Jean-Louis Tu wrote:

> I don't see the connection with quality, unless you can prove that
> high-quality vegetables contain less oxalic acid.

There's no 'proving' needed for that one.  Just go eat some raw store bought
junk spinach and see how it sets your teeth on edge.  Then eat some high Brix
spinach and notice it doesn't.  The difference is oxalic acid crystals.  Or, if
you don't trust your own taste, give some of each to children.  They'll tell
you which is OK.

Regards,
Rex Harrill