Birch G G
CRC Crit Rev Food Sci Nutr. 1976 Sep;8(1):57-95. doi: 10.1080/10408397609527217.
Chemical modification of sugars and their simple analogues indicates that these types of compound are almost always sweet, bitter, or bitter/sweet; hence, the two basic tastes may be intimately associated features of the same molecule. Stepwise modification at each chiral center around the sugar ring allows the sapid functions in these molecules to be mapped and leads to the inescapable conclusion that sugar molecules may be "polarized" on taste bud receptors, so that one end of the molecule elicits sweetness and the other bitterness. However, more extensive chemical modification evidently causes the molecule to realign itself in entirely different ways on the receptor. In most oligosaccharides only one sugar residue is likely to bind to the taste receptor, and this is probably a nonreducing end group, because the anomeric center of glucopyranose types of structure does not appear to affect sweetness. Sweetness depresses bitterness and bitterness depresses sweetness. Hence, it is not possible to make structural comparisons between analogues without correcting for these effects. However, some semiquantitative studies have established the value of current hydrogen bond theories of sweetness and the ideal oxygen-oxygen interorbital spacings for sweetness criteria in sugar molecules.
糖类及其简单类似物的化学修饰表明，这类化合物几乎总是甜的、苦的或苦甜兼具的；因此，这两种基本味道可能是同一分子紧密相关的特征。对糖环周围每个手性中心进行逐步修饰，能够绘制出这些分子中的味觉功能图谱，并得出一个不可避免的结论：糖分子在味蕾受体上可能是“极化”的，这样分子的一端引发甜味，另一端引发苦味。然而，更广泛的化学修饰显然会使分子在受体上以完全不同的方式重新排列。在大多数寡糖中，可能只有一个糖残基与味觉受体结合，而且这可能是一个非还原端基，因为吡喃葡萄糖类型结构的异头中心似乎不影响甜度。甜味抑制苦味，苦味抑制甜味。因此，在不校正这些效应的情况下，无法对类似物进行结构比较。然而，一些半定量研究已经确定了当前甜味氢键理论的价值以及糖分子中甜味标准的理想氧 - 氧轨道间距。
