高纯度对称型脂肪酸甘油酯的同质多晶现象

本文报导了高纯度（９９．９％）的两种对称型饱和脂肪酸不饱和脂肪酸甘油三酯－ＰＯＰ与ＳＯＳ的同质多晶现象的研究结果。即它们具有的多晶质的种类、熔点、多晶质间的迁移规律、转化速度等。通过对ＰＯＰ与ＳＯＳ的ＸＲＤ及ＤＳＣ分析，明确了ＰＯＰ与ＳＯＳ均含有α、γ、ｐｅｓｕｄｏ－β、β２、β１这种多晶态，ＰＯＰ的ｐｅｓｕｄｏ－β’型还可分为ｐｅｓｕｄｏ－β’２、ｐｅｓｕｄｏ－β’１两种多晶态。α型和ＰＯＰ的ｐ     

酶促酯交换对棕榈硬脂基塑性脂肪甘三酯组成及物理性能的影响

利用脂肪酶Lipozyme TLIM催化棕榈硬脂(PS)与大豆油(SO)(PS∶SO分别为9∶1,8∶2,7∶3,6∶4,5∶5,wt%)酯交换反应,研究酯交换反应前后混合油脂体系中甘三酯组成的变化及其与油脂物理性能的关系。结果发现,酯交换后油脂中PPP、LLL、POP、PPL、PLL、PLO六种甘三酯含量发生明显变化,其中PPP、LLL含量下降,PPL、PLL、PLO含量增加,而POP除9∶1外,其含量均下降;SSS(S代表饱和脂肪酸)和UUU(U代表饱和脂肪酸)型甘三酯含量下降,而SUU和SUS含量增大,导致油脂熔点和固体脂肪含量(SFC)均不同程度下降,从而可制备不同SFC要求的塑性脂肪。PS∶SO为7∶3、6∶4、5∶5时,酯交换后油脂β'晶型增多,可为人造奶油、速冻专用油脂等塑性脂肪提供理想晶型。     

不同硬度棕榈油基人造奶油组成及结晶行为研究

对比分析了两个不同硬度棕榈油基人造奶油的甘三酯组成、结晶特性及微观结构,试验表明人造奶油B中饱和脂肪酸含量较高,SUS型甘三酯(POP,PLP)含量偏大,同时含有少量的中碳链甘三酯;X-衍射观察到两个样品中均含有β和β′晶型,但是样品B中β′晶型占主导;SEM图像显示硬度较小的样品显微结构更疏松多孔.     

利用Sn-2位富含多不饱和脂肪酸的改性椰子油制备低热量型有机凝胶及其特性研究

采用富含月桂酸的椰子油与富含多不饱和脂肪酸的鱼油为原料,对椰子油进行酶法改性,通过酯交换反应合成Sn-2位富含长链多不饱和脂肪酸(EPA,DHA)的结构脂。以此结构脂为基料油,γ-谷维素与β-谷甾醇的混合物作为凝胶剂制备油脂凝胶。以熔点和机械稳定性为指标,确定了γ-谷维素和β-谷甾醇制备结构脂凝胶油的最优工艺条件,并研究了油脂凝胶的质构、流变性质及微观形态。结果表明:改性椰子油Sn-2位的不饱和脂肪酸含量达到66. 62%;制备油脂凝胶的最优工艺条件为γ-谷维素与β-谷甾醇质量比6∶4、凝胶剂含量8%、加热温度90℃、冷却温度5℃。在最优工艺条件下,油脂凝胶的熔点为35℃,机械稳定性达到95. 3%,硬度为60. 61 g,固体脂肪含量为1. 33%。该油脂凝胶表现出假塑性流体特性,样品的表观黏度-剪切速率的关系符合幂律方程关系,在频率扫描范围内,油脂凝胶体系的G'明显大于G″,样品形成较为紧密的凝胶结构,具有较好的涂抹性和可塑性。样品微观网络结构分析表明,晶体呈现玫瑰状形态,形成了完整致密的三维超分子网络结构。     

