蔗糖水解物合成GCA的研究

研究利用蔗糖水解物合成ＧＣＡ（２－甲基－５－（Ｄ－阿糖四羟基丁基）－３－甲酸忆 喃），对蔗糖水解及转化为糖浆浓缩的条件进行了探讨，利用正交实验对转化糖交与乙酰乙酸乙酯反应合成ＧＣＡ的工艺条件进行优化，取得了较好的结果。     

Influence of processing on the content of sugars in green Arabica coffee beans

Quantitative analyses of low molecular sugars in green coffees (Coffea arabica L. var. Acaià) that were processed in parallel either by the traditional wet or the traditional dry method, revealed a close correlation between the kind of post-harvest treatment and the contents of fructose and glucose. While in washed coffee beans (wet processing) only low amounts of these both hexoses were present, those in unwashed coffees (dry processing) were significantly higher. Model-processing experiments in the laboratory confirmed these findings. Moreover, a comparison with the untreated controls revealed that the low levels of both sugars are the consequence of a decrease in the case of wet processing, whereas they remained unchanged or even increased in the case of dry processing. Further minor sugars are also affected by post-harvest treatment. The amounts of galactose, arabinose and mannose show a similar arrangement as those for glucose and fructose, although their overall concentration is about 100-fold lower. Sucrose, the major low molecular sugar in green coffee beans, is not significantly affected by coffee processing. The influence of an active seed metabolism on the observed alterations of the sugar concentrations is discussed.     

酒精液滴在蔗糖溶液中汽化冷却传热及其结晶过程

在一汽升式循环管中于减压条件下研究了冷剂酒精在高粘度高浓度的蔗糖水溶液中直接接触汽化传热过程，讨论了冷剂流量，冷剂进口温度和蔗糖溶液的粘度和浓度等操作条件对体积传热量的影响。实验结果表明：冷剂流量Ｖｄ＝０．９￣１．９ｍｌ／ｍｉｎ，冷剂进口温度为４５￣６０℃时，传热效果较好，在此基础上初步探讨了酒精汽化冷却法制取蔗糖晶核的过程，利用显微照相技术分析了晶核的外观特性。     

高岭土负载KF固体碱催化制备乙二醇单甲醚酯

以高岭土为载体,采用浸渍法制备了高岭土负载KF固体碱催化剂,并用于月桂酸甲酯(ML)与乙二醇单甲醚(EGME)的酯交换制备乙二醇单甲醚月桂酸酯(EGMEML)反应,考察了不同KF负载量催化剂的用量、醇酯摩尔比、反应时间和反应温度等条件对EGMEML收率的影响。通过XRD、SEM、FTIR、CO_2-TPD和N_2吸附-脱附等方法对催化剂结构进行了表征。表征结果显示,KF负载高岭土固体碱催化剂中,出现了K3AlF_6晶相,且随KF负载量增加,碱量明显增加,催化活性显著提高。实验结果表明,在催化剂用量为4.5%(w)(基于EGME)、n(EGME)∶n(ML)=3.0、反应时间6h、反应温度120℃的条件下,催化剂表现出良好的活性,E GMEML收率可达92.0%;当KF负载量为15%(w)时,催化活性最强。催化剂的高活性可能与KF和高岭土作用生成的K_3AlF_6有关,催化剂重复使用后,仍保持较高活性和稳定性。     

Crystallization behavior of lactose/sucrose mixtures during water-induced crystallization

The crystallization behavior of lactose/sucrose mixtures during water-induced crystallization was studied to gain more insight about their crystallization during storage. Solutions with different ratios of lactose and sucrose, 75:25 and 50:50, were spray dried to produce amorphous powders. The powders were kept at a controlled temperature and humidity to study their sorption–desorption behavior. X-ray diffraction and light microscopy analysis were performed to study their crystallization behavior. Two-step desorption was observed after sieving the powders as sample preparation. Sieving decreased the crystallization time for lactose/sucrose mixture 75:25 from 22 days to 2.5 days. Based on the X-ray diffraction analysis during this two-step process of water desorption, it was concluded that lactose crystallizes first and more quickly than sucrose. The degree of crystallization for the lactose crystals increases by 89% (relative to their final level of crystallinity), whereas sucrose crystals increase their level of crystallinity by only 28% during the first step of crystallization in the lactose/sucrose (75:25) mixtures. The light microscopy images also suggested that the crystallization of amorphous lactose/sucrose powders during water-induced crystallization may occur as a solution rather than in the solid phase.     

