Effects of polyphenol oxidases on proteolysis and lipolysis during ensiling of Moringa oleifera leaves with or without pyrocatechol

The goal of this paper was to investigate the effects of polyphenol oxidases (PPO) on proteolysis and lipolysis during ensiling of Moringa oleifera leaves with or without pyrocatechol. Directly, 30 U/g and 60 U/g PPO with or without 1% pyrocatechol were added to M.oleifera leaves. Fermentation characteristic, microbial population, antioxidant capacity, protein fraction and lipids composition were analyzed after 10 days and 20 days ensiling. The addition of PPO alone showed little influence on the silage quality, though it decreased (p < 0.05) the coliform bacteria number and ammonia-N concentration after 20 days fermentation. The addition of PPO and 1% pyrocatechol increased dry matter recovery and decreased (p < 0.05) lactic, acetic acid contents. It also reduced nonprotein-N and ammonia-N contents. The numbers of lactic acid bacteria and coliform bacteria in PPO and pyrocatechol treatments were lower (p < 0.05) than that of the control and PPO alone treatments. The compositions of lipids, amino acids and derivatives were altered. The contents of chemicals which were abundant in M. oleifera leaves and decreased during ensiling were improved by PPO and pyrocatechol addition. Opposite results were observed for those chemicals which had low contents in M. oleifera leaves and increased during ensiling. Therefore, the combination of PPO and pyrocatechol could be used to improve proteins and lipids protection during ensiling. The improvement might be because of microorganisms activities limitation and fermentation process inhibition. It provides new information for proteolysis and lipolysis controlling during ensiling.