蔗渣纤维制备高取代度羧甲基纤维素

采用三次醚化法 ,并加入双氧水活化 ,由甘蔗渣纤维在乙醇溶液中制备了取代度 ( DS)可达 1 .3的羧甲基纤维素( CMC) ,考察了各种因素对取代度的影响。     

高取代度羧甲基小麦淀粉制备工艺的优化及表征

摘 要：以小麦淀粉为原料,以氯乙酸作为醚化剂,采用两次加碱法制备了高取代度的羧甲基小麦淀粉。以4.05g淀粉为基准,采用正交实验对反应条件进行了优化,得到的最佳工艺条件为：水用量6mL,无水乙醇用量60mL,氯乙酸与淀粉摩尔比1.4,氢氧化钠与氯乙酸摩尔比1.8,碱化用氢氧化钠百分比70%,碱化温度35～40℃,碱化时间0.5～1h,醚化温度50～55℃,醚化时间2～3h,在此条件下制得了取代度高达1.21的羧甲基小麦淀粉。     

羟丙基淀粉合成过程取代度变化规律的研究

基于环氧丙烷的用量、反应时间和NaOH的用量对羟丙基淀粉合成过程产物取代度的变化趋势,建立了预测羟丙基淀粉取代度变化规律的数学经验模型,即DS=k1tk2ln(k3DN+1).结果表明:在本实验条件下,羟丙基淀粉取代度的实验值和模型预测值之间的相关系数(R2)为0.981 7,这说明该模型可以很好地预测合成羟丙基淀粉过程中取代度的变化规律.     

Determination of protein concentration in raw milk by mid-infrared fourier transform infrared/attenuated total reflectance spectroscopy

This study investigates the potential use of attenuated total reflectance spectroscopy in the mid-infrared range for determining protein concentration in raw cow milk. The determination of protein concentration is based on the characteristic absorbance of milk proteins, which includes 2 absorbance bands in the 1500 to 1700 cm(-1) range, known as the amide I and amide II bands, and absorbance in the 1060 to 1100 cm(-1) range, which is associated with phosphate groups covalently bound to casein proteins. To minimize the influence of the strong water band (centered around 1640 cm(-1)) that overlaps with the amide I and amide II bands, an optimized automatic procedure for accurate water subtraction was applied. Following water subtraction, the spectra were analyzed by 3 methods, namely simple band integration, partial least squares (PLS) and neural networks. For the neural network models, the spectra were first decomposed by principal component analysis (PCA), and the neural network inputs were the spectra principal components scores. In addition, the concentrations of 2 constituents expected to interact with the protein (i.e., fat and lactose) were also used as inputs. These approaches were tested with 235 spectra of standardized raw milk samples, corresponding to 26 protein concentrations in the 2.47 to 3.90% (weight per volume) range. The simple integration method led to very poor results, whereas PLS resulted in prediction errors of about 0.22% protein. The neural network approach led to prediction errors of 0.20% protein when based on PCA scores only, and 0.08% protein when lactose and fat concentrations were also included in the model. These results indicate the potential usefulness of Fourier transform infrared/attenuated total reflectance spectroscopy for rapid, possibly online, determination of protein concentration in raw milk.     

Direct determination of lactulose in heat‐treated milk using diffuse reflectance infrared Fourier transform spectroscopy and partial least squares regression

The aim of this work was the direct determination of lactulose (LCT) concentration in freeze‐dried heat‐treated milks using diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS) without any chemical pretreatment of the milk. The ‘actual’ lactulose concentrations estimated by means of high‐performance liquid chromatography (HPLC) were correlated with the spectral region 1286–754 cm^?1 of DRIFTS spectra in the second‐derivative form of the milk samples using partial least squares (PLS) regression. A linear relationship was established between the ‘actual’ and the concentrations recalculated using the built model. The proposed DRIFTS method is simple, rapid and low cost.     

高取代度柠檬酸酯淀粉制备研究

柠檬酸酯淀粉是一种具有抗性作用酯化变性淀粉,在国外广泛应用于面包、饼干及其它食品中,以改善食品品质。该研究以玉米淀粉为原料,采用酯化变性方法,在干法条件下制备高取代度柠檬酸酯淀粉,探讨反应时间、反应温度、pH值、柠檬酸浓度对淀粉酯化过程影响;并获得高取代度柠檬酸酯淀粉最佳实验条件为:反应时间7．4h、反应温度140℃、pH为2．51、柠檬酸浓度为43．16％,样品最高取代度可达0．1776。     

Monitoring of fatty acid composition in virgin olive oil by Fourier transformed infrared spectroscopy coupled with partial least squares

