The Photoxidative Alteration of Chlorophylls in Methyl Linoleate and Prooxidant Activity of Their Decomposition Products

Methyl linoleate containing chlorophylls and/or pheophytins was exposed to light in the presence of oxygen. The photooxidative reaction of both chlorophylls a and b was first-order, and the reaction rate for chlorophyll a was higher than that for chlorophyll b. On the other hand, pheophytins a and b hardly decomposed even after irradiation for 24 hr, and retained a green or a brownish-green color. In qualitative analysis of the photooxidation products of chlorophylls a and b, no pheophytins or pheophorbides were detected, while green and polar red pigments were observed on a thin layer chromatogram near the spot of chlorophyll and the origin, respectively. These photooxidation compounds also had prooxidant effects as well as did chlorophyll.     

食用植物油脂的代谢工程

植物种子油可提供人类营养所需的多种脂肪酸,也是工业用油的原料之一。文章结合我们对植物种子发育、脂肪酸生物合成途径和大豆油脂遗传改良的研究,重点论述参与脂肪酸合成及其调控的一些关键酶的基因、代谢工程改良植物油脂营养价值的技术策略及其研究进展,分析目前应用油料作物种子作为“生物反应器”规模化生产有重要营养价值和特殊用途的脂肪酸的问题及技术“瓶颈”,讨论未来植物脂肪酸代谢工程主攻方向以及在培育可再生资源和推动人类社会及经济可持续发展中的应用前景。     

Relationship between the Molecular Structures and Emulsification Properties of Edible Oils

Emulsification properties are very important to control the texture of foods. However, the relationship between the molecular structure and emulsification properties of edible oils is not understood. To analyze this relationship, the emulsification susceptibilities of various kinds of single triacylglycerol molecular species and edible oils were systematically measured. The emulsification susceptibility increased as the carbon number and double bond number of triacylglycerol molecular species consisting oils increased. In addition, the effect of the double bond number was predominant. These results demonstrate that the emulsification property is affected by the molecular structure of oils. Furthermore, the emulsification susceptibilities of edible oils modified by enzymatic interesterification were changed as compared with those of native oils. This shows that emulsification property can be changed by the modification of the molecular structure of edible oils.     

废弃食用油脂生物合成鼠李糖脂研究进展

碳源的成本过高限制了鼠李糖脂的工业化生产及应用,废弃食用油脂作为一种廉价易得的碳源,越来越多的研究者开始关注用它发酵生产鼠李糖脂.废弃食用油脂的种类、投加量对鼠李糖脂的产量、结构、性质均会产生影响,目前研究中用废弃食用油脂作碳源,鼠李糖脂产量最高可达24.61g/L、表面张力最低达到24mN/m、产物CMC最低可达40.19mg/L.此外,本文还总结了菌株、氮源、微量元素、pH、溶氧及培养方式等因素对废弃食用油脂生产鼠李糖脂的影响,并展望了利用废弃食用油脂生产鼠李糖脂实现产业化的重点研究方向.     

Simplifying Hansen Solubility Parameters for Complex Edible Fats and Oils

Hansen solubility parameters (HSPs), often used to predict the miscibility between two compounds, are an alternative tool in evaluating the ability of the solvent to interact via dispersion, dipole-dipole, and hydrogen bonding interactions. The aim of this paper is to find a simple way to calculate HSPs for complex mixtures of triglycerides (TAGs). HSPs were calculated using two approaches: the first assumes that the contributions to the dispersion, dipole-dipole, and hydrogen bonding interactions may be subdivided into larger functional moieties (i.e., fatty acids and fatty acid methyl esters) that are additive, while the second approach assumes that vegetable oils are comprised of mixtures of simple TAGs in the same mass fractions as the fatty acids. The HSPs obtained using the two approaches are compared to reference values determined using the “Hansen Solubility Parameters in Practice” software (HSPiP) considering the complex TAG profile for each vegetable oil.HSPs for vegetable oils, obtained with the HSPiP software, did not correspond well to the HSPs obtained from the group contribution approach, when using fatty acids, fatty acids + glycerol or fatty acid methyl esters. In contrast, the HSPs calculated for vegetable oils, assuming that all TAGs are simple and in the same mass fractions as the fatty acids, provide similar values to the HSPs obtained from the HSPiP software. Therefore, it is possible to calculate the HSPs for complex oils by simply knowing the fatty acid composition. Knowledge of HSPs may be used to rationalize the ability of certain low molecular weight molecules to develop organogels in vegetable oils as well as the crystallization of triglycerides.     

