Mitochondria isolated from local market potato tubers contain L-lactate dehydrogenase in an inactive state.

In order to gain some insight into metabolism of mitochondria isolated from materials subjected to storage treatments, we compared mitochondria isolated from potato tubers grown and stored in the post-harvest without any chemicals (N-PTM), and tubers, from local market, treated for commercial purpose (T-PTM) with respect to the L-lactate metabolism. Although no oxygen consumption due to L-lactate was found in T-PTM, L-lactate dehydrogenase existence was shown as immunologically investigated. Consistently, no L-lactate dehydrogenase activity was detected. Contrarily, N-PTM proved to metabolize externally added L-lactate, with oxygen consumption and intramitochondrial pyridine nucleotide reduction. All together these findings show that commercial treatments of foodstuffs could result in changes in their metabolism.