低次烟叶中蛋白质提取工艺优化及氨基酸分析研究

为了充分综合利用低次烟叶蛋白资源,采用碱溶酸沉法对低次烟叶中蛋白质的提取工艺进行了研究,并利用高效液相色谱系统对其氨基酸组成进行了分析。研究结果表明：烟叶磨浆的最佳工艺为固液比1∶17,提取温度60℃,提取液pH值8.0,磨浆两次;烟叶蛋白碱溶最佳工艺为温度60℃,pH8.0,时间60 min,搅拌条件下碱溶提取3次;烟叶蛋白酸沉工艺中,在pH3.0,4℃下静置8 h效果最佳,烟叶蛋白酸沉提取率最高为86.71％;烟叶蛋白的氨基酸分析结果显示,烟叶蛋白的氨基酸组成种类齐全,必需氨基酸含量较高,氨基酸分数较高,表明低次烟叶蛋白是一类比较优质的蛋白质资源。     

冷榨菜籽蛋白的碱性电解水提取工艺及其结构性能表征

为探寻一种油料蛋白提取方法,该研究以双低冷榨菜籽饼为原料,碱性电解水为溶剂,通过单因素与响应面试验确定了碱性电解水提取冷榨菜籽饼分离蛋白（Alkaline electrolyzed water extracted Rapeseed Protein,ARP）的优化条件,并与相同条件下碱溶酸沉法提取菜籽分离蛋白（Ultrapure water extracted Rapeseed Protein,URP）的结果进行对比。结果表明: 提取工艺各环节因素对菜籽蛋白提取率影响的主次顺序分别为：碱性电解水pH值、温度、料液比、时间;提取优化工艺条件为温度45 ℃、碱性电解水pH值11.5、料液比1:10 g/mL和提取时间60 min,蛋白质提取率为59.34%。与相同条件下碱溶酸沉法相比,碱性电解水提取的菜籽分离蛋白游离巯基和二硫键含量高、表面疏水性强、粒径小、ζ电位绝对值大,同时其提取率、溶解性、持油性、乳化性和起泡性均显著得到改善（P＜0.05）;此外,ARP内源荧光光谱强度更高,二级结构更有序。由此可知,该研究结果为碱性电解水提取冷榨菜籽饼蛋白提供参考,不仅提高了提取率,而且最大程度地减少了对菜籽蛋白结构和功能特性的破坏。     

采用碱提酸沉与淀粉酶解复合法制备小麦胚芽蛋白的试验研究

为了改善小麦胚芽蛋白质的提取效果，建立了“碱提+α-淀粉酶水解+酸沉淀”分离小麦胚芽蛋白的新方法。与传统的碱溶酸沉淀法相比，该方法明显地提高了小麦胚芽蛋白的纯度和得率，其数值分别达到94.5%和81.36%。用高效毛细管电泳定性测定了小麦胚芽蛋白的纯度，结果进一步证明该方法得到的小麦胚芽蛋白纯度较高。用SDS-PAGE电泳测定了小麦胚芽蛋白的分子量，结果表明小麦胚芽蛋白的分子量主要由35kDa和55kDa组成。     

不同制备方法对花生蛋白功能性质的影响(简报)

该文研究了不同制备方法对花生浓缩蛋白功能性的影响,以期为不同制备方法制得的花生浓缩蛋白在食品中的广泛应用提供理论支持。以脱脂花生蛋白粉（DPF）为原料,通过等电沉淀、乙醇浸提、等电沉淀与乙醇浸提相结合及碱溶酸沉技术制备花生浓缩蛋白,并分别测定其蛋白功能性（蛋白溶解性、吸水性、持油性、乳化能力及乳化稳定性、起泡能力及泡沫稳定性、凝胶性质）。结果表明：碱溶酸沉技术制备的蛋白溶解性、起泡能力及泡沫稳定性最好;而乙醇浸提制备的蛋白吸水性、持油性和凝胶性质要显著性的高于其他方法制备的蛋白产品的;不同方法制备的花生浓缩蛋白的乳化稳定性均明显低于对照（DPF）,尤以碱溶酸沉技术制备的最低。因此可知,乙醇浸提制备的蛋白适用于对吸水性、持油性和凝胶性质要求较高的食品中;碱溶酸沉技术制备的蛋白适用于对起泡能力要求较高的食品中。     

酶法预处理对花生蛋白提取效果的影响(简报)

