高效液相色谱法测定蜂蜜中的果糖、葡萄糖和蔗糖

蜂蜜是一种高度复杂的糖类过饱和混合物。蜂蜜的主要成分是碳水化合物,含有果糖、葡萄糖、蔗糖、麦芽糖、松二糖和糊精等20余种。蜂蜜中的糖类占总成分的70%~80%,蜂蜜中以单糖(果糖、葡萄糖)为主要成分,约占总成分的60%以上,其次是双糖,双糖中以蔗糖占绝对优势,成熟的蜂蜜平均不超过5%(少数     

不同冻藏时间对速冻草莓营养品质的影响

用非破坏快速分析方法-近红外光谱法（NIRs）分析草莓在-18℃条件下冻藏1个月、2个月、4个月和6个月时维生素C、柠檬酸、苹果酸、蔗糖、葡萄糖和果糖等6种营养成分的变化。结果表明冻藏过程中速冻草莓维生素C、柠檬酸和蔗糖含量逐渐降低；苹果酸、葡萄糖和果糖含量逐渐增加。     

如何正确食用蜂蜜

正蜂蜜是蜜蜂从开花植物的花中采得的花蜜在蜂巢中酿制的蜜。蜂蜜的成分除了葡萄糖、果糖之外还含有各种维生素、矿物质、氨基酸。蜂蜜比蔗糖(砂糖的主要成份)更容易被人体吸收,蜂蜜是由单糖类的葡萄糖和果糖构成,可以被人体直接吸收,而不需要酶的分解。蜂蜜具有补中、润燥、止痛、解毒、治肺燥咳嗽、肠燥便秘、胃脘疼痛、鼻渊、口疮、汤火烫伤、解乌头毒等功效。下面我们就一起来学习一下如何正确食用蜂蜜。     

监督抽查

江西36款食品抽检不合格日前,江西向社会公布2010年全省食品安全统一抽检工作结果,36款食品被抽检不合格。其中,多款蜂蜜存在掺假、果糖和葡萄糖值偏低等问题,一些被检的皮蛋铅含量严重超标。公布的《江西省食品安全统一抽检不合格食品名单》显示,有7款蜂蜜的果糖和葡萄糖值均没有达到≥60的标准值,最低的一款是南昌旺纯食品有限公司生产的正纯蜂蜜,果糖和葡萄糖值只有12.6;而江西专宝药业有限公司生产的紫云英蜂蜜存在掺假的问题,检出含蔗糖值严重超标,达到10.3。     

单糖对玉米淀粉基复合膜性能的影响

目的研究D-果糖和葡萄糖作为增塑剂对玉米淀粉-壳聚糖复合膜性能的影响。方法糊化后的玉米淀粉溶液与壳聚糖溶液混合,分别添加5%,20%,35%,50%,65%(质量分数)的D-果糖及葡萄糖,均质后流延成膜;测定膜的力学性能,并通过扫描电镜、接触角、傅里叶红外扫描和X-衍射对复合膜相关特性进行表征。结果成膜物质之间相容性好,增塑剂用量由5%增加至65%,膜的厚度增加,经D-果糖和葡萄糖增塑的复合膜抗拉强度分别由73.99,70.88 MPa减至18.08,40.53 MPa。经D-果糖增塑的复合膜断裂伸长率呈递增趋势,在添加量为65%时达到19.03%,经葡萄糖增塑的复合膜呈现递减趋势。结论同一含量下,2种复合膜的厚度相近,抗拉强度相差不大,但经D-果糖增塑的复合膜断裂伸长率高,亲水性较好,更适合作为增塑剂应用在复合膜的制备中。     

国家蜂产品检测重点实验室(秦皇岛)

正业务范围目前,实验室检测的蜂产品种类有蜂蜜,蜂王浆,蜂胶,冻干粉,蜂蛹粉,蜂花粉及蜂蜡等。实验室检测的项目有,蜂蜜的真假鉴别检测项目,包括碳同位素六项,碳四植物糖,大米糖浆,甜菜糖浆,木薯糖浆,高果糖淀粉糖浆,β-呋喃果糖苷酶,转基因检测等。蜂蜜的常规检测,包括水分,灰分,果糖,葡萄糖,蔗糖,麦芽糖,色泽,酸度,pH值,净含量,羟甲基糖醛,酶值,花粉     

