高效液相色谱法测定纳豆及纳豆胶囊中的大豆异黄酮含量

建立了纳豆及纳豆胶囊中大豆异黄酮的高效液相色谱分析方法,该方法重复性及样品稳定性良好.实验对原料黄豆、纳豆和纳豆胶囊样品采用石油醚索氏脱脂后,对固体样品进行乙醇回流提取,分析了4种大豆异黄酮组分,即大豆苷、染料木苷、大豆素和染料木素.结果表明,原料黄豆总异黄酮质量比为1 260 mg/kg,纳豆比原料黄豆总异黄酮含量明...     

纳豆咀嚼片中微量元素铁、锌、铜、锰的分析

采用湿法消化样品,确定了检测纳豆咀嚼片微量元素的最佳处理条件。试验证明,混酸HNO3：HClO4的比例为4：1,消化温度为140℃,消化时间80min时样品可以得到充分分解。采用了ICP-AES法测定纳豆咀嚼片中微量元素铁、锌、铜、锰的含量,测定结果比较准确。     

纳豆中异黄酮组成含量变化研究

研究了纳豆芽胞杆菌(Bacillus subitilis natto)发酵大豆(纳豆)中的异黄酮含量及其组成变化。采用高效液相色谱法,通过梯度洗脱的方式,在261nm处测定吸光度。结果通过发酵,异黄酮苷元含量显著增加。高效液相色谱分析显示在发酵过程中可能生成了新的异黄酮化合物。     

霉菌型豆豉和纳豆中异黄酮含量的比较研究

目的:比较纳豆和豆豉中异黄酮含量的组成变化。方法:利用超声波提取,采用高效液相色谱法测定,色谱柱填料为Hypersil ODS2(4.6 mm×250 mm,5μm),流动相为甲醇(A)-水(B)进行梯度洗脱,检测波长为255 nm。结果:豆豉与纳豆相比较,豆豉中大豆苷、黄豆黄苷、染料木苷、大豆甙元、黄豆黄素、染料木素的含量分别为11,未检出,25,320,65,380μg/g;纳豆中中大豆苷、黄豆黄苷、染料木苷、大豆甙元、黄豆黄素、染料木素的含量分别为330,73,410,12,3.3,28μg/g。结论:豆豉中甙元的含量高,纳豆中糖苷的含量高。     

纳豆咀嚼片的工艺研究

研究了纳豆咀嚼片的生产工艺，通过试验确定了比较合理的原料配比，经原料混合、制软材、制粒、干燥、压片等工序，制成表面光滑、香甜适口、营养丰富的纳豆咀嚼片。     

纳豆系列咀嚼片产品工艺研究

研究开发纳豆系列产品(纳豆咀嚼片、纳豆奶咀嚼片),确定最佳主辅料配比及成型制备工艺。通过试验,选取合适的辅料、主辅料比例以及润湿剂选取等,经过原料混合、制软材、制粒、干燥、压片等一系列实验工序,制成外表均匀光洁、香甜适口、营养丰富的系列健康产品。     

ICP-AES法测定大豆膳食纤维咀嚼片中金属元素的含量

通过对大豆膳食纤维咀嚼片样品消化方法进行研究,确定了实验的最佳消化方法是:混酸HNO3和HCl O4比例为4∶1,消化温度为140℃,消化时间为80 min;同时采用电感耦合等离子体原子发射光谱(ICP-AES)法测定大豆膳食纤维咀嚼片中钠、钙、镁、钾、锰、铁、铜、锌的含量。这种检测方法具有快速、简便、消解完全等特点,且测定结果准确,为建立大豆膳食纤维咀嚼片质量标准建立了科学的检测方法。     

