The malic acid used in blends is a mixture of the two isomers; only the
L-isomer portion will undergo MLF. You are right about the D-isomer not
being biologically active.

Gene

Joe Sallustio wrote:
I'm not a chemist but I'm pretty sure the malic used in acid blends is
usually the wrong isomer for ML to work on. Opening it a day early
does sound like it would be the ticket for me in this situation;
that's great advice. I'm not sure aging strawberry will work out
well, it's color seems to fade quickly and it's freshness is it's main
virtue as I see it. If you did add sorbate the odor can change to
something gawd awful too. I don't use it anymore, it never seems to
work out for me.

Joe

If you add an acid mixture
(tartaric-citric-malic blend) to adjust your acidity, you increase the
malic acid content. Also, if you use grape juice in your recipe, you
bring along the malic acid from the grapes. Both can result in
uncontrolled in-the-bottle malolactic fermentation.