不同食用植物油中维生素E组分及含量研究

通过对9个不同品种的138个食用植物油样品中维生素E组分及含量的测定,分析研究不同食用植物油中维生素E组分及含量的分布情况。结果表明:9个油脂品种、101个一级油样品中维生素E含量范围为5.9~1 246.6 mg/kg,平均值652.4 mg/kg,维生素E总量的平均值排序为大豆油棉籽油玉米油葵花籽油菜籽油米糠油花生油芝麻油山茶油;不同油脂样品中维生素E的组分有明显差别,米糠油含有最齐全的8种维生素E组分,并且生育三烯酚含量的平均值占维生素E总量平均值的44.2%;玉米油含有3种生育酚和2种生育三烯酚,棉籽油中含有3种生育酚和1种生育三烯酚,但这两种油脂中生育三烯酚含量平均值分别仅占维生素E总量平均值的5.8%和2.8%;大豆油、菜籽油、花生油、葵花籽油均含有α-、γ-、δ-生育酚3种组分;山茶油中含有α-、γ-生育酚2种组分;芝麻油仅含有γ-生育酚1种组分。除芝麻油之外,所有油脂中均含有α-生育酚和γ-生育酚,其中葵花籽油中α-生育酚含量最高,大豆油中γ-生育酚含量最高。同一油脂品种、不同等级的油脂中维生素E含量也存在差异,总体趋势是维生素E含量随油脂精炼程度的加深而降低,但个别二级菜籽油样品中维生素E含量低于一级菜籽油,这与所采集油脂样品的来源不同有关。不同油脂品种、不同等级的食用植物油中维生素E组分及含量因油料品种、油脂精炼工艺的不同显示出明显差异。     

对称型甘油三酯BOB的多晶制作研究

ＢＯＢ是油脂中最稳定的成分之一，以它的β２晶体做为晶种投入待调温的巧克力中，既可减少晶种投入量，又可提高产品稳定性。但ＢＯＢ因碳链长，熔点高，晶体转移慢，制出ＢＯＢ的β２晶体耗时极长。本研究找出循环温度，粉碎及最佳温度等条件，只用８天即帛出ＢＯＢ的β２晶体。     

高效液相色谱法测定维生素E

高效液相色谱法可以快速地(十分钟内)定量测定谷物或油脂中的α、β、γ、δ四种生育酚的异构体。油脂样品直接溶在流动相溶液中进样。谷物样品用索氏法提取油脂,低温挥发溶剂后,再溶于流动相溶液中,进样分析。高效液相色谱法与     

椰子油与棕榈硬脂油物理混合及其结构脂熔融特性的比较研究

油脂的相容性和非等温结晶性质对油脂的口感品质有重要影响。为了拓宽椰子油和棕榈油的应用范围,开发以其为主要原料的专用油脂产品,本文通过GC-MS测得椰子油和棕榈硬脂油不同混合比例的总脂肪酸和Sn-2位脂肪酸组成,研究了脂肪酸组成与熔融特性的相关性,再利用脉冲核磁共振仪研究了椰子油和棕榈油的相容性,并用差式扫描量热仪对二者按一定比例混合的复配体系和酶法制备结构脂的非等温结晶行为进行研究。结果表明:不同比例酶法制备结构脂中Sn-2位的月桂酸含量(12.35~46.72%)明显高于物理混合油(5.86~30.75%)。该复配体系整体上存在一定程度的共晶现象,在较高温度(25~45℃)时,相容性较好。在非等温结晶过程中,在同一降温速率条件下,随着椰子油比例的增加,2倍链长的β′型晶体,转变为低熔点的3倍链长β′晶型。     

粉丹竹SCMP木素结构的2D NMR分析

采用二维核磁共振(2D NMR)波谱对粉丹竹磺化化学机械浆(SCMP)木素结构进行了分析。研究结果表明,粉丹竹SCMP的木素是由愈创木基型(G)、紫丁香基型(S)和对-羟基苯基型(H)等三种木素结构单元组成;木素结构的连接方式主要是β-O-4′醚键结构,还有树脂酚结构(β-β′,α-O-γ′,α′-O-γ)、苯基香豆满结构(β-5′,α-O-4′)、二苯并-二氧桥-松柏醇结构(5′-5″,α-O-4′,β-O-4″)和β-1′结构等;H型木素主要以对-香豆酸的形式与β-O-4结构木素侧链的γ位羟基形成酯键。     

