P35 shows sodium erythorbate as a cure accelerator and as such is replaceable by sodium ascorbate which is (or was) available from Holland and Barret.
This is assuming that it used as an accelerant in your recipe.
It gives me no idea what the purpose of this ingredient is ,all i know it is a very small amount and it is the only thing keeping me from completeing this recipe ,im no good at chemistry so i would imagine the substitute you mentioned will do the same,only one way to find out.
grisell wrote:If you can't find neither erythorbate nor ascorbate, ordinary ascorbic acid (vitamin C) will do. You can even use pills crushed in a mortar.