该文首次提出了以低温预榨花生饼为原料,经Viscozyme酶预处理后再碱溶酸沉提取蛋白质的新工艺,研究了酶处理条件对花生蛋白提取率的影响,通过中心组合试验设计和响应面分析优化的试验结果是：当花生饼浓度为15%,温度为45℃,酶用量1.26%,pH值为4.3,反应时间为134 min时,蛋白提取率为79.38%,而未用酶处理者蛋白提取率为58.35%,表明酶法预处理花生饼可以显著改善花生蛋白的提取效果。     

黑水虻幼虫蛋白质的制备及体外抗氧化活性

本文主要研究黑水虻幼虫蛋白质的制备及其体外抗氧化活性。以黑水虻幼虫为原料,采用碱提酸沉法提取黑水虻幼虫蛋白质,并于等电点沉淀,沉淀复溶后再浓缩、透析、冻干。分别测定了其总还原力,超氧阴离子自由基清除活性、羟基自由基清除活性、DPPH自由基清除活性、ABTS自由基清除活性、金属离子螯合能力及脂质体系中抗氧化能力,并将其体外抗氧化能力与维生素C(测定金属离子螯合能力时与EDTA)和卵清白蛋白进行比较。结果显示:BSFLP的等电点在4.8左右,并且该法所提蛋白纯度较高,表明利用碱提酸沉法对黑水虻幼虫进行蛋白的提取的方法可行。BSFLP的总还原力约是VC的0.013倍,是OVA的1.319倍;BSFLP的超氧阴离子自由基清除活性强于OVA,而弱于VC;其清除羟基自由基、清除DPPH自由基、清除ABTS自由基、螯合亚铁离子、亚油酸体系中抑制过氧化的IC50分别为2.577、3.965、0.228、0.876、5.050 mg·m L-1,也均介于VC(或EDTA)和OVA之间,说明BSFLP具有较高的体外抗氧化活性。本文为黑水虻的进一步研究与综合利用及抗氧化功能蛋白食品的研发提供了一定的依据。     

复合多糖酶Viscozyme L在制备燕麦麸分离蛋白中的应用

以脱脂燕麦麸为原料,通过碱溶酸沉工艺制备燕麦麸分离蛋白。在传统工艺基础上增加了复合多糖酶Viscozyme L预处理过程,并通过响应面回归分析方法对预处理条件进行了优化,确定最优的工艺参数为：加酶量3.02 FBG/g,pH 4.6,温度44℃,预处理时间2.8 h。与传统工艺相比,燕麦麸蛋白的提取率由6.6%提高到56.2％,分离蛋白制品纯度由72.9%提高到81.7％。     

蚕豆蛋白酶法改性增溶工艺优化及功能性研究

为了拓宽蚕豆蛋白在食品中的应用,解决传统工业方法制备的蚕豆蛋白溶解性差的问题,本文以传统的碱溶酸沉法提取的蚕豆蛋白为原料,采用限制性酶法对其进行增溶改性工艺优化,并对改性后的蚕豆蛋白的功能性质进行了研究。结果表明:风味蛋白酶是提高蚕豆蛋白溶解性的适宜用酶,酶解改性的最佳工艺条件为:料液比1∶14、酶加量(ES)0.1%、温度58℃、pH值7.5、酶解时间30 min,此条件下蚕豆蛋白的溶解性达到99.73%。改性后的蚕豆蛋白的溶解性、起泡性、乳化性及乳化稳定性在酸性和碱性条件下均显著提高,泡沫稳定性在碱性条件下显著提高,持水力在pH值为2~12的范围内显著下降。     

