基于人乳脂肪组成的酶法人乳脂肪替代物的构建

为了开发新型高相似性人乳脂肪替代物,依据中国人乳脂肪的脂肪酸组成和甘油三酯结构,以巴沙鱼油、樟树籽仁油、亚麻籽油、微生物油(富含ARA)及DHA藻油(质量比为153.81∶15.16∶62.33∶7.89∶10.81)为原料油脂,以固定化脂肪酶Lipozyme RM为催化剂,在60℃下酯交换反应8 h制备人乳脂肪替代物,测定其脂肪酸、sn-2位脂肪酸及甘油三酯组成及含量,分析其红外光谱图、熔融性质、结晶性质及流变学性能。结果表明,构建的人乳脂肪替代物中链脂肪酸含量为12%、亚油酸和亚麻酸总含量为19.53%且比例约为1∶1.5,ARA含量为1.17%,DHA含量为1.11%,其sn-2位富含棕榈酸(43.10%),结构甘油三酯含量高(58.75%),无反式脂肪酸生成,熔融温度低于人体温度且在20℃下仍能保持18.7%的固体脂肪含量,结晶形态细腻且流变性能优异。制备的人乳脂肪替代物具有应用于婴幼儿配方奶粉、婴幼儿米糊和婴幼儿饼干等各种婴幼儿食品的潜力。     

类可可脂原料油中低熔点甘油三酯的组成、含量调控与综合利用

为了实现类可可脂在巧克力中更为高效的应用,降低其对产品品质的影响,综述了类可可脂原料油中低熔点甘油三酯的组成与熔化性质,概括了不同种类甘油三酯对巧克力霜变行为的作用特征;进一步讨论了控制低熔点甘油三酯含量的技术方法,包括基因工程和分提;最后,总结了经分提获得的低熔点成分的再利用。类可可脂原料油中低熔点甘油三酯可能对巧克力的制造(尤其是调温)和质量控制(如软化、起霜等)产生不利影响。通过分提选择性降低低熔点甘油三酯含量是制备高品质类可可脂的优选路径。     

Effects of monoacylglycerols on the oxidative stability of olive oil

BACKGROUND: The study of pro‐ and anti‐oxidant compounds is important for their influence on the shelf‐life and nutritional value of food. The aim of this research was to evaluate the activity of monoacylglycerols (MAG), obtained by partial saponification of a purified olive oil, added in increasing amounts to the same oil and submitted to the Rancimat test and oven test at 60 °C. Besides routine analyses, high‐performance size exclusion chromatography analysis of polar compounds was performed. RESULTS: The addition of MAG led in all cases to a significant slowdown of the oxidative processes. These trends were more evident as the oxidation went on. The purified oil added with 30 g kg^?1 of MAG after 9 days of oven test at 60 °C presented a level of oxidative degradation significantly lower than the control after only 4 days. CONCLUSION: The data showed a marked antioxidant effect of MAG in purified olive oil, contrary to what has been observed by other authors, who noticed either a pro‐oxidant or a non‐antioxidant activity of these compounds in soybean oil. A different behaviour of MAG during oxidation could depend on the different fatty acid composition of the oil matter they are added to. Copyright © 2010 Society of Chemical Industry     

Composites from northern red oak (Quercus robur) leaves and plant oil‐based resins

Composite materials were successfully made out of plant oil‐based resin and northern red oak (Quercus robur) leaves collected in the fall. The viscosities of the bio‐based resins (MAESO and MAELO) were suited to high temperature resin transfer molding (RTM) and vacuum‐assisted resin transfer molding (VARTM) processing. The leaves have a waxy epidermal surface layer that needs to be dewaxed prior to use in a composite part. We used different treatments (such as benzene–ethanol, boiling water, and strong detergent) to dewax the leaves; all three methods seem to give good results; but boiling water and strong detergent were considered the best treatments for the dewaxing of leaves and boiling water was considered the greenest dewaxing method. The compatibility between the resin and the leaves was improved with a silane treatment which resulted in composites with higher mechanical stiffness than the resin itself. With 10 wt % leaves, we obtained an improvement in the composite modulus of about 14% from which we could estimate the leaf modulus at about 5.3 GPa. An alternative method to produce biocomposites from leaves without the need for silane treatments consists in carbonizing the leaves first at 215°C for 12 h, and then at 450°C for 1 h. The composites made with leaves and bioresins derived from functionalized triglycerides have the potential for use in high volume applications with low costs such as housing, construction, civil infrastructure, toys, and furniture. The use of leaves as a biocomposite filler has several advantages including (a) reduced cost, (b) improved properties of the resin, (c) composites with high bio content, (d) removal of a waste material with subsequent prevention of burning with attendant health hazards, and (e) interesting design aesthetics for interior and exterior decoration. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2013     

Photopyroelectric determination of thermophysical parameters and detection of phase transitions in fatty acids and triglycerides. Part II: Temperature dependence of thermophysical parameters

