Effect of physical changes on the rates of nonenzymic browning and related reactions
Effect of physical changes on the rates of nonenzymic browning and related reactions
复制标题
物理变化对非酶褐变及相关反应速率的影响
DOI：
10.1016/0308-8146(94)p4199-p
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发表时间：
1995
期刊：
影响因子：
8.8
通讯作者：
M. Karel
中科院分区：
文献类型：
--
作者：
M. Buera;M. Karel
研究了不同平均分子量聚乙烯吡咯烷酮（PVP）脱水基质中木糖和赖氨酸反应引起的非酶布朗宁（NEB）。物理变化（塌陷）和NEB研究温度（T）和水分含量导致不同的值（T-Tg），其中Tgis玻璃化转变温度。非酶的布朗宁率在低和中等水分含量的聚合物基质以上的玻璃化转变被证明是密切相关的（T-Tg）。最初的多孔矩阵经历了一个时间依赖性的收缩（崩溃）高于Tg和这种收缩增加了布朗宁的速度，大概是通过最小化反应物的扩散路径。当反应物（PVP中的木糖和赖氨酸）被PVP的无反应物层分离时，反应速率随着空层厚度的增加而降低。观察到滞后时间，其与该层的厚度直接相关。
Nonenzymic browning (NEB) due to reaction of d-xylose and l-lysine was studied in a dehydrated matrix based on poly(vinylpyrrolidone) (PVP) of different average molecular weights. Physical changes (collapse) and NEB were studied temperatures (T) and moisture contents resulting in different values of (T − Tg), where Tgis the glass transition temperature. Nonenzymic browning rates at low and intermediate moisture contents in a polymeric matrix above its glass transition were shown to be closely related to (T − Tg). The initially porous matrices underwent a time-dependent shrinkage (collapse) above Tgand this shrinkage increased the rate of browning, presumably by minimizing diffusion paths for reactants. When the reactants (xylose and lysine in PVP) were separated by a reactant-free layer of PVP, the reaction rate decreased as the thickness of the empty layer increased. A lag time was observed, which was directly related to the thickness of this layer.