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.
>