彼阳新盖口服液中乳酸钙和葡萄糖酸锌含量测定

本文研究乳酸钙、葡萄糖酸锌含量的测定。以(2-吡啶偶氮)-2-萘酚(PAN)为指示剂,乙二胺四乙酸二钠为滴定剂,通过控制溶液酸度分别测定彼阳新盖口服液中乳酸钙和微量葡萄糖酸锌的含量;同时还应用meso-四-(4-(4-甲基,3-磺基苯)卟啉分光光度法直接测定口服液中微量的葡萄糖酸锌,结果准确。     

电化学法测定库拉索芦荟凝胶多糖的含量

本文用电化学差示脉冲伏安法,分别以甘露糖、葡萄糖、半乳糖和果糖为标准品,测定库拉索芦荟凝胶多糖的含量。研究表明以这四种不同的单糖做标准,其检测结果无显著性差别,均可以采用,平均回收率为107.9%,RSD为2.4%,检出限为2.09ug/ml。     

基于低场磁共振技术的糖溶液检测

采用低场核磁共振分析测试技术研究糖溶液的自旋-自旋弛豫特性.利用Carr-Purcell-MeiboomGill(CPMG)序列采集糖溶液的核磁共振回波信号,以多重指数衰减模型对采集的信号数据进行分析,探讨糖溶液中含糖量的多少与自旋-自旋弛豫时间的相关性,采用加权几何平均法计算不同浓度糖溶液的自旋-自旋弛豫时间.实验结果表明,蔗糖、葡萄糖和果糖的亲水性均能改变蒸馏水的自旋-自旋弛豫时间,并且,随着含糖量的升高,自旋-自旋弛豫时间呈指数降低;蔗糖、葡萄糖和果糖的相关系数均达到0.9以上.     

江西36款食品抽检不合格

日前,江西向社会公布20t0年全省食品安全统一抽检工作结果,36款食品被抽检不合格。其中,多款蜂蜜存在掺假、果糖和葡萄糖值偏低等问题,一些被检的皮蛋铅含量严重超标。     

Use of selective TOCSY NMR experiments for quantifying minor components in complex mixtures: application to the metabonomics of amino acids in honey

The application of the traditional methods of multivariate statistics, such as the calculation of principle components, to the analysis of NMR spectra taken on sets of biofluid samples is one of the central approaches in the field of metabonomics. While this approach has proven to be a powerful and widely applicable technique, it has an inherent weakness, in that it tends to be dominated by those chemical species present at relatively higher concentrations. Using a set of commercial honey samples, a comparison of this classical metabonomics approach to one based on the use of the selective TOCSY experiment is presented. While the NMR spectrum of honey and its classical metabonomic analysis is completely dominated by a very few chemical species, specifically alpha-glucose and fructose, the statistical signal carried by minor honey components, such as amino acids, may be accessed using a selective TOCSY-based approach. This approach has the intrinsic virtue that it focuses the statistical analysis on a set of predefined chemical species, which might be chosen for their metabolic significance, and could be composed of either major or minor mixture constituents. Furthermore, the selective TOCSY method allows for more certain chemical identification, acquisition times of approximately 1 min, and accurate quantification of the species contributing to the statistical discriminatory signal.     

New oral dosage form for elderly patients. III. Stability of trichlormethiazide in silk fibroin gel and various sugar solutions

The hydrolysis of trichlormethiazide (TCM) in silk fibroin gel (SFG) prepared in various sugar solutions (such as ribose, fructose, mannose, and glucose solutions) was determined. The hydrolysis rate of TCM differed with the variety of sugars utilized in this study; that is, it decreased in the following order: ribose > fructose > mannose > glucose. To investigate the relationship between the hydrolysis rate of TCM and the physicochemical properties of the sugar molecule, the amount of unfrozen water of sugar molecules was calculated from differential scanning calorimetry (DSC). The amount of unfrozen water increased with an increase in the number of the equatorial OH groups n(e-OH) per sugar molecule that are able to hydrate favorably to the surrounding water molecules. The hydrolysis rate constant decreased with increase in n(e-OH); glucose, having a large n(e-OH) in this study could effectively stabilize TCM.     