含醇溶蛋白小麦回生抗性直支链淀粉性质分析

为研究含醇溶蛋白小麦回生抗性直支链淀粉性质,该文采用醇溶法从小麦粉中提取醇溶蛋白,采用回生-酶解法分离得到小麦直、支链淀粉。通过可见光谱、红外光谱、X-射线衍射、差热扫描等方法分析研究醇溶蛋白对小麦直、支链淀粉回生的影响。结果表明,在凝胶化及回生过程中醇溶蛋白与淀粉相互作用,导致淀粉回生率增加。红外光谱研究表明,直链淀粉与醇溶蛋白在高压糊化后干燥或回生的条件下,醇溶蛋白的酰胺Ⅱ键伸缩振动从1 546 cm~(-1)降低至1 539 cm~(-1),即直链淀粉与醇溶蛋白通过氢键结合。X-射线衍射图谱显示在2θ衍射角为17°,19°,22°等的衍射峰没有发生明显变化,表明添加醇溶蛋白后,直、支链淀粉的晶型未发生明显改变。DSC结果显示直链淀粉与醇溶蛋白之间的氢键是在共同回生过程中产生的,样品中多晶结构和双螺旋结构共存。研究结果表明,淀粉中空间位阻小的6位碳原子上的羟基与醇溶蛋白中的脯氨酸和谷氨酰胺通过氢键结合,这种类型的氢键阻碍了α淀粉酶对淀粉的解离,即醇溶蛋白通过与淀粉形成新型氢键而促进了淀粉的回生。该研究提供了一种提高小麦淀粉的回生率的新技术,为进一步深入研究醇溶蛋白促进淀粉回生的机理提供理论支撑。     

响应面优化花生叶可溶性蛋白提取工艺及抗氧化活性分析

为确定花生叶可溶性蛋白提取最佳工艺,本试验以花生叶为材料,利用碱溶酸沉法提取花生叶可溶性蛋白,分析浸提pH值、料液比及提取时间对蛋白提取率的影响;在单因素试验的基础上,采用Box-Behnken响应面分析法(RSM)优化花生叶可溶性蛋白提取条件,并对所得蛋白进行抗氧化活性分析。结果表明,各影响因素主次顺序为浸提pH值>提取时间>料液比,最佳提取条件为料液比1∶20(w/v)、提取时间40 min、浸提pH值 9.0,以此条件建立的响应面试验回归模型拟合性好(R²=0.992 7),花生叶可溶性蛋白理论提取率为52.8%,实际提取率为54.2%,纯度为63.8%。花生叶可溶性蛋白具有较强的DPPH自由基、超氧阴离子自由基清除能力,以及较好的还原能力。本研究结果为花生叶的开发利用及花生产业链的延长提供了一定的数据支持。     

Quantitative analysis of polymeric procyanidins (Tannins) from grape (Vitis vinifera) seeds by reverse phase high-performance liquid chromatography

A reverse phase C(18) HPLC method with potential for high automated throughput has been developed for the quantitative analysis of polymeric procyanidins (tannins) in grape seed extracts. Chromatography gave rise to 13 distinct UV-absorbing peaks with good baseline separation. The UV-absorbing peak eluting last is distinct and therefore easily quantified. Biochemical analyses including ultrafiltration, protein precipitation, and Sephadex LH20 chromatography combined with electrospray mass spectrometric analyses establish that this peak predominantly contains polymeric procyanidins. The polymers, which appear to be galloylated to various degrees and seem to fragment in a characteristic manner during electrospray mass spectrometry, are well separated from catechins and procyanidin oligomers of up to 4 units. The recovery of polymeric grape seed tannins with this HPLC method was 86%, which is similar to the 89% recovery achieved with commercial quebracho tannins. The concentration of tannins in seeds from ripe Vitis vinifera cv. Shiraz grapes ranged from 1360 to 2830 mg/kg of berries.     

Evolution of the Concentration of Inorganic Ions during the Initial Stages of Precipitation Events

Ion concentrations in relatively low-intensity precipitation were measured in southern Indiana, USA and are presented as a function of their temporal evolution during individual precipitation events with a specific focus on the first 30 min of those events. These data indicate that during individual rain events potassium concentrations in precipitation may decline by up to 70%–80% in the first 30 min of the event. The other ions exhibited less rapid concentration declines during this event which are in rank order (highest to lowest); sodium, chloride, magnesium, nitrate, calcium, sulfate and ammonium. There is some evidence that the initial declines for precipitation accumulations up to 2 mm in the concentrationof chloride, calcium and sulfate in precipitation more closely approximate a power-law dependency on precipitation depth than the commonly applied exponential form which, if confirmed, may have implications for efforts to correct flux networks for under-sampling due to delay in sample collection. Scavenging coefficients (b) derived using an exponential relationship over entire events for sodium, chloride, nitrate, calcium, sulfate and ammonium indicate highest values for sodium and lowest for ammonium, but the uncertainty bounds on ion-specific values of b are sufficiently large that they are statistically indistinguishable.     

