Most recipes that I see for soy and nut milks ask you to soak the seeds and discard the soaking water.
The only plant milk recipe I've used that keeps the soaking water (Scratch Soy Milk by Andrea Nguyen) turns out just fine.
I've also experimented with using the soaking water in almond milk, and this too is fine.
So why should I discard the soaking water? Is it just a matter of taste, or is there more to it?
Generally, we soak grains and pulses then throw away the soaking water. If we didn’t it would likely turn sour in a few days. Also soaking helps remove some of the phytic acid, therefore unlocking more nutrients. I suspect the phytic acid will be in the soaking water which we flush away. Phytic acid prevents absorption of a number of minerals.
It's to remove all "extras" that could gather surface.
As we know everything gather dust, bacteria and we don't know where it have been before. That standing water is perfect for all little things to thrive.
BUT your almonds for example have been pasteurized, but with what? The cheapest method is to use polyphenylene oxide.
All of the above stay in that water if you don't discard it. It's not for taste purpose but rather healthy reasons.
Also I discovered that when making aquafaba from soaked chickpeas using soaking water make foam turn to water in matter of minutes. When boiling them in new water foam is much better and usable.