The effects of MgSO4, d-glucono-δ-lactone (GDL), sucrose,and urea on gelation properties of pectic polysaccharide from soy hull

The monosaccharide composition of pectic polysaccharide extracted from soy hull under assistance of microwave was firstly analyzed. Soy hull pectic polysaccharide (SHPP) mainly contains galactose, xylose, galacturonic acid, arabinose, glucose and rhamnose with a molar ratio of 4.7:2.5:1.5:3.8:3.2:3.0. The gelation properties of SHPP as a function of Mg²⁺, GDL, sucrose, and urea concentration were then systematically studied. Mg²⁺ can induce the gelation of SHPP but low concentration Mg²⁺ require more time to cross-linking SHPP molecular chains. GDL can strengthen the elasticity of SHPP/Mg²⁺ gel, while sucrose can also strengthen the network through hydrophobic interaction, however 30 wt% sucrose can weaken the SHPP/Mg²⁺ gel network. 2 mol/L urea can collapse the gel network formed by 3 wt% GDL with 0.1 mol/L Mg²⁺, which suggests that the junction zone of SHPP/GDL/Mg²⁺ system is formed through hydrogen bonding.     

椰子油和单月桂酸甘油酯对断奶仔猪生产性能及粪便微生物的影响

研究椰子油和单月桂酸甘油酯对断奶仔猪生长性能、血清生化指标及粪便微生物的影响.结果表明:饲料中添加椰子油和单月桂酸甘油酯对断奶仔猪生产性能影响差异不显著(P＞0.05),豆油组较椰子油组中添加单月桂酸甘油酯平均日增重效果更好(P＜0.05).与豆油组相比,椰子油组血清甘油三酯含量显著降低(P＜0.05);添加单月桂酸甘油酯血清甘油三酯含量显著降低(P＜0.05),碱性磷酸酶极显著升高(P＜0.01);与豆油加椰子油组相比,添加单月桂酸甘油酯血清中总胆固醇、甘油三酯和肌酐含量显著提高(P＜0.05),血清中碱性磷酸酶极显著提高(P＜0.01);椰子油组较豆油组中添加单月桂酸甘油酯,血清中总胆固醇、甘油三酯和肌酐含量显著提高(P＜0.05),总蛋白含量极显著提高(P＜0.01),血清中碱性磷酸酶含量极显著降低(P＜0.01).椰子油和单月桂酸甘油酯都能极显著降低粪便中总菌落数(P＜0.01).     

Extrusion of soy protein with gelatin and sugars at low moisture content

Soy protein-based materials modified with gelatin, lactose and sucrose were prepared by extrusion at low moisture content. The effect of composition on the extrusion parameters was investigated and specific mechanical energy (SME) was measured as an indication of extrusion processability, thus providing good characterization of the extrusion process in order to make it highly energy efficient and cost effective. Water content was the most important factor on the extrusion parameters and product properties. The incorporation of gelatin increased SME and the product obtained at the extruder die was not continuous. However, when lactose was added, SME decreased and the color of the product changed due to Maillard reaction. This reaction could be analyzed by Fourier transformed infrared spectroscopy (FTIR) where the changes of the amide I and amide II bands reflected that hydroxyl groups in sugars and amino groups in soy protein isolate (SPI) were consumed during extrusion. These results are in good agreement with total soluble matter (TSM) values, which were lower for mixtures with lactose than sucrose due to a higher degree of Maillard reaction. Moreover, X-ray diffraction (XRD) and scanning electron microscopy (SEM) results also showed the influence of Maillard reaction, which lead to more ordered and compact structures, respectively.     

间苯二酚与蔗糖反应的动力学研究

本文研究了间苯二酚与蔗糖在盐酸溶液中的反应机理,发现间苯二酚与蔗糖在盐酸溶液中反应,其实质是蔗糖先水解成果糖和葡萄糖,然后果糖在盐酸催化下与间苯二酚反应生成有色物质,实验结果表明,当问苯酚的浓度远大于果糖时,果糖与间苯二酚的反应为准一级反应,其表观活化能为127kJ／mol,推导了蔗糖与间苯二酚反应的动力学方程,提出间苯二酚法测定蔗糖理论依据,与实验结果吻合。