Separation and characterization of acetyl and non-acetyl hemicelluloses of Arundo donax by ammonium sulfate precipitation

Delignified Arundo donax was sequentially extracted with DMSO, saturated barium hydroxide, and 1.0 M aqueous NaOH solution. The yields of the soluble fractions were 10.2, 6.7, and 10.0% (w/w), respectively, of the dry Arundo donax materials. The DMSO-, Ba(OH)(2)- and NaOH-soluble hemicellulosic fractions were further fractionated into two subfractions by gradient 50% and 80% saturation ammonium sulfate precipitation, respectively. Monosaccharide, molecular weight, FT-IR, and 1D ((1)H and (13)C) and 2D (HSQC) NMR analysis revealed the differences in structural characteristics and physicochemical properties among the subfractions. The subfractions precipitated with 50% saturation ammonium sulfate had lower arabinose/xylose and glucuronic acid/xylose ratios but had higher molecular weight than those of the subfractions precipitated by 80% saturation ammonium sulfate. FT-IR and NMR analysis revealed that the highly acetylated DMSO-soluble hemicellulosic subfraction (H(D50)) could be precipitated with a relatively lower concentration of 50% saturated ammonium sulfate, and thus the gradient ammonium sulfate precipitation technique could discriminate acetyl and non-acetyl hemicelluloses. It was found that the DMSO-soluble subfraction H(D50) precipitated by 50% saturated ammonium sulfate mainly consisted of poorly substituted O-acetyl arabino-4-O-methylglucurono xylan with terminal units of arabinose linked on position 3 of xylose, 4-O-methylglucuronic acid residues linked on position 2 of the xylan bone, and the acetyl groups (degree of acetylation, 37%) linked on position 2 or 3. The DMSO-soluble subfraction H(D80) precipitated by 80% saturated ammonium sulfate was mainly composed of highly substituted arabino-4-O-methylglucurono xylan and β-d-glucan.     

Pelleting or Priming Seed with Calcium Improves Groundnut Seedling Survival in Acid Soils

A growth chamber experiment and a field experiment were conducted to investigate the effects of pelleting or priming groundnut seed with calcium (Ca), either as calcium sulfate (CaSO₄), calcium chloride (CaCl₂), calcium nitrate [Ca(NO₃)₂], calcium carbonate (CaCO₃) or Calcimax on growth of groundnut seedlings in acid soils. In the growth chamber experiment, Ca-treated and non-treated groundnut seeds were planted in acid-washed sand and watered with a dilute nutrient solution of pH 4.0 or 5.5. In the field experiment, the seeds were planted in an acid sand clay loam of pH [potassium chloride (KCl)] 4.8. Generally, pelleting or priming the seed with a Ca compound significantly reduced seedling mortality. Also, pelleting groundnut seed with Ca enhanced plant growth. An additional effect of priming was earlier emergence. The most effective Ca compound was CaSO₄ among the priming treatments, whereas CaCO₃ was the most effective among the pelleting treatments to reduce seedling mortality.     

Purification and some properties of an Aspergillus niger beta-apiosidase from an enzyme preparation hydrolyzing aroma precursors.

A beta-apiosidase was isolated and purified to electrophoretic homogeneity from an enzyme preparation, Klerzyme 200, through ammonium sulfate precipitation, gel filtration chromatography, ion-exchange chromatography, and HPLC on ion-exchange and size exclusion columns. The purification of the enzyme was aided by the synthesis of 4-methylumbelliferyl beta-D-apiofuranoside for the specific detection of activity on electrophoresis gels. The molecular mass estimated by SDS-PAGE was 120 kDa. The optimum activity of the beta-apiosidase was found at pH 5 and 40 degrees C. The K(m) and V(max) for p-nitrophenyl beta-D-apiofuranoside were 4.2 mM and 2460 nkat/mg of protein, respectively. The enzyme was not inhibited by glucose and ethanol. This enzyme hydrolyzed the intersugar linkages of apiofuranosylglucosides, aroma precursors from grape.     

Partial Purification of a Water-Extractable Rye (Secale cereale) Protein Capable of Improving the Quality of Wheat Bread

Rye water-soluble extracts contain a protein fraction that, when added at low concentrations to a straight-dough breadmaking recipe, significantly increased bread volume. Enrichment of the active component is possible by anion-exchange fractionation with diethylaminoethyl-cellulose (DEAE), by ammonium sulfate precipitation, or by using rye bran or shorts milling fractions as the starting material. The active material was not bound to DEAE-cellulose. With ammonium sulfate precipitation, the fractions obtained at 30, 40, and 50% saturation were active in straightdough baking experiments. Iso-electric focusing revealed that fractions active in breadmaking invariably contained alkaline protein fractions (pI > 7.5). Inactivation of enzyme material by boiling the water-soluble extract from rye destroyed all breadmaking activity. The activity of the bread improver was additive to that of potassium bromate but not to that of ascorbic acid. It was not counteracted by catalase, showing that it does not work by a mechanism involving the production of hydrogen peroxide. The extract was not able to overcome the detrimental effect on bread quality resulting from mixing dough in a nitrogen atmosphere.     

