食用玉米黄色素不同溶剂提取方法的比较研究

用研磨和浸提法处理玉米淀粉饼渣,蒸馏色素浸提混合液,回收提取液,用不同比例的混合试剂提取以选择最佳方法。结果发现以石油醚∶乙醇＝３∶２和丙酮∶乙醇＝３∶２提取液效果最佳,色素产率高,色质好,提取溶剂回收率升高。     

固态发酵玉米淀粉渣生产蛋白饲料的研究

本文对同化淀粉能力强的糖化酵母菌Ｙ９６０１株在固态发酵玉米淀粉渣生产蛋白饲料中的应用进行了研究,在合适的发酵条件下,３０℃发酵３６ｈ,发酵产物（干基）酵母达到７．４５×１０＾９个／ｇ,粗蛋白从２５．５％提高到３８．２％,增加１２．７％,粗蛋白增幅为４９．８％。     

百合鳞茎淀粉磷酸化酶提取条件的优化

为深入研究百合鳞茎淀粉磷酸化酶（SP）的性质及其在鳞茎淀粉代谢中的生理作用;本试验确定了兰州百合鳞茎内SP的最佳提取和测定条件;并对部分酶学性质进行了初步探索。结果表明:SP的最适提取缓冲液为pH5.8的琥珀酸缓冲液;最佳反应体系为以25 mmol·L^-1的Glc-1-P为底物;在30℃条件下反应10 min。在pH5~6范围内;SP活性最高;百合鳞茎的SP不易保存且不耐热;4℃条件下保存12 h;酶活力最高残留50%;40℃条件下保存30 min后;SP活力几乎完全丧失。     

甘薯凝集素的提取及性质研究

抗蔓割病甘薯的叶片组织浸取液,经硫酸铵分级沉淀,甲壳素柱层析及葡聚糖凝胶过滤得到一种在PAGE或SDS－PAGE上均呈现单一蛋白带的甘薯凝集素。该凝集素没有血型专一性及被测动物红细胞专一性,其凝集活性可被N－乙酰葡萄糖胺或岩藻糖所抑制。甘薯凝集素在75℃加热10min,即丧失全部凝集活性,其凝集活性依赖于Ca^2 和Mg^2 ,Mn^2 则无作用。经Sephadex G-100和SDS－PAGE测定,凝集素相对分子质量为63000,中性糖含量为6.21%,该凝集素对蔓割病菌有抑制作用,是一种酸性糖蛋白。     

甘薯品种F3282凝集素的提取及性质研究

甘薯品种Ｆ３２８２的浸取液,经硫酸铵分级,甲壳素层析后,再经分子筛过滤,获得在ＰＡＧＥ上呈现单一蛋白质带的甘薯凝集素（Ｉｐｏｍｏｅａ Ｂａｔａｔａｓ Ｌｅｃｔｉｎ,ＩＢＬ）。ＩＢＬ对鸽、兔、人血等红细胞均有凝集作用,其中对鸽血的凝集活性最高,最低凝集浓度为０．０５μｇ／ｍｌ。ＩＢＬ除凝集红细胞外,还可凝集小鼠脾细胞和肿瘤细胞;其对热相当稳定,９０℃加热１０ｍｉｎ,仍有部分活性;ＩＢＬ对酸处理较碱处理稳定,但可被阿拉伯糖或乳糖等解除凝集活性。ＩＢＬ的中性糖含量为５．４％。     

散囊菌黄色素的提取及稳定性研究

为寻找优质黄色素生产资源及研究其在不同条件下的稳定性,以冠突散囊菌（Eurotium cristatum）为材料,利用有机溶剂辅助超声波破碎等方法从固体平板和液体培养的菌丝体中提取黄色素,并分别研究了光、温度等理化因子对该色素的影响。结果表明,采用有机溶剂辅助超声波等方法成功提取出黄色素;该色素耐受日光灯光、室内散射光,不耐阳光和紫外光;耐酸,不耐碱;对温度敏感。各种金属离子对该色素有不同程度的影响;磷酸的破坏性显著;H2O2、NaHSO3对该色素有较强的破坏力;柠檬酸有一定的破坏作用;同等条件下,苯甲酸钠的破坏大于山梨酸钾;EDTA-Na2和Vc有一定的护色作用;糖类、NaCl、草酸和乳酸几乎无影响。     

茯苓中多糖的提取及含量测定

采用水煎煮、稀碱浸提茯苓中的多糖,通过正交试验优选工艺条件。结果表明,稀碱浸提茯苓中的多糖的工艺较为合理,其操作简单,提取时间短,收率较高．为测定提取液中的多糖含量,以苯酚—硫酸法,制得有色糖醛衍生物,用分光光度法,在490nm波长处测定吸光度,回归方程线性关系好。方法简单易行、稳定、快速。     