New Oral Dosage Form for Elderly Patients. III. Stability of Trichlormethiazide in Silk Fibroin Gel and Various Sugar Solutions

The hydrolysis of trichlormethiazide (TCM) in silk fibroin gel (SFG) prepared in various sugar solutions (such as ribose, fructose, mannose, and glucose solutions) was determined. The hydrolysis rate of TCM differed with the variety of sugars utilized in this study; that is, it decreased in the following order: ribose > fructose > mannose > glucose. To investigate the relationship between the hydrolysis rate of TCM and the physicochemical properties of the sugar molecule, the amount of unfrozen water of sugar molecules was calculated from differential scanning calorimetry (DSC). The amount of unfrozen water increased with an increase in the number of the equatorial OH groups n(e–OH) per sugar molecule that are able to hydrate favorably to the surrounding water molecules. The hydrolysis rate constant decreased with increase in n(e–OH); glucose, having a large n(e–OH) in this study could effectively stabilize TCM.     

MADSTRESS: a linear approach for evaluating scattering and absorption coefficients of samples measured using time-resolved spectroscopy in reflection

Time-resolved spectroscopy is a powerful technique permitting the separation of the scattering properties from the chemical absorption properties of a sample. The reduced scattering coefficient and the absorption coefficient are usually obtained by fitting diffusion or Monte Carlo models to the measured data using numerical optimization techniques. However, these methods do not take the spectral dimension of the data into account during the evaluation procedure, but evaluate each wavelength separately. A procedure involving multivariate methods may seem more appealing for people used to handling conventional near-infrared data. In this study we present a new method for processing TRS spectra in order to compute the absorption and reduced scattering coefficients. This approach, MADSTRESS, is based on linear regression and a two-dimensional (2D) interpolation procedure. The method has allowed us to calculate absorption and scattering coefficients of apples and fructose powder. The accuracy of the method was good enough to provide the identification of fructose absorption peaks in apple absorption spectra and the construction of a calibration model predicting the sugar content of apples.     

Development of robust calibration models using support vector machines for spectroscopic monitoring of blood glucose

Sample-to-sample variability has proven to be a major challenge in achieving calibration transfer in quantitative biological Raman spectroscopy. Multiple morphological and optical parameters, such as tissue absorption and scattering, physiological glucose dynamics and skin heterogeneity, vary significantly in a human population introducing nonanalyte specific features into the calibration model. In this paper, we show that fluctuations of such parameters in human subjects introduce curved (nonlinear) effects in the relationship between the concentrations of the analyte of interest and the mixture Raman spectra. To account for these curved effects, we propose the use of support vector machines (SVM) as a nonlinear regression method over conventional linear regression techniques such as partial least-squares (PLS). Using transcutaneous blood glucose detection as an example, we demonstrate that application of SVM enables a significant improvement (at least 30%) in cross-validation accuracy over PLS when measurements from multiple human volunteers are employed in the calibration set. Furthermore, using physical tissue models with randomized analyte concentrations and varying turbidities, we show that the fluctuations in turbidity alone causes curved effects which can only be adequately modeled using nonlinear regression techniques. The enhanced levels of accuracy obtained with the SVM based calibration models opens up avenues for prospective prediction in humans and thus for clinical translation of the technology.     

Detection of Low Sugar Concentration Solution Using Frequency Selective Surface (FSS)

Sugar is important in daily food intake since it is used as food preservative and sweetener. Therefore, is important to analyze the influence of sugar on the spectroscopic properties of the sample. Terahertz spectroscopy is proven to be useful and an efficient method for sugar detection as well as for future food quality industry. However, the lack of detection sensitivity in Terahertz Spectroscopy has prevented it from being used in a widespread spectroscopic analysis technology. In this paper, Frequency Selective Surface (FSS) using the Terahertz Spectroscopy Time Domain Spectrum (THz-TDS) which operates at terahertz frequency range has been demonstrated for application of sugar detection. The FSS is designed with a circle slot structure and has been optimized in line with the molecular resonance of glucose and fructose at different level concentration at 1.98 THz and 1.80 THz, respectively. Transmission magnitude of glucose and sucrose is inversely proportional with the level of sugar concentrations. The realization of the FSS structure is using electron beam lithography and wet etching technique. Results show that the FSS performance for glucose and sucrose reveal fair shifts in measured transmission magnitude from its original in CST by approximately 30%. The use of fabricated FSS with circle structure indicates that the concentration can be improved averagely at 25% for glucose and 13% for sucrose. Thus, it shows that the FSS circle structure combined with THz-TDS has the potential to become an alternative method for food sensing technology in the future.     

