果葡糖浆中果糖分离方法研究进展

介绍了离子交换树脂分离法、色谱分离法、结晶分离法、硼酸盐法、参数泵分离法、复盐分离法等几种果葡糖浆中果糖分离纯化方法,并对各种分离方法的优、缺点进行了阐述。经对比认为,离子交换树脂分离法与色谱分离法因其可以大规模生产而在工业生产中占主导地位;结晶分离法、硼酸盐分离法和复盐分离法等则因其工艺简单、耗能少而更适合于中、小企业生产;参数泵分离法则在节省能源方面独具优势。     

果葡糖浆对焦糖色素质量影响的研究

本文利用双酶法生产的果葡糖浆(DE值相同、果糖和葡萄糖含量不同)制作焦糖色素,在相同制备工艺下,对焦糖色素的吸光度进行了比较.发现相同的DE值条件下,果糖和葡萄糖含量越高,吸光度就越大;果葡糖浆的DE值越高,吸光度也越大.     

Formation of glucose and fructose acetates during maturation and ageing of balsamic vinegars

We report for the first time the detection of glucose acetates in balsamic vinegars. It is well known that during traditional balsamic vinegar (TBV) ageing several modifications occur. In this paper it was experimentally determined that some modifications take also place during the short maturation time of balsamic vinegar of Modena (BVM), with an increase of the esters content due to the reaction between acetic acid and sugars, in particular glucose. The formation of esters was observed both on reference solutions containing glucose and acetic acid, subjected to an accelerated ageing by heating at 50 °C, and on real balsamic vinegar samples. Glucose esters were mainly detected as α- and β-glucopyranose acetates. The formation of fructose acetates in reference solutions, was also studied, recording a more complex pattern of products. The structures of the esters were determined by GC/MS analyses and NMR spectroscopy.     

Impact of xanthan gum,sucrose and fructose on the viscoelastic properties of agarose hydrogels

Mixed carbohydrate systems are of special interest for the food and non-food industry as they offer a versatile range of unique and novel functional properties. However, intense research is required to understand the complex processes occurring in such systems on a molecular level and to be able to modify them aim-oriented. In food, characteristic properties are based on the physicochemical functions of the biopolymers added. Thus, small deformation tests and moisture analysis have been applied to study the impact of xanthan gum and two types of sugar on the viscoelastic properties, the sol–gel transition and the water holding capacity of 1% agarose hydrogels. Agarose gels are very elastic, turbid and prone to synaeresis, which impinges on their mouth feeling. Additions of xanthan gum revealed less elastic gels with an unaffected water holding capacity. Progressive addition of two different types of up to 40% of sugar yield an increase of the elasticity of agarose gels, whereby sugar concentrations of 60% partially result in a structural breakdown and thus a significant lower network structure but better water holding. In ternary systems, the effect of the sugar concentration and sugar type used is diminished by xanthan gum. The gelation mechanism of agarose gels with a distinct amount of co-solutes is presumably mainly affected by the water shortage evolved from the competition for it of all solutes present.     

Viscosity of Aqueous Carbohydrate Solutions at Different Temperatures and Concentrations

Experimental viscosity values of sucrose, glucose, and fructose aqueous solutions in a large range of temperatures (0 to 85°C) and concentrations (10 to 60% w/w) that might be encountered in food processes were obtained in order to contribute to extending the available database of food properties. The temperature dependence of viscosity could be adequately described by the Arrhenius model, and the activation energy was well represented by a unique function of the solute volume fraction, valid for sucrose, glucose, and fructose solutions.     

On the production of glucose and fructose syrups from cashew apple juice derivatives

The cashew crop is an important agro-economic activity in many equatorial areas, although less than 10% of the cashew apple production is exploited industrially. This work focuses on two aspects: obtaining food-grade syrups from cashew apple juice and studying fixed bed adsorption dynamics to separate fructose from glucose. Syrups obtained by concentrating clarified cashew apple juice under vacuum showed similar characteristics to a reference food-grade syrup, with a higher content in fructose, which may contribute to a higher sweetening power with less caloric intake. Adsorption equilibrium studies were performed with synthetic solutions of fructose and glucose by frontal analysis under the concentration range found in the syrups (10-120 g/L) at 30, 40 and 60 °C, using the cation exchange resin Dowex MTO 99Ca. Fructose was more strongly adsorbed than glucose, with measured selectivities ranging from 1.50 to 2.25. Resistance to mass transfer was significant and thought to be due to resin crosslinkage. Glucose and fructose breakthrough curves using cashew apple syrup as feed were practically identical to those measured with synthetic solutions, which leads us to believe that high-fructose syrups may be readily obtained by using current continuous chromatographic units, such as SMB.     

Molecular imprinting of fructose using a polymerizable benzoboroxole: Effective complexation at pH 7.4

Covalent molecularly imprinted polymers against d-fructose employing 5-methacrylamido-2-hydroxymethylphenylboronic acid as functional monomer and trimethylpropane trimethacrylate (TRIM) as the crosslinking agent were prepared by a conventional radical bulk polymerization (MIP-BX(Fru)). Batch binding studies for fructose in aqueous buffers containing 10% methanol revealed that the binding capability of MIP-BX(Fru) is paramount compared to a MIP prepared with vinylphenylboronic acid MIP-BA(Fru). Especially, at the biological important pH-value of 7.4 the rebinding of fructose to the MIP-BX(Fru) is with 60 nmol per mg polymer about 3.2 higher compared to the MIP-BA(Fru). A pinacol imprinted polymer was also investigated and showed in case of MIP-BX still an imprinting of 1.7 at pH 7.4 whereas MIP-BA did not show a difference. Cross-reactivity studies at pH 7.4 show the shape-selectivity of the MIP-BX(Fru) in the order of l-fructose, sorbitol, glucose and sucrose.