蒙古扁桃仁油脂维生素E含量的测定

用高效液相色谱法对蒙古扁桃仁油脂维生素E含量进行测定。结果表明,α、β、γ、δ–维生素E标准样品可定量范围分别为120.0~602.0、8.8~264.0、10.0~204.0、158.0~789.0μg/m L,其线性回归系数分别为0.997、0.994、0.957、0.997。蒙古扁桃仁油脂含α、β、γ、δ–维生素E,其中δ–维生素E含量最高,总含量为135.09~163.21 mg/100g。用索氏提取法和低水分酶法提取油脂维生素E含量差异不显著(Ρ>0.05),用振荡皂化和回流皂化处理油脂维生素E含量差异显著(Ρ<0.05)。     

FUNCTIONALITY OF PALM OIL IN FOODS

The functional properties of commercial solid fats such as shortening and margarine are closely related to their fatty acid and triacylglycerol compositions. Plastic fats produced from hydrogenated seed oils may suffer from undesirable crystal structure changes during handling and storage. It has been demonstrated that this problem increases with increasing chain length uniformity of the component fatty acids. This is also evidenced by the carbon number composition of the high melting triacylglycerols of the plastic fats. Triacylglycerols with carbon numbers 48 and 54 promote β crystallization, those with carbon numbers 50 and 52 promote β' crystallization. Since palm oil and its products contain high levels of C50 and C52 triacylglycerols they are useful for improving the functional properties of plastic fats.     

Isolation and Partial Properties of Cyclomaltodextrin Glucanotransferase-producing Alkaliphilic Bacillus spp. from a Deep-sea Mud Sample

Cyclomaltodextrin glucanotranferase (CGTase) producing alkaliphilic bacteria were isolated from deep-sea bottom mud samples. Isolates no. 3–22 and no. 1–7 were identified as an alkaliphilic Bacillus sp. and an alkaliphilic Bacillus subtilis strain from their taxonomic characteristics, respectively. Isolate no. 3–22 grew at 4°C whereas isolate no. 1–7 did not. The crude enzymes of both strains showed activity in both broad temperature and broad pH (5–9) ranges, Isolate no. 3–22 produced the main product. β-cyclodextrin (β-CD), and minor products, α- and γ-CDs from starch. On the other hand, isolate no. 1–7 produced the main product, β-CD, and the minor product, γ-CD from starch; no α-CD was detected.     

Oxidative Stability of Soybean Triacylglycerol Using Carotenoids and Y-Tocopherol

The effect of lycopene, β-carotene, and γ-tocopherol on the oxidative stability of soybean triacylglycerol was evaluated under Schaal oven conditions at 60°C. Peroxide value, conjugated diene, hydroperoxides, and thiobarbituric acid reactive substances were used as indicators for primary and secondary lipid oxidation products, whereas Rancimat method was used to study the oil stability. Results indicated that lycopene and β-carotene acted as pro-oxidants, whereas γ-tocopherol acted as antioxidant in triacylglycerol. Pro-oxidative activity of lycopene was higher than β-carotene at 100 and 200 ppm levels under Schaal oven thermal conditions. The combination of lycopene and γ-tocopherol (1:2) acted as antioxidant with better efficiency than γ-tocopherol alone in inhibiting the hydroperoxide formation in triacylglycerols.     

Determination of thermal oxidation and oxidation products of β-carotene in corn oil triacylglycerols

