稻米胚及米胚油的品质分析

从原料米糠中分离出纯稻米胚和纯米糠,利用溶剂浸出法分别提取其中油脂并进行品质分析对比,以研究稻米胚及米胚油的营养品质。结果表明:稻米胚粗脂肪含量27.06%,粗蛋白含量19.50%,粗纤维含量4.88%,比米糠粗脂肪、粗蛋白含量明显提高,粗纤维含量降低;米胚油的酸值(KOH)、过氧化值、维生素E含量、谷维素含量、植物甾醇含量分别为21.7 mg/g、6.1 mmol/kg、43.18 mg/100 g、0.47%、3.07%,与米糠油相比,米胚油的酸值(KOH)降低了23.8 mg/g,过氧化值降低了1.7 mmol/kg,维生素E含量提高了17.18 mg/100 g,植物甾醇含量相差不大,谷维素含量降低0.93个百分点。米胚油在酸值和维生素E含量方面较米糠油具有明显优势,新鲜稻米胚既可以直接作为营养丰富的产品,也是优质食用油的原料。     

Purification and characterization of glutamate decarboxylase from rice germ

Glutamate decarboxylase (EC 4.1.1.15, GAD) is a pyridoxal 5′-phosphate (PLP) dependent enzyme, which catalyses the irreversible α-decarboxylation of l-glutamic acid to γ-aminobutyric acid. GAD was purified 186-fold from rice germ using a combination of ammonium sulfate fractionation, DEAE-Sepharose FF ion exchange chromatography, Superdex-200 gel filtration chromatography, and Glu-Sepharose CL 4B affinity chromatography. The purified preparation showed a single peak on SE-HPLC with an approximate molecular mass of 78 kDa and a single band on SDS–PAGE with a subunit Mr of 40 kDa. This indicated that the GAD from rice germ existed as a dimer of homological subunits. Rice germ GAD has an optimum pH range between 5.5 and 5.8, and an optimum temperature at 40 °C. K_m values for glutamic acid and PLP were determined at 32.3 mM and 1.7 μM, respectively. Chemicals reagents such as HgCl₂, KI and AgNO₃ decreased the enzyme activity by 68.5%, 44.9% and 32.4%, respectively, but 500 μM of CaCl₂ at the optimum pH could increase the activity by 145%.     

米胚芽酶法制备γ-氨基丁酸的研究

研究了利用米胚芽中的谷氨酸脱羧酶转化谷氨酸制备γ-氨基丁酸(GABA)的方法。在最佳的酶反应条件下,米胚芽谷氨酸脱羧酶可以将添加的谷氨酸全部转化为GABA,转化率达到100%,米胚芽中的GABA为20.6g/100g。     

Some molecular properties of glutamate decarboxylase from rice germ

Glutamate decarboxylase (EC 4.1.1.15, GAD) is a pyridoxal 5′-phosphate (PLP) dependent enzyme, which catalyses the irreversible α-decarboxylation of l-glutamic acid to γ-aminobutyric acid (GABA). GAD was purified 186-fold from rice germ. Ultraviolet–visible spectra showed that the rice germ holoGAD presented a weak peak at 420 nm, but the inactivated apoGAD did not. The holoGAD also exhibited a strong peak at 308 nm and a weak peak at 336 nm in its fluorescence emission spectrum. The apoGAD led to a 20% increase in the fluorescence emission at 308 nm. The contents of the secondary structure elements of the holoGAD and apoGAD were estimated from the values of the mean residue ellipticity based on the CD spectra. The holoGAD had a greater β-sheet content than the apoGAD (39% versus 27%), whereas both had a similar α-helix content (13% versus 14%). These findings confirmed that a slight conformational change had occurred when PLP bound to the apoGAD to form the holoGAD. Chemical modifications of the GAD by some selected reagents indicated that histidine residue(s) might be involved in the enzymatic functions, but were not essential for the enzyme activity. The study also suggested there was one arginine residue in the GAD active site, and most likely at the substrate-binding site.     

米胚芽中胰脂肪酶抑制剂的分离纯化

由米胚芽中提取的胰脂肪酶抑制剂经鉴定主要为蛋白质.通过硫酸铵分级沉淀(40%～80%)、凝胶层析(Sephadex G-75)对米胚芽水溶物进行分离纯化.所得的洗脱峰I和洗脱峰Ⅱ的组分进行高效液相色谱分析,测定了胰脂肪酶活性抑制率较高的组分的分子量,分别为125KD和21KD.     

