一种新型二肽甜味剂的合成及表征

以3-环己基-L-丙氨酸、Boc-L-天冬氨酸-4-苄酯为原料合成二肽L-天冬氨酰-3-环己基-L-丙氨酸-1-甲酯(Ⅰ),以3-羟基-4-甲氧基苯甲醛为原料经过Witting反应、H2还原和DIBAL-H还原三步反应合成3-羟基-4-甲氧基苯丙醛(Ⅱ),然后Ⅰ与Ⅱ在氢气、Pd/C催化作用下进行还原氨化反应,得到目标产物N-[3-(3-羟基-4-甲氧基苯基)丙基]-α-L-天冬氨酰-3-环己基-L-丙氨酸-1-甲酯(Ⅲ),总产率为47%。产物的结构采用IR、~1HNMR、~(13)CNMR和HRMS进行表征,并验证其甜度约为蔗糖的25000倍。合成终产物的最佳工艺条件为:n(Ⅱ)∶n(Ⅰ)=1∶1,Pd/C催化剂用量为反应物总重的10%,体积分数80%的甲醇水溶液为溶剂,反应温度35℃,反应时间20 h。     

Oral and intestinal digestion of oligosaccharides as potential sweeteners: A systematic evaluation

The utilisation of oligosaccharides by oral microorganisms and intestinal enzymes are important factors in determining their effectiveness as alternative sweeteners. In this study, classes of naturally occurring sugars were assessed using in vitro models for oral and intestinal digestibility, in order to test the influence of chemical structure on functional properties. Amongst the classes of sucrose isomers, α-glucobioses, β-glucobioses and sucrose-based oligosaccharides, structures were identified that were not utilised by the common oral bacterium Streptococcus mutans, and would therefore contribute to the non-cariogenic potential of a sweetener. Analysis of the rate and products of digestion by a rat glucosidase mixture was used to determine the relative intestinal digestibility. The results showed that oligosaccharides containing a (1 → 6)-β-Glc group, including gentiobiose and gentiobiitol, together with melezitose, a sucrose-derived oligosaccharide containing a α-Glc-(1 → 3)-Fru moiety were resistant to digestion by both S. mutans and mammalian intestinal enzymes, highlighting their potential as dietary sugar substitutes.     

Sugar replacement in sweetened bakery goods

This review presents the state‐of‐the‐art concerning the application of natural and artificial high‐intensity sweeteners, fructans and bulking agents such as polyols as sugar replacers in sweet‐baked goods and their effects on product characteristics. The recent much publicised attention given to weight gain of the population and its consequences on the occurrence of diet‐related diseases in developed countries has influenced the food manufacturers attempts to provide the consumer with reduced energy products. The replacement of sucrose in sweet bakery products by alternative natural or artificial sweeteners can be a challenging issue. Sucrose as a main ingredient in sweet bakery products contributes, aside from providing sweetness, to numerous processing and product characteristics. Intense sweeteners have a high sweetness compared with sucrose but lack in their contribution to the body of the product, whereas the replacement of sucrose with bulking sweeteners may result in products with a similar body but a lack in taste and flavour.     

湿法烟气脱硫技术的应用概述

分析了湿法烟气脱硫的基本原理、脱硫剂的要求、脱硫的类型、工艺和主要的设备。重点分析了石灰石/石灰—石膏法湿法烟气脱硫技术的应用。     

紫苏葶和乳酸薄荷酯滴丸在卷烟中的应用研究

为改善卷烟抽吸时容易产生的干燥感,增加卷烟的生津感和甜润感,提高卷烟抽吸舒适性,采用化学合成方法并选用合适的复配比例,制备得到具有较好清甜味的新型甜味剂———紫苏葶和乳酸薄荷酯复配物。将该甜味滴丸添加到卷烟滤棒中,通过烟气气流的带动缓慢释放出其中的甜味物质。对添加有该种滴丸的卷烟各项理化指标及烟气中甜味剂转移率进行测试评价。结果显示:在卷烟滤棒中添加0.15 mg/支的该新型甜味剂,烟气较协调,而且烟气变细腻柔和、有较强的清甜味,刺激性降低。烟支外观和常规理化指标均能满足产品要求,烟气中甜味剂有效成分转移率达到2.5‰以上。     

Redesigning a sweet protein: increased stability and renaturability

Monellin is one of two natural proteins from African berrieswith potent sweet taste. Monellin is the smaller of the two,and consists of two peptides. The protein loses sweetness whenheated above 50°C under acidic pH. Based on the crystalstructure of monellin we have fused the two chains into a singlechain using several different linkers copied and ‘transplanted’from the same molecule. One of the newly designed proteins isas potently sweet as the natural one, is more stable upon temperatureor pH changes, and renatures easily even after heating to 100°Cat low pH.     

蔗糖改性制备的甜味剂

蔗糖是最常见的营养性双糖,蔗糖的大量食用对糖尿病患者等特殊人群有一定的影响。而将蔗糖进行生物改性,得到的功能性的甜味剂,不仅仍具有味甜又具有功能性,拓宽用途,适用人群更广;而进行物理改性可满足特殊应用要求。     

二肽甜味剂结构的研究进展

二肽甜味剂对N-端的结构有严格的要求，C-端却是经常可以变化的。为进一步揭示二肽甜味剂的结构，分析了一系列aspartame衍生物。研究表明，苯丙氨酸上的疏水基团X当改变其结构大小时，甜度的变化不大。而肽键对于维持甜味是必需的，用酯键取代肽键导致甜味消失，氨基上的氢键对于维持甜味来说也是必需的，当它被甲基取代时甜味也消失了。