柚子皮中果胶提取工艺的优化及其理化性质测定

以新鲜柚子皮为原料,将柚子皮处理成干燥的粉末,采用酸水解乙醇沉淀法提取果胶。在考察料液比、提取酸度、提取温度和提取时间等4个单因素提取效果的基础上,进行了L9（34）正交试验。结果表明,从柚子皮中提取果胶的最佳工艺条件为：料液比为1∶90、提取酸度为pH=2、提取温度为90℃、提取时间为60min。在上述条件下,制得的果胶成品为白色,产率为24.87%。在对果胶的提取工艺进行优化的同时,也对所得的果胶成品进行理化性质的测定。     

不同类型玉米发育籽粒中淀粉合成及相关酶活性比较

以普通玉米、爆裂玉米、甜玉米和糯玉米为试材,分析和比较不同类型的玉米品种之间籽粒发育过程中淀粉合成及相关酶活性的变化。结果表明,淀粉合成速率和蔗糖合成酶(SS)、可溶性淀粉合成酶(SSS)、束缚态淀粉合成酶(GBSS)、淀粉分支酶(SBE)、去分支酶(DBE)活性都呈单峰曲线变化。30～40 DAP,普通玉米的SS活性显著高于其他3种类型;类型间平均和最大SSS活性水平的顺序为普通玉米>糯玉米>爆裂玉米>甜玉米;30～40 DAP,普通玉米GBSS活性最高,糯玉米GBSS活性最低;20～40 DAP,糯玉米SBE活性最高;甜玉米的DBE活性很低,并且在40 DAP完全丧失。淀粉合成速率与SS、SSS、GBSS和SBE活性相关程度比较高,与腺苷二磷酸葡萄糖焦磷酸化酶(AGP酶)和DBE活性相关不显著。推测AGP酶虽然为淀粉合成提供直接前体ADPG,但可能SS活性过低致使其限速作用比AGP酶的还强,AGP酶潜在的限速作用无法表现,SS成为玉米籽粒淀粉合成的限速因子。GBSS对直链淀粉积累起重要的促进作用;SSS和SBE对支链淀粉积累起重要的促进作用。     

响应面法优化混合酶-超声波联合提取栀子黄色素工艺研究

以栀子为原料提取栀子黄色素,将混合酶-超声波技术相结合,对栀子黄色素进行了提取的研究。为了获得提取栀子黄色素最佳工艺条件,采用响应面法组合设计试验方法,建立了酶的用量、提取温度、提取时间之间关系。结果表明,最佳工艺条件为酶的用量4.33%,提取温度61.84℃,提取时间65.06 min,在此最佳提取条件下,栀子黄色素的吸光度为0.914。     

Effect of sulfate and citrate salts on derivatization of amylose and amylopectin during hydroxypropylation of corn starch

Common corn starch was modified in 0.56 M sodium sulfate solution and in 0.31 M potassium citrate solution. It was found that about 1.8 times the amount of reagent (propylene oxide) was needed to get a same molar substitution (MS) when potassium citrate was used. Hydroxypropylated starches were fractionated on a size-exclusion column to separate amylose from amylopectin, and MS values of the whole starch, the amylose, and the amylopectin were determined. In all preparations, amylose was derivatized to a greater extent than was amylopectin. The data indicate that, with common corn starch: (1) the greater the overall derivatization, the greater was the preference for derivatization of amylose; and (2) the preference for amylose derivatization was greater for corn starch modified in potassium citrate solution than in sodium sulfate solution when the MS values for the two preparations were essentially the same.     

Ultrasound effect on physical properties of corn starch

High power ultrasound (HPU) represents a non-thermal processing method that has been rapidly researched and used in the last 10 years. The application of power ultrasound offers the opportunity to modify and improve some technologically important compounds which are often used in food products. One of them is starch. The aim of this research was to examine the effect of the high power ultrasound of 24 kHz frequency on rheological and some physical properties of corn starch. Various ultrasound treatments were used; an ultrasound probe set with different intensities (34, 55, 73 W cm⁻²) and treatment times (15 and 30 min) and ultrasound bath of 2 W cm⁻² intensity and treatment times (15 and 30 min). Rheological parameters, turbidity and swelling power of corn starch suspensions were determined for native and ultrasonically treated corn starch suspensions. Differential scanning calorimetry was used in order to examine the pasting properties of corn starch. The results have shown that the ultrasound treatment of corn starch distorts the crystalline region in starch granules. The results of differential scanning calorimetry measurements have shown a decrease in enthalpy of gelatinization. A significant decrease in consistency coefficient (k) has also been observed. The consistency coefficient decreases stepwise jointly with the increasing ultrasound power. The increase in the swelling power is associated with water absorption capacity and corn starch granules solubility, respectively.     