Antioxidant Effect of Peptide in Combination with Sugar on Autoxidation of Edible Oils

The antioxidant effect of various combinations of peptide and sugar was investigated by an oven-storage test using lard as substrate. High antioxidant activity was resulted from combining a peptides with branched-chain amino acids and xylose. For this effect, the presence of a branched-chain amino acid was more favorable at the N-terminal position of the peptide than at the C-terminal position. A synergistic effect was observable with xylose at a molar ratio of xylose-peptide of 0.05. The leucylglycine-xylose composition was also effective for preventing oxidation in selected vegetable oils.     

重庆市售塑桶装食用油中塑化剂含量调查

目的：了解重庆市售塑桶装食用油中塑化剂的污染情况,为相关行政职能部门加强监管提供依据。方法：2014 年9-11 月,在重庆市内7 个区县的大型超市和农贸市场等流通领域随机采购16 个品牌的塑桶装食用油共143 件,采用在线凝胶渗透色谱- 气象色谱- 质谱法检测其中的16 种邻苯二甲酸酯类物质含量,并用《GB/T 21911-2008 食品中邻苯二甲酸酯的测定》对所得到的阳性结果进行复查。结果：所采集的143件食用油样品中DBP检出率为40 %;DEHP 检出率为100 %;DINP 检出率为16 %,其余种类的邻苯二甲酸酯类物质未检出,所有检出样品中除3 件DBP 样品超标外,其余均小于法规限量。结论：重庆市售塑桶装食用油中不同程度的检出邻苯二甲酸酯类物质,其污染来源极有可能是从塑料包装迁移到食用油中,塑桶装食用油中的塑化剂迁移问题需要引起监管部门的重视。     

Chemical Composition and Character Impact Odorants in Volatile Oils from Edible Mushrooms

The aim of this study was to investigate the chemical composition and the odor‐active components of volatile oils from three edible mushrooms, Pleurotus ostreatus, Pleurotus eryngii, and Pleurotus abalonus, which are well‐known edible mushrooms. The volatile components in these oils were extracted by hydrodistillation and identified by GC/MS, GC‐olfactometry (GC‐O), and aroma extract dilution analysis (AEDA). The oils contained 40, 20, and 53 components, representing 83.4, 86.0, and 90.8% of the total oils in P. ostreatus, P. eryngii, and P. abalonus, respectively. Odor evaluation of the volatile oils from the three edible mushrooms was also carried out using GC‐O, AEDA, and odor activity values, by which 13, eight, and ten aroma‐active components were identified in P. ostreatus, P. eryngii, and P. abalonus, respectively. The most aroma‐active compounds were C₈‐aliphatic compounds (oct‐1‐en‐3‐ol, octan‐3‐one, and octanal) and/or C₉‐aliphatic aldehydes (nonanal and (2E)‐non‐2‐enal).     