分光光度法校正测定大豆异黄酮总含量

以染料木素(Genistein)为标准样品，用分光光度法测定了Genistein和大豆苷原(Daidzein)混合标准溶液的异黄酮总浓度。结果表明：混合物中不同种类异黄酮含量的比例严重影响着测定的精确度(测定值，实际值)；回归分析显示测定精确度与混合溶液在262nm和250nm收值之比呈显著线性相关，通过该相关性可校正计算混合溶液异黄酮测定值，加样回收试验表明校正前后的平均回收率分别为91．8％和97.3％。     

纳豆中氨基酸态氮含量的测定

采用电位滴定法对纳豆(Natto)中的氨基酸态氮含量进行了研究。研究表明,不同批次的纳豆样品中氨基酸态氮含量均在0·424%以上。本实验的相对标准偏差小于2·76%,回收率在94·12%～100·56%之间。此法简便、快速且重现性好,可作为纳豆生产工艺中关键控制点的检测方法之一,为纳豆食品生产和质量控制提供可靠的技术支持。      

纳豆中氨基酸态氮含量的测定

采用电位滴定法对纳豆(Natto)中的氨基酸态氮含量进行了研究。研究表明,不同批次的纳豆样品中氨基酸态氮含量均在0·424%以上。本实验的相对标准偏差小于2·76%,回收率在94·12%～100·56%之间。此法简便、快速且重现性好,可作为纳豆生产工艺中关键控制点的检测方法之一,为纳豆食品生产和质量控制提供可靠的技术支持。     

紫外分光光度法测定柑桔皮中总黄酮的含量

建立以芦丁为标准品的柑桔皮黄酮类含量测定方法,采用3种紫外-可见分光光度法对不同条件处理下的柑桔皮中总黄酮含量进行了测定和比较分析。研究表明,3种分光光度测定方法中,黄酮含量以硝酸铝显色法（345nm）为最高,直接测定法（270nm）次之,氯化铝显色法（415nm）最低;经过HPLC检测后,选定氯化铝（275nm）为显色系统的含量测定方法。回归方程为：Y=28.891X＋0.0002,相关系数r=1,平均加样回收率为99.3%,RSD=1.84%（n=5）,经不脱脂超声处理过的柑桔皮中所得黄酮含量为3.09%。该法操作简便,结果准确,重复性好,为柑桔皮中黄酮含量的测定提供了一种切实可行的途径。     

三波长分光光度法测定芹菜叶中黄酮的含量

采用三波长分光光度法测定芹菜叶中黄酮的含量，消除了由于芹菜叶中黄酮光谱吸收峰不对称给定量分析造成的影响。并校正了由于干扰组分的吸收光谱具有线性吸收产生的基线倾斜。实验结果回归方程为△A=0．0045C-0．0007相关系数r=0．9996；黄酮的浓度在30～300μg/mL范围内，分别在波长为λ1=460nm、λ2=420nm、λ3=380nm处测吸光度时，则△A与浓度C之间呈良好的线性关系，可按标准曲线法进行定量分析。本法的回收率为96．8％-105．9％，变异系数小于0．49％。方法的准确度与精密度均令人满意，而且操作简便易行。     

DETERMINATION OF SOLUBLE NITROGEN BY SPECTROPHOTOMETRY

A simple spectrophotometric method for the determination of nitrogen in unhopped wort has been tested by the EBC Analysis Committee and accepted for inclusion in Analytica-EBC. The spectrophotometric method is intended as a quick method for routine quality control. It is emphasized that the procedure has to be followed in detail and that the precautions stated under Notes on Procedure are most important. The average precision values obtained for the range 600 to 850 mg/litre were r₉₅=30 and R₉₅ = 104.     