Studies on the plasticization efficiency of deep eutectic solvent in suppressing the crystallinity of corn starch based polymer electrolytes

A series of polymer electrolytes composed of corn starch (CS), lithium bis(trifluoromethanesulfonyl)imide (LITFSI) and deep eutectic solvent (DES) were fabricated by solution casting technique. The DES was synthesized from a mixture of choline chloride and urea at a molar ratio of 1:2. The addition of DES is crucial in enhancing the room temperature ionic conductivity by increasing the amorphous elastomeric phase in CS:LITFSI matrix. The ionic transport mechanism is improved and appreciable amount of ion conducting polymer electrolytes is produced. The highest ionic conductivity achieved for the polymer electrolyte composition CS:LiTFSI:DES (14 wt.%:6 wt.%:80 wt.%) is 1.04 × 10⁻³ S cm⁻¹. The anomalies that were observed with the addition of DES upon formation of neutral ion multiples were visually revealed by the SEM micrographs. The possible dipole-dipole interaction between the constituents was visualized by the FTIR spectroscopy upon change in cage peaks.     

荔枝核淀粉特性研究

本文采用扫描电镜观察荔枝核淀粉颗粒呈椭圆或多边形。差示扫描量热仪分析荔枝核淀粉的热力学特性表明,其起始温度、峰温度、终止温度和吸热焓值分别为69．04℃、78．79℃、87．08℃和7．5J/g。X射线衍射分析表明荔枝核淀粉呈C型结晶。Brabender粘度分析表明荔枝核淀粉糊化温度为85．3℃,淀粉糊高温稳定。     

Retrogradation of corn starch after thermal treatment at different temperatures

Multi-endotherms of the gelatinization of corn starch, such as G, M1, M2, and Z endotherms, have been detected by DSC. The retrogradation of corn starch after initial thermal treatment at different temperatures was studied by DSC; in particular, the effect of thermal treatment before and after each endotherm of gelatinization on retrogradation was determined as a function of annealing time. The effect of thermal treatment at a certain temperature on the residual gelatinization endotherm at a higher temperature is also discussed. It was found that the higher temperature of thermal treatment always removed all the endotherms below that temperature. However, a certain thermal treatment temperature could affect the residual endotherm above this treatment temperature. The time-dependent retrogradation of corn starch is mainly due to G and M1 endotherms. The temperature and enthalpy of the melting of amylose–lipid complexes M2 and nonlipid complex amylose Z were not affected by aging time. The final enthalpy of retrogradation was found to be lower than that of gelatinization.     

Effect of alkaline and autohydrolysis processes on the purity of obtained hemicelluloses from corn stalks

A study of the potential of autohydrolysis and alkaline extraction processes from corn stalks was performed for high purity hemicellulose extraction. The influence of process parameters on the purity of obtained hemicelluloses was analyzed. An experimental design was developed for the autohydrolysis treatments to determine the optimal conditions to solubilize the hemicelluloses with lowest content in contaminants. On the other hand, alkaline extraction, including raw material pretreatment (dewaxing and delignification step) was carried out analyzing the effectiveness of this processes for maximum pure hemicellulose recovery. The maximum yield (54% of the raw material hemicelluloses) and the best physicochemical properties (highest hemicellulose content free of lignin) were obtained with these pretreatments in alkaline extraction. Moreover, the effect of lignin removal by sulfuric acid from the autohydrolysis liquors before hemicellulose precipitation was studied. This purification step has allowed to obtain lignin-free autohydrolysis hemicellulose but with the presence of sulfur as predominant contaminant.     

Pasting viscosity and in vitro digestibility of retrograded waxy and normal corn starch powders

Pasting viscosity and in vitro digestibility of oven-dried powders of waxy and normal corn starch gels (40% solids) retrograded under an isothermal (4 °C) or temperature cycled (4/30 °C) storage were investigated. Temperature cycling induced higher onset temperature for melting of amylopectin crystals than isothermal storage under a differential scanning calorimeter whereas little difference in crystalline type was observed under X-ray diffraction analysis. Temperature cycling caused higher pasting temperature and viscosity for the retrograded starches than isothermal storage. The retrograded waxy corn starch powders exhibited pasting behaviors similar to that of native waxy corn starch. However, the retrograded normal corn starch powders showed very much different pasting patterns with lower pasting viscosity but higher pasting temperature than native starch counterpart. The retrogradation increased slowly digestible starch content without changing resistant starch content, more effectively by the temperature cycling than the isothermal storage.     