Enhanced Removal of Lead from Soil Using Biosurfactant Derived from Edible Oils

ABSTRACT

Lead contamination in soil due to anthropogenic activities has amplified and therefore, remediation is of prime significance due to its nonbiodegradability and toxicity effects. This study focuses on lead removal from the soil collected from a rifle range using biosurfactants produced from native microorganisms and edible oils. Native microorganisms in contaminated soil served as a source for biosurfactant production aided by edible vegetable oils such as palm oil and gingelly oil. Preliminary isolation and characterization studies indicated the presence of Pseudomonas aeruginosa that produced biosurfactant and removed lead simultaneously. Batch adsorption experiments showed 96%–99.6% of lead adsorption following Langmuir isotherm model. Lead desorption of 23.6% occurred without biosurfactant. Whereas in the presence of biosurfactants, enhanced desorption of 62.3% was observed. Of both palm oil and gingelly oil derived biosurfactants, the former reached a lead removal efficiency of 93.6% indicating the feasibility and effectiveness of the biosurfactants for contaminated site remediation.     

食药用真菌多糖抗氧化作用研究进展

食药用真菌多糖由于其独特的生理活性,目前正成为国内外众多学科领域研究的热点之一。综述了食药用真菌多糖抗氧化作用研究现状、作用机理及其构效与量效关系,并对其发展前景进行了展望,旨在为其深入研究和开发利用提供参考。     

桑黄等十种食药用菌抗氧化和延缓衰老功效的比较研究

以桑黄、桦褐孔菌、灵芝、蛹虫草、姬松茸、鸡腿菇、猴头、灰树花、香菇和杏鲍菇等十种食药用菌作为研究对象,利用超氧阴离子和过氧化氢自由基清除模型、H2O2和NaN3分别诱导的PC12细胞氧化损伤和细胞衰老模型,比较了10种食药用菌醇提物抗氧化和抗衰老功效。研究结果表明,200 mg/mL桑黄、桦褐孔菌和灵芝子实体醇提物对超氧阴离子和过氧化氢的清除率分别为96.11%±0.30%、75.92%±0.77%、65.60%±6.66%和99.31%±0.03%、97.51%±0.05%、71.01%±0.79%;对PC12细胞氧化损伤和细胞衰老的修复作用分别达到0.868%±0.078%、0.270%±0.004%、0.261%±0.013%和1.419%±0.070%、0.693%±0.036%、0.701%±0.031%,均明显好于其它食药用菌。     

植物精油生物活性作用机理研究进展

植物精油具有多种生物活性,被广泛应用于医疗保健、食品工业、化妆品、农业等多个领域.本文综述植物精油抗菌、抗癌、抑制肿瘤细胞生长、抗氧化、延缓衰老、防治心血管疾病、抗病毒、消炎等多种生物活性的作用机理,并展望植物精油今后研究的重点及突破方向.     

Chemical Composition and Biological Activities of Tunisian Cupressus arizonica Greene Essential Oils

The chemical composition of the essential oils obtained by hydrodistillation of leaves, stems, and female cones of Cupressus arizonica Greene , grown in Tunisia, was studied by GC‐FID and GC/MS analyses. Altogether, 62 compounds were identified, 62 in the leaf oil, 19 in the cone oil, and 24 in the stem oil. The cone and stem oils were mainly composed by monoterpene hydrocarbons (96.6 and 85.2%, resp.). In the leaf oil, the total sesquiterpene fraction constituted 36.1% and that of the monoterpene hydrocarbons 33.8% of the total oil composition. The three oils were evaluated for their in vitro herbicidal activity by determining their influence on the germination and the shoot and root growth of the four weed species Sinapis arvensis L., Lolium rigidum Gaudin , Trifolium campestre Schreb ., and Phalaris canariensis L. At the highest doses tested (0.8 and 1.0 mg/ml), the leaf essential oil inhibited either totally or almost completely the seed germination and the shoot and root growth of S. arvensis and T. campestre. The oils were also tested for their antifungal activity; however, their effects on the fungal growth were statistically not significant.     