The photopyroelectric (PPE) technique was used to detect solid-to-liquid phase transitions in saturated [C6:0, C10:0, C12:0, C16:0 palmitic acid (P), C18:0 stearic acid (S)] and unsaturated (C18:2) fatty acids and some triglycerides (PSP, PPS). By using the standard PPE configuration with a thermally thin and optically opaque sample and a thermally thick sensor (a1.1); the temperature behavior of the volume-specific heat in a temperature range that includes the melting points for C10:0, C12:0, C16:0, and C18:0 was obtained. When the standard PPE configuration, with sample and sensor both being thermally thick and the sample being optically opaque (a1.2), was used, the information contained in the phase of the PPE signal allowed direct measurement of the thermal diffusivity for C10:0, C12:0, and PSP. The inverse configuration with a thermally thick sample and thermally thin sensor (b1.2) or a semitransparent thermally thick sensor (b2) was used to obtain critical behavior of the thermal effusivity for C10:0 and C12:0, respectively. Critical behavior of the thermal conductivity for same samples was computed from information obtained from amplitude and phase measurements (a1.2), or by combining a1.1 and b1.2 data. The history (age, storage conditions, annealing) of the samples affects the critical behavior of thermal parameters.     

A facile synthesis of aminohydroxy triglycerides from new crop oils

Vegetable oils as the main source of plant lipids are currently generating much interest as renewable industrial feedstocks for nonfood industrial applications both as biobased lubricants and biodiesel fuels. But of particular interest for us is use of new crop oils in novel industrial applications. These oils, in general, are glyceryl esters with olefinic bonds, which are readily functionalizable. Aminated lipids are important intermediates in many applications including pharmaceutical formulations because they have a modifying effect on cell membranes. We have exploited the nucleophilic property of the carbon-carbon double bonds in two seed oils to generate the oxirane derivatives of the lipids. Ring opening of the epoxy intermediates with amines under anhydrous ZnCl₂ catalysis is facile, and the reaction proceeds smoothly at moderate temperatures to given the aminohydroxy TG of milkweed and salicornia oils.     

Effect of CLA on the cellular lipids of <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis>

The yeast Saccharomyces cerevisiae was cultivated in the presence of free CLA that was either a pure trans-10, cis-12 isomer, a pure cis-9, trans-11 isomer, or a 1∶1 mixture of the two, and the influence of these supplementations on the content and FA composition of the lipids in the yeast was determined. Neither the pure isomers nor their 1∶1 mixture influenced the growth of the yeast, but the trans-10, cis-12 isomer reduced the amount of cellular lipids by 40%. The reduction in total cellular lipids by the trans-10, cis-12 CLA was due to a reduction in TAG. Both of the isomers were incorporated into the yeast lipids, reaching a proportion of about 33% in TAG. With the incorporation of CLA, the yeast reduced the amount and desaturation of endogenously synthesized FA. These clear and pronounced isomer-specific effects of CLA on the yeast suggest that yeast might be a useful model to obtain a more comprehensive view of the mechanisms of the action of CLA on lipid metabolism.     

Differential scanning calorimetry of confectionery fats. Pure triglycerides: Effects of cooling and heating rate variation

Differential scanning calorimetry (DSC) measurements of the crystallization and melting phenomena of pure forms of the three principal triglycerides present in cocoa butter and related confectionery fats are presented. The results are used to exhibit the usefulness of the DSC technique for potential application in quality control of these types of material, but also as a warning of the difficulties in interpretation of data. The results also serve as a reference for future use in DSC studies of similar materials. On behalf of Loders-Croklaan.     

Applications of chromatographic techniques to evaluate enzymatic hydrolysis of oxidized and polymeric triglycerides by pancreatic lipase in vitro

With the aim of studying the susceptibility to enzymatic hydrolysis of oxidized and polymeric triglycerides (TG) that are formed during frying, various chromatographic techniques were applied in combination, i.e., adsorption chromatography, high-performance size-exclusion chromatography (HPSEC), and thin-layer chromatography-flame ionization detection (TLC-FID). Polar fractions, isolated by adsorption chromatography from thermoxidized trilinolein as model system, and real used frying fats and oils, were analyzed by HPSEC before and after incubation with pancreatic lipase in vitro. Also, the influence of degradation level of used frying oils on hydrolysis of intact TG was investigated with the additional aid of TLC-FID. Results showed the high hydrolysis rate of oxidized TG monomers in contrast to the significant discrimination of pancreatic lipase against TG dimers and, particularly, TG polymers. On the other hand, hydrolysis of intact TG can be affected by the presence of dimers and polymers in abused frying oils.     

Differential extraction of eleostearic acid-rich lipid-protein complexes in tung seeds

Lipid-protein complexes were identified in the 104,000×g supernatant fraction of developing tung seeds. Incubation of this fraction with linoleoyl-CoA promoted an increase of chloroform-extractable lipids in a time-dependent manner. High-performance liquid chromatography analysis indicated that the extracted lipids were similar to mature tung oil triglycerides. Differential extraction using chloroform or chloroform/methanol indicated that linoleoyl-CoA promoted extraction of pre-existing lipids rather than de novo synthesis. An increase in extractable lipids was also observed after incubation with proteinase K. Isolation of lipid-protein complexes by sucrose density centrifugation and analysis of proteins by gel electrophoresis revealed several proteins specifically associated with this lipid fraction.