米胚芽中脂肪酶抑制剂提取工艺及其性质的研究

主要研究了脱脂米胚芽中脂肪酶抑制剂的提取工艺及性质。通过正交实验确定了最佳的提取工艺参数:料水比1∶15,提取温度50℃,提取pH7.0,提取时间3h,此工艺能使脱脂米胚芽胰脂肪酶抑制剂的抑酶活性达43.81%未纯化。同时,米胚芽中脂肪酶抑制剂的活性成分分析表明,其主要为蛋白质。     

超声波处理对发芽糙米GABA积累及抗氧化能力影响的研究

以有机糙米为材料,利用不同超声波处理时长、频率在糙米萌发不同阶段进行处理,探讨促进发芽糙米中抗氧化成分积累的较优超声波处理条件。结果发现,在发芽前期(0~16 h)进行超声波处理会显著促进GABA的积累,优于在发芽中后期(16~32 h)累积效果、且在相同时长处理情况下,低频率超声波处理对GABA含量的积累优于高频处理。同时在发芽期间进行超声波处理会提高多酚提取量,处理过的发芽糙米清除羟基自由基效果是普通发芽糙米的1.3倍,超氧阴离子清除能力比前者高10.34%。      

超声波处理对发芽糙米GABA积累及抗氧化能力影响的研究

以有机糙米为材料,利用不同超声波处理时长、频率在糙米萌发不同阶段进行处理,探讨促进发芽糙米中抗氧化成分积累的较优超声波处理条件。结果发现,在发芽前期(0~16 h)进行超声波处理会显著促进GABA的积累,优于在发芽中后期(16~32 h)累积效果、且在相同时长处理情况下,低频率超声波处理对GABA含量的积累优于高频处理。同时在发芽期间进行超声波处理会提高多酚提取量,处理过的发芽糙米清除羟基自由基效果是普通发芽糙米的1.3倍,超氧阴离子清除能力比前者高10.34%。     

米胚芽中胰脂肪酶抑制剂的抑制机理研究

由米胚芽中提取的胰脂肪酶抑制剂主要为蛋白质,研究了不同因素对抑酶活性的影响,并初步探讨了从米胚芽中提取的脂肪酶抑制剂对胰脂肪酶的抑制机理抑制剂不直接与酶分子作用,而是间接改变底物乳化来阻碍底物-酶结合达到抑制作用。通过试验测定了抑制常数Ki=9.8×10-2mg/mL。从Dixon图和Lineweaver-Burk图的特征,表明该抑制剂对胰脂肪酶的抑制呈非竞争性抑制。     

膜分离提纯发酵液中GABA的过程模型和优化

探讨了用超滤分离γ-氨基丁酸（GABA）发酵液中的工程问题。以实验数据为基础,建立了间歇和连续操作时的模型。在两种操作方式下,循环流速对通量均有重要的影响。连续操作时阻力模型能较好地与实验数据吻合,总阻力由三部分组成:分别代表膜的阻力、垢层阻力和浓差极化层的阻力。用常规的工程处理方法分别建立了间歇稀释过滤和连续稀释过滤的数学模型,2次间歇稀释过滤能达到95%的总回收率,是较理想的效果。      

原料米对广东客家黄酒发酵及产γ-氨基丁酸的影响

该文研究不同原料米(糯米、粳米、籼米)对客家黄酒发酵过程中总糖、总酸、氨基酸态氮、γ-氨基丁酸(GABA)含量及谷氨酸脱羧酶(GAD酶)活性的影响。结果表明,在总糖、总酸、氨基酸态氮指标方面,糯米、粳米、籼米都适合酿制客家黄酒,但糯米黄酒、粳米黄酒总糖、总酸和氨基酸态氮含量较高;发酵过程中,GABA含量糯米黄酒最高,粳米黄酒次之,籼米黄酒最低;贮藏一个月后,糯米黄酒GABA含量达到260.45 mg/L,分别为粳米黄酒、籼米黄酒的1.13、1.44倍。糯米、粳米黄酒的GAD酶活性较大且两者接近,而籼米GAD酶活性较小,与糯米、粳米相差较大。综上所述,对比三种原料米,糯米最适合发酵客家黄酒及产GABA,粳米次之,籼米较不利。     

Protective effect of resveratrol against pseudorabies virus-induced reproductive failure in a mouse model

Resveratrol (RES), a natural polyphenol that is abundant in grapes, exerts anti-inflammatory, anti-oxidative, and antiviral bioactive effects. Protective effects of RES against pseudorabies virus (PrV)- induced reproductive failure were investigated in a mice model. Injection of PrV partially induced stillbirth and abortion, and caused poor growth of progeny. Treatment with RES attenuated the reproductive failure induced by the virus with recovery of the serum progesterone level. RES improved the growth performance of newborn mice. RES can attenuate the reproductive failure induced by PrV in mice.     

米胚蛋白组分的提取及功能性质研究

采用Osborne的方法,从米胚中提取清蛋白、球蛋白、醇溶蛋白和谷蛋白,4种蛋白中谷蛋白的含量最高,占72.69%,其余3种蛋白的含量相差不大;考察4种蛋白的溶解性得出,在pH5下4种蛋白的溶解性最低,随着pH的增大或减小,溶解性逐渐增加,且清蛋白和球蛋白的溶解性较醇溶蛋白和谷蛋白高;在pH11、0.1mol/L NaCl浓度、1mg/mL蛋白浓度下,加入3mL大豆油,4种蛋白的乳化活性及乳化稳定性均达到最大值。     

