Andersson A, Gekas V, Lind I, Oliveira F, Oste R
Department of Food Chemistry and Applied Nutrition, Lund University, Sweden.
Crit Rev Food Sci Nutr. 1994;34(3):229-51. doi: 10.1080/10408399409527662.
Preheating potatoes at 50 to 80 degrees C has a firming effect on the cooked potato tissue. This effect is particularly pronounced at a preheating temperature of 60 to 70 degrees C followed by cooling. Several theories have been presented in the literature to explain this firming effect: retrogradation of starch, leaching of amylose, stabilization of the middle lamellae and cell walls by the activation of the pectin methylesterase (PME) enzyme, and by the release of calcium from gelatinized starch and the formation of calcium bridges between pectin molecules. Most probably, none of these theories alone can explain the phenomenon and more than one mechanism seems to be involved. Some of these mechanisms seem to be interdependent. As an example, calcium could be considered as a link all the way through release after starch gelatinization to cross-linking pectin substances in the cell wall and the middle lamellae, which has been demethylated by the PME enzyme. More research and "clear cut" experiments are needed in order to elucidate the role of each mechanism, especially which of them is the main contributor to the process of firming. Most probably, the calcium-pectin-PME mechanism plays a secondary role, that is, it only retards the collapse of the tissue structure that would otherwise occur during the final heating without preheating, and it is not the main factor of firmness.
将土豆在50至80摄氏度下预热，对煮熟的土豆组织有硬化作用。这种作用在60至70摄氏度的预热温度下尤为明显，随后进行冷却。文献中提出了几种理论来解释这种硬化作用：淀粉的回生、直链淀粉的浸出、通过果胶甲酯酶（PME）的激活使中层和细胞壁稳定，以及通过从糊化淀粉中释放钙并在果胶分子之间形成钙桥。很可能，这些理论单独都无法解释这一现象，似乎涉及不止一种机制。其中一些机制似乎相互依存。例如，钙可以被视为一个贯穿始终的环节，从淀粉糊化后释放，到交联细胞壁和中层中已被PME酶去甲基化的果胶物质。为了阐明每种机制的作用，尤其是其中哪种是硬化过程的主要贡献者，需要更多的研究和“明确的”实验。很可能，钙-果胶-PME机制起次要作用，也就是说，它只是延缓了在没有预热的最终加热过程中否则会发生的组织结构塌陷，而不是硬度的主要因素。