A rapid Fourier transformed infrared (FTIR) attenuated total reflectance (ATR) spectroscopic method was applied to the determination of fatty acid (FA) profile and peroxide value (PV) of virgin olive oil. Calibration models were constructed using partial least squares (PLS) regression. A FA calibration model was constructed in the spectral range from 3033 to 700 cm⁻¹. Oleic acid (62.0–80.0%), linoleic acid (5.3–15.0%), saturated fatty acids (SFA, 12.6–19.7%), mono-unsaturated fatty acids (MUFA, 64.4–81.0%) and poly-unsaturated fatty acids (PUFA, 6.0–15.9%) were considered for chemometric analysis. PV (5.7–15.7 meq O₂ kg⁻¹) was calibrated using the signal of the full spectral range 4000–700 cm⁻¹ with first derivative pre-treatment. The LODs of the FTIR-chemometric methods were: 3.0% for oleic acid, 0.5% for linoleic acid, 1.3% for SFA, 3.0% for MUFA, 0.3% for PUFA and 1.0 meq O₂ kg⁻¹ for PV. Analytical methods were evaluated by use of validation samples (n = 25 for all the FA related parameters and n = 10 for PV) with nearly quantitative recovery rates (98–103%). The proposed method provided results comparable to official procedures, with the advantages of being less expensive and more rapid.     

水相中高取代度低黏度羧甲基淀粉的制备

羧甲基淀粉(CMS)是一种阴离子淀粉醚,广泛应用于医药、食品、纺织、石油钻探等领域。以玉米淀粉为原料,采用酸化-醚化复合变性的方法在水相中制备高取代度低黏度羧甲基淀粉(CMS),探讨了酸化时间、液固比、NaOH用量、ClCH2COOH用量、醚化反应时间、反应温度对羧甲基化过程的影响,研究发现,对原淀粉进行酸化,可以在不增加其它反应试剂用量的基础上提高产物的取代度(DS),但是酸化时间不应过长。同时得到了其他单因素变化时各自对产物取代度的变化趋势,为进一步优化反应条件提供了依据。     

Effect of different carboxymethyl cellulose structure parameters on tartrates stability of red wine: viscosity and degree of substitution

ABSTRACT

The aim of this study was to investigate the effects of carboxymethyl celluloses (CMC) with different structures (viscosity and degree of substitution) on the stability of tartrates as well as the growth mechanism of potassium bitartrate (KHT) crystals. Six CMC samples with different viscosity and degree of substitution were investigated by GPC, XRD and SEM to establish their molecular weight, crystal structure, particle size and molecular morphology. As oenological additives, they were studied in model solution and in Cabernet Sauvignon wine. The tartaric stability and inhibitory efficiency were evaluated by conductivity via mini-contact test and compared with metatartaric acid and mannoproteins commercial additives. The results suggest that under the same degree of substitution (DS), with an increase of viscosity, CMC molecular chains agglomerate and fold, the solubility in the wine decreases, thus the effect of stabilising tartrate deteriorates. Whilst at the same viscosity, with an increase of DS, the charge density of CMC molecules increases and the binding ability of ions increases and thus the stabilising tartrate has an obvious effect. The negative charge on the ?COO? groups extended from CMC polymer tends to repulse the HT^? group in solution while attracting K⁺ ions to produce a concentration gradient at the crystal surface. In addition, CMC complexes with K⁺ ions in solution, reducing the number of K⁺ ions able to diffuse to the adsorption layer. Generally, CMC-6 with a higher the degree of substitution and lower viscosity had best application effect on tartrate stabilisation, and from the price and application performance, CMC was found to be superior to commercial additives like metatartaric acid and mannoproteins.     

Analysis of potential lard adulteration in chocolate and chocolate products using Fourier transform infrared spectroscopy

Fourier transform infrared (FTIR) spectroscopy, in combination with attenuated total reflectance (ATR) and partial least square (PLS) regression, was used to detect the presence of lard in chocolate formulation. The spectral bands associated with lard, cocoa butter and their blends (ranging from 0% to 15% of lard in cocoa butter) were recorded, interpreted and identified. A semi-quantitative approach is proposed to measure the percent of lard in blends on the basis of spectral data at the frequency region 4000–650 cm⁻¹, using the equation y = 0.9225x + 0.5539. The coefficient of determination (R²) was 0.9872 with a standard error (SE) of 1.305. In this paper, the potential of FTIR spectroscopy as a rapid analytical tool for the quantitative determination of adulterants especially lard, in chocolate, is demonstrated.     