五味子藤茎木脂素对小鼠镇静催眠及抗焦虑作用研究

目的:研究五味子藤茎木脂素（Schisandra chinensis vine stem lignans,SSL）的镇静、抗焦虑及催眠作用并初步探讨其作用机制。方法:将150只ICR雄性小鼠平均随机分为5组,分别为空白对照组、SSL低、中、高剂量组和地西泮阳性对照组。采用灌胃给药,每次0.1 mL/10 g,每天一次,连续7 d。应用小鼠自主活动实验观察镇静效果;应用高架十字迷宫、高架零迷宫实验观察抗焦虑作用;通过戊巴比妥钠协同睡眠实验观察催眠作用;用酶联免疫吸附法检测小鼠脑组织中γ-氨基丁酸（γ-aminobutyric acid, GABA）、谷氨酸（glutamate, Glu）含量。应用Western blot方法检测小鼠脑组织中GABA_Aα1表达水平。结果:与对照组比,各剂量SSL显著减少小鼠站立次数和活动次数（P<0.01）;中、高剂量SSL显著增加小鼠进入开放臂次数（open arm entry, OE）,开放臂停留时间（open arm time, OT）和开放探头次数（open arm probe, OP）（P<0.05或P<0.01）;各剂量SSL均增加阈下剂量戊巴比妥钠诱导小鼠睡眠只数,显著延长阈剂量戊巴比妥钠诱导的小鼠睡眠时间（P<0.05或P<0.01）,缩短小鼠睡眠潜伏期（P<0.01）;各剂量SSL组小鼠脑组织中GABA含量极显著增加（P<0.01）,而中、高剂量SSL组小鼠脑组织中Glu含量极显著降低（P<0.01）,GABA/Glu极显著增加（P<0.01）。高剂量SSL组小鼠脑组织中GABA_Aα1蛋白表达极显著增加（P<0.01）。结论:SSL对小鼠具有镇静、催眠及抗焦虑作用,其机制可能与其调节其脑组织中GABA及Glu含量及GABA_Aα1受体表达水平有关。     

The effect of fermented rice germ extracts on the inhibition of glucose uptake in the gastrointestinal tract in vitro and in vivo

Food Science and Biotechnology - This study aimed to evaluate the effect of fermented rice germ extracts on the inhibition of glucose uptake in the gastrointestinal (GI) tract. Samples were...     

Processing of commercial rice bran for the production of fat and nutraceutical rich rice brokens,rice germ and pure bran

Successive sieving of commercial rice bran on the basis of particle size was performed and different fractions were obtained of which the rice brokens and rice germ fractions contained fat 33 g/kg and 207 g/kg, oryzanol 400 mg/kg and 874 mg/kg, total tocols (tocopherols and tocotrienols) 16.5 mg/kg and 87.8 mg/kg, and total phytosterols 128.7 mg/kg and 769.6 mg/kg respectively, thus indicating that these fractions are a good source of fat and nutraceuticals. The residual fat (6 g/kg) from commercial defatted rice bran contained high oryzanol content of 4.8 g/100 g, indicating that commercial defatted rice bran as a source of oryzanol. The fat from pure rice bran fraction of commercial rice bran decreased in the color value (48.5%) indicating that sieving could also improve the quality of crude rice bran oils.     

Milk basic protein supplementation exerts an anti-inflammatory effect in a food-allergic enteropathy model mouse

To examine novel functions of milk basic protein (MBP) in T-cell-related inflammatory diseases, such as autoimmune diseases and allergies, we evaluated the effects of MBP on the causative responses of ovalbumin (OVA)-specific T cells in a food-allergic enteropathy model, OVA23–3 mice, which express an OVA-specific T-cell receptor gene. The OVA-specific CD4⁺ T cells of the mesenteric lymph nodes (MLN) from OVA23–3 mice were cultured with CD11c⁺ dendritic cells of MLN from BALB/cA mice in the absence or presence of MBP following stimulation with OVA; then the levels of CD69 expression and the levels of cytokine production by CD4⁺ T cells were measured to evaluate activation. The effects of MBP supplementation of OVA 23–3 mice were assessed by feeding a diet containing OVA (OVA diet) with or without MBP for 28 d. Intestinal inflammation, together with activation and cytokine production of CD4⁺ T cells by MLN, as well as femoral bone mineral density, were measured. In in vitro culture, MBP inhibited excess activation and IL-4 production by CD4⁺ T cells. The supplementation of MBP to the OVA diet attenuated OVA-specific IgE production in OVA-diet-fed OVA23–3 mice and slightly resolved developing enteropathy caused by excess IL-4 production by CD4⁺ T cells. Feeding OVA diet to OVA23–3 mice exhibited bone loss accompanied with enteropathy, whereas MBP supplementation prevented bone loss and increased osteoprotegerin, an osteoclastogenesis inhibitory factor, in the mice. The inhibition of T-cell-activation in both MLN and bone marrow by MBP supplementation may help prevent increased IgE levels caused by excessive IL-4 production and bone loss accompanied by enteropathy. Our findings show that MBP may help attenuate both T-cell-related inflammation and bone loss.     

留胚米的营养、生产及食用方法

回顾了留胚米的发展简史,着重介绍了留胚米的营养特性、生产方法、包装要求及食用时的注意事项;就如何加快留胚米的发展提出了几点建议,以供业内人士参考.