tion of lactate in the cytosol could cause acidification,
and under these low pH conditions, lactate dehydrogenase is inhibited. The formation of
acetaldehyde by the decarboxylation of pyruvate is stimulated by the activation of pyruvate
decarboxylase under low pH conditions in the cytosol. It is also likely that the increase in
concentration of pyruvate in the cytoplasm may stimulate pyruvate decarboxylase directly.
Acetaldehyde is reduced to ethanol by alcohol dehydrogenase using NADH as the reducing
power. Thus, acetaldehyde and ethanol are common volatile components observed in the
headspace of fruits, indicative of the occurrence of anaerobic respiration. Cytosolic acidi-