A reversed phase HPLC-DAD coupled to APCI-MS method is reported for the determination of the degradation of β-carotene and characterization of the oxidation products in corn oil. Corn oil containing β-carotene was oxidized in the Rancimat at 110 °C from 1 to 14 h. A significant degradation of β-carotene was observed in corn oil during accelerated thermal oxidation. A total of eight different oxidized products of β-carotene were identified, which includes 8′-apo-β-carotenal, 6′-apo-β-carotenal, 5,6-epoxy-8′-apo-β-carotenal, β-carotene-2,2′-dione, 13-Z-5,6,5′,6′-diepoxy-β-carotene, all-E-5,8-epoxy-β-carotene, all-E-5,6-epoxy-β-carotene, and 15-Z-5,6-epoxy-β-carotene. Corn oil triacylglycerols (TAGs) oxidation products were also identified using isocratic HPLC–ESI-MS. It was found that β-carotene promoted oxidation of TAGs especially at longer exposure times. For the first time two new classes of oxidized TAGs have been identified in corn oil, which were epidioxy bis-hydroperoxides and hydroxy bis-hydroperoxides. Other oxidation products of TAGs were mono-epoxides, mono-hydroperoxides, and epoxy hydroperoxides. It was found that complementing the HPLC-DAD method for β-carotene with ESI-MS method for TAGs oxidation provides a comprehensive set of analytical tools to characterize carotenoids and triacylglycerols oxidation and degradation in edible oils.     

猴头菇β-葡聚糖的结构表征及其稀溶液性质

以猴头菇子实体为原料,通过水提醇沉法提取得到猴头菇β-葡聚糖（Hericium erinaceus β-glucan,HEBG）。采用高效液相色谱、气相色谱、傅里叶变换红外光谱、高碘酸氧化、Smith降解、甲基化分析和核磁共振分析对HEBG的一级结构进行表征;通过特性黏度测定实验和刚果红实验对HEBG溶液性质进行探究,并通过扫描电子显微镜和原子力显微镜对HEBG进行显微结构的观察。结果表明：HEBG是由β-D-葡萄糖组成的均一性多糖;高碘酸氧化、Smith降解、甲基化分析和核磁共振分析结果表明HEBG主链由1,3-β-D-葡萄糖残基组成,支链是由1,6-β-D-葡萄糖残基组成,且1,3-β-D-葡萄糖与1,6-β-D-葡萄糖的物质的量比为1∶1。特性黏度和刚果红实验表明,HEBG稀溶液中不仅存在无规线团结构,还存在三股螺旋结构;扫描电子显微镜和原子力显微镜更加清晰地观察到多糖的无规线团结构、分子链的分支状结构,分子链直径为（0.55±0.11）nm,宽度为1.9 nm。该实验为深入研究HEBG的生物活性以及构效关系提供一定参考依据。     

Importance of β,β-carotene 15,15'-monooxygenase 1 (BCMO1) and β,β-carotene 9',10'-dioxygenase 2 (BCDO2) in nutrition and health

In humans, varying amounts of absorbed β-carotene are oxidatively cleaved by the enzyme β,β-carotene 15,15'-monooxygenase 1 (BCMO1) into two molecules of all-trans-retinal. The other carotenoid cleavage enzyme β,β-carotene 9',10'-dioxygenase (BCDO2) cleaves β-carotene at the 9',10' double bond forming β-apo-10'-carotenal and β-ionone. Although the contribution of BCDO2 to vitamin A formation has long been debated, BCMO1 is currently considered the key enzyme for retinoid metabolism. Furthermore, BCMO1 has limited enzyme activity towards carotenoids other than provitamin A carotenoids, whereas BCDO2 exhibits a broader specificity. Both enzymes are located at different sites within the cell, with BCMO1 being a cytosolic protein and BCDO2 being located in the mitochondria. Expression of BCMO1 in tissues other than the intestine has recently revealed its function for tissue-specific retinoid metabolism with importance in embryogenesis and lipid metabolism. On the other hand, biological activity of BCDO2 metabolites has been shown to be important in protecting against carotenoid-induced mitochondrial dysfunction. Single-nucleotide polymorphisms (SNPs) such as R267S and A379V in BCMO1 can partly explain inter-individual variations observed in carotenoid metabolism. Advancing knowledge about the physiological role of these two enzymes will contribute to understanding the importance of carotenoids in health and disease.     