High ionic strength glucose-sensing photonic crystal

We demonstrate a colorimetric glucose recognition material consisting of a crystalline colloidal array embedded within a polyacrylamide-poly(ethylene glycol) (PEG) hydrogel, or a polyacrylamide-15-crown-5 hydrogel, with pendent phenylboronic acid groups. We utilize a new molecular recognition motif, in which boronic acid and PEG (or crown ether) functional groups are prepositioned in a photonic crystal hydrogel, such that glucose self-assembles these functional groups into a supramolecular complex. The formation of the complex results in an increase in the hydrogel cross-linking, which for physiologically relevant glucose concentration blue shifts the photonic crystal diffraction. The visually evident diffraction color shifts across the visible spectral region over physiologically important glucose concentration ranges. These materials respond to glucose at physiological ionic strengths and pH values and are selective in their mode of response for glucose over galactose, mannose, and fructose. Thus, we have developed a new recognition motif for glucose that shows promise for the fabrication of noninvasive or minimally invasive in vivo glucose sensing for patients with diabetes mellitus.     

Blood glucose regulation in type 1 diabetic patients: an adaptive parametric compensation control‐based approach

Here, a direct adaptive control strategy with parametric compensation is adopted for an uncertain non‐linear model representing blood glucose regulation in type 1 diabetes mellitus patients. The uncertain parameters of the model are updated by appropriate design of adaptation laws using the Lyapunov method. The closed‐loop response of the plasma glucose concentration as well as external insulin infusion rate is analysed for a wide range of variation of the model parameters through extensive simulation studies. The result indicates that the proposed adaptive control scheme avoids severe hypoglycaemia and gives satisfactory performance under parametric uncertainty highlighting its ability to address the issue of inter‐patient variability.Inspec keywords: patient monitoring, adaptive control, diseases, Lyapunov methods, closed loop systems, medical control systems, patient treatment, medical computing, sugar, uncertain systems, blood, nonlinear control systems, physiological modelsOther keywords: blood glucose regulation, type 1 diabetic patients, adaptive parametric compensation control‐based approach, direct adaptive control strategy, nonlinear model, type 1 diabetes mellitus patients, uncertain parameters, appropriate design, adaptation laws, closed‐loop response, plasma glucose concentration, external insulin infusion rate, model parameters, adaptive control scheme, parametric uncertainty, inter‐patient variability     

Probing nonlinear systems with the Wigner distribution

A new way to study nonlinear systems under forced oscillations is presented. The approach is based on the analysis of the time-frequency spectrum of the output signal of the nonlinear system when a chirp (a frequency increasing in time) is applied as input signal. The time-frequency spectrum is a way to characterize the instantaneous frequency content of a signal. In this paper it is shown that this approach gives a physical explanation of the mechanism that generates forced nonlinear oscillations. Results with simulated and real data prove the validity of the method.     

Quantitative modeling of the third harmonic emission spectrum of plasmonic nanoantennas

Plasmonic dimer nanoantennas are characterized by a strong enhancement of the optical field, leading to large nonlinear effects. The third harmonic emission spectrum thus depends strongly on the antenna shape and size as well as on its gap size. Despite the complex shape of the nanostructure, we find that for a large range of different geometries the nonlinear spectral properties are fully determined by the linear response of the antenna. We find excellent agreement between the measured spectra and predictions from a simple nonlinear oscillator model. We extract the oscillator parameters from the linear spectrum and use the amplitude of the nonlinear perturbation only as scaling parameter of the third harmonic spectra. Deviations from the model only occur for gap sizes below 20 nm, indicating that only for these small distances the antenna hot spot contributes noticeable to the third harmonic generation. Because of its simplicity and intuitiveness, our model allows for the rational design of efficient plasmonic nonlinear light sources and is thus crucial for the design of future plasmonic devices that give substantial enhancement of nonlinear processes such as higher harmonics generation as well as difference frequency mixing for plasmonically enhanced terahertz generation.