DL VS L MALIC ACID

[Tom Bell]

Malic acid has two isomers, L and D.  I see that many commercial ciders list malic acid in their contents but have not seen any indication of which isomer they use. Does it make any difference which one I use to adjust the final acidity of my cider?  I wonder if malolactic bacteria or a yeast like 71B prefer one over another or can they even metabolize both?  -- Tom

[Andrew Lea]

I think you will find that the synthetic chemical DL malic racemic mixture is far cheaper than either of the pure stereoisomers. Hence the racemic mixture is the normal form that’s used in the beverage business. The individual isomers are synthesised via microbial routes AFAIK hence this pushes up their price. 

Generally speaking most micro-organisms prefer to metabolise L malic rather than D.  Hence it is possible when you add DL malic that the L malic is preferentially metabolised. Having said that, there are organisms which will metabolise D malic as well. 

It’s hard to second guess what might happen in any particular case. 

Andrew

Wittenham Hill Cider Portal
www.cider.org.uk

On 15 Aug 2018, at 20:15, Tom Bell <strat...@gmail.com> wrote:

Malic acid has two isomers, L and D.  I see that many commercial ciders list malic acid in their contents but have not seen any indication of which isomer they use. Does it make any difference which one I use to adjust the final acidity of my cider?  I wonder if malolactic bacteria or a yeast like 71B prefer one over another or can they even metabolize both?  -- Tom

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[Tom Bell]

Thanks Andrew.  I was looking for malic acid to bump the TA up about 0.7g/l. I found a mix of DL which is 50% L and 50% D and wondered what that was all about.