Improving fermentation, protein preservation and antioxidant activity of Moringa oleifera leaves silage with gallic acid and tannin acid

Abstract

Whether tannins reducing proteolysis is related to protease or the antioxidant capacity could be preserved during Moringa oleifera leaves (MOL) ensiling are unclear. In the present study, MOL ensiled with 1% and 2% gallic acid (GA) or tannic acid (TA) were analyzed for fermentation parameters, protein fractions, protease activities and antioxidant capacity on day 3, 7, 14 and 30 of ensiling. The results showed that GA and TA decreased dry matter loss (11.13% vs 8.35% and 3.11%, in the level of 2%) and proteolysis (nonprotein-N: 56.31% vs 32.64% and 26.04% TN). Meanwhile, GA and TA increased pH, yeasts number, ammonia-N content and aminopeptidase activity. The antioxidant capacity of MOL silage gradually increased during ensiling, and was dramatically enhanced by the addition of GA and TA. In conclusion, this study suggests that GA and TA could help to improve the preservation of protein and antioxidant capacity during MOL ensiling.

Keywords: Antioxidant activity; Gallic acid; Moringa oleifera; Protease activity; Tannin acid.