Molecular and granular characteristics of corn starch modified by HCl-methanol at different temperatures

Native corn starch was hydrolyzed with 0.36% HCl in methanol at 25 and 45 °C for periods of time up to 240 h. The action of acid penetration and hydrolysis was investigated by confocal laser scanning microscopy (CLSM), scanning electron microscopy (SEM), high-performance anion-exchange chromatography (HPAEC) and high-performance size-exclusion chromatography (HPSEC) equipped with viscometry, right-angle laser light scattering (RALLS) and refractive index (RI) detectors. Corn starch hydrolyzed at 45 °C for 240 h showed strong intensity of APTS (8-amino-1,3,6-pyrenetrisulfonic acid) fluorescence and sharp growth ring structure. Exocorrosion over the surface of corn starch was only observed on the corn starch hydrolyzed at 25 °C for 240 h and observed on all corn starch hydrolyzed at 45 °C. The M_w and R_h of acid-hydrolyzed corn starch decreased with increasing the degree of hydrolysis. The acid hydrolysis rate in methanol of corn starch was mainly dependent on the temperature, which dominated the penetration efficiency of acid.     

Relationships between kernel vitreousness and dry matter degradability for diverse corn germplasm: I. Development of near-infrared reflectance spectroscopy calibrations

Negative correlations between corn vitreousness and ruminal dry matter and starch degradabilities have been widely reported. To measure corn vitreousness and density more rapidly, Correa et al. [Correa, C.E.S., Shaver, R.D., Pereira, M.N., Lauer, J.G., Kohn, K., 2002. Relationship between corn vitreousness and ruminal in-situ starch degradability. J. Dairy Sci. 85, 3008–3012] initiated the development of near-infrared reflectance spectroscopy (NIRS) calibrations from 47 samples derived from 14 US and five Brazilian commercial hybrids. In this study, we generated more data to add to these NIRS calibrations with the objective of making them more robust. We also evaluated the potential of using Stenvert hardness measurements for NIR calibrations. Thirty-three diverse corn germplasm sources were grown at University of Wisconsin West Madison Research Station. These included a wide range of endosperm characteristics from opaque 2 (o2) types to densely packed flint types, and a number of intermediates. Harvest was at 1/2 milkline and black-layer maturity stages. Dried kernels from middle portions of ears from 12 selected inbreds, four each from low (0–30%), medium (30–70%), and high (70–100%) vitreousness classifications were used to determine vitreousness by manual dissection and density by water displacement using a pycnometer. Hardness was determined on all 33 inbreds on a 20 g sample using a Stenvert micro hammer-cutter mill with 2 mm screen size and 3600 rpm to measure time to collect ground sample to a set receptacle height (T); total column height (CH); and height ratio of coarse to fine (C/F) particles. The NIRS equations were selected on the basis of high R²-values (0.90, 0.92, 0.85, and 0.85) and low SEC (4.85, 0.01, 1.39, and 0.19) and SECV (6.04, 0.02, 1.79, and 0.25), for vitroueness, density, T and CH factors, respectively. Calibrations for vitreousness and density were regarded as the best prediction models compared to stenvert hardness measurements as determined by their RPD values (3.73 and 2.50, respectively). These results show that NIRS can be used as a screening tool in large-scale breeding trials to develop corn hybrids of desired endosperm properties for improved ruminal degradabilities.     

Effect of corn preparation methods on dry-grind ethanol production by granular starch hydrolysis and partitioning of spent beer solids

Two corn preparation methods, rollermill flaking and hammermill grinding, were compared for efficient processing of corn into ethanol by granular starch hydrolysis and simultaneous fermentation by yeast Saccharomyces cerevisiae. Corn was either ground in a hammermill with different size screens or crushed in a smooth-surfaced rollermill at different roller gap settings. The partitioning of beer solids and size distribution of solids in the thin stillage were compared. The mean particle diameter d₅₀ for preparations varied with set-ups and ranged between 210 and 340 μm for ground corn, and 1180-1267 μm for flaked corn. The ethanol concentrations in beer were similar (18-19% v/v) for ground and flaked preparations, however, ethanol productivity increased with reduced particle size. Roller versus hammermilling of corn reduced solids in thin stillage by 28%, and doubled the volume percent of fines (d₅₀ ∼ 7 μm)in thin stillage and decreased coarse (d₅₀ ∼ 122 μm) by half compared to hammermilling.