Given P S
Kraft General Foods, Glenview, IL 60025.
Adv Exp Med Biol. 1991;302:465-83. doi: 10.1007/978-1-4899-0664-9_25.
The molecular behavior of water in complex food systems, via bonding and solvation reactions with low molecular weight solutes or high molecular weight macromolecules, is intimately linked with both the palatability and storage stability of those systems. Due to the difficulty in interpreting data derived from multicomponent finished food products, water behavior in a baked flour-water "matzo" model system was studied. Water behavior was assessed from high resolution [1H] nuclear magnetic resonance (NMR) spin-spin relaxation studies and differential scanning calorimetric (DSC) measurements of unfreezable water content. The unfreezable water capacity of "matzo" model crackers, as measured by DSC, ranged from ca. 24-30% (w/w). These results were corroborated by NMR data. Only one exponent (less than 0.46 msec greater than) is required to fit spin-echo evolution curves below a total moisture content of ca. 20% (w/w), whereas two exponents (less than 0.46 greater than and 1.6 msec) are observed when the moisture content exceeds 20% (w/w). Expert sensory texture assessments parallel unfreezable (= total) water contents between 2.9% (w/w) and 20.1% (w/w). This relationship may be explained by the known tendency for water to plasticize biological polymers, e.g. wheat starch and proteins, and to render these macromolecules incrementally more mobile with increasing water concentration. The similarities (if any) between water of plasticization, immobile water, and "bound" water are discussed, in terms of theoretical physicochemical "states" of water and the various techniques utilized to assess (define) those "states."
在复杂食品体系中，水通过与低分子量溶质或高分子量大分子发生键合和溶剂化反应，其分子行为与这些体系的适口性和储存稳定性密切相关。由于难以解读来自多组分成品食品的数据，因此对烘焙面粉 - 水“无酵饼”模型体系中的水行为进行了研究。通过高分辨率[1H]核磁共振（NMR）自旋 - 自旋弛豫研究以及差示扫描量热法（DSC）测量不可冻结水含量来评估水行为。通过DSC测量，“无酵饼”模型饼干的不可冻结水容量范围约为24 - 30%（w/w）。这些结果得到了NMR数据的证实。当总水分含量低于约20%（w/w）时，仅需一个指数（大于0.46毫秒）来拟合自旋回波演化曲线，而当水分含量超过20%（w/w）时，则观察到两个指数（大于0.46和1.6毫秒）。专业的感官质地评估表明，不可冻结（=总）水含量在2.9%（w/w）至20.1%（w/w）之间。这种关系可以用已知的水使生物聚合物（如小麦淀粉和蛋白质）增塑的趋势来解释，并且随着水浓度的增加，这些大分子的流动性会逐渐增加。从水的理论物理化学“状态”以及用于评估（定义）这些“状态”的各种技术的角度，讨论了增塑水、固定水和“结合”水之间的相似性（如果有的话）。
