Are you asking why the color of apple lactic acid fermentation chromatography experiment is wrong? The color of malic acid-lactic acid fermentation chromatography experiment is wrong because:

1, the total acid of malic acid decreased, resulting in the increase of malic acid pH, which led to the color error in lactic acid fermentation chromatography experiment.

2. The decrease of malic acid concentration leads to the color error in lactic acid fermentation chromatography experiment.