Overexpression, purification, and in vitro refolding of the 11S globulin from amaranth seed in Escherichia coli

An amarantin 11S globulin cDNA encoding one of the most important storage proteins of amaranth seeds, with a high content of essential amino acids, was expressed in Escherichia coli. A good level of expression of recombinant amarantin with a molecular weight of 59 kDa was obtained. The recombinant protein was extracted by ammonium sulfate precipitation and purified to homogeneity using ion-exchange chromatography and reversed phase high-performance liquid chromatography. The expressed protein exhibited electrophoretic, immunochemical, and surface hydrophobicity properties similar to those of native amarantin from amaranth seed. Also, the recombinant protein was refolded in vitro using two different methods.     

Phenolics from commercialized grape extracts prevent early atherosclerotic lesions in hamsters by mechanisms other than antioxidant effect

The aim of this study was to evaluate the antiatherosclerotic effect of commercially available phenolic-rich extracts from grape seeds (ExGrape seeds, EGS; grape seed extract, GSE) and marc (ExGrape total, EGT) in cholesterol-fed hamsters and to investigate possible operating mechanisms. These extracts fed at a moderate dose mimicking two glasses of red wine per meal reduced plasma cholesterol (-11% on average) but did not affect plasma antioxidant capacity of hamsters. The extracts prevented the development of aortic atherosclerosis by 68% (EGS), 63% (EGT), and 34% (GSE). Elsewhere, in an ex vivo experiment using rat aortic rings, EGS (7 microg/mL) induced 77% endothelium-dependent relaxation, whereas EGT and GSE (30 microg/mL) induced 84 and 72%, respectively. These results suggests that phenolic extracts from grape seeds and marc are beneficial in inhibiting atherosclerosis by indirect mechanism(s).     

Sequential fractionation of grape seeds into oils, polyphenols, and procyanidins via a single system employing CO2-based fluids

Pure supercritical CO(2) was used to remove >95% of the oil from the grape seeds. Subcritical CO(2) modified with methanol was used for the extraction of monomeric polyphenols, whereas pure methanol was used for the extraction of polyphenolic dimers/trimers and procyanidins from grape seed. At optimum conditions, 40% methanol-modified CO(2) removed >79% of catechin and epicatechin from the grape seed. This extract was light yellow in color, and no higher molecular weight procyanidins were detected. Extraction of the same sample after removal of the oils and polyphenols, but now under enhanced solvent extraction conditions using methanol as a solvent, provided a dark red solution shown via electrospray ionization HPLC-MS to contain a relatively high concentration of procyanidins. The uniqueness of the study is attested to by the use of CO(2)-based fluids and the employment of a single instrumental extraction system.     

Effect of Harvest Timing on Yield and Mineral Nutritional Value of Kabuli Type Chickpea Seeds

Chickpea (Cicer arietinum L.) seeds are a good source of protein and mineral nutrients. However, there is no information regarding harvest timing on yield and mineral composition of chickpea seeds. The effect of harvest timing on seed yield, some yield components and mineral nutritional value of seeds of field grown chickpea plants in two different sites were studied. The mineral composition of chickpea straw depending on harvest timing was also evaluated in order to explain the variations of seed mineral concentrations in sink-source relationship manner. Yield and mineral nutritional value of chickpea were significantly affected by harvest timing. When compared to the seed yield at optimal harvest time, seed yield was 18% and 9% lower in the early harvest and 27% and 31% in the late harvest in Site 1 and Site 2, respectively. Late harvest of chickpea crops resulted in significant pod dropping and shattering. Generally, protein, phosphorus (P), calcium (Ca), magnesium (Mg), copper (Cu), zinc (Zn), and manganese (Mn) concentrations of the seeds in optimal harvest were found to be greater than in early and late harvested plants. Harvest timing also results in significant variations in straw mineral nutrient concentrations of the plants. As the results of this study, it was concluded that the harvest timing is critical for yield losses and mineral nutritional value of chickpea seeds.