Effects of Two Highly Monounsaturated Oils on Lipid Composition and Enzyme Activities in Rat Jejunum

The effects of two monounsaturated fatty acid (MUFA) oils, olive oil (OO)and high-oleic sunflower oil (HOSO), with high content in oleic acid butdiffering in their non-fatty acid fraction, on brush-border membrane(BBM) lipid composition and fluidity and on mucosal enzyme activitiesof rat jejunum were studied. Animals were given semipurified diet withlinoleic acid to prevent essential fatty acid deficiency (control group)or semipurified diet containing 10% of either OO or HOSO for 12weeks. There was a significant decrease in the content of jejunalBBM phospholipids together with an increase in the level of freecholesterol in both oil-fed rats, when compared to controlgroup. Although the increase in the BBM free cholesterol levelwas not statistically significant in HOSO-fed rats, a significantdecrease in the phospholipid/free cholesterol ratio was found inboth OO and HOSO-fed animals compared to control group. Rat jejunalBBM had a high level of free fatty acids which was increased in BBMisolated from OO and HOSO-fed animals. There was no statisticalsignificant difference in the phospholipid distribution between thecontrol and the OO group. However, HOSO-fed animals showed the lowestlevel of phosphatidylethanolamine together with the highestphosphatidylcholine content and the phosphatidylcholine/sphingomyelinratio. The fatty acid pattern of jejunal BBM lipids was modifiedaccording to the major fatty acids in the oils. There was a decreasein both stearic acid (18:0) and linoleic acid (18:2 n-6), togetherwith an increase in oleic acid (18:1 n-9) in jenunal BBM isolatedfrom both oil experimental groups. All these results were accompaniedby a significant increase in the BBM fluidity (as assessed bysteady-state fluorescence polarization of diphenylhexatriene) isolatedfrom oil-fed rat, when compared to control group. OO and HOSO-fedanimals had the lowest activities of sucrase and maltase, whilealkaline phosphatase activity only was decreased in HOSO-fedanimals. The specific activity of maltase was not modified in anyexperimental rats. In summary, both MUFA oils induced similar effectson jejunal BBM lipid composition, fluidity, sucrase, maltase andlactase activities. Furthermore, HOSO intake resulted in a lowestalkaline phosphatase activity which was accompanied by changes inindividual phospholipid composition. All these results suggest thateffects of MUFA oils on jejunal BBM lipid composition and hydrolaseactivities are most likely due to the presence of high content ofoleic acid rather than other components contained in the non-fattyacid of olive oil.     

Red Chlorophylls in the Exciton Model of Photosystem I

Structural arrangement of pigment molecules of Photosystem I of photosynthetic cyanobacterium Synechococcus elongatus is used for theoretical modeling of the excitation energy spectrum. It is demonstrated that a straightforward application of the exciton theory with the assumption of the same molecular transition energy does not describe the red side of the absorption spectrum. Since the inhomogeneity in the molecular transition energies caused by a dispersive interaction with the molecular surrounding cannot be identified directly from the structural model, the evolutionary search procedure is used for fitting the low temperature absorption and circular dichroism spectra. As a result, one dimer, three trimers and one tetramer of chlorophyll molecules responsible for the red side of the absorption spectrum with their assignment to the spectroscopically established three bands at 708, 714 and 719 nm are determined. All of them are found to be situated not in the very close vicinity of the reaction center but are encircling it almost at the same distance. In order to explain the unusual broadening on the red side of the spectrum the exciton state mixing with the charge transfer (CT) states is considered. It is shown that two effects can be distinguished as caused by mixing of those states: (i) the oscillator strength borrowing by the CT state from the exciton transition and (ii) the borrowing of the high density of the CT state by the exciton state. The intermolecular vibrations between two counter-charged molecules determine the high density in the CT state. From the broad red absorption wing it is concluded that the CT state should be the lowest state in the complexes under consideration. Such mixing effect enables resolving the diversity in the molecular transition energies as determined by different theoretical approaches.     

植物精油的抗菌特性及在食品工业中应用研究新进展

概述了植物精油和其单组分的来源、安全性评价、抗菌性能以及在食品工业上应用研究的新进展。并简要讨论了在食品应用中,食物中脂肪、蛋白、水、盐、pH等含量以及外在条件如包装、精油的添加形态和病菌的特性对植物精油的抗菌活性的影响。