Effect of oxidative deterioration on flavour and aroma components of lemon oil

Reactions of five major components (citral, α- and β-pinene, limonene and γ-terpinene) of lemon oil in the presence of Cu catalysts and air have been shown to lead to significant oxidation of α- and β-pinene and γ-terpinene, even when the catalyst concentration was comparable to that present in copper-plumbed tap water. Addition of commercial antioxidants (BHA and tocopherol) generally led to suppression of oxidation. UV degradation of these compounds in the presence of air was most significant for γ-terpinene and limonene which gave products similar to those obtained from the Cu-catalysed thermal reactions. Citral gave different products, mainly photocitrals, in contrast to the thermal reactions. The sensitivity of lemon oil to temperature and the presence of air was confirmed.     

Effect of Crystalline Structure on Oxidation of Fish Oil in Stearin:Fish Oil Mixtures

Effects of incorporation of stearin fraction into fish oil on crystallisation behaviour and oxidative stability of fish oil were examined. The stearin fraction (S₂₅) was obtained from step-wise dry fractionation of anhydrous milk fat at 25 °C. Analysis of fatty acid composition by gas chromatography showed that unsaturated fatty acids (89.3 %) were enriched in the fish oil whereas the S₂₅ typically comprises of saturated fatty acids (79.4 %). A series of S₂₅:fish oil mixtures (0:100, 25:75, 50:50, 75:25; 90:10 and 100:0) was prepared by mixing the S₂₅ and fish oil at 50 °C under flushing of nitrogen gas. Crystallisation and thermal properties and crystal structures of the mixtures were investigated by differential scanning calorimetry and small- and wide-angle X-ray scattering, respectively. The crystallisation/melting temperatures and crystallisation/melting enthalpies of the mixtures increased with increasing ratios of S₂₅ blended into fish oil. All mixtures showed similar crystal structures (double- and triple-chain length) and crystal polymorphs (α, β’ and β) at 4 °C. A decrease in S₂₅ fraction in the mixtures caused a higher proportion of triple-chain length crystal packing and β polymorph. Measurement of peroxide values of the mixtures upon storage at 8 °C for 42 days showed that blending as low as 25 % S₂₅ sufficiently delayed the lipid oxidation of fish oil by about two-fold and the rancidity threshold to 16 days instead of 9 days for fish oil only. This study demonstrates that mobility of oxygen and triacylglycerol (TAG) molecules in fish oil can be restricted by crystalline state of milk fat, in turn, limiting the propagation of oxidative reaction in fish oil.     

玉米醇溶蛋白组分的分级及表征

根据玉米醇溶蛋白(zein)组分在不同的异丙醇浓度、盐浓度、pH下溶解度的差异,从玉米中成功分离出α–zein,β–zein,γ–zein 3种组分,并对其提取率、相对分子质量、氨基酸组成、二级结构及界面特性进行表征。结果表明:α-zein的疏水性氨基酸含量最高,占比为54.3%;其次是γ-zein为47.1%;β-zein最低,疏水性氨基酸含量为38.2%。α-zein具有高含量α-螺旋结构,低含量的β-折叠结构;β-zein具有高含量β-折叠结构,低含量α-螺旋结构;γ-zein具有较高含量的β-转角结构。利用LB膜天平表征zein不同组分在空气-纯水界面的吸附行为,发现α-zein在空气-纯水界面平均分子所占面积最高,β-zein所占面积最低;α-zein形成的单分子层发生从液态扩张相到液态凝聚相的转变点最大,β-zein的相转变点最小。通过AFM表征zein不同组分在空气-纯水界面的形貌,发现α-zein以颗粒形态存在,β-zein呈紧密的网络结构,γ-zein形成类似蠕虫状的结构。研究能为玉米醇溶蛋白组分的应用研究提供理论依据。     

Tocopherol losses in peanut oil during pressure frying of marinated chicken strips coated with edible films

Tocopherol losses were observed in peanut oil used for frying both marinated and non-marinated chicken products. The largest losses were seen for γ-tocopherol followed by α-tocopherol and then β- and δ-tocopherols. γ-Tocopherol losses were significantly reduced when hydroxypropylmethylcellulose was applied either as a film or as a breading mix ingredient to pre-fried chicken strips that had been marinated in pickle juice. It is conjectured that the edible film material served as a hydrophilic barrier to migration of the pro-oxidant, acetic acid, from the product to the oil.