Understanding reaction kinetics at elevated pressures is of importance for the development of pressure-based technologies and especially for hyperbaric storage (HS), a potential alternative for the energy-consuming refrigeration. The effect of pressure on degradation kinetics of a polyphenol, Epigallocatechin-gallate (EGCG), was explored at pressures up to 200 MPa (HS levels) for several hours, with and without fructose. In a baroresistant buffer, pressure enhanced EGCG degradation, due to a negative activation volume, while in phosphate buffer the pH decreased (as is also expected to occur in many foods) resulting in a superposition of accelerating and protective effects. A previously undescribed protective, pressure-level dependent, effect of fructose was identified. Novel in situ spectroscopy and HPLC analysis revealed that in addition to the effect on EGCG degradation rate, pressure also modifies the ratios between the numerous degradation products, likely due to a varying effect on the different steps involved in the degradation pathway.

Industrial relevance

The effect of pressure on reaction kinetics in food systems can be of great importance in processing conditions combining thermal and high pressure, and critical for the emerging concept of hyperbaric storage, where the food is exposed to high pressures for long duration of time, allowing a plethora of reactions to take place, all varyingly affected by pressure. Yet the effects of pressure on kinetics are often overlooked. Polyphenolic compounds are a large group of molecules responsible for both sensorial and health-promoting functionality in plant-based foods. Those compounds are known to undergo degradation by several mechanisms during processing and storage and their successful conservation is often considered of significant industrial importance. The presented work provides fundamental information regarding the effects of pressure on the kinetics of EGCG (Epigallocatechin-gallate) degradation, as a model for relatively unstable, polyphenolic compound, (taking into account pressure-induced pH shifts, and the presence of co-solutes). EGCG is also of specific importance in many products where it naturally occurs (green tea drinks etc.) and where it is externally added as a valuable supplement.

中文翻译：

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压力对多酚降解动力学的影响-使用表没食子儿茶素-没食子酸酯作为模型的高压存储的含义

了解高压下的反应动力学对于基于压力的技术的发展，尤其对于高压存储（HS）（对于耗能制冷的潜在替代品）而言非常重要。在有和没有果糖的情况下，在高达200 MPa（HS含量）的压力下，研究了压力对多酚表没食子儿茶素-没食子酸酯（EGCG）的降解动力学的影响，持续了几个小时。在耐压缓冲液中，由于负激活量，压力增强了EGCG降解，而在磷酸盐缓冲液中，pH降低了（正如许多食品中预期的那样），导致加速和保护作用叠加。确定了果糖先前未描述的保护性，依赖于压力水平的作用。原位小说 光谱和HPLC分析表明，除了对EGCG降解速率的影响外，压力还改变了许多降解产物之间的比率，这可能是由于对降解途径中不同步骤的影响不同所致。

行业相关性

压力对食品系统中反应动力学的影响在热和高压相结合的加工条件下可能非常重要，对于新兴的高压存储概念至关重要，在高压存储中，食品要长时间暴露在高压下，从而允许食品长期处于高压状态。发生过多的反应，所有反应均受压力影响。然而，压力对动力学的影响常常被忽略。多酚化合物是一大类负责植物性食品中的感官和促进健康功能的分子。已知这些化合物在加工和存储过程中会通过几种机理降解，因此，成功地保存通常被认为具有重要的工业意义。呈现的工作提供了有关压力对EGCG（表没食子儿素-没食子酸酯）降解动力学的影响的基本信息，作为相对不稳定的多酚化合物的模型（考虑到压力引起的pH值变化和共溶质的存在） ）。EGCG在许多天然存在的产品（绿茶饮料）中也特别重要等），并在外部将其作为有价值的补充添加。