近红外光谱应用于高粱中总淀粉、直链淀粉与支链淀粉的定量分析

酱香型白酒以高粱为主要原料发酵而成,高粱中的淀粉,尤其是支链淀粉的含量对于酱香型白酒的产品质量起着至关重要的作用,因此针对其总淀粉、直链淀粉与支链淀粉的检测手段研究也应受到人们高度的重视。傅里叶变换近红外光谱法因其准确性高、稳定性好以及快速无损检测等特点,在建立总淀粉、直链淀粉和支链淀粉同时定量分析模型方面得到了较为成功的应用。结果表明,总淀粉、直链淀粉以及支链淀粉的定量分析模型相关系数分别达到0.954 9、0.923 6和0.940 1,交互验证均方根误差分别为1.027 1、0.088 5和1.264 6。可见,基于近红外光谱技术的定量分析方法可适用于高粱中总淀粉、直链淀粉与支链淀粉的同时定量分析。     

取代度对醋酸酯变性淀粉及新鲜湿面品质的影响

研究了不同取代度对醋酸酯变性淀粉理化特性包括淀粉糊化特性和淀粉糊透光率以及对新鲜湿面品质的影响。结果表明,引入乙酰基后,随着取代度的升高,糊化温度相应降低,产生峰值黏度所对应的时间也降低,淀粉糊透明度增加,加工成湿面的弹性明显提高,硬度、咀嚼度、内聚性以及回复性降低。     

Determination of structural changes in microwaved rice starch using Fourier transform infrared and Raman spectroscopy

FTIR and confocal laser micro‐Raman spectroscopy methods were used to investigate the differences in chemical bond types, bond energy, and skeleton connection system between rice starch heated in a microwave and rice starch heated rapidly using a traditional method. The temperature of the peak absorption position of C H mode vibration of microwaved sample was lower and the temperature of peak position of C O related mode vibration on skeleton of microwaved sample were higher than those of the rapid heating sample, but there were no changes to other skeletal mode vibrations such as glycosidic linkage and pyranose ring. Overall, microwave‐heat treatment did not change the type of chemical groups in starch molecules, and induce the formation of new chemical group bonds, or change the way that they interact with each other in rice starch. Furthermore, the vibrational energy of the chemical‐bond of microwave‐treated rice starch changes gradually during the heating process.     

机械活化干法制备玉米羧甲基淀粉工艺研究

以玉米淀粉为原料,氯乙酸钠为醚化剂,氢氧化钠为催化剂,采用机械活化干法制备羧甲基淀粉。以取代度（degree of substitution,DS）为评价指标,通过单因素和正交实验设计优化玉米羧甲基淀粉制备工艺。采用红外光谱（sourier transform infrared spectroscopy,FTIR）、X-射线衍射（x-ray diffraction,XRD）、扫描电镜（scanning electron microscope,SEM）对羧甲基淀粉的结构进行表征。结果表明,机械活化干法制备羧甲基淀粉最佳工艺条件:淀粉与氯乙酸钠摩尔比为1∶1、淀粉与氢氧化钠摩尔比为1∶1.25（以淀粉干基计）、球磨时间为90 min,球磨温度为60℃,球磨转速为380 r·min-1、球磨介质堆体积500 m L,在该实验条件下制备的玉米羧甲基淀粉的取代度为0.5086。FTIR、XRD、SEM进一步证实玉米淀粉发生了醚化反应。      

应用傅立叶变换近红外光谱检测婴幼儿配方奶粉中的乳糖含量

利用傅立叶变换近红外光谱（FT-NIR）技术结合偏最小二乘法（PLS）对婴幼儿配方奶粉中的乳糖进行快速检测分析。搜集 94个不同产地、不同品牌的婴幼儿配方奶粉中乳糖的实验室数据,并采集婴幼儿配方奶粉的近红外光谱图,选择最优的光谱预处理方法,优化、验证和建立模型,并预测6个未知品牌的婴幼儿配方奶粉样品的乳糖含量。结果表明,不同阶段的婴幼儿配方奶粉有非常相似 的近红外特征图谱,图谱处理后的方差为95.423 5%,该模型测定的乳糖值与高效液相色谱（HPLC）法测定的乳糖值之间的平均相对误 差均≤0.67%,相对标准偏差（RSD）均≤0.88%,均符合误差范围。该方法可以无损、快速、高效地测定婴幼儿配方奶粉中的乳糖含量。     

3种植物油傅里叶变换红外光谱信息的判别分析研究

针对花生油、大豆油和棕榈油样品,采用傅里叶变换红外光谱仪,采集红外吸收光谱,对光谱预处理后,提取红外特征信息,以1 746 cm-1和2 855 cm-1波数处吸收峰特征参数比值为X轴, 1 099 cm-1与1 119 cm-1波数处吸收峰特征参数的比值为Y轴,及3种油O-C-C对称伸缩振动各自所产生的吸收带所在波数(cm-1)值作为Z轴,绘制三维分布图,对这3种油样进行判别分析.结果显示这3种油样之间有明显区分.