Purpose of acid in san pedro recipe

[Paddomania]

Hi,

In many recipes you have to add an acid - e.g. lime juice - to the water in which the cactus is being boiled.
Why is this? The only reason I can make up is that it will cause an acid / base reaction, thus creating a salt. And this salt can be dissolved (more) easily in water? But perhaps I am complety wrong! If so, what is it?!



And what would be the best ph to achieve this?



Thanks in advance!