DETERMINATION OF TOTAL SULPHUR DIOXIDE IN BEER BY FLOW INJECTION SPECTROPHOTOMETRY USING GAS-DIFFUSION AND THE MERGING ZONES TECHNIQUE

A flow injection system for the determination of total sulphur dioxide in beer is described. The methodology involves the same colorimetric reaction of the reference method between SO₂, prosaniline and formaldehyde. The sample is introduced into the manifold without previous pretreatment, the hydrolysis process, isolation of the SO₂ from the matrix and the colorimetric reaction, being carried out inside the flow tubes. To isolate the SO₂, a gas-diffusion unit was included in the system and to minimise p-rosaniline consumption, a merging zones technique was used. The results obtained were in good agreement with a reference method (relative deviations lower than 5%), the precision being better than 2.5% (relative standard deviation). A sampling-rate of 30 samples per hour was obtained and the consumption of p-rosaniline was reduced 10 fold when compared to the reference method.     

QUANTITATIVE DETERMINATION OF METMYOGLOBIN AND TOTAL PIGMENT IN AN INTACT MEAT SAMPLE USING REFLECTANCE SPECTROPHOTOMETRY

SUMMARY— A technique for determining the relative quantities of oxymyoglobin, metmyoglobin and total pigment concentration at the surface of on intact meat sample was developed. A Beck-man DK-2 spectrophotometer with reflectance attachment was used and spectra were recorded on the R_A scale. The sample port of the spectrophotometer was modified so that a uniform and high intensity light beam measuring 0.5 × 0.6 cm reached the surface being evaluated. A sample holder was constructed so that known proportions of oxygenated and oxidized meat could be exposed to the light beam. A family of curves representing varying known amounts of metmyoglobin and oxymyoglobin were obtained. The height of the peak at 632 nm (ΔR_A632) was directly related to the amount of metmyoglobin at the surface of the meat sample. For 100% oxymyoglobin, ΔR_A632 was at a minimum and equal to R_A750. For 100% metmyoglobin, ΔR_A632 was at a maximum and the height of the response depended upon the amount of total pigment present. A linear relation was obtained when ΔR_A362 was plotted against percent metmyoglobin or against total pigment determined by the Hornsey (1956) method. The method requires making two readings of the meat samples at a single wave length. One reading of the sample followed by one reading of the same sample after oxidation with K₃ Fe(CN)₆ provides a quantitative evaluation of the metmyoglobin concentration and the total heme pigment concentration. The accuracy of the method may be improved by making multiple readings.     

可见分光光度法测定马蹄皮中总黄酮的含量

建立测定马蹄皮中总黄酮含量的光谱分析方法.以40%乙醇为溶剂,微波辅助提取马蹄皮中的总黄酮.以芦丁为标准样品,以NaNO2-Al(NO3)3-NaOH为显色剂,采用可见分光光度法在510 nm测量波长测定马蹄皮中总黄酮含量.回归方程A=0.0105 C+0.0014,相关系数R2=1,黄酮浓度在8.41 mg/L～82.88 mg/L范围内服从比耳定律.测定结果显示,马蹄皮中总黄酮的平均含量为1.59%,重现性试验RSD=1.38%(n=6),平均回收率99.6%(RSD=0.799%,n=6),精密度试验RSD=1.64%(n=6).     

肉类中蛋白质分析—紫外光度测定法研究

前言 目前,国内肉食品中蛋白质的常规测定仍采用凯氏定氮法,该方法操作繁琐,需时冗长,作为常规分析或中控分析,太费时,难以适应目前食品工业发展和肉食品常规监测的要求。因此,必须改善的测试方法,探索出一种快速、操作简化、满足质量控制要求的和符合我国测试仪器发展现状的测试方法。笔者采用紫外光度法进行这方面的研究,取得了一些符合上述要求的结果,报导如下:     

流动注射分光光度法测定食品中的微量硼

基于硼和3-甲氧基-甲亚胺H在HAC-NH4AC缓冲溶液中的显色反应,建立了流动注射光度分析测定微量硼的新方法.在28样/h采样频率下检出限为0.033 mg/L,硼浓度在0.033 mg/L～5 mg/L范围内符合比耳定律,相对标准偏差为0.54%.该法快速,简便、灵敏、试剂用量少、选择性好,用于食品中微量硼的测定,结果令人满意.