Malolactic fermentation is not a fermentation in the true sense of the word but since it evolves C02 it has been traditionally called a fermentation. Basically Lactobacilli rather than yeasts convert malic acid to lactic acid and evolve C02. Since lactic acid has one less proton to donate it is less acidic than malic acid. For years the benefit that Lactobacilli could possibly get from undertaking this process baffled since there was no net energy gain from the conversion but very recently it was revealed that since a higher concentration lactic acid would be inside the cell membrane than in the surrounding liquid the pH gradient could act as a "battery"... very cool. Life finds a way!vinceg wrote:Tastes pretty good now, just like a west country scrumpy. One question, I read about something called malo-lactic fermentation, which starts the brew bubbling again once the ambient temperature gets over 15 degrees. What does this do to the brew and is it worth waiting for? The intention is for this to be my summer drinking anyway so I might wait and see what occurs.

A bit of a side track there but since you made your cider from desserts (high acid compared to cider apples) a malolactic fermentation is very advisable - lactic acid is also a mellower acid in the mouth. Think of the acidic sensation unsweetened yoghurt or homemade sauerkraut. Don't add any more S02 until you are satisfied with the acidic balance - lactobacilli are very S02 sensitive.