏分离提纯甘二酯的工艺方法。棕榈油在一定的条件下经过中试分子蒸馏设备蒸馏,得到重相与轻相。轻相主要是甘二酯,重相主要是甘三酯。通过进料量、温度及刮膜转速的控制可以得到纯度70%以上的甘二酯。研究结果表明,在温度220℃、压力0.01 Pa、进料量10 L/h、蒸发器转速200 r/min的条件下,通过脱气,薄膜蒸发与短程蒸馏可以得到纯度较高的甘二酯。用棒状薄层色谱―氢火焰离子化检测器法(TLC–FID)与反相高效液相色谱–蒸发光散射检测法(RP–HPLC–ELSD)分别分析测定了棕榈油以及轻相、重相中甘油酯的含量,并进行了对比;用气相色谱分析了棕榈油以及轻相、重相脂肪酸组成。     

Weak gels of fat crystals in oils at low temperatures and their fractal nature

The formation of fat crystal gels in soybean oil has been studied by sedimentation in a low concentration region at 10–25°C. At 10°C, weak gels were formed with 1% crystals, and no gels formed at concentrations of 2–5%. At temperatures of 15–25°C, no gels were formed at concentrations of 1–5%, and samples sedimented. Stronger gels of fat crystals were formed with ∼10% fat crystals at all temperatures examined. Formation of weak gels is a consequence of the fractal nature of fat crystal aggregates and sediments. At low temperature, the interaction is weak. The fractal dimension is then high, and the floc size is large for low crystal concentrations. These large flocs form a three-dimensional network that act as a weak gel and withstand gravitational force. When the temperature is increased, the fat crystal interaction becomes stronger, fractal dimension decreases, and floc size decreases. Smaller flocs have a higher density, pack more easily, and sediment. Similar effects are observed when the concentration of fat crystals is increased at low temperature due to a decrease in floc size.     

复合型海藻膳食纤维功能食品的降血脂作用

研究以海藻膳食纤维为主,传统降脂中药山楂、绞股蓝、泽泻为辅的功能食品的降血脂作用。参考卫生部保健食品辅助降血脂功能评价方法,以高脂饲料建立高脂血症小鼠模型,灌胃给予含不同成分的复合物（海藻膳食纤维高、中、低剂量组,复合物Ⅰ、Ⅱ、Ⅲ组,辛伐他汀组,正常对照组和模型组灌胃生理盐水）。4 周后,测定血清总胆固醇（total cholesterol,TC）、甘油三酯（triglyceride,TG）、高密度脂蛋白胆固醇（high densitylipoprotein cholesterol,HDL-C）以及低密度脂蛋白胆固醇（low density lipoprotein cholesterin,LDL-C）水平,计算肝脏系数,苏木精-伊红染色观察肝脏脂肪变性程度。结果表明：海藻膳食纤维能显著降低高脂血症小鼠血清TC、TG及LDL-C水平,升高HDL-C水平;且加入少量药食同源的中药（绞股蓝提取物和泽泻提取物）后的复合型海藻膳食纤维能使高脂小鼠血脂水平更接近正常值。说明复合型海藻膳食纤维功